PubMed · 6401051
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M Stejfa. 1983. [Heart failure].. https://pubmed.ncbi.nlm.nih.gov/6401051/
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Most patients presenting with heart failure have severe coronary artery disease. The identification of viable hibernating myocardium is of paramount clinical importance for a correct indication of revascularization. Contractile reserve may be identified when regional asynergy improves during low or moderate doses of dobutamine. Dipyridamole, given at infra-low dose, alone or preferably in association with a low dose of dobutamine, is another possible pharmacologic stress protocol. Dobutamine echocardiography has been found to be more specific than thallium scintigraphy for predicting functional recovery after revascularization. However, the absence of contractile reserve does not exclude the presence of myocardial viability: perfusion reserve may be too low because of a critical coronary artery stenosis, or profound ultrastructural changes of myocardial cells may be present, including significant loss of contractile material. Inotropic reserve can also be assessed by dobutamine stress echocardiography in patients with idiopathic cardiomyopathy. The evolution of hemodynamic variables can be measured during the stress test. Stress echocardiography, especially during exercise, could probably provide important information about heart failure associated with valvular heart disease.
Evidence of normal systolic left ventricular function has been reported in up to 30-40% of patients with clinical signs of congestive heart failure, suggesting that diastolic dysfunction is an important predictor of prognosis and mortality. Doppler echocardiography as a noninvasive diagnostic procedure is able to provide immediate and relevant information on functional and structural changes underlying the clinical syndrome of heart failure. Four distinct early filling/late diastole (E/A) ratio patterns (normal, delayed relaxation, pseudonormal, restrictive) can be discerned if viewed within the context of other available clinical information. These patterns evolve from one to another in a single individual, with changes in disease evolution, treatment, and loading condition. They represent a continuum from normal to severe diastolic dysfunction, showing progressively increasing left ventricular (LV) chamber stiffness and subsequently decreasing deceleration time. The combination of Doppler restrictive filling pattern and decreased deceleration time provides important information that helps to differentiate gradations of diastolic dysfunction and has been found to be a potent predictor of prognosis and mortality in various cardiac conditions. When clinical and transthoracic data alone are not sufficient in guiding therapy of congestive heart failure, transesophageal echocardiography can be used to assess most Doppler flows, especially pulmonary venous and left atrial (LA) appendage flows. The use of the multiplane transducer in multiple intermediate scan planes further improves the possibility of optimizing the Doppler incident angle and obtaining the best Doppler recordings of the left upper or right upper pulmonary venous flow. Whereas LV diastolic dysfunction is common in patients with congestive heart failure and appears to be an important predictor of prognosis, little information is available about right ventricular (RV) diastolic dysfunction. The role of RV function in congestive heart failure has probably been underestimated and it is possible that RV diastolic dysfunction assessment is equally important in the follow-up of heart failure patients. Recently, 2 novel echocardiographic technologies for the assessment of ventricular wall dynamics have been developed--color kinesis and tissue Doppler imaging. Both techniques have recently been shown to provide global as well as regional information on LV contraction and filling. Complementary use of both techniques may allow a more complete noninvasive assessment of global and regional systo-diastolic LV function.
To develop a submaximal constant work rate exercise test able to grade cardiovascular dysfunction in patients with chronic heart failure, 80 patients and 59 control subjects performed a symptom-limited incremental exercise test and a constant work rate exercise test at a fixed work rate (50 W for 4 minutes). The time constant of VO2 at the start of constant work rate exercise and time for gas exchange ratio (respiratory exchange ratio) to equal 1 were independent predictors of cardiovascular functional class and correctly classified the functional class in 89 +/- 9% and 83 +/- 11% of patients, respectively.