What is Congestive Heart Failure (CHF)?
Congestive heart failure is a combined right and left heart failure, producing both pulmonary congestion and peripheral edema.
Causes of heart failure include:
- valvular disease
- coronary heart disease
The low cardiac output in heart failure results in increased sympathetic nervous activity, which stimulates the rate and force of the heart beat and maintains the blood pressure by increasing the vascular resistance. In the failing heart, the resulting increase in the resistance against which the heart has to pump (after-load) further depresses cardiac output.
Reduced renal blood flow results in renin secretion and increased plasma angiotensin and aldosterone levels. Sodium and water retention increase the blood volume, increasing the central venous pressure (pre-load) and the likelihood of edema formation.
These compensatory changes at first help to maintain cardiac output but, in the longer term, lead to changes (e.g. abnormal ventricu- lar dilatation) that increase morbidity and mortality.