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Biomedical subjects

R H Beekman

Publications and source records attributed to R H Beekman.

At least 109 records · Page 6Linked to original sources
PubMed1988

Acute hemodynamic effects of nifedipine in infants with bronchopulmonary dysplasia and pulmonary hypertension.

The acute hemodynamic effects of nifedipine were evaluated and compared to the effects of 95% oxygen in six children with bronchopulmonary dysplasia and pulmonary artery hypertension. The children ranged in age from 7-26 months and all were oxygen dependent. In the cardiac catheterization laboratory, hemodynamic data were collected in 95% oxygen, room air, and 15 and 30 min after nifedipine administration (0.5-0.6 mg/kg per nasogastric tube). Compared to values in room air, nifedipine resulted in a 34% decrease in pulmonary artery mean pressure (from 69.3 +/- 2.4 to 45.8 +/- 1.2 mm Hg, p = 0.03) and a 49% decrease in pulmonary vascular resistance (from 14.8 +/- 1.4 to 7.5 +/- 0.9 U/m2, p = 0.03). A linear relationship was found between the arterial pO2 and the change in the ratio of pulmonary to systemic resistance after nifedipine (% decrease in Rp/Rs ratio = 86.3 - 1.3 x pO2, r = -0.95, p = 0.004) suggesting that nifedipine may act to oppose the vascular effects of arterial hypoxemia. There was no significant change in heart rate, arterial pO2, or pCO2 with nifedipine, but cardiac output increased significantly. Compared to 95% oxygen, nifedipine achieved a lower pulmonary vascular resistance (7.5 +/- 0.9 versus 10.9 +/- 1.2 U/m2, p = 0.03) and a greater cardiac output (5.25 +/- 0.71 versus 3.54 +/- 0.35 liter/min/m2, p = 0.03) with comparable systemic oxygen delivery (699 +/- 85 ml versus 698 +/- 91 ml O2/min/m2, p = 1.0). Thus, nifedipine is an acute pulmonary vasodilator in some children with bronchopulmonary dysplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1988

Repair of interrupted aortic arch in infancy.

Twenty-one patients undergoing repair of interrupted aortic arch between December of 1979 and January of 1987 were reviewed to determine the cause(s) of late morbidity and mortality. Ten underwent staged repair, and 11 had complete repair including all coexisting defects at the initial operation. Sixty-two percent are alive and clinically well 6 months to 6 years after the initial operation. Among the five patients who died late postoperatively, four had severe left ventricular outflow tract obstruction. Two other patients have had surgical relief of severe subaortic stenosis. In addition, significant recurrent or residual coarctation was found in four patients; it was relieved by balloon angioplasty in two patients, and two had surgical repair. None of the most recent seven patients, however, have had a residual ascending-descending aortic gradient. Careful follow-up for the detection of previously masked or newly developed left ventricular outflow tract obstruction is imperative and may be lifesaving.

Aorta, Thoracic↗
PubMed1988

Arterial repair for transposition of the great arteries and large ventricular septal defect in early infancy.

Arterial repair for transposition of the great arteries and large ventricular septal defect (VSD) may be superior to atrial correction, but the risk of either approach in early infancy has been high. The results of early correction were therefore assessed in 12 children with transposition of the great arteries and a large VSD who underwent arterial repair. Patients ranged in age from 3 to 90 days (median age, 19 days) and in weight from 2.5 to 3.7 kg. The VSD was infundibular in eight, inlet in three, and muscular in one. Coronary artery anomalies were present in five patients, including one patient with a single left coronary artery. There was one early death (8%) in the only patient with a pulmonary artery band. There were no late deaths. The 11 survivors have been followed up from 2 to 59 months (mean follow-up period, 20 months) and remain free of cardiac symptoms. Catheterization (n = 5) and Doppler echocardiography in all patients show no significant left ventricular outflow obstruction, aortic insufficiency, or residual VSD. Catheterization documented normal pulmonary artery pressure and unobstructed coronary arteries. Only one patient had significant pulmonary stenosis and underwent successful reoperation. These data indicate that arterial repair and VSD closure can be successfully performed in early infancy with low mortality and morbidity. Repair in this age group is advocated before changes of pulmonary vascular disease occur.

Angiography↗
PubMed1988

Lymphocyte phenotyping of infants with congenital heart disease: comparison of cell preparation techniques.

