| 51. |
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| 52. |
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| 53. |
- Holmberg, Erica, et al.
(författare)
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More than 20 years' experience of left ventricular assist device implantation at a non-transplant Centre
- 2017
-
Ingår i: Scandinavian Cardiovascular Journal. - : Taylor & Francis. - 1401-7431 .- 1651-2006. ; 51:6, s. 293-298
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Over recent decades implantable left ventricular assist devices (LVAD) have increased the possibility of improved survival in patients with advanced heart failure who also benefit from a better quality of life. The aim of this retrospective survey was to review the clinical results of LVAD implantation at a low-volume non-transplant centre (Linköping, Sweden) between 1993 and 2016. Our aim was also to assess the mortality and morbidity rates associated with implantation of three LVAD versions at our centre, and to compare our results with those from transplant centres.DESIGN: A retrospective cohort study was performed examining the medical records of patients who had a HeartMate(®) (HMI, HMII, HMIII) LVAD implanted as a bridge to heart transplantation (BTT) or as destination therapy (DT) at the University Hospital, Linköping.RESULTS: Our main finding was a survival to heart transplantation rate of 82% among our BTT LVAD patients. The most common adverse event among our patients was infection. A higher frequency of temporary dialysis was seen in the HMII group compared to the HMI group, and the frequency of right ventricular failure was higher in our HMII material.CONCLUSIONS: Our data suggests that patients requiring long-term LVAD support can safely have their device implanted and cared for at a non-transplant centre.
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| 54. |
- Hubbert, Laila, et al.
(författare)
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Acoustic Analysis of a Mechanical Circulatory Support
- 2014
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Ingår i: Artificial Organs. - : Wiley-Blackwell. - 0160-564X .- 1525-1594. ; 38:7, s. 593-598
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical circulatory support technology is continually improving. However, adverse complications do occur with devastating consequences, for example, pump thrombosis that may develop in several parts of the pump system. The aim of this study was to design an experimental clot/thrombosis model to register and analyze acoustic signals from the left ventricular assist device (LVAD) HeartMate II (HMII) (Thoratec Corporation, Inc., Pleasanton, CA, USA) and detect changes in sound signals correlating to clots in the inflow, outflow, and pump housing. Using modern telecom techniques, it was possible to register and analyze the HMII pump-specific acoustic fingerprint in an experimental model of LVAD support using a mock loop. Increase in pump speed significantly (P less than 0.005) changed the acoustic fingerprint at certain frequency (0-23 000 Hz) intervals (regions: R1-3 and peaks: P1,3-4). When the ball valves connected to the tubing were narrowed sequentially by similar to 50% of the inner diameter (to mimic clot in the out-and inflow tubing), the frequency spectrum changed significantly (P less than 0.005) in P1 and P2 and R1 when the outflow tubing was narrowed. This change was not seen to the same extent when the lumen of the ball valve connected to the inflow tube was narrowed by similar to 50%. More significant (P less than 0.005) acoustic changes were detected in P1 and P2 and R1 and R3, with the largest dB figs. in the lower frequency ranges in R1 and P2, when artificial clots and blood clots passed through the pump system. At higher frequencies, a significant change in dB figs. in R3 and P4 was detected when clots passed through the pump system. Acoustic monitoring of pump sounds may become a valuable tool in LVAD surveillance.
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| 55. |
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| 56. |
- Hübbert, Laila, et al.
(författare)
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Axial flow pump treatment during myocardial depression in calves : an invasive hemodynamic and echocardiographic tissue Doppler study.
- 2008
-
Ingår i: ASAIO journal (1992). - Philadelphia, PA USA : Lippincott Williams & Wilkins. - 1058-2916 .- 1538-943X. ; 54:4, s. 367-371
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate flow characteristics and myocardial function after implantation of an axial pump left ventricular assist device while varying afterload and during progressive myocardial depression. Ten calves were included, seven of which fulfilled the protocol. Invasive hemodynamic monitoring and echocardiography with color-coded systolic tissue Doppler velocity (TD velocity) were used during prepump conditions, at three different pump speeds, during modification of the systemic vascular resistance (SVR), and during increasing degrees of beta-blockade. The TD velocity decreased with the myocardial function whereas left ventricular size, fractional shortening, and pump speed did not correlate significantly with the TD velocity. The TD velocity correlated significantly with native stroke volume, heart rate, SVR and cardiac output but none of these alone could explain more than 20% of the changes in TD velocity. The axial flow pump studied is effective in unloading the severely depressed heart and has a high capacity for maintaining an adequate cardiac output, regardless of differing hemodynamic conditions, pump speed or decreasing LV function. Echocardiography with volumetric rendering and TD velocity imaging are valuable tools for monitoring and quantifying residual myocardial function during pump treatment.
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| 57. |
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| 58. |
- Hübbert, Laila, et al.
