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Left ventricular filling in hypertrophic cardiomyopathy. An angiographic study
Insights
Peak left ventricular filling rate is normal in hypertrophic cardiomyopathy patients, but abnormal relaxation and cavity shape disrupt the filling pattern. This study highlights impaired relaxation as a key factor in diastolic dysfunction.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex condition affecting heart muscle structure and function.
- Understanding left ventricular filling dynamics is crucial for diagnosing and managing HCM.
- Previous studies have yielded conflicting results regarding diastolic filling in HCM.
Purpose of the Study:
- To investigate left ventricular (LV) filling patterns in patients with hypertrophic cardiomyopathy.
- To compare LV filling parameters between HCM patients and healthy individuals.
- To identify factors contributing to abnormal diastolic function in HCM.
Main Methods:
- Digitized left ventricular cineangiograms from 20 HCM patients and 10 normal subjects.
- Frame-by-frame analysis to assess LV dimensions and filling rates.
- Comparison of filling parameters including peak filling rate, mitral valve opening time, and rate of dimensional change.
Main Results:
- Peak LV filling rate was not significantly different between HCM patients and controls.
- Mitral valve opening was significantly delayed in HCM patients, indicating impaired relaxation (P < 0.01).
- Abnormal LV cavity shape led to reduced end-systolic dimension and increased peak rate of dimensional change during filling (P < 0.01).
Conclusions:
- Peak left ventricular filling rate is preserved in hypertrophic cardiomyopathy.
- Abnormal relaxation and altered LV cavity shape contribute to a disturbed filling pattern in HCM.
- These findings suggest diastolic dysfunction in HCM is primarily due to impaired relaxation and geometry, not inflow obstruction.
Abstract:
In order to study left ventricular filling in hypertrophic cardiomyopathy, left ventricular cineangiograms of 20 patients were digitised frame by frame and compared with those of 10 normal subjects. Peak left ventricular filling rate was 770+/-260 ml s-1 (mean+/-1 standard deviation), not significantly different from normal. Mitral valve opening was delayed, occurring 140+/-40 ms after time of minimum cavity area, compared with 93+/-14 msec in normals (P less than 0-01), indicating abnormal relaxation. Peak left ventricular filling rate was correlated inversely with this delay (r = 0-69, P less than 0-01), which was greater in patients with angina (155+/-27 ms) than in those without (85+/-23 ms) (P less than 0-01). The rapid filling period was also abnormally prolonged in 8 patients. End-diastolic transverse dimension was normal (5-3+/-0-7 cm) but end-systolic dimension was reduced (2-4+/-0-4 cm) (P less than 0-01) because of abnormal cavity shape. Peak rate of change of dimension during filling (18-7+/-5-3 cm s-1) was greater than normal (11-3+/-3-9 cm s-1) (P less than 0-01), and correlated with peak filling rate (r = 0-82, P less than 0-001). Thus, peak filling rate is normal in hypertrophic cardiomyopathy, but the filling pattern may be abnormal, apparently because of impaired relaxation and abnormal cavity shape rather than mechanical obstruction to inflow.