Cardiovascular Physiology and Pathophysiology
PhysiologyStructure and Function4 Topics
Lymphatics and Edema Formation
Vascular Control3 Topics
The Cardiac Cycle
Compensation for Circulatory Failure
Determinants of Myocardial Performance7 Topics
Neuro-Control of Heart and Vasculature4 Topics
Electro-Mechanical Association4 Topics
Electrical Side of the Heart4 Topics
Causes of Heart Failure
PathophysiologyDefining Heart Failure
MVO2 and Heart Failure
Cardiac Output and Heart Failure7 Topics
Vascular Tone in Heart Failure
Distensibility refers to the ease of ventricular filling during diastole (ability to stretch).
Lusitropy refers to the ability of the ventricle to distend/relax and fill.
Factors affecting distensibility
Distensibility is reduced by:
- Reduced sympathetic tone
- Increased wall thickness
- Increased collagen, scarring, or cellular infiltration within the ventricular wall
Distensibility is increased by the opposite effects.
Measures of distensibility
Measurement of distensibility involves determining the instantaneous changes in pressure and volume within the chamber, which is invasive and difficult. Therefore, distensibility is not routinely measured clinically.
Indirect measures of the filling properties of the heart are obtained by echocardiography.
Effect of distensibility on myocardial performance
The effect of a reduction in distensibility is identical to the effect of an increase in preload. Thus, for the same volume of the heart at the end of diastole, there will be an increase in pressure in the ventricle.
Manifestations of abnormal distensibility
If distensibility is reduced:
- The clinical signs will be those of excessive preload with a reduction in stroke volume
If distensibility is increased:
- This is a situation not encountered in clinical practice.
- Disease typically results in reduced distensibility, not increased.
Effect of the autonomic nervous system on distensibility
Beta-adrenergic receptor activation increases the ability of the ventricle to relax.