(författare)
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Echocardiography and myocardial Doppler indices in the anesthetized calf : A closed and open chest study
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Aim: the aim of this study was to provide baseline central hemodynamic and echocardiographic values in an anaesthetized calf model before and after sternotomy, and to include tissue Doppler imaging (TDI) modalities so that they may be applied to future anaesthetized calf models in cardiovascular research. Method and results: twenty-one healthy anaesthetized calves were catheterized and invasively and echocardiographic monitored before and after sternotomy using a pulmonary artery catheter, left atrial and carotid artery catheters, and transthoracic or pericardial echocardiography. The following data were registered: heart rate, mean arterial pulmonary and systemic pressures, central venous pressure and saturation, cardiac output, left and right ventricular dimensions and their myocardial regional basal peak velocity and strain rate during systole, early diastolic and atrial filling and systolic peak strain and systolic displacement. After sternotomy, the heart rate, systemic arterial pressure and left ventricular size increased, but other cardiovascular parameters, including echocardiographic myocardial velocities, strain and displacement did not change. Conclusion: transthoracic and pericardial echocardiography including TDI, is feasible and applicable to the anaesthetized calf model. The normal ranges for baseline hemodynamic and echocardiographic variables derived from this study demonstrate that, as in humans, sternotomy influences basic hemodynamic variables such as heart rate, blood pressure and heart volumes but does not significantly affect TDI. The data collected may be useful in the future development of cardiovascular research using the anaesthetized calf model.
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| 59. |
- Hübbert, Laila, et al.
(författare)
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Endovascular stenting of an outflow graft thrombosis in a continuous-flow left ventricular assist device.
- 2017
-
Ingår i: ASAIO journal (1992). - 1058-2916 .- 1538-943X. ; 63:1, s. e3-e5
-
Tidskriftsartikel (refereegranskat)abstract
- We report the endovascular stenting of an outflow tract thrombosis in a left ventricular assist device in a patient with relative contraindications to sternotomy and pump exchange. This report highlights the importance of simultaneous prevention of stroke using filter devices in the common carotid arteries.
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| 60. |
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| 61. |
- Hubbert, Laila, et al.
(författare)
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Left atrial pressure monitoring with an implantable wireless pressure sensor following implantation of a left ventricular assist device
- 2017
-
Ingår i: ASAIO journal (1992). - 1058-2916 .- 1538-943X. ; 63:5, s. E60-E65
-
Tidskriftsartikel (refereegranskat)abstract
- Following implantation of a continuous-flow left ventricular assist device (LVAD), left atrial pressure (LAP) monitoring allows for precise management of intravascular volume, inotropic therapy and pump speed. In this case series of 4 LVAD recipients we report the first clinical use of this wireless pressure sensor for long-term monitoring of LAP during LVAD support. A wireless microelectromechanical system (MEMS) pressure sensor, (Titan™, ISS Inc., Ypsilanti, MI, USA) was placed in the left atrium in four patients at the time of LVAD implantation. Titan sensor LAP was measured in all 4 patients on the ICU and in 3 patients at home. Ramped speed tests were performed using LAP and echocardiography in 3 patients. The left ventricular end diastolic diameter (cm), flow (L/min), power consumption (W) and blood pressure (mmHg) were measured at each step.Measurements were performed over 36, 84, 137, and 180 days, respectively. The three discharged patients had equipment at home and were able to perform daily recordings. There were significant correlations between sensor pressure and pump speed, LV and LA size and pulmonary capillary wedge pressure, respectively (r= 0.92-0.99, p < 0.05). There was no device failure and there were no adverse consequences of its use.
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| 62. |
- Hübbert, Laila, et al.
(författare)
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Second Harmonic Echocardiography and Spontaneous Contrast during Implantation of a left Ventricular Assist Device
- 2010
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Ingår i: ASAIO journal (1992). - : Wolters Kluwer. - 1058-2916 .- 1538-943X. ; 56:5, s. 417-421
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Tidskriftsartikel (refereegranskat)abstract
- Implantable mechanical left ventricular assist devices (LVADs) are used as a bridge or alternative to heart transplantation. Peroperative transesophageal echocardiography is commonly applied during implantation. Significant air embolism may occur as a result of air leakage at connections and anastomoses when LV filling becomes inadequate, and this must be prevented. Early suspicion and detection of air is mandatory to avoid negative circulatory effects. We hypothesized that monitoring of heart chamber size and occurrence of single air bubbles using second harmonic imaging (SHI) echocardiography may prevent risk for significant air embolism. After implantation of the LVAD in 10 calves, invasive hemodynamic monitoring and epicardial SHI were performed while increasing pump speed. Air bubbles in the ascending aorta were monitored and the left heart visualized for off-line dimensional analysis. Detection of air bubbles in the ascending aorta preceded their appearance in the left ventricle. They occurred exclusively but not always after a decrease in left atrial (LA) size. Decrease in LA pressure did not predict bubble detection or reduction in LA size. We conclude that SHI detects spontaneous ultrasound contrast during implantation of a LVAD and that a decrease in LA size is a warning that air embolism is imminent.
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| 63. |
- Häggblad, Erik, et al.
