Casimir Eubig

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.

Miscellaneous TopicExercise-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.

The value, limitations, and applications of nuclear dacryocystography

Nuclear dacryocystography is simple, relatively harmless method of evaluating patients suspected of having abnormalities of the nasolacrimal drainage system. A group of normal saline containing approximately 100 muCi of 99mTc-pertechnetate is placed on the conjunctiva near the lateral canthus, and serial scintigrams are obtained as the pertechnetate flows along the tear strips, through the nasolacrimal drainage system, into the nasal fossa. By using a pinhole collimator with a very small aperture (1mm), the canaliculi, the nasolacrimal sac, and the nasolacrimal duct are readily visualized. When flow is impaired, the site of obstruction can often be identified. Contrast dacryocystography provides similar information but requires the injection of contrast material directly into a canaliculus. Nuclear dacryocystography provides good functional assessment of nasolacrimal drainage but has serious shortcomings in defining pathologic anatomy. Contrast dacryocystography outlines the anatomy well but often misses minor obstructions. The two studies are complementary and together provide an effective means of evaluating the nasolacrimal drainage system.

Thermodilution Qp/Qs: An indicator dilution method

SummaryThe pulmonary-to-systemic blood flow ratio (Qp/Qs) is critical in the appraisal of the need for surgery in patients with left-to-right shunts. Because of the drawbacks present with conventional Fick, indicator dilution, and radionuclide techniques of Qp/Qs measurement, we sought to determine whether an extension of thermodilution technology could accurately predict Qp/Qs. We studied 30 children with clinically suspected or postoperative atrial or ventricular septal defects. The thermodilution temperature curves from the pulmonary artery were printed on a strip chart recorder after right atrial injection of iced solution. Gamma variate curve fitting and area analysis were used to determine Qp/Qs. The correlation between Fick and thermodilution Qp/Qs values was excellent (r=0.95). The thermodilution technique was rapid, and did not require either arterial entry, radiation after venous catheter placement, or multiple sampling.

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

SummaryVentricular 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≥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≤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 (>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≤0.01). The lower GFRs were associated with the lower early postoperative ejection fractions.

123 VALIDATION OF A PRACTICAL CARDIAC OUTPUT DETERMIN ATION IN CHILDREN WITH SHUNTS AND VALVULAR REGURGITATION

A first pass cardiac output determination was tailored to meet the needs of children with congenital heart disease. Acquisition was complete 3.5 minutes after a single peripheral injection of TC-99m albumin. The anterior projection was used to enable shunt determination from time activity histograms over the right lung. Cardiac output was measured over the right atrium in 31 children (6.2-61.0 Kg, mean 22.4) with a wide range of cardiac diagnoses. Cardiac output was measured over the left ventricle from the same bolus in 24 of these children and validated by cardiac catheterization (Fick method) in 15. In the absence of a shunt or valvular regurgitation cardiac output over right atrium and left ventricle were equivalent (r=.83, n=17, p <.001). In the presence of a left to right shunt the cardiac output at one site was equivalent to the output at the volume overloaded site divided by the pulmonary to systemic flow ratio (r=.96, n=5, p<.001). In two children with left heart valvular regurgitation, the time activity curves over their left ventricles were broadened giving spuriously low cardiac outputs, but their right atrial outputs were nearly identical to those at catheterization. The catheterization cardiac outputs correlated well with right atrial outputs (r=.79, n=15, p <.001). Cardiac output can be determined from a single injection and in a short time for children with the full spectrum of cardiac diseases.