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Left ventricular emptying dynamics in patients with asymmetric septal hypertrophy and concentric hypertrophic
Insights
Asymmetric septal hypertrophy (ASH) and concentric hypertrophic cardiomyopathy (CHC) show faster left ventricular (LV) ejection dynamics. ASH patients may have obstructed LV emptying, indicated by unchanged ejection dynamics after premature ventricular contractions (PVCs).
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Medical Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) is a complex condition affecting the heart muscle.
- Asymmetric septal hypertrophy (ASH) and concentric hypertrophic cardiomyopathy (CHC) are distinct forms of HCM.
- Understanding left ventricular (LV) ejection dynamics is crucial for diagnosing and managing HCM.
Purpose of the Study:
- To investigate and compare the left ventricular (LV) ejection dynamics in patients with ASH and CHC versus normal controls.
- To assess the impact of premature ventricular contractions (PVCs) on LV ejection patterns in these groups.
- To identify potential indicators of LV outflow obstruction in ASH.
Main Methods:
- Utilized cineangiography for frame-by-frame analysis to determine LV volumes.
- Measured end-diastolic and end-systolic volumes, and maximum dV/dt.
- Calculated total systolic contraction time (SCT) and the ratio of 90% ejection time to SCT (90%T/SCT) in basal and post-PVC beats.
Main Results:
- End-diastolic volumes were similar across all groups.
- End-systolic volumes were significantly lower in ASH and CHC patients compared to normals.
- ASH and CHC patients exhibited significantly faster ejection dynamics (shorter 90%T/SCT) than normals.
- Normals and CHC patients showed a significant decrease in 90%T/SCT after PVCs, while ASH patients did not.
Conclusions:
- Both ASH and CHC demonstrate enhanced systolic LV ejection dynamics at rest.
- The inability of ASH patients with post-PVC gradients to alter their ejection dynamics suggests potential LV outflow obstruction.
- These findings highlight differences in LV emptying characteristics between ASH and CHC, particularly under stress conditions.
Abstract:
We studied the dynamics of left ventricular (LV) emptying in 8 patients with asymmetric septal hypertrophy (ASH), 6 patients with concentric hypertrophic cardiomyopathy (CHC), and 6 normal controls. Four patients with ASH had resting systolic gradients greater than 20 mmHg, all had significant post premature ventricular contraction (PVC) systolic pressure gradients. LV volume (V) was obtained by frame-by-frame analysis of cineangiograms. End-diastolic volume was similar for all groups; end-systolic volume was significantly less in ASH and CHC patients than in normals. Maximum dV/dt was similar in ASH and CHC, and significantly greater than normals. Total systolic contraction time (SCT), i.e., time from peak volume to last cine frame at minimum volume, was similar for all groups, but the time required to eject 90% of stroke volume (90%T), as a fraction of SCT, was shorter for ASH (0.52 +/- 0.07) and CHC patients (0.51 +/- 0.05) than normals (0.67 +/- 0.07) (p less than 0.05 vs myopathy groups). In the sinus beat following a PVC, however, this ratio decreased significantly in normals and CHC patients, but did not change in ASH patients. We conclude that ASH and CHC have similar exaggerated systolic LV ejection dynamics in the basal state; the failure of ASH patients with post-PVC systolic outflow gradient to reduce 90% T/SCT post PVC may reflect obstruction to LV emptying.