(författare)
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Myocardial tissue oxygenation estimated with calibrated diffuse reflectance spectroscopy during coronary artery bypass grafting
- 2008
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 13:5, s. 054030-
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Tidskriftsartikel (refereegranskat)abstract
- We present a study using a method able to assess tissue oxygenation, taking into account the absorption and the level of scattering in myocardial tissue using a calibrated fiber optic probe. With this method, interindividual comparisons of oxygenation can be made despite varying tissue optical properties during coronary artery bypass grafting (CABG). During CABG, there are needs for methods allowing continuous monitoring and prediction of the metabolism in the myocardial tissue. 14 patients undergoing CABG are investigated for tissue oxygenation during different surgical phases using a handheld fiber optic spectroscopic probe with a source-detector distance of less than 1 mm. The probe is calibrated using a light transport model, relating the absorption and reduced scattering coefficients (mu(a) and mu()(s)) to the measured spectra. By solving the inverse problem, absolute measures of tissue oxygenation are evaluated by the sum of oxygenized hemoglobin and myoglobin. Agreement between the model and measurements is obtained with an average correlation coefficient R-2 of 0.96. Oxygenation is found to be significantly elevated after aorta cross-clamping and cardioplegic infusion, as well as after reperfusion, compared to a baseline (p < 0.05). Tissue oxygenation decreases during cardiac arrest and increases after reperfusion.
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| 64. |
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| 65. |
- Jönsson, Anders, et al.
(författare)
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Microwave Ablation in Mitral Valve Surgery for Atrial Fibrillation (MAMA)
- 2012
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Ingår i: Journal of Atrial Fibrillation. - : Cardiofront. - 1941-6911. ; 5:2, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Microwave ablation in conjunction with open heart surgery is effective in restoring sinus rhythm (SR) in patients with atrial fibrillation (AF). In patients assigned for isolated mitral valve surgery no prospective randomized trial has reported its efficacy.Methods: 70 patients with longlasting AF where included from 5 different centres. They were randomly assigned to mitral valve surgery and atrial microwave ablation or mitral valve surgery alone.Results: Out of 70 randomized, 66 and 64 patients were available for evaluation at 6 and 12 months. At 12 months SR was restored and preserved in 71.0 % in the ablation group vs 36.4 % in the control group (P=0.006), corresponding figures at 6 months was 62.5 % vs 26.5 % (P=0.003). The 30-day mortality rate was 1.4 %, with one death in the ablation group vs zero deaths in the control group. At 12 months the mortality rate was 7,1 % (Ablation n=3 vs Control n=2). No significant differences existed between the groups with regard to the overall rate of serious adverse events (SAE) during the perioperative period or at the end of the study. 16 % of patients randomized to ablation were on antiarrhytmic drugs compared to 6 % in the control group after 1 year (p=0.22).Conclusion: Microwave ablation of left and right atrium in conjunction with mitral valve surgery is safe and effectively restores sinus rhythm in patients with longlasting AF as compared to mitral valve surgery alone.
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| 66. |
- Karlsson, Daniel M G, 1974-, et al.
(författare)
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Analysis and processing of laser Doppler perfusion monitoring signals recorded from the beating heart
- 2003
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Ingår i: Medical and Biological Engineering and Computing. - : Springer. - 0140-0118 .- 1741-0444. ; 41:3, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- Laser Doppler perfusion monitoring (LDPM) can be used for monitoring myocardial perfusion in the non-beating heart. However, the movement of the beating heart generates large artifacts. Therefore the aim of the study was to develop an LDPM system capable of correlating the laser Doppler signals to the cardiac cycle and to process the signals to reduce the movement artifacts. Measurements were performed on three calves, both on the normal beating heart and during occlusion of the left anterior descending coronary artery (LAD). The recorded LDPM signals were digitally processed and correlated to the sampled ECG. Large variations in the output (perfusion) and DC signals during the cardiac cycle were found, with average coefficients of variation of 0.36 and 0.14 (n-14), respectively. However, sections with a relatively low, stable output signal were found in late diastole, where the movement of the heart is at a minimum. Occlusion of the LAD showed the importance of recording the laser Doppler signals at an appropriate point in the cardiac cycle, in this case late systole, to minimise movement artifacts. It is possible to further reduce movement artifacts by increasing the lower cutoff frequency when calculating the output signal.
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| 67. |
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| 68. |
- Karlsson, Daniel M. G., et al.
(författare)
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Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique
- 2005
-
Ingår i: Medical and Biological Engineering and Computing. - : Springer. - 0140-0118 .- 1741-0444. ; 43:5, s. 582-588
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Tidskriftsartikel (refereegranskat)abstract
- Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.
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| 69. |
- Karlsson, M G Daniel, 1974-, et al.
(författare)
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Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging
- 2004
-
Ingår i: Medical and Biological Engineering and Computing. - : Springer. - 0140-0118 .- 1741-0444. ; 42:6, s. 770-776
-
Tidskriftsartikel (refereegranskat)abstract
- Tissue motion of the beating heart generates large movement artifacts in the laser Doppler perfusion monitoring (LDPM) signal. The aim of the study was to use tissue Doppler imaging (TDI) to localise intervals during the cardiac cycle where the influence of movement artifacts on the LDPM signal is minimum. TDI velocities and LDPM signals were investigated on three calves, for normal heartbeat and during occlusion of the left anterior descending coronary artery. Intervals of low tissue velocity (TDIint<1 cm s−1) during the cardiac cycle were identified. During occlusion, these intervals were compared with low LDPM signal intervals (LDPMint<50% compared with baseline). Low-velocity intervals were found in late systole (normal and occlusion) and late diastole (normal). Systolic intervals were longer and less sensitive to heart rate variation compared with diastolic ones. The overlap between LDPMint and TDIint in relation to TDIint length was 84±27% (n=14). The LDPM signal was significantly (p<0.001, n=14) lower during occlusion if calculated during minimum tissue motion inside TDIint), compared with averaging over the entire cardiac cycle without taking tissue motion into consideration. In conclusion, movement artifacts are reduced if the LDPM signal is correlated to the ECG and investigated during minimum wall motion. The optimum interval depends on the application; late systole and late diastole can be used.
