Diastolic dysfunction overview
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Congestive heart failure and cardiac dysfunction are not interchangeable definitions. Whereas heart failure is a clinical definition that illustrates the occurrence of symptoms of fatigue, dyspnea, and fluid overload; cardiac dysfunction is a mechanical definition that includes abnormalities in heart contraction (called systolic dysfunction) or abnormalities in heart relaxation and filling (called diastolic dysfunction) or both.
Therefore, diastolic dysfunction refers to a mechanical dysfunction of the heart during the diastolic phase of the cardiac cycle in the presence or absence of any clinical symptoms. When clinical symptoms are present on top of the mechanical dysfunction of the heart, the condition is called diastolic heart failure.
Diastole is the phase of the cardiac cycle when the heart ( i.e. ventricle) is not contracting but is actually relaxed and filling with blood that is being returned to it, either from the body (into right ventricle) or from the lungs ( into left ventricle). The mechanical abnormality in diastolic dysfunction is characterized by a decrease in the ventricular filling in the context of an elevated left ventricular end diastolic pressure and a normal ejection fraction.Diastolic dysfunction is caused by decrease cardiac muscle relaxation or increased stiffness. The ejection fraction of the heart is preserved in this type of dysfunction.Systolic and diastolic dysfunction commonly occur in conjunction with each other.
There are four basic echocardiographic patterns of diastolic heart failure, which are graded I to IV. Grade I is called an "abnormal relaxation pattern", grade II is called "pseudonormal filling dynamics", grade III is called "restrictive filling dynamics", and grade IV is called "reversible restrictive diastolic dysfunction".
Diastolic dysfunction is the impairment of the heart muscle in its ability to properly relax and fill with blood during diastole. Diastolic dysfunction is mainly the result of either impaired myocardial relaxation or increased cardiac muscle stiffness. As a result, the pressure in the left ventricle increases at the end of diastole and causes a build up of pressure in the left atrium and consequently in the pulmonary circulation. The result is pulmonary edema and dyspnea.
Diastolic dysfunction is the mechanical abnormality of the heart to properly relax and fill with blood during diastole. Several medical conditions may cause this to occur; namely cardiovascular conditions, genetic conditions, pulmonary conditions, rheumatologic conditions, and diabetes.
Differentiating Diastolic dysfunction from other Diseases
Diastolic heart failure is one of the examples of heart failure with preserved ejection fraction. Other causes that cause heart failure and do not affect ejection fraction need to be differentiated from this condition.
Epidemiology and Demographics
About half of patients with heart failure have a normal ejection fraction. The prevalence of diastolic dysfunction has increased, although mortality rates have stayed the same. Diastolic dysfunction is more common in females than in males, and more common in the elderly.
Natural History, Complications and Prognosis
Heart failure associated with diastolic dysfunction has a slightly better prognosis than that of systolic heart failure. However, the presence or absence of coronary artery disease, the age, and the left ventricular ejection fraction cut off level must all be taken into consideration in stratifying patients and assessing their prognosis.
The evaluation of the presence of diastolic dysfunction in patients presenting with symptoms of heart failure is of paramount importance. The diagnosis of diastolic dysfunction or diastolic heart failure is not clinical and requires a work up that goes beyond the history, physical exam, echocardiography and chest X-rays. Several studies have evaluated the diagnostic criteria to follow in differentiating systolic dysfunction from diastolic dysfunction.
History and Symptoms
The classic symptoms of heart failure include dyspnea, fatigue, and fluid retention. Patients with diastolic heart failure may present in different ways. Some patients present with exercise intolerance but show little evidence of congestion or edema. Other patients present with mild symptoms of edema and pulmonary congestion.
In general, signs of both left sided heart failure and right sided heart failure are present. Signs that represent acute left sided failure include cool clammy skin, cyanosis, rales and a gallop rhythm. Signs that represent right sided failure include an elevated JVP, pedal edema, ascites, hepatomegaly, a parasternal heave and hepatojugular reflux.
The initial laboratory tests in diastolic dysfunction or failure include complete blood count, urinalysis, serum electrolytes, blood urea nitrogen, serum creatinine, fasting blood glucose (glycohemoglobin), lipid profile, liver function tests, and thyroid-stimulating hormone. The measurement of BNP is done only when diagnosis is unclear.
Diastolic dysfunction, in the presence or absence of diastolic heart failure, is a challenging diagnosis that has several diagnostic approaches. While cardiac catheterization can be used to establish the diagnosis of diastolic dysfunction by the invasive measurement of elevated left ventricular end diastolic pressure and mean pulmonary capillary pressure, echocardiography provides an alternative noninvasive diagnostic tool.
Other Diagnostic Studies
Cardiac catheterization can be used to measure the PCWP and the LVEDP. These are important predictors of the filling pressure and the degree of myocardial disease progression in dilated cardiomyopathy.
The chronic treatment of diastolic dysfunction involves aggressive management of the underlying disorder that is causing the diastolic dysfunction such as diabetes or hypertension. Mild diastolic dysfunction that is well tolerated requires no specific treatment. Rate control is an important part of the acute therapy of the patient with diastolic heart failure. It takes a longer period of time for a stiff left ventricle to fill, and therefore rate control is a critical part of the acute therapy of diastolic dysfunction.
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