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Left ventricular relaxation and filling in hypertrophic cardiomyopathy. An echocardiographic study
Insights
This study reveals abnormal relaxation in hypertrophic cardiomyopathy using echocardiograms. Findings suggest segmental left ventricular dysfunction due to delayed mitral valve opening and altered wall motion during filling.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex cardiac condition.
- Understanding left ventricular (LV) diastolic function is crucial in HCM.
- Noninvasive assessment of LV filling dynamics can provide insights into HCM pathophysiology.
Purpose of the Study:
- To investigate LV diastolic function and mitral valve dynamics in patients with HCM.
- To compare echocardiographic and apex cardiogram parameters between HCM patients and healthy controls.
- To identify noninvasive markers of abnormal relaxation and segmental LV dysfunction in HCM.
Main Methods:
- Simultaneous echocardiography and apex cardiography in 36 HCM patients and 20 controls.
- Digitization of cardiac signals to plot LV dimension, rate of change, and mitral leaflet velocity.
- Analysis of peak mitral diastolic closure rate, LV filling patterns, and mitral valve opening timing.
Main Results:
- Reduced peak mitral diastolic closure rate in HCM patients (120 mm/s vs. 250 mm/s in controls).
- Delayed mitral valve opening (mean 76 ms) and abnormal LV dimension increase during early diastole.
- Disturbed LV filling patterns, with prolonged or shortened rapid filling duration, suggesting restriction.
- Abnormal early diastolic LV dimension increase and delayed peak filling rate, indicating segmental abnormalities.
Conclusions:
- Noninvasive methods demonstrate impaired LV relaxation in hypertrophic cardiomyopathy.
- Delayed mitral valve opening and altered LV wall motion during diastole suggest segmental LV dysfunction.
- Echocardiography and apex cardiography can reveal subtle abnormalities in HCM not solely related to global relaxation.
Abstract:
Echocardiograms showing left ventricular cavity and mitral valve cusps simultaneously were recorded in 36 patients, apex cardiograms being obtained in 26 of them. These were digitised and continuous plots made of left ventricular dimension, its rate of change, and anterior mitral leaflet velocity, and were compared with those in 20 normal subjects. Peak mitral diastolic closure rate was reduced to 120 +/- 80 mm/s, compared with normal (250 +/- 60 mm/s). Peak rate of increase of dimension was normal (13.4 cm/s), though the pattern of filling was disturbed, with the duration of rapid filling prolonged in 5, and shortened in 15, suggesting restriction. Mitral valve opening, normally synchronous with minimum dimension, was delayed by a mean of 76 ms, and during this period there was an abnormal increase in dimension. Dimension also increased by 50 +/- 25 per cent of the total diastolic excursion before the 'O' point of the apex cardiogram compared with 21 +/- 7 per cent in normals, and the timing of peak rate of increase of dimension was delayed by 50 +/- 20 ms instead of being synchronous with the 'O' point as normal. None of these findings correlated with the reduction in peak mitral diastolic closure rate. Noninvasive methods thus show that relaxation may be abnormal in hypertrophic cardiomyopathy. Delay in mitral valve opening and disturbances in the rate, duration, and co-ordination of wall movement during filling suggest the presence of segmental abnormalities of left ventricular function.