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Biomedical subjects

W Covitz

Publications and source records attributed to W Covitz.

34 records · Page 2Linked to original sources
PubMed1984

Longitudinal exercise hemodynamics in children with sickle cell anemia.

To define further the natural history and causative factors in exercise-related cardiac dysfunction in children and adolescents with sickle cell anemia (SS), we studied the results of 74 patients' initial and follow-up exercise tests. The follow-up study was done one to three years after the first study in 36 children and four to seven years after initial testing in 38 children. Split-plot analysis of covariance did not show any temporal deterioration in exercise hemodynamic variables. Correlation analysis defined hemoglobin and hematocrit levels as critical determinants of cardiac functional reserve capacity in these patients. Several exercise ECG patterns, formerly considered abnormal in children with SS, are now considered to be variants of normal. Studies are presently in progress that should further define the nature and severity of the cardiac impairment during exercise in children with SS.

Adolescent↗
PubMed1984

Cardiac size and function in children with sickle cell anemia.

Cardiac size and function were studied echocardiographically in 124 children with sickle cell anemia. A group of 78 healthy black children served as control subjects. Sickle cell patients exhibited progressive chamber enlargement and progressively increasing left ventricular mass. Although contractility indices were normal, when the opposing influences of volume overload due to anemia and ventricular dysfunction were separated, abnormalities of systolic time intervals were identified. Left ventricular systolic time interval ratio and left ventricular preejection period were higher in the sickle cell group and became increasingly abnormal with growth, suggesting that left ventricular function deteriorated with time.

Adolescent↗
PubMed1983

Exercise-induced cardiac dysfunction in sickle cell anemia. A radionuclide study.

Cardiac performance was studied by radionuclide angiography at rest and during exercise in 22 adolescents with sickle cell (SC) anemia and the results were compared with those in 12 control subjects. At rest, cardiac contractility was normal; cardiac output and end-diastolic volume were increased. At maximal exercise, heart rate, cardiac output response, and work capacity were reduced; the reduction was related to the degree of anemia. Left ventricular end-diastolic volume decreased with exercise most markedly in patients with ischemic exercise electrocardiograms. An abnormal ejection fraction response to exercise occurred in 4 patients; electrocardiographic signs of ischemia developed in all 4, and wall motion abnormalities in 2. Those patients who had electrocardiographic signs of ischemia had a significantly lower heart rate, ejection fraction, and cardiac output response to exercise, and a lower hematocrit level than subjects with normal results on exercise electrocardiography. The increase in cardiac output was not sufficient to maintain a normal level of exercise. The decrease in end-diastolic volume suggests that diastolic function was abnormal during exercise. Cardiac dysfunction was manifested by an abnormal ejection fraction response, wall motion abnormalities, and incomplete left ventricular filling during exercise.

Adolescent↗
PubMed1982

Radionuclide angiographic and echocardiographic quantitation of left-to-right shunts in children with ventricular septal defect.

Pulmonary to systemic blood flow ratios (Qp:Qs) were estimated in 16 children with ventricular septal defects using simultaneous echocardiography and radionuclide angiography, and compared to Qp:Qs measured at cardiac catheterization by the Fick principle method (Fick). When ratios of echographic left atrial dimensions (LAD) to body surface area (LAD/M2), body length (LAD/ht), and aortic root diameter (LAD/Ao) were compared to the Qp:Qs determined by Fick, the correlation coefficients were r = 0.70 for LAD/M2, r = 0.66 for LAD/ht, and r = 0.54 for LAD/Ao. The correlation coefficients between Qp:Qs by Fick, and left ventricular dimensions/M2 and fractional shortening of the left ventricle were not significant. The correlation coefficients between Qp:Qs and the ratios estimated by gamma-variate and area-ratio analysis of radioisotope pulmonary dilution curves were r = 0.92 and r = 0.84, respectively. Thus, radionuclide angiography provided more accurate quantitation of left to right shunting through a ventricular septal defect than echocardiography. However, difficulty in obtaining adequate bolus injections of the radioisotope may result in technical failures whereas echocardiographic measurement is possible in almost all pediatric patients. Finally, the gamma-variate method cannot accurately quantitate shunt ratios greater than 3.5 to 1.

Adolescent↗
PubMed1982

Echocardiographic assessment of the aortic root in syndromes with left ventricular hypoplasia.

Echocardiograms and angiograms of six infants with left ventricular hypoplasia were examined. Three observations were made: (1) A normal-sized aortic root echogram may be seen in infants with mitral atresia, intact ventricular septum and normally related great arteries. (2) A recognizable mitral valve echogram may be seen in mitral atresia. (3) The true echocardiographic left ventricular dimension may be exceedingly difficult to measure, the tendency being to overestimate it. Awareness of these pitfalls with aid in the echocardiographic diagnosis of left ventricular hypoplasia in infants.

Aortic Coarctation↗
PubMed1982

Long-term follow-up study after closure of secundum atrial septal defect in children: an echocardiographic study.

Serial echocardiography was performed in 51 children with isolated secundum atrial septal defect before and after surgery to measure the effects of chronic right ventricular overload on ventricular function. Right ventricular dilation increased dramatically with growth and with size of the left to right shunt only in the youngest children (body surface area less than 0.5 m2). A lesser effect of growth and no significant effect of shunt size were noted in older children. Although an initial decrease in right ventricular size occurred in the first 3 months after operation, persistent right ventricular dilation remained up to 5 years after closure of the interatrial defect in more than 80 percent of patients. Preoperatively, the ratio of the right ventricular preejection period to ejection time was significantly less than that of normal children. This ratio increased dramatically after operation, exceeding normal values early in the postoperative period in 18 of 48 children and persisting in 6 of 22 after 3 months. Left ventricular dimensions were normal early and late after operation. Left ventricular function was apparently normal, although an exceptionally high shortening fraction was noted in 22 (44 percent) of 51 children after operation. Aortic systolic time interval ratios decreased after operation from high normal to low normal values. It is hypothesized that the persistent enlargement of the right ventricle after operation may be due to the chronic preoperative dilation secondary to chronic interatrial shunting. The abnormally high shortening fraction after operation may result from an abnormal left ventricular geometric configuration or abnormality of filling. It is suggested that surgical closure of the atrial defect in the first 3 years of life may prevent these abnormalities.

Adolescent↗
PubMed1978

Echocardiography in infants and children.

Echocardiography is a well established, non-invasive diagnostic technique that has assumed a prominent place in the armamentarium of the pediatric cardiologist. The principles and techniques of echocardiography are explained. In addition, the measurements and interpretation are described, as well as the deductive approach that leads to a specific diagnosis. The purpose of this discussion is to provide the pediatrician with an understanding of the appropriate application, value, and limitation of the echocardiogram.

Cardiomegaly↗
PubMedDate not supplied

Assessment of cardiac and renal function in children immediately after open-heart surgery: the significance of a reduced radionuclide ejection fraction (postoperative ejection fraction).

Ventricular ejection fractions, calculated from radionuclide studies, and inulin clearance, were determined in 33 infants and children immediately after surgical repair of their congenital or rheumatic heart defects. Of these children, the seven whose surgery did not require a period of ischemic arrest served as controls. The immediate postoperative ejection fractions in the 26 children who did undergo a period of ischemic arrest were significantly less than their preoperative values (P less than or equal to 0.001), but this decline was not observed in the control group. Ejection fraction tended to be depressed, transiently, in children 3-5 h after open-heart surgery. Early postoperative ejection fraction was significantly related to aortic cross-clamp time even when controlling for preoperative ejection fraction (r = 0.74, n = 25, P less than or equal to 0.001). Some striking declines in ejection fraction were observed among children whose aortic cross-clamp time exceeded 42 min. The decline in ejection fraction was transient; late postoperative (greater than 1 week) ejection fraction was not significantly different from preoperative values. Though glomerular filtration rates (GFRs) were often above normal, they were significantly correlated with ejection fraction (r = 0.74, n = 19, P less than or equal to 0.01). The lower GFRs were associated with the lower early postoperative ejection fractions.

Adolescent↗
PubMedDate not supplied

Echocardiographic demonstration of a ventriculocoronary artery communication in a neonate with hypoplastic left heart syndrome.

A neonate diagnosed with aortic atresia and mitral hypoplasia had a ventriculocoronary artery communication demonstrated by use of echocardiography. These communications have been noted by angiography and on pathologic specimens in the past, but their clinical importance in the surgical management of these patients remains unclear. The ability to noninvasively identify these communications and study their flow characteristics would help to define their impact on surgical outcome.

Aortic Coarctation↗