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| 70. |
- Kircher, Albert, et al.
(författare)
-
Knowledge representation forms for data mining methodologies as applied in thoracic surgery
- 2000
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Ingår i: AMIA,2000. - Philadelphia : Hanley & Belfus Inc. - 156053480X ; , s. 428-432
-
Konferensbidrag (refereegranskat)abstract
- Typical ways of disseminating and using results of clinical research are scientific journals and reports. Presentation forms are condensed and comprehensible mainly to the experts following the specific topics. A vast amount of information remains unutilized due to the complex form of presenting the knowledge. Subject of this research is to explore possibilities of representation and also visualization of the results obtained using data mining methodologies. The intention is to formulate more than scientific ways to communicate facts that are of interest for the clinicians, medical students and even patients. Internet technologies as already widely established media support knowledge representation forms such as hypertext documents and structured knowledge components. The "Assist Me" decision support system for surgical treatment of cardiac patients integrates several forms of data mining and representation methodologies. We are showing a feasibility study in which scientific outcomes were forwarded to a broad group of potential users.
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| 71. |
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| 72. |
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| 73. |
- Kirchhoff, Tomas, et al.
(författare)
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Breast cancer risk and 6q22.33 : combined results from Breast Cancer Association Consortium and Consortium of Investigators on Modifiers of BRCA1/2
- 2012
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Ingår i: PLOS ONE. - : Public library of science. - 1932-6203. ; 7:6
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, a locus on chromosome 6q22.33 (rs2180341) was reported to be associated with increased breast cancer risk in the Ashkenazi Jewish (AJ) population, and this association was also observed in populations of non-AJ European ancestry. In the present study, we performed a large replication analysis of rs2180341 using data from 31,428 invasive breast cancer cases and 34,700 controls collected from 25 studies in the Breast Cancer Association Consortium (BCAC). In addition, we evaluated whether rs2180341 modifies breast cancer risk in 3,361 BRCA1 and 2,020 BRCA2 carriers from 11 centers in the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA). Based on the BCAC data from women of European ancestry, we found evidence for a weak association with breast cancer risk for rs2180341 (per-allele odds ratio (OR) = 1.03, 95% CI 1.00-1.06, p = 0.023). There was evidence for heterogeneity in the ORs among studies (I(2) = 49.3%; p = <0.004). In CIMBA, we observed an inverse association with the minor allele of rs2180341 and breast cancer risk in BRCA1 mutation carriers (per-allele OR = 0.89, 95%CI 0.80-1.00, p = 0.048), indicating a potential protective effect of this allele. These data suggest that that 6q22.33 confers a weak effect on breast cancer risk.
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| 74. |
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| 75. |
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| 76. |
- Lindbergh, Tobias, et al.
(författare)
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Improved model for myocardial diffuse reflectance spectra by including mitochondrial cytochrome aa3, methemoglobin, and inhomogenously distributed RBC
- 2011
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Ingår i: Journal of Biophotonics. - : John Wiley & Sons. - 1864-063X .- 1864-0648. ; 4:4, s. 268-276
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Tidskriftsartikel (refereegranskat)abstract
- Hemo- and myoglobin oxygen saturation and cytochrome aa3 oxidation was locally assessed using calibrated diffuse reflectance spectroscopy in fourteen patients undergoing coronary artery bypass grafting. Diffuse spectral reflectance data, recorded with a handheld fiberoptic probe with a single source-detector separation, was analyzed using an empirical light transport model relating the absorption and reduced scattering coefficients to the measured spectrum. The absorption coefficient has previously been modeled as a sum of hemoglobin and myoglobin, fat, and water. In this study, inclusion of cytochrome aa3 and the sum of methemoglobin and metmyoglobin improved the spectral fit, especially in the wavelength regions where their absorption is prominent. On average, the extended model increased the mean R2 from 0.96 to 0.99 and displayed 4% units higher saturation levels. After aorta cross-clamping, the sum of hemo- and myoglobin oxygen saturation increased while cytochrome aa3 oxidation decreased slightly. Opposite trends were observed during cardiac arrest. At reperfusion, the saturation increased compared to the levels found at cardiac arrest, and the cytochrome aa3 oxidation was restored. The estimated tissue chromophore fractions, saturation and oxidation, were in agreement with other studies.
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| 77. |
- Lindbergh, Tobias, et al.
(författare)
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Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves
- 2010
-
Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 15:2
-
Tidskriftsartikel (refereegranskat)abstract
- Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin, were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas; 21%-50%-100%, in five calves (group A) gave an oxygen saturation of 19+/-4%, 24+/-5% and 28+/-8%, and mean tissue fractions of 1.6% (cytochrome aa3), and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B) a left ventricular assistive device (LVAD pump) was implanted. Group B animals displayed similar trends in hemo- and myoglobin oxygen saturation as in group A, but at higher levels (maxima of 38% (B1) and 44% (B2)). The cytochrome aa3 oxidation level was above 96% in both group A and B calves, including the two cases involving cardiac arrest.In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations where in agreement with previously presented results, demonstrating the potential of the method.
