Cardiac function in sickle cell anemia.
Although ventricular dysfunction is suspected to underlie congestive heart failure in sickle cell anemia (SCA), ejection indexes of left ventricular (LV) pump performance have been found to be normal. The increased preload and decreased afterload of SCA increases the ejection phase indexes and might obscure true LV dysfunction. Therefore, the preload and afterload independent end-systolic stress-volume index was compared in 11 patients with SCA and in 11 normal volunteers. End-systolic pressure and echocardiographic LV dimensions were determined during rest, leg raise, hand-grip and amyl nitrite inhalation. Systemic vascular resistance (afterload) was decreased to 1,033 +/- 314 dynes s cm-5 (mean +/- standard deviation) in SCA from 1,701 +/- 314 dynes s cm-5 in normal subjects. End-diastolic volume index (preload) was increased to 102 +/- 24 ml/m2 in SCA from 66 +/- 10 ml/m2 in normal subjects. Cardiac index was increased to 4.7 +/- 1.1 liters/min/m2 in SCA from 2.8 +/- 0.8 liters/min/m2 in normal subjects. Ejection fractions were similar: 0.59 +/- 0.09 in SCA versus 0.62 +/- 0.07 in normal subjects. However, in patients with SCA, the ratio of resting end-systolic stress-volume index was decreased (1.5 +/- 0.5 in SCA versus 2.8 +/- 0.6 in normal subjects) and the slope of the end-systolic stress versus end-systolic volume index relation was decreased (2.7 +/- 1.3 in SCA versus 4.4 +/- 1.8 in normal subjects), suggesting LV dysfunction in those patients. Thus, LV muscle contractile performance is depressed in SCA. Increased preload and decreased afterload compensate for the LV dysfunction and maintain a normal ejection fraction and high cardiac output.
D000293:Adolescent; D000328:Adult; D000680:Amyl Nitrite; D000755:Anemia, Sickle Cell / Q000503:physiopathology*; D002302:Cardiac Output; D002648:Child; D004452:Echocardiography; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D009200:Myocardial Contraction; D005082:Physical Exertion; D012146:Rest; D013318:Stroke Volume
D000680:Amyl Nitrite