The diagnostic evaluation of infants with suspected DiGeorge syndrome includes peripheral blood lymphocyte phenotype analysis by flow cytometry. Mononuclear cells are typically concentrated from infants' blood samples by Ficoll-Hypaque (FH) density gradient centrifugation prior to monoclonal antibody (Mab) staining. Having observed that lymphocyte percentages in samples prepared by this technique were low more often than anticipated based on the prevalence of the suspected diagnosis, we undertook a prospective study of 55 infants with congenital heart disease comparing FH with a whole-blood (WB) technique. Sixty healthy adult controls were similarly studied. We report the observation that FH-prepared mononuclear cells from blood samples of infants less than 4 months of age yield substantially different phenotypes than WB-prepared samples. The differences are related to red blood cell (RBC) contamination. No such difference was seen with adult samples. Unlike FH-prepared adult samples, contaminating RBCs are indistinguishable from lymphocytes through at least 4 months of age when assessed by the standard cytometric gating parameters of forward and 90 degrees light scatter. The use of a WB ammonium chloride lysis technique is recommended as most appropriate for the preparation of infants' blood samples.

Antigens, Surface↗
PubMed1987

Sinus of Valsalva aneurysm complicating bacterial endocarditis in an infant: diagnosis with two-dimensional and Doppler echocardiography.

Sinus of Valsalva aneurysm is a rare complication of bacterial endocarditis in infancy and childhood. This report describes an infant with congenital aortic stenosis who developed bacterial endocarditis after abdominal surgery and placement of indwelling central venous catheters for long-term parenteral nutrition. Bacterial endocarditis in this infant was complicated by the development of an aneurysm of the left sinus of Valsalva. Surgical intervention was necessary because of gradual expansion of the aneurysm with compression of the adjacent right pulmonary artery and descending aorta. Two-dimensional and Doppler echocardiography proved useful for the initial diagnosis and serial follow-up of this unusual disorder and for its successful surgical management.

Aortic Aneurysm↗
PubMed1987

Quinidine syncope in children.

Quinidine syncope and factors associated with it are well known among adult patients treated for cardiac arrhythmias. To define factors that may influence the occurrence of syncope in children taking quinidine, the clinical, anatomic, electrocardiographic, roentgenographic and pharmacologic data were compared in six patients with syncope (Group A) and 22 patients without syncope (Group B). There was a significant (chi-square = 10.2, p = 0.001) relation between heart disease and quinidine syncope: all six Group A (syncopal) patients had heart disease whereas 15 of the 22 Group B (non-syncopal) patients had no structural heart disease. In contrast, no significant difference was noted between Group A and Group B patients in mean age (11.4 versus 11.4 years), mean quinidine serum concentration (2.9 versus 2.3 micrograms/ml), mean corrected QT interval before quinidine (0.43 versus 0.40 second) or mean corrected QT interval during quinidine therapy (0.46 versus 0.46 second) or between those taking digitalis and those not. Two of the six Group A (syncopal) patients died during therapy, one 6 days after initiating therapy and one suddenly at home 6 months after beginning quinidine. Another two of the six Group A patients exhibited hypokalemia (both 2.9 mEq/liter) at the time of syncope, 2 weeks and 6 months, respectively, after initiation of quinidine therapy; both survived. Syncope occurred within 8 days of initiation of quinidine therapy in three of the six patients. Sustained ventricular tachycardia was observed during quinidine associated arrhythmia in three of six patients with syncope; nonsustained ventricular tachycardia or complex ventricular ectopic activity while on this therapy was observed before syncope in the other three patients in Group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1987

Percutaneous balloon angioplasty for native coarctation of the aorta.

Twenty-six children, aged 5 weeks to 14.7 years, underwent percutaneous balloon angioplasty for a discrete native coarctation of the aorta. The procedure reduced the systolic coarctation gradient acutely in all children. The mean systolic gradient decreased by 75%, from 48.6 +/- 2.4 before to 12.3 +/- 1.9 mm Hg after angioplasty (p less than 0.001). Long-term results were evaluated in 14 children by follow-up catheterization 12 to 26 months (mean 15.3) after angioplasty. At follow-up, the residual gradient averaged 11.7 +/- 3.7 mm Hg (range -5 to 36) and had not changed from that measured immediately after angioplasty (p = 0.64). Compared with preangioplasty values, the systolic pressure in the ascending aorta had improved substantially at follow-up (116.0 +/- 3.2 versus 143.9 +/- 3.1 mm Hg, p less than 0.001). On the basis of follow-up data, two groups of children were identified: Group 1 consisted of nine children with a good result, defined as a residual gradient less than 20 mm Hg and no aneurysm; Group 2 consisted of five children with a poor result, four with a residual gradient greater than 20 mm Hg (range 25 to 36) and one with an aneurysm at the dilation site. There was no statistical difference between the two groups in age at angioplasty, balloon size, ratio of balloon to isthmus diameters, follow-up duration, heart rate or cardiac output. However, of the four children with a residual gradient greater than 20 mm Hg, two were the youngest in the study, and in two the aorta was inadvertently dilated with a balloon 4 to 5 mm smaller than the isthmus diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Paradoxical hypertension after repair of coarctation of the aorta in children: balloon angioplasty versus surgical repair.

