Experimental subendocardial ischemia in dogs with normal coronary arteries.
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Biomedical subjects
Publications and source records attributed to D E Fixler.
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The hypothesis that mild recurrent aortic obstruction produces subtle changes in ambulatory blood pressure was investigated by performing 24-hour monitoring on 11 postoperative coarctation patients. Patients (age 16.1 +/- 2.7 years) were compared with normal controls (age 15.7 +/- 2.5 years, n = 15). Surgery (end-to-end anastomosis) was performed at 6.0 +/- 1.0 years of age. There were no significant differences between patients and controls in terms of baseline blood pressure (right arm 123/78 +/- 4/3 mmHg versus 120/75 +/- 3/2 mmHg) or right leg systolic pressure (125 +/- 6 mmHg versus 123 +/- 4 mmHg). Of the 11 patients 8 had recoarctation by Doppler study (mean gradient 25.3 +/- 2.1 mmHg), 5 of 11 had a postexercise arm-leg pressure difference of > 30 mmHg, and 6 patients had aortic diameters at the site of surgery < 70% of the descending aortic diameter (by magnetic resonance imaging). There were no significant differences between the coarctation and control groups in terms of mean ambulatory systolic (125 +/- 3 mmHg versus 119 +/- 2 mmHg) or diastolic (69 +/- 2 mmHg versus 72 +/- 2 mmHg) pressures throughout the day. However, coarctation patients had a larger number of systolic pressures that exceeded the 95th percentile (18.2 +/- 5.6% versus 6.8 +/- 1.2%). These labile increases in systolic pressure correlated with residual coarctation (r = 0.642, p = 0.003). Ambulatory monitoring is a useful tool for detecting and monitoring subtle abnormalities of blood pressure control after coarctation repair.
This paper reviews recent changes in morbidity and mortality of respiratory syncytial virus (RSV) infection in infants with congenital heart disease. Mortality since the late 1970s has declined substantially, from approximately 37% to 3%. Although the frequency of admission to intensive care units has declined from approximately 60% to 30%, the frequency for mechanical ventilatory support has not changed significantly. Because mortality dropped prior to the widespread use of ribavirin, it is difficult to ascribe the improvement to this therapy. In infants with congenital heart disease (CHD), nosocomial infection remains a significant problem, accounting for approximately 33% of the RSV cases. Some authors report significant reductions in hospital-acquired RSV by use of gloves and gowns for contacts with infectious cases. Efforts at primary prevention have encountered problems with development of an RSV vaccine. Preliminary data from studies of passive immunization using immune globulins with high RSV antibody titers suggest that this therapy may reduce the severity of RSV infection in infants with serious heart disease.
This report reviews the results of six large blood pressuree surveys done on pediatric populations and points out factors responsible for differences in the blood pressure norms. The studies were selected on the basis of there being recent examinations of large numbers of children. Important differences in mean systolic pressures and 95th percentile values were found among the studies, which may be attributed to: 1) actual differences among the populations; 2) biases due to methodological differences; or 3) increased sampling variability with small sample sizes. Actual differences in pressures among the populations surveyed may be due to differences in geographic location, racial composition, or average body sizes. Discrepancies due to methodological biases may have occurred because of associated venipuncture or exercise stress on the day of the examination; differences in selection of blood pressure cuff sizes; differences in the number of measurements averaged. In several studies, small sample sizes for each age-race-sex subclass accounted for considerable variability of the 95th percentile value. The implication of this analysis is that before the 95th percentile norms for children of different ages, races, and sexes can be more firmly established, it is necessary to collect larger sample sizes controlling for known biasing factors and using a standardized methodology.
Increased body size is often found in children with elevated blood pressures, but it is not clear whether this is a result of obesity or early maturity. Similarly, levels of activity and fitness have marked effects on blood pressure and body composition. To study these interrelated factors, we measured height, weight, and body composition (skinfold thickness and total body water) as well as heart rate, blood pressure, and oxygen consumption at rest and during exercise in 192 ninth grade boys and girls, 102 with persistently elevated blood pressures at or above the 95th percentile and 90 matched controls with blood pressures below the 50th percentile for the entire population of 10,641 Dallas County ninth graders tested. Differences in resting blood pressures also were present during maximal exercise and recovery periods. Boys with persistently elevated blood pressures were characterized by increased supine and recovery heart rates, normal fitness, excess size for age in the absence of obesity, and early maturation. Girls with persistently elevated blood pressures had increased heart rates, decreased fitness, and obesity.