Related Experiment Videos
Preload dependency of left atrial pump function in hypertrophic cardiomyopathy
T Nakao1, M Shimizu, N Sugihara
1Second Department of Internal Medicine, School of Medicine, Kanazawa University, Japan.
Japanese Circulation Journal
|January 1, 1993
Summary
Patients with hypertrophic cardiomyopathy show reduced left atrial function during lower body negative pressure (LBNP). This is due to impaired left atrial contractility, not preload or afterload changes.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Previous studies indicated a greater decrease in left atrial contribution to left ventricular filling in hypertrophic cardiomyopathy (HCM) patients during lower body negative pressure (LBNP).
- Understanding the underlying mechanisms for this differential response is crucial for managing HCM.
Purpose of the Study:
- To investigate the hemodynamic and echocardiographic factors contributing to the reduced left atrial function in HCM during LBNP.
- To compare the response between patients with HCM and myocardial infarction (MI).
Main Methods:
- M-mode echocardiography and hemodynamic measurements were performed during LBNP in patients with HCM and MI.
- Left atrial preload, afterload, and fractional shortening during left atrial systole (%LAFS) were analyzed.
Main Results:
- Both HCM and MI groups experienced similar reductions in left atrial preload and afterload during LBNP.
- Patients with HCM showed no change in %LAFS, while MI patients exhibited a significant increase.
- This indicates preserved left atrial contractility augmentation in MI but not in HCM.
Conclusions:
- The diminished left atrial contribution in HCM during LBNP is not attributable to altered preload or afterload.
- Limitations in compensatory left atrial contractility augmentation appear to be the primary factor in HCM patients.