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[Left ventricular outer wall motion in hypertrophic cardiomyopathy assessed by biplane coronary cineangiograms]
Insights
Patients with hypertrophic cardiomyopathy exhibit impaired systolic shortening in the outer left ventricular walls. This reduced motion, particularly at the apex, may stem from myocardial thickening and fiber disorientation.
Area of Science:
- Cardiology
- Biomedical Engineering
- Cardiac Imaging
Context:
- Hypertrophic cardiomyopathy (HCM) involves abnormal thickening and disorganization of myocardial fibers.
- Assessing left ventricular (LV) wall motion is crucial for understanding HCM pathophysiology.
Purpose:
- To investigate epicardial segment shortening in patients with HCM using biplane coronary cineangiography.
- To quantify systolic shortening and compare it between HCM patients and normal subjects.
Summary:
- Epicardial chord segment length and systolic shortening were measured in 5 HCM patients.
- Average systolic shortening in HCM patients (6.9 ± 5.1%) was significantly lower than in normal subjects (9.0 ± 4.1%).
- Apical segments in HCM patients showed near-zero or negative shortening, indicating systolic expansion.
Impact:
- Reduced epicardial shortening in HCM may be due to geometric differences between endocardial and epicardial layers caused by wall thickening.
- Myocardial fiber degeneration or disorientation further contributes to impaired outer myocardium function.
- Findings highlight the impact of structural changes in HCM on regional myocardial mechanics.
Abstract:
Left ventricular wall motion in patients with hypertrophic cardiomyopathy may show a characteristic movement since this condition is characterized by a disproportionate thickening of the wall and disorientation of myocardial muscle fibers. Biplane coronary cineangiograms were performed in 5 patients with hypertrophic cardiomyopathy and the spatial distance between the bifurcation of the left coronary artery was calculated using a digitizer-computer-plotter system as a measure of epicardial chord segment length. Systolic shortening of the segment was calculated as (LECG R--LES)/ECG R x 100 (%), where LECG R and LES represent segment lengths at the R wave of the electrocardiogram and at the end of systole, respectively. The value amounted 6.9 +/- 5.1 (+/- SD)% on the average which was significantly lower than the previously described values (9.0 +/- 4.1%) in 19 normal subjects. In all of 3 segments at the apex, systolic shortening showed nearly zero or negative indicating systolic expansion. Reduced shortening in patients with hypertrophic cardiomyopathy observed at the epicardial segment in the present study might be a reflection of geometrical difference between endocardial and epicardial segments because shortening of the epicardium will be reduced even the endocardium shortens considerably if the thickness of the wall is markedly increased. Anterior surface of the interventricular septum might be unable to shorten freely along the long axis since it is a junction of trifurcation among right and left ventricular free walls and the interventricular septum if these three walls are thickened. The present study indicated that shortening characteristics in the outer myocardium in patients with hypertrophic cardiomyopathy is markedly impaired possibly due to geometrical difference between endocardial and epicardial segments caused by marked thickening of the wall and also due to the degeneration or disorientation of myocardial fibers.