| 1. |
- Albano, Amanda, et al.
(författare)
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Echocardio-variability - Low and high frequency beat-to-beat variability in echocardiographic signals
- 2013
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Ingår i: Computing in Cardiology 2013. - 9781479908844 ; , s. 767-770
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Konferensbidrag (refereegranskat)abstract
- Measurement signals originating from the cardiovascular system are known to comprise oscillating components and beat-to-beat variability, e.g., heart-rate variability and blood pressure variability. In clinical echocardiographic procedures, typically only a few cardiac cycles are acquired. This pilot study analyses the beat-to-beat variability of echocardiographic variables (echocardio-variability) in minute long acquisitions.
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| 2. |
- Gerdle, Björn, et al.
(författare)
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Altered neuromuscular control mechanisms of the trapezius muscle in fibromyalgia
- 2010
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Ingår i: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 11:42
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Tidskriftsartikel (refereegranskat)abstract
- Background: fibromyalgia is a relatively common condition with widespread pain and pressure allodynia, but unknown aetiology. For decades, the association between motor control strategies and chronic pain has been a topic for debate. One long held functional neuromuscular control mechanism is differential activation between regions within a single muscle. The aim of this study was to investigate differences in neuromuscular control, i.e. differential activation, between myalgic trapezius in fibromyalgia patients and healthy controls. Methods: 27 fibromyalgia patients and 30 healthy controls performed 3 minutes bilateral shoulder elevations with different loads (0-4 Kg) with a high-density surface electromyographical (EMG) grid placed above the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. Results: the median frequency of the differential activations was significantly lower, and the average duration of the differential activations significantly longer in fibromyalgia compared with controls at the two lowest load levels (0-1 Kg) (p andlt; 0.04), but not at the two highest load levels (2 and 4 Kg). Conclusion: these findings illustrate a different neuromuscular control between fibromyalgia patients and healthy controls during a low load functional task, either sustaining or resulting from the chronic painful condition. The findings may have clinical relevance for rehabilitation strategies for fibromyalgia.
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| 3. |
- Grönlund, Christer, et al.
(författare)
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Imaging two-dimensional mechanical waves of skeletal muscle contraction
- 2013
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 39:2, s. 360-369
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Tidskriftsartikel (refereegranskat)abstract
- Skeletal muscle contraction is related to rapid mechanical shortening and thickening. Recently, specialized ultrasound systems have been applied to demonstrate and quantify transient tissue velocities and one-dimensional (1-D) propagation of mechanical waves during muscle contraction. Such waves could potentially provide novel information on musculoskeletal characteristics, function and disorders. In this work, we demonstrate two-dimensional (2-D) mechanical wave imaging following the skeletal muscle contraction. B-mode image acquisition during multiple consecutive electrostimulations, speckle-tracking and a time-stamp sorting protocol were used to obtain 1.4 kHz frame rate 2-D tissue velocity imaging of the biceps brachii muscle contraction. The results present novel information on tissue velocity profiles and mechanical wave propagation. In particular, counter-propagating compressional and shear waves in the longitudinal direction were observed in the contracting tissue (speed 2.8-4.4 m/s) and a compressional wave in the transverse direction of the non-contracting muscle tissue (1.2-1.9 m/s). In conclusion, analysing transient 2-D tissue velocity allows simultaneous assessment of both active and passive muscle tissue properties. (E-mail: christer.gronlund@vll.se) (C) 2013 World Federation for Ultrasound in Medicine & Biology.
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| 4. |
- Grönlund, Christer, 1975-, et al.
(författare)
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Significant beat-to-beat variability of E/e’ irrespective of respiration
- 2013
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Ingår i: International cardiovascular forum. - : Barcaray Publishing. - 2409-3424 .- 2410-2636. ; 1:2, s. 88-89
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Tidskriftsartikel (refereegranskat)abstract
- The E/e’ ratio is commonly used in Doppler echocardiographic examinations to estimate the pulmonary capillary wedge pressure. The rationale of using this ratio is to combine left ventricular (LV) filling (E) and relaxation (e’) velocities to indirectly assess left atrial pressure. However, the accuracy of this index has recently been questioned, particularly in patients with controlled heart failure. Likewise, the potential beat-to-beat variability of such measurements remains undetermined. The cardiovascular system is subject to several oscillations with the potential of influencing LV function and its intra-cavitary pressures, hence measurements of its filling and relaxation velocities. The aim of this pilot study was to assess the beat-to-beat variability of the E/e’ ratio in one minute long examination in healthy subjects, and patients with various severity of amyloid heart disease. The results show that despite critical application of the standard echocardiographic recording recommendations, E/e’ beat-to-beat variability was 36 % (22 to 50%) in healthy subjects and 17 % (11-26%) in patients, and where the most severe amyloid heart disease had the least variability. Thus, clinical use of a single or few cardiac beats might not necessarily reflect an accurate ratio between the two velocities, and hence casts doubt over their diagnostic value.
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| 5. |
- Grönlund, Christer, et al.
(författare)
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Simultaneous quantification of myocardial and blood flow velocities based on duplex mode ultrasound imaging
- 2013
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Ingår i: Biomedical engineering online. - : BioMed Central (BMC). - 1475-925X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Ultrasound imaging of the heart is a commonly used clinical tool to assess cardiac function. The basis for this analysis is the quantification of cardiac blood flow and myocardial velocities. These are typically measured using different imaging modes and on different cardiac cycles. However, due to beat-to-beat variations such as irregular heart rhythm and transient events, simultaneous acquisition is preferred. There exists specialized ultrasound systems for this purpose; however, it would be beneficial if this could be achieved using conventional ultrasound systems due to their wide availability. The conventional Duplex mode ultrasound allows simultaneous acquisition, however at a highly reduced spatial and temporal resolution.METHODS: The aim of this work was to present and evaluate the performance of a novel method to recover myocardial tissue velocity using conventional Duplex ultrasound imaging, and to demonstrate its feasibility for the assessment of simultaneous blood flow and myocardial velocity in-vivo. The essence of the method was the estimation of the axial phase shift of robust echogenic structures between subsequent image frames. The performance of the method was evaluated on synthetic tissue mimicking B-mode image sequences at different frame rates (20--60 Hz) and tissue velocities (peak velocities 5-15cm/s), using cardiac deformation and displacement characteristics. The performance was also compared to a standard 2-D speckle tracking technique.RESULTS: The method had an overall high performance at frame rates above 25 Hz, with less than 15% error of the peak diastolic velocity, and less than 10 ms peak timing error. The method showed superior performance compared to the 2-D tracking technique at frame rates below 50 Hz. The in-vivo quantification of simultaneous blood flow and myocardial tissue velocities verified the echocardiographic patterns and features of healthy subjects and the specific patient group.CONCLUSIONS: A novel myocardial velocity quantification method was presented and high performance at frame rates above 25Hz was shown. In-vivo quantification of simultaneous myocardial and blood flow velocities was feasible using the proposed method and conventional Duplex mode imaging. We propose that the methodology is suitable for retrospective as well as prospective studies on the mechanics and hemodynamics of the heart.
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| 6. |
- Gustafsson, Sandra, et al.
(författare)
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Can echocardiography differentiate hereditary transthyretin amyloidosis from hypertrophic cardiomyopathy?
- 2013
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 34:Supplement: 1, s. 213-213
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: Hereditary transthyretin amyloidosis (ATTR) andhypertrophic cardiomyopathy (HCM) have many phenotypic similarities when examined by echocardiography. As the two conditions have different treatment strategies it is of importance to accurately diagnose these patients early in the disease. This study aimed to identify the most accurate echocardiographic method in differentiating these two conditions by using traditional and speckle tracking echocardiographyas well as myocardial texture analysis.Methods: We investigated 40 healthy controls, 33 patients with biopsy proven ATTR and 20 with HCM. All patients had septal thickness >12 mm. We measured left ventricular (LV) global strain as intrinsic systolic function and LV E/e' to estimate filling pressures. We also tested septal cyclic integrated backscatter (cIBS) and septal entropy as both being measures for myocardial highly reflection pattern whereas cIBS showing motion of highly reflective echoes and entropy the distribution of highly reflective echoes.Results: LV global strain, cIBS and E/e' were not useful in differentiating ATTR from HCM. However, septal entropy was found to be significantly different and showed an area under the curve from ROC analysis of 0.66 separating ATTR from HCM.Conclusion: After using detailed analysis of different aspects of LV morphology and function we found that myocardial texture behavior from entropy analysis was the only method useful in differentiating patients with ATTR fromHCM.
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| 7. |
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| 8. |
- Henein, Mark, et al.
(författare)
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Left atrial strain rate estimates PCWP
- 2013
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Ingår i: International cardiovascular forum. - 2409-3424. ; :1, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Raised left atrial (LA) pressure is a common pathway for many pathologies and is known for its complications. It has a direct effect on LA cavity size and potentially also its function. We hypothesized that raised LA pressure, as shown by pulmonary capillary wedge pressure (PCWP), correlates with severity of global LA deformation abnormalities during atrial systole (LASRa). DESIGN AND PATIENTS: We prospectively studied 46 consecutive patients, mean age 61 ±13 years, 17 males, of various etiologies who underwent right heart catheterization and simultaneous Doppler echocardiography using spectral, tissue Doppler and speckle tracking echocardiography techniques for assessing LA structure and function. RESULTS: PCWP correlated with direct measurements of LA structure and function: LA volume (r= 0.43, p<0.01) and LASRa (r=0.79, p<0.001). PCWP correlated also with other indirect measures of LA pressure such as E/A (r=0.65, p<0.001), E wave deceleration time (r=0.54, p<0.001), E/e’ (r=0.49, p<0.001) and LA systolic filling fraction (r=0.52, p<0.001). However, LASRa together with LA systolic filling fraction, had the highest areas under the curve (0.83 and 0.87, respectively) for identifying patients with PCWP > 15 mmHg. CONCLUSION: PCWP correlates with LA deformation rate during atrial systole and to a higher extent than conventional Doppler measures of raised LA pressures. These findings should have significant clinical implications in correctly identifying breathless patients due to raised LA pressure.
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| 9. |
- Holtermann, A, et al.
(författare)
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Duration of differential activations is functionally related to fatigue prevention during low-level contractions.
- 2010
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Ingår i: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology. - : Elsevier BV. - 1873-5711. ; 20:2, s. 241-245
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the importance of duration of differential activations between the heads of the biceps brachii on local fatigue during prolonged low-level contractions. Fifteen subjects carried out isometric elbow flexion at 5% of maximal voluntary contraction (MVC) for 30 min. MVCs were performed before and at the end of the prolonged contraction. Surface electromyographic (EMG) signals were recorded from both heads of the biceps brachii. Differential activation was analysed based on the difference in EMG amplitude (activation) between electrodes situated at the two heads. Differential activations were quantified by the power spectral median frequency of the difference in activation between the heads throughout the contraction. The inverse of the median frequency was used to describe the average duration of the differential activations. The relation between average duration of the differential activations and the fatigue-induced reduction in maximal force was explored by linear regression analysis. The main finding was that the average duration of differential activation was positively associated to relative maximal force at the end of the 30 min contraction (R(2)=0.5, P<0.01). The findings of this study highlight the importance of duration of differential activations for local fatigue, and support the hypothesis that long term differential activations prevent fatigue during prolonged low-level contractions.
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| 10. |
- Holtermann, Andreas, et al.
(författare)
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The relation between neuromuscular control and pain intensity in fibromyalgia
- 2011
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Ingår i: JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY. - : Elsevier Science B.V., Amsterdam.. - 1050-6411 .- 1873-5711. ; 21:3, s. 519-524
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Tidskriftsartikel (refereegranskat)abstract
- Fibromyalgia patients are shown to have a different neuromuscular control (differential activation) than healthy persons. Before clinical trials can be initiated, the relation between differential activations and pain intensity among fibromyalgia patients needs to be investigated. Twenty-seven fibromyalgia patients performed 3 min bilateral shoulder elevations with different loads (0-4 kg) with a high-density surface electromyographical (EMG) grid placed on the upper trapezius. Differential activation was quantified by the power spectral median frequency of the difference in EMG amplitude between the cranial and caudal parts of the upper trapezius. The average duration of the differential activation was described by the inverse of the median frequency of the differential activations. The relation between frequency and duration of differential activations as an average of the 4 loads and pain intensity the same day prior to the experiment was explored by Pearsons correlation coefficients. A strong negative relation between frequency of differential activations and pain intensity (R = -0.67, p andlt; 0.001) and a strong positive association between duration of differential activations and pain intensity (R = 0.66, p andlt; 0.001) were found. The significant association between frequency and duration of differential activations and pain intensity among the fibromyalgia patients indicates a relation between this neuromuscular control pattern and pain intensity. This finding support initiation of clinical trials for investigating effects on pain intensity of modifying differential activations among fibromyalgia patients.
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