More specialized studies may help establish the diagnosis or assess the course of the disease. Echocardiography is the most useful test when there is diagnostic uncertainty, because it can exclude the cardiac diseases similar to heart failure, assess left ventricular contractility, and give physiologic data such as estimates of pulmonary artery pressure. The radionuclide ventriculogram is best at quantifying ejection fraction. Right heart catheterization is useful in assessing response to therapy in some situations.
An exercise treadmill test, particularly when combined with expired gas analysis, is a useful functional test for determining the degree of heart failure and response to therapy. In difficult cases, it can separate cardiac disease from pulmonary disease.
Define âœdiastolic dysfunction.â
The term diastolic dysfunction refers to cardiac dysfunction that results from excessive stiffness of the heart, resulting in an inability of the heart to fill properly. It contrasts with systolic dysfunction, which is an impairment of contractility. Diastolic dysfunction may be severe enough to cause congestive heart failure. This occurs through two mechanisms. First, the noncompliant left ventricle develops a high pressure during diastole, causing an elevation in pulmonary capillary wedge pressure. Second, less blood fills the ventricle during diastole, reducing preload, which in turn reduces cardiac output. Heart failure from diastolic dysfunction is seen in a wide variety of cardiac diseases.
What are some causes of diastolic dysfunction?
Familial hypertrophic obstructive cardiomyopathy (also known as asymmetric septal hypertrophy or idiopathic hypertrophic subaortic stenosis)
Severe hypertrophy (as in hypertensive heart disease or aortic stenosis)
Restrictive cardiomyopathies (such as amyloidosis or endomyocardial fibroelastosis) Although not usually classified with diastolic heart failure, constrictive pericarditis represents the same pathophysiology. Occasionally, ischemic heart disease may cause intermittent heart failure in the absence of systolic dysfunction.