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| 78. |
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| 79. |
- Lindbergh, Tobias
(författare)
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Quantitative diffuse reflectance spectroscopy : myocardial oxygen transport from vessel to mitochondria
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the field of biomedical optics, diffuse reflectance spectroscopy (DRS) is a frequently used technique for obtaining information about the optical properties of the medium under investigation. The method utilizes spectral difference between incident and backscattered light intensity for quantifying the underlying absorption and scattering processes that affects the light-medium interaction.In this thesis, diffuse reflectance spectroscopy (DRS) measurements have been combined with an empirical photon migration model in order to quantify myocardial tissue chromophore content and status. The term qDRS (quantitative DRS) is introduced in the thesis to emphasize the ability of absolute quantification of tissue chromophore content. To enable this, the photon migration models have been calibrated using liquid optical phantoms. Methods for phantom characterization in terms of scattering coefficient, absorption coefficient, and phase function determination are also presented and evaluated. In-vivo qDRS measurements were performed on both human subjects undergoing routine coronary artery bypass grafting (CABG), and on bovine heart during open-chest surgery involving hemodynamic and respiratory provocations. The application of a hand-held fiber-optic surface probe (human subjects) proved the clinical applicability of the technique as the results were in agreement with other studies. However, problems with non-physiological variations in detected intensity due to intermittent probe-tissue discontact were observed. Also, systematic deviations between modeled and measured spectra were found. By model inclusion of additional chromophores revealing the mitochondrial oxygen uptake ability, an improved model fit to measured data was achieved. Measurements performed with an intramuscular probe (animal subjects) diminished the influence of probe-tissue discontact on the detected intensity. It was demonstrated that qDRS could quantify variations in myocardial oxygenation induced by physiological provocations, and that absolute quantification of tissue chromophore content could be obtained.The suggested qDRS method has the potential of becoming a valuable tool in clinical practice, as it has the unique ability of monitoring both the coronary vessel oxygen delivery and the myocardial mitochondrial oxygen uptake ability. This makes qDRS suitable for directly measuring the result of different therapies, which can lead to a paradigm shift in the monitoring during cardiac anesthesia.
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| 80. |
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| 81. |
- Litaudon, X., et al.
(författare)
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14 MeV calibration of JET neutron detectors-phase 1: Calibration and characterization of the neutron source
- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 58:2
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Tidskriftsartikel (refereegranskat)abstract
- In view of the planned DT operations at JET, a calibration of the JET neutron monitors at 14 MeV neutron energy is needed using a 14 MeV neutron generator deployed inside the vacuum vessel by the JET remote handling system. The target accuracy of this calibration is 10% as also required by ITER, where a precise neutron yield measurement is important, e.g. for tritium accountancy. To achieve this accuracy, the 14 MeV neutron generator selected as the calibration source has been fully characterised and calibrated prior to the in-vessel calibration of the JET monitors. This paper describes the measurements performed using different types of neutron detectors, spectrometers, calibrated long counters and activation foils which allowed us to obtain the neutron emission rate and the anisotropy of the neutron generator, i.e.The neutron flux and energy spectrum dependence on emission angle, and to derive the absolute emission rate in 4π sr. The use of high resolution diamond spectrometers made it possible to resolve the complex features of the neutron energy spectra resulting from the mixed D/T beam ions reacting with the D/T nuclei present in the neutron generator target. As the neutron generator is not a stable neutron source, several monitoring detectors were attached to it by means of an ad hoc mechanical structure to continuously monitor the neutron emission rate during the in-vessel calibration. These monitoring detectors, two diamond diodes and activation foils, have been calibrated in terms of neutrons/counts within ± 5% total uncertainty. A neutron source routine has been developed, able to produce the neutron spectra resulting from all possible reactions occurring with the D/T ions in the beam impinging on the Ti D/T target. The neutron energy spectra calculated by combining the source routine with a MCNP model of the neutron generator have been validated by the measurements. These numerical tools will be key in analysing the results from the in-vessel calibration and to derive the response of the JET neutron detectors to DT plasma neutrons starting from the response to the generator neutrons, and taking into account all the calibration circumstances.
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| 82. |
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| 83. |
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| 84. |
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| 85. |
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| 86. |
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| 87. |
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| 88. |
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| 89. |
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| 90. |
- Nielsen, Niels Erik, et al.
(författare)
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Transvenous Implantation of a Stent Valve for Calcified Native Mitral Stenosis
- 2015
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Ingår i: Annals of Thoracic Surgery. - : ELSEVIER SCIENCE INC. - 0003-4975 .- 1552-6259. ; 100:1, s. E21-E23
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Tidskriftsartikel (refereegranskat)abstract
- We used a modified combination of the transseptal and transapical methods to facilitate the controlled delivery and use of a stent valve in a patient with calcified native mitral stenosis. A loop from the right femoral vein passing transseptally and then through the apex of the left ventricle was created, enabling highly controlled positioning and deployment of the stent valve.
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| 91. |
- Olofsson, Pia, et al.
(författare)
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Gastrointestinal microcirculation and cardiopulmonary function during experimentally increased intra-abdominal pressure
- 2009
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 37:1, s. 230-239
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to assess gastric, intestinal, and renal cortex microcirculation parallel with central hemodynamics and respiratory function during stepwise increase of intra-abdominal pressure (IAP). Design: Prospective, controlled animal study. Setting: Research laboratory, University Hospital. Subjects: Twenty-six anesthetized and mechanically ventilated pigs. Interventions: Following baseline registrations, CO2 peritoneum was inflated (n = 20) and IAP increased stepwise by 10 mm Hg at 10 mins intervals up to 50 mm Hg and subsequently exsufflated. Control animals (n = 6) were not insufflated with CO2. Measurements and Main Results: The microcirculation of gastric mucosa, small bowel mucosa, small bowel seromuscular layer, colon mucosa, colon seromuscular layer, and renal cortex were selectively studied at all pressure levels and after exsufflation using a four-channel laser Doppler flowmeter (Periflex 5000, Perimed). Central hemodynamic and respiratory function data were registered at each level and after exsufflation. Cardiac output decreased significantly at IAP levels above 10 mm Hg. The microcirculation of gastric mucosa, renal cortex and the seromuscular layer of small bowel and colon was significantly reduced with each increase of IAP. The microcirculation of the small bowel mucosa and colon mucosa was significantly less affected compared with the serosa (p < 0.01). Conclusions: Our animal model of low and high IAP by intraperitoneal CO2-insufflation worked well for studies of microcirculation, hemodynamics, and pulmonary function. During stepwise increases of pressure there were marked effects on global hemodynamics, respiratory function, and microcirculation. The results indicate that intestinal mucosal flow, especially small bowel mucosal flow, although reduced, seems better preserved in response to intra-abdominal hypertension caused by CO2-insufflation than other intra-abdominal microvascular beds.
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| 92. |
- Olofsson, Pia H., 1962-, et al.
(författare)
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Increased transmucosal uptake of E. coli K12 in porcine small bowel following experimental short term abdominal compartment syndrome
- 2009
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: Abdominal compartment syndrome (ACS) may lead to bacterial translocation and possibly be of importance for development of multiorgan failure. However, the underlying mechanisms have not been fully elucidated. In a porcine model we recently demonstrated preserved intestinal mucosal blood flow during experimental short duration ACS. In the present study we used the same model to determine mucosal barrier function and morphology in the small bowel and colon of pigs before and after short term ACS. Methods: The study comprised 12 anaesthetized pigs exposed to experimental ACS and 6 control animals. Via laparotomy, samples of small bowel and colon were taken out for studies before short term ACS, where the abdomen was inflated with CO2 and IAP was increased stepwise by 10 mm Hg at 10-minute intervals up to 50 mm Hg, and again 10 minutes after exsufflation. Mucosal microcirculation was measured by laser Doppler flowmetry, and mucosal tissues were mounted in modified Ussing chambers for assessment of barrier function (E. coli K12 uptake and 51Cr-EDTA permeability). Specimens were also fixed in formaldehyde, stained with eosin-hematoxylin and evaluated blindly using an 8-grade scale for assessment of mucosal damage. Results: Transmucosal passage of E. coli was three-fold increased in the small bowel after ACS (22.6 [18.2 – 54.4] units) vs. baseline (8.1 [2.0 – 13.9]; P< 0.050) with a significant correlation to alterations of mucosal microcirculation. In the colon bacterial passage was unchanged, whereas 51Cr-EDTA permeability after ACS increased to 181% of baseline (P<0.05) and was correlated to significant mucosal histopathological changes (P<0.03). Conclusion: Short term ACS with reperfusion induced significant dysfunction of the intestinal mucosal barrier. The response patterns concerning barrier dysfunction differed between small bowel and colonic mucosa, with increased bacterial passage and paracellular permeability, respectively.
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| 93. |
- Peterzén, Bengt, et al.
(författare)
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Anesthetic management of patients undergoing coronary artery bypass grafting with the use of an axial flow pump and a short-acting beta-blocker
- 1999
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Ingår i: Journal of cardiothoracic and vascular anesthesia. - 1053-0770. ; 13:4, s. 431-436
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To describe the clinical protocol regarding monitoring, pharmacologic interventions, and postoperative care during and after coronary artery bypass grafting (CABG) on the beating heart with an axial flow pump and a short-acting β-blocker. Design: A retrospective study. Setting: A university hospital. Participants: Seventeen patients scheduled for elective CABG. Interventions: Invasive monitoring was performed with either a standard pulmonary artery catheter (PAC) or a surgically placed PAC. An axial flow pump was inserted through a graft sutured to the ascending aorta. A short-acting β-blocker was administered to decrease the motion of the heart and make conditions for CABG adequate and safe. Measurements and main results: Compared with baseline measurements, there were significant decreases in mean arterial blood pressure, mixed venous oxygen saturation, and right ventricular ejection fraction during maximal axial flow pump support and β-blockade. No significant change in heart rate was observed at this time. Hemodynamic variables were normalized in the intensive care unit. All patients were separated from the Hemopump without inotropic support, and values of troponin-T, aspartate aminotransferase, and alanine aminotransferase were low postoperatively. All patients survived and were discharged from the hospital. Conclusion: The anesthetic protocol for patients undergoing surgery with a beating heart and the combined use of an axial flow pump and a short-acting β-blocker is outlined. Multiple-vessel CABG on the beating heart was performed with maintenance of an acceptable hemodynamic situation.
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| 94. |
- Peterzén, Bengt, 1949-
(författare)
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Management of patients treated with left ventricular assist devices : A clinical and experimental study
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the management of patients treated with mechanical circulatory support devices for short- or long-term use. Twenty-four patients suffering from postcardiotomy heart failure were treated with a minimally invasive axial flow pump. The device was effective in unloading the failing left ventricle and in maintaining an adequate systemic circulation. The principles of perioperative monitoring, and pharmacological therapy are outlined. The pump was also used as an alternative to the heart-lung machine in conjunction with coronary artery bypass surgery. Together with a short-acting β-blocker, esmolol, the heart was decompressed and heart motion was reduced, facilitating bypass surgery on the beating heart. The anesthesiological considerations using this method are described.An implantable left ventricular assist device was used as a bridge to heart transplantation in 10 patients. We were interested in assessing the possibility to establish such a treatment program at a non-transplanting center. A multidisciplinary approach was enabled thanks to the organization of our Heart Center and due the close collaboration with our transplant center at Lund University. As one of the first centers in Europe, we established a well-functioning program with good results. Nine out of 10 of the bridge patients, with treatment times varying between 53 to 873 days, survived pump treatment and were eventually transplanted. The device proved to be powerful enough to support the failing heart and enable rehabilitation of the patients. Outpatient management became simpler when using the electrical device with belt-worn batteries. The uncertain durability and the high risk of device-related complications are shortcomings that limit its potential for more permanent treatment of heart failure.A new generation of small implantable axial blood flow pumps has therefore been developed. The principles of these pumps are based on the first generation axial flow pumps evaluated in this thesis. After several years of basic research and experimental studies, the first human implants have been performed. In the thesis, the hemodynamic effects of such a novel axial flow pump have been evaluated in an acute heart failure model. This technology holds great promise, both as a bridge to heart transplantation, and as a permanent circulatory support system.
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| 95. |
- Peterzén, Bengt, et al.
(författare)
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Management of patients with end-stage heart disease treated with an implantable left ventricular assist device in a nontransplanting center
- 2000
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Ingår i: Journal of cardiothoracic and vascular anesthesia. - : Elsevier BV. - 1053-0770. ; 14:4, s. 438-443
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To describe the setup of a left ventricular assist device (LVAD) program in a nontransplanting center. Design: A prospective study from February 1993 to June 1999. Setting: A university hospital. Participants: Ten patients, 6 men, with a mean age of 44 years (range 16 to 63 years) and with end-stage heart failure resulting from dilated cardiomyopathy (n = 7) or ischemic heart disease (n = 3). Interventions: The patients received the TCI (Thermo Cardiosystems Inc, Woburn, MA) Heart Mate implantable assist device. Five patients had a pneumatic device, and 5 had an electric device. All except 1 patient with an electric device had the pump for an extended period. Measurements and Main Results: Median time on the ventilator was 6.2 days, and median time in the ICU was 14 days. Significant hemodynamic improvement was observed by echocardiography and invasive monitoring. Milrinone and epinephrine supplemented by prostaglandin E1 were the most commonly used drugs to avoid right-sided heart failure. Nine patients were transplanted after pump therapy of 241 days (median) (range, 56 to 873 days). One patient died because of endovascular infection and septicemia. Infectious complications were frequent, especially when the pump time was extended. Conclusions: The introduction of an LVAD program in a nontransplanting center can be achieved with good results. Intense collaboration with a transplant center is mandatory. The complication rate increased when treatment times were extended.
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| 96. |
- Peterzén, Bengt, et al.
(författare)
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Postoperative management of patients with Hemopump support after coronary artery bypass grafting
- 1996
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Ingår i: The Annals of thoracic surgery. - 0003-4975. ; 62:2, s. 378-385
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Tidskriftsartikel (refereegranskat)abstract
- Background In this study, we describe postoperative monitoring, pharmacologic therapy, and hemodynamic responses in patients receiving Hemopump support after postcardiotomy heart failure. Methods The Hemopump was used in 24 patients with severe left ventricular dysfunction after coronary artery bypass grafting. Results Fourteen patients (58%) were weaned from the Hemopump. Low to moderate doses of a combination of catecholamines, phosphodiesterase inhibitors, vasodilators, and vasoconstrictors were required to optimize Hemopump function and left ventricular unloading. Mean arterial blood pressure, mixed venous oxygen saturation, and urinary output were the most important therapy guidelines. Conclusions Together with our clinical protocol, the Hemopump effectively unloaded the failing ventricle while maintaining vital-organ perfusion. Doses of vasoactive drugs could be kept low. This approach to treatment provides good conditions for recovery of the stunned myocardium.
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| 97. |
- Peterzén, Bengt, et al.
(författare)
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Response : Is an axial flow pump necessary during beating heart surgery? Volume14, Issue 3, p. 361
- 2000
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Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier. - 1053-0770 .- 1532-8422. ; 14:3, s. 3611-361
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We thank Dr D'Ancona and coworkers for their comments regarding our previous article.1 The reasons for the combined use of an axial flow pump and β-blocker during bypass surgery are two: (1) This is one of many techniques to perform coronary artery bypass graft surgery on the beating heart. Few alternatives, including mechanical stabilizers, were available when this study began. The development in this area of cardiac surgery and anesthesia has been rapid. All this work is a part of an evolutionary process. (2) In some patients, it still can be difficult to perform bypass graft surgery on the posterior part of the heart. In these situations, the technique described by us could be an alternative. We do not state that this is a necessary technique for grafting of the circumflex system; it should be regarded as an option if the global circulation does not tolerate an off-pump technique....
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| 98. |
- Sonntag, Simon J., et al.
(författare)
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Virtual implantations to transition from porcine to bovine animal models for a total artificial heart
- 2020
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Ingår i: Artificial Organs. - : Wiley-Blackwell Publishing Inc.. - 0160-564X .- 1525-1594. ; 44:4, s. 384-393
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Tidskriftsartikel (refereegranskat)abstract
- Realheart total artificial heart (TAH) is a novel, pulsatile, four-chamber total artificial heart which had been successfully tested acutely in a porcine animal model. However, the bovine model is better suited for long-term testing and thus an evaluation of how the design would fit the bovine anatomy was required. Virtual implantation is a method that enables a computer simulated implantation based on anatomical 3D-models created from computer tomography images. This method is used clinically, but not yet adopted for animal studies. Herein, we evaluated its suitability in the redesign of the outer dimensions and vessel connections of Realheart TAH to transition from the porcine to the bovine animal model. Virtual implantations in combination with bovine cadaver studies enabled a series of successful acute bovine implantations. Virtual implantations are a useful tool to replace the use of animals in early device development and refine subsequent necessary in vivo experiments. The next steps are to carry out human virtual implantations and cadaver studies to ensure the design is optimized for all stages of testing as well as the final recipient.
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| 99. |
- Strüber, Martin, et al.
(författare)
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HeartMate II left ventricular assist device, early European experience
- 2008
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Ingår i: European Journal of Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940 .- 1873-734X. ; 34:2, s. 289-294
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The novel axial flow left ventricular assist device HeartMate II was introduced into clinical practice in Europe as part of the pilot study and after CE approval in November 2005. In order to get an overview of the use and performance of the device in Europe a group of investigators was founded to compare the initial results. Methods: In a retrospective analysis of the first 101 consecutive cases in Europe, data were collected with regard to postoperative outcome and severe adverse events and anticoagulation protocols. Results were stratified by intention to treat as a bridge to transplant or as chronic support therapy in heart failure (destination therapy). Results: In 70% of patients, the HeartMate II was intended as a bridge to transplant therapy, in 30%, it was used as a destination therapy device. The perioperative mortality post implant was 20% in the bridge to transplant patients and 7% in the destination therapy arm. However, after 1 year a comparable survival was observed in both groups (69% destination therapy, 63% bridge to transplant). Main causes of death were multiple organ failure (n = 12) and cerebrovascular accidents (n = 5). All, but one cerebrovascular accident occurred in the first 9 days after surgery. Only one other death was reported thereafter and there was no mechanical failure of the device. Conclusions: Even in the early experience the HeartMate II was used as a chronic support device in a substantial number of patients in Europe. Although the total experience is still limited, the incidence of cerebrovascular accidents is very low and the survival beyond the perioperative period is excellent. © 2008 European Association for Cardio-Thoracic Surgery.
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| 100. |
- Sundbom, Per, et al.
(författare)
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(556) – Change in Acoustic Fingerprints at Increased Pump Speed During Echocardiographic Ramp Test
- 2014
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Ingår i: The Journal of Heart and Lung Transplantation. - : Elsevier. - 1053-2498.
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Konferensbidrag (refereegranskat)abstract
- PurposeThe continuous flow mechanical circulatory support HeartMate II™ (Thoratec Corporation, Inc. Pleasanton, USA) (HMII), generates an auditory signal (acoustic fingerprint) that can be registered by routine auscultation. A temporary or permanent change in sound indicates a change in pump function. Previous mock loop studies have shown that changes in acoustic fingerprint are due to changes in speed, so the aim of this study was to see if the acoustic fingerprint changed during an echocardiographic ramp test.MethodsFour stable, event-free patients included in the SoundMate study performed an echocardiographic ramp test. The speed was increased stepwise by 400 rpm between 8 000 and 12 000 rpm, and the left ventricular end diastolic diameter, flow, power consumption and blood pressure were measured. Sounds from HMII were recorded using an iPhone™ (Apple Inc. Cupertino, CA, USA) with the stethoscope application iStethPro™ (Dr. Peter J Bentley, UK) and the frequency map analyzed using the Audacity™ program (Unicode, Ash, Chinen and Crook, USA). The acoustic fingerprint is divided into regions (R1: 1 000-6 500, R2: 8 500-14 000, R3: 15 000-21 000 Hz) and peaks (P1: 0-1 000, P2: 6 500-8 500, P4: 21 000-23 000 Hz) in order to facilitate calculations and clarify changes in frequency.ResultsThere were significant (p<005) changes in the acoustic fingerprint when increasing the pump speed between 8 000 and 12 000 rpm. In 2/4 patients there were no significant changes in P1, otherwise there were significant changes in all regions and peaks. During the ramp test the power increased in mean 7 W, flow 3,1 L/min and the blood pressure measured with Doppler increased by ~15 mmHg. The left ventricular size decreased with ~2 cm.ConclusionThe acoustic fingerprint changes with pump speed. This implies that when using sound check for detection of pump dysfunction, a new baseline should be set after every adjustment of speed.
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