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 in diastole (ability to stretch). Lusitropy is the term used to refer to the distensible state of a cardiac chamber.
How do changes in distensibility change cardiac performance?
As a chamber becomes less distensible an equal end-diastolic volume (preload) causes higher chamber pressures. These are transmitted upstream and can lead to pulmonary edema if it is the left ventricle or left atrium that is affected with a reduced distensibility. Thus, for the same amount of preload the less distensible chamber generates higher pressures. Most cardiac disorders tend to reduce distensibility, some very much more than others. Chronic distention of a chamber, particularly the atria, results in an increase in distensibility.
How are changes in distensibility detected on physical examination?
Reduced distensibility of left ventricle or left atrium – may show evidence of left heart congestion:
- pulmonary edema causing increased respiratory rate and effort, crackles or increased broncho-vesicular lung sounds on auscultation
- excessive right ventricular preload
Reduced distensibility of right ventricle or right atrium – may show evidence of right heart congestion:
- jugular venous distention or peripheral venous distention
- positive hepato-jugular reflux
- pleural effusion (increased or laboured respiration, diminished lung sounds)
- hepatomegaly and/or splenomegaly
- ascites (abdominal effusion)
- subcutaneous edema
Comments: Note how this looks like elevated preload in the adjacent upstream chamber. In fact, reduced distensibility causes a form of elevated preload in the adjacent upstream chamber.