Echocardiographic evidence of increased obstruction following long cycle lengths in atrial fibrillation in patients with hypertrophic cardiomyopathy
✍ Scribed by Patricia C. Come; BS Marilyn F. Riley; Candace L. Miklozek
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 353 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0091-2751
No coin nor oath required. For personal study only.
✦ Synopsis
Left ventricular outflow tract obstruction, when present in hypertrophic cardiomyopathy, can vary markedly depending upon changes in left ventricular preload, afterload, and contractil-it^.'-^ Indeed, the remarkable variability of the resultant murmur often provides one of the first clues to the diagnosis of dynamic obstruction.
Arrhythmias, which are accompanied by changes in ventricular preload, afterload, and contractility, may be accompanied by dramatic changes in auscultatory and hemodynamic findings of o b s t r ~c t i o n . ~-~
The left ventricular outflow tract gradient, for example, has been observed to increase appreciably in beats following relatively long RR intervals in patients with a variety of rhythm disturbances, including ectopic beats, sinus arrhythmia, Wenckebach atrioventricular block, and atrial f i b r i l l a t i ~n . ~. ~ While an increase in stroke volume alone, resulting from increased preload, could theoretically increase the left ventricular outflow tract gradient, hemodynamic observations at catheterization have implicated an increase in magnitude of the o b s t r ~c t i o n . ~. ~ Specifically, the aortic systolic pressure has been observed to decrease despite an increase in left ventricular systolic pressure, suggesting increasing severity of obstruction. If an increase in stroke volume alone were responsible for the increased gradient, then aortic systolic pressure should increase in association with the observed increases in left ventricular systolic pressure in beats following long RR intervals.
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