| 1. |
- Li, Y., et al.
(författare)
-
Hyperoxia affects the regional pulmonary ventilation/perfusion ratio : an electrical impedance tomography study
- 2014
-
Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 58:6, s. 716-725
-
Tidskriftsartikel (refereegranskat)abstract
- Background The way in which hyperoxia affects pulmonary ventilation and perfusion is not fully understood. We investigated how an increase in oxygen partial pressure in healthy young volunteers affects pulmonary ventilation and perfusion measured by thoracic electrical impedance tomography (EIT). Methods Twelve semi-supine healthy male volunteers aged 21-36 years were studied while breathing room air and air-oxygen mixtures (FiO2) that resulted in predetermined transcutaneous oxygen partial pressures (tcPO2) of 20, 40 and 60kPa. The magnitude of ventilation (Zv) and perfusion (ZQ)-related changes in cyclic impedance variations, were determined using an EIT prototype equipped with 32 electrodes around the thorax. Regional changes in ventral and dorsal right lung ventilation (V) and perfusion (Q) were estimated, and V/Q ratios calculated. Results There were no significant changes in Zv with increasing tcPO2 levels. ZQ in the dorsal lung increased with increasing tcPO2 (P=0.01), whereas no such change was seen in the ventral lung. There was a simultaneous decrease in V/Q ratio in the dorsal region during hyperoxia (P=0.04). Two subjects did not reach a tcPO2 of 60kPa despite breathing 100% oxygen. Conclusion These results indicate that breathing increased concentrations of oxygen induces pulmonary vasodilatation in the dorsal lung even at small increases in FiO2. Ventilation remains unchanged. Local mismatch of ventilation and perfusion occurs in young healthy men, and the change in ventilation/perfusion ratio can be determined non-invasively by EIT.
|
|
| 2. |
- Baranowski, Jacek, et al.
(författare)
-
Echo-guided presentation of the aortic valve minimises contrast exposure in transcatheter valve recipients
- 2011
-
Ingår i: Catheterization and cardiovascular interventions. - : Wiley. - 1522-1946 .- 1522-726X. ; 77:2, s. 272-275
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We have developed a method using transthoracic echocardiography in establishing optimal visualization of the aortic root, to reduce the amount of contrast medium used in each patient. BACKGROUND: During transcatheter aortic valve implantation, it is necessary to obtain an optimal fluoroscopic projection for deployment of the valve showing the aortic ostium with the three cusps aligned in the beam direction. This may require repeat aortic root angiograms at this stage of the procedure with a high amount of contrast medium with a risk of detrimental influence on renal function. METHODS: We studied the conventional way and an echo guided way to optimize visualisation of the aortic root. Echocardiography was used initially allowing easier alignment of the image intensifier with the transducer's direction. RESULTS: Contrast volumes, radiation/fluoroscopy exposure times, and postoperative creatinine levels were significantly less in patients having the echo-guided orientation of the optimal fluoroscopic angles compared with patients treated with the conventional approach. CONCLUSION: We present a user-friendly echo-guided method to facilitate fluoroscopy adjustment during transcatheter aortic valve implantation. In our series, the amounts of contrast medium and radiation have been significantly reduced, with a concomitant reduction in detrimental effects on renal function in the early postoperative phase.
|
|
| 3. |
- Broomé, Michael, et al.
(författare)
-
Closed-loop real-time simulation model of hemodynamics and oxygen transport in the cardiovascular system
- 2013
-
Ingår i: Biomedical engineering online. - 1475-925X. ; 12:1, s. 69-
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Computer technology enables realistic simulation of cardiovascular physiology. The increasing number of clinical surgical and medical treatment options imposes a need for better understanding of patient-specific pathology and outcome prediction. Methods: A distributed lumped parameter real-time closed-loop model with 26 vascular segments, cardiac modelling with time-varying elastance functions and gradually opening and closing valves, the pericardium, intrathoracic pressure, the atrial and ventricular septum, various pathological states and including oxygen transport has been developed. Results: Model output is pressure, volume, flow and oxygen saturation from every cardiac and vascular compartment. The model produces relevant clinical output and validation of quantitative data in normal physiology and qualitative directions in simulation of pathological states show good agreement with published data. Conclusion: The results show that it is possible to build a clinically relevant real-time computer simulation model of the normal adult cardiovascular system. It is suggested that understanding qualitative interaction between physiological parameters in health and disease may be improved by using the model, although further model development and validation is needed for quantitative patient-specific outcome prediction.
|
|
| 4. |
- Ghareh Baghi, Ghareh Baghi
(författare)
-
Assessment of Valvular Aortic Stenosis by Signal Analysis of the Phonocardiogram
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aortic stenosis (AS) is one of the most prevalent valvular heart diseases in elderly people. According to the recommendations of both the American Heart Association and the European Society of Cardiology, severity assessment of AS is primarily based on echocardiographic findings. The experience of the investigator here play important roles in the accuracy of the assessment, and therefore in the disease management. However, access to the expert physicians could be limited, especially in rural health care centers of developing countries.This thesis aims to develop processing algorithms tailored for phonocardiographic signal with the intension to obtain a noninvasive diagnostic tool for AS assessment and severity grading. The algorithms employ a phonocardiogram as input signal and perform analysis for screening and diagnostics. Such a decision support system, which we call “the intelligent phonocardiography”, can be widely used in primary healthcare centers.The main contribution of the thesis is to present innovative models for the phonocardiographic analysis by taking the segmental characteristics of the signal into consideration. Three novel methodologies are described, based on the presented models, to perform robust classification. In the first attempt, a novel pattern recognition framework is presented for screening of AS-related murmurs. The framework offers a hybrid model for classifying cyclic time series in general, but is tailored to detect the murmurs as a special case study. The time growing neural network is another method that we use to classify short time signals with abrupt frequency transition. The idea of the growing frames is extended to the cyclic signals with stochastic properties for the screening purposes. Finally, a combined statistical and artificial intelligent classifier is proposed for grading the severity of AS.The study suggests comprehensive statistical validations not only for the evaluation and representation of systolic murmurs but also for setting the methodology design parameters, which can be considered as one of the significant features of the study. The resulting methodologies can be implemented by using web and mobile technologies to be utilized in distributed healthcare system.
|
|
| 5. |
- Grishenkov, Dmitry, 1983-, et al.
(författare)
-
Ultrasound contrast agent loaded with nitric oxide as a theranostic microdevise for myocardial ischemia
- 2013
-
Ingår i: European Heart Journal Cardiovascular Imaging.
-
Konferensbidrag (refereegranskat)abstract
- Cardiovascular disease (CVD) accounts for 1/3 of total global deaths worldwide. The most widespread CVD is ischemic heart disease. It is the leading cause of death in both genders, equally diagnosed in developed and developing countries with mortality exponentially increasing with age. Efforts of healthcare system should be primary focused on prevention, timely detection, efficient differentiation and instant treatment of the disease.
|
|
| 6. |
- Hildebrand, Eric, et al.
(författare)
-
Impact of a standardized training program on midwive’s ability to assess fetal heart anatomy by ultrasound
- 2014
-
Ingår i: BMC Medical Imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 14:20
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Studies of prenatal detection of congenital heart disease (CDH) in the UK, Italy, and Norway indicate that it should be possible to improve the prenatal detection rate of CDH in Sweden. These studies have shown that training programs, visualization of the outflow tracts and color-Doppler all can help to speed up and improve the detection rate and accuracy. We aimed to introduce a more accurate standardized fetal cardiac ultrasound screening protocol in Sweden.Methods: A novel pedagogical model for training midwives in standardized cardiac imaging was developed, a model using a think-aloud analysis during a pre- and post-course test and a subsequent group reflection. The self-estimated difficulties and knowledge gaps of four midwives were identified. A two-day course with mixed lectures, demonstrations and handson sessions was followed by a feedback session one month later consisting of an interview and check-up. The long-term effects were tested two years later.Results: At the post-course test the self-assessed uncertainty was lower than at the pre-course test. The qualitative evaluation showed that the color Doppler images were difficult to interpret, but the training seems to have enhanced the familiarity with the new technique. The ability to perform the method remained at the new level at follow-up both three months and two years later.Conclusions: Our results indicate that by implementing new imaging modalities and providing hands-on training, uncertainty can be reduced and time decreased, but they also show that continuous on-site training with clinical and technical back-up is important.
|
|
| 7. |
- Holmgren, Theresa, et al.
(författare)
-
Supervised strengthening exercises versus home-based movement exercises after arthroscopic acromioplasty : A randomized clinical trial
- 2012
-
Ingår i: Journal of rehabilitation medicine : official journal of the UEMS European Board of Physical and Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1651-2081. ; 44:1, s. 12-18
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To evaluate and compare the efficacy of 2 rehabilitation strategies after arthroscopic acromioplasty: supervised physical therapy focusing on strengthening exercises of the rotator cuff and scapula stabilizers (PT-group) vs home-based movement exercises (H-group). Design: A randomized, single-blinded, clinically controlled study. Patients: Thirty-six patients entered the study. Thirteen in the PT-group and 16 in the H-group fulfilled all the assessments. Methods: For 12 weeks following surgery, patients performed either supervised physical therapy or home exercises. Follow-ups were conducted periodically for 6 months after surgery to evaluate shoulder function, pain (Constant-Murley (CM) and Disabilities of the Arm, Shoulder, and Hand (DASH) scores), and health-related quality of life. Results: The PT-group exhibited significantly greater improvements in CM (p =0.02) and DASH (p = 0.05) scores. After treatment, the between-group mean difference in CM scores was 14.2 p (95% confidence interval 2-26). At the 6-month follow-up, the between-group mean difference in DASH scores was 13.4 p (95% confidence interval 0.1-23). Conclusion: PT-supervised rehabilitation with strengthening exercises of the rotator cuff and scapula stabilizers seems to be superior to home exercises focusing on mobility for improving shoulder function after arthroscopic acromioplasty.
|
|
| 8. |
- Hübbert, Laila
(författare)
-
Between the Probe and the Pump : An experimental study on cardiac performance analysis based on Echocardiography, tissue and laser Doppler
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Echocardiography is an ultrasound-based bedside, non-invasive and easily available cardiac diagnostic technique visualising the heart’s morphology and function. Quantification of cardiac wall motion can be measured with the tissue Doppler Imaging (TDI) modality which provides in humans a high diagnostic capacity to differentiate healthy from diseased myocardium with reduced function. Heart failure, as a consequence of, for example, myocardial or ischaemic heart disease, demands both bedside and intraoperative diagnostic procedures for myocardial functional and perfusion assessment. In the late stages of heart failure cardiac left ventricular assist devices (LVAD) may be the treatment of choice. Such new technologies are commonly evaluated in large animals before application in humans is accepted.With the aim of evaluating TDI´s applicability and feasibility in a large animal model 21 calves (aged 3 months and weight around 70 kg), were studied with colour TDI (Paper I). Analysis was performed either during coronary artery occlusion when the laser Doppler perfusion imaging technique (LDMP) was refined (Paper II), or after implantation of the LVAD, Heart Mate II® (Papers III, IV). All animals were haemodynamically monitored (pressures, flows, heart rate) and ECG was continuously recorded. Transthoracic and epicardial echocardiography (TTE) were performed before and after sternotomy and intraoperatively during experimental progressive heart failure. Heart chamber dimensions, native stroke volume, systolic and diastolic regional basal myocardial peak velocities (cm/s; systolic S´, early diastolic E´, and atrial A´, strain (%), strain rate (s-1) and displacement (mm) were determined. Second harmonic imaging (SHI) was applied in order to better visualise air bubbles (Paper IV).In Paper I compiled baseline values were established before and after sternotomy for central haemodynamic and echocardiographic parameters, including the TDI myocardial motion variables velocity, strain rate, strain and displacement. Blood pressure and heart rate changed significantly after sternotomy, but the TDI derived data did not change significantly.In Paper II we report that movement artifacts of the laser Doppler myocardial perfusion measurements can be reduced, both when myocardium is normally perfused and during coronary occlusion, by using the TDI velocity registrations showing wall motion to be minimal. The optimum interval depends on the application but late systole as well as late diastole is preferred.After LVAD implantation in Paper III the flow characteristics and myocardial motion during variations in afterload TDI show that myocardial velocities decrease concomitantly with myocardial depression and are significantly correlated to native stroke volume, heart rate, systemic arterial resistance and cardiac output, but not with left ventricular size, fractional shortening or pump speed. Echocardiography together with TDI thereby offers additional means for monitoring and quantifying residual myocardial function during LVAD treatment.SHI is superior in the early detection of single air-bubbles in the ascending aorta prior to significant air embolism during manipulation of the LVAD pump speed, as shown in Paper IV. A prompt decrease in size of the left atrium during speed adjustment may be a warning that massive air embolism is imminent whereas the commonly used left atrial pressure not provide the same warning.
|
|
| 9. |
- Hübbert, Laila, et al.
(författare)
-
Second Harmonic Echocardiography and Spontaneous Contrast during Implantation of a left Ventricular Assist Device
- 2010
-
Ingår i: ASAIO journal (1992). - : Wolters Kluwer. - 1058-2916 .- 1538-943X. ; 56:5, s. 417-421
-
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.
|
|
| 10. |
|
|