The incidence and possible causes of paradoxical hypertension were evaluated in eight children who underwent balloon dilatation and seven children who underwent surgical repair of coarctation of the aorta. Both procedures resulted in a significant reduction in the coarctation gradient. Both systolic and diastolic blood pressures increased in the surgical group after repair, whereas systolic pressures decreased and diastolic pressures remained unchanged after balloon angioplasty. In the surgical group, but not in the balloon angioplasty group, plasma catecholamines and plasma renin activity rose during the first 2 days after relief of the coarctation. The data presented in this report support the hypothesis that the sympathetic nervous system and the renin angiotensin system are important mediators of the paradoxical hypertension that occurs after surgical repair of coarctation. Furthermore, balloon angioplasty of coarctation of the aorta does not stimulate either system and thus paradoxical hypertension is not a complication of this procedure.

Angioplasty, Balloon↗
PubMed1986

The congenital long QT syndrome. An unusual cause of childhood seizures.

The congenital long QT syndrome is an unusual disorder characterized by Q-T interval prolongation on electrocardiogram that predisposes the heart to ventricular tachycardia and fibrillation. We describe herein four patients with the congenital long QT syndrome who initially presented with generalized seizures. Three of these children were initially misdiagnosed as having a primary seizure disorder. The causal relationship of complex ventricular arrhythmias to seizure activity was documented in each child. This experience emphasizes the importance of obtaining an electrocardiogram in all children with a seizure disorder of unknown origin.

Arrhythmias, Cardiac↗
PubMed1986

Exercise-induced hypertension after repair of coarctation of the aorta: arm versus leg exercise.

The etiology of exercise-induced upper limb hypertension after repair of coarctation of the aorta is unknown. We hypothesized that blood flow across the coarctation repair site is a major determinant of such exercise-induced hypertension. Because arm ergometry should produce a smaller increase in descending aortic blood flow than treadmill exercise, we compared the changes in upper limb pressure and the coarctation gradient produced by each type of exercise at equivalent levels of heart rate and peak oxygen consumption in 28 children with repaired coarctation of the aorta. The children were classified into three groups: Group I, resting gradient less than 15 mm Hg and treadmill gradient less than 20 mm Hg; Group II, resting gradient less than 15 mm Hg and treadmill gradient greater than 20 mm Hg; and Group III, resting gradient greater than or equal to 15 mm Hg. Twelve children with no heart disease served as control subjects. All children were exercised to exhaustion with 45 minutes' rest between the two exercise protocols. There were no differences in maximal heart rate and oxygen consumption between the two types of exercise. In all groups, treadmill exercise produced a larger increase in arm systolic blood pressure and arm-leg gradient than did arm exercise. With treadmill exercise coarctation Groups II and III developed a greater rise in both arm-leg gradient and arm systolic pressure than was observed in the control subjects (p less than 0.05). However, with arm exercise, Group III developed a significantly greater rise in both arm pressure and arm-leg gradient (p less than 0.05) than was observed in the control subjects.

Adolescent↗
PubMed1986

Long-term outcome after repair of coarctation in infancy: subclavian angioplasty does not reduce the need for reoperation.

To assess the influence of surgical technique on the need for reoperation after coarctation repair in infancy, follow-up data were analyzed for 125 consecutive infants (less than 12 months) who underwent repair of coarctation of the aorta by subclavian angioplasty or resection and end to end anastomosis. Sixty-three infants underwent coarctation repair by resection between 1960 and 1980, and 62 underwent subclavian angioplasty between 1977 and 1985. The mean age (+/- SEM) at operation for infants with subclavian flap angioplasty was 1.54 +/- 0.93 months and for infants with resection was 2.70 +/- 0.93 months (p = 0.02). There was no difference between the groups in patient weight at initial repair or the proportion of patients with complex anatomy or aortic arch hypoplasia. Follow-up duration for the subclavian flap group was 2.55 +/- 0.51 years (range 0.3 to 8.2), and for the resection group was 7.97 +/- 3.61 years (range 0.6 to 21). Indication for reoperation was the presence of a coarctation gradient at rest of 40 mm Hg or greater and arm hypertension. Reoperation was required in 5 patients in the subclavian flap group and 12 patients in the resection group. The mean reoperation rate after subclavian flap repair was 0.0356 reoperations per patient-year, and after resection was 0.0342 reoperations per patient-year (p = 0.94). To determine an individual's risk of requiring reoperation from these group measures, a reoperation risk model was developed. The risk of reoperation by the fifth postoperative year was found to be 16.3% after subclavian flap repair and 15.7% after resection.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1986

Comparison of high pulse repetition frequency and continuous wave Doppler echocardiography for velocity measurement and gradient prediction in children with valvular and congenital heart disease.

To compare the ability of high pulse repetition frequency and continuous wave Doppler echocardiography to detect the peak velocity of a jet flow disturbance and to predict pressure gradients accurately, two groups of children with valvular or congenital heart disease were examined using both Doppler techniques. The use study group included 84 children or adolescents (aged 1 day to 19 years) who underwent examination in the echocardiography laboratory with both Doppler techniques in a randomized sequence. The peak velocity recorded with high pulse repetition frequency Doppler echocardiography was compared with the peak velocity recorded with the continuous wave technique. The accuracy study group included 41 children or adolescents (aged 1 day to 16 years) who underwent examination with both Doppler techniques at the time of cardiac catheterization. Doppler pressure gradients were calculated from the peak velocity using the simplified Bernoulli equation and were compared with peak instantaneous gradients and peak to peak gradients measured at catheterization. In the use study, a high correlation was found between peak velocities detected by high pulse repetition frequency and continuous wave Doppler echocardiography (r = 0.94, SEE = 0.28 m/s). In the accuracy study, close correlations were found between measured peak to peak pressure gradients and pressure gradients calculated from continuous wave (r = 0.95, SEE = 7.9 mm Hg) and high pulse repetition frequency Doppler echocardiography (r = 0.94, SEE = 8.7 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Balloon angioplasty in the treatment of pulmonary valve stenosis and coarctation of the aorta.

When balloon angioplasty of the pulmonary valve was attempted in 42 children, aged 1 day to 19 years (mean, 3.1 years), immediate relief of pulmonary stenosis was achieved in 37 cases. In two groups, angioplasty was not uniformly successful: these included (1) two neonates and (2) three out of seven children with dysplastic pulmonary valves, who had an unsuccessful early result. Long-term (>1-year) follow-up of 28 successful cases supports the contention that balloon angioplasty provides effective long-term relief of pulmonary valve stenosis and that it should be considered the treatment of choice for this lesion. The results of angioplasty were also studied in 36 children who underwent this procedure to treat coarctation of the aorta (involving 21 native and 15 recurrent lesions). Angioplasty effectively relieved the obstruction in 30 cases (17 native and 13 recurrent lesions). In the six unsuccessful cases, poor hemodynamic results were due to age (three failures occurred in children less than 2 years old), tubular hypoplasia of the aorta (in one case), and the use of an undersized angioplasty balloon (in four cases, the diameter of the balloon was > or =3 mm less than that of the aortic isthmus). The 36 patients had two major complications: A cerebral vascular accident occurred in one case, and a late aortic aneurysm developed in another. Our results indicate that angioplasty is an effective form of therapy for most cases of coarctation of the aorta (whether native or recurrent).

Journal Article↗
PubMed1986

Exercise recommendations for adolescents after surgery for congenital heart disease.

Due to recent improvements in medical and surgical therapy, many children with congenital heart disease are now surviving to adolescence and beyond. The pediatrician is thus presented with a new challenge: caring for the adolescent and young adult with surgically corrected congenital heart disease. The purpose of this paper is to provide recommendations regarding exercise and sports participation for adolescents after surgical repair of congenital heart disease. Four major defects are discussed in detail: aortic stenosis, coarctation of the aorta, tetralogy of Fallot and transposition of the great arteries. Exercise restrictions must be based on a thorough knowledge of each patient's postoperative hemodynamic and electrophysiologic abnormalities, and his or her response to exercise. It is emphasized that, with reasonable limits, adolescents with surgically repaired congenital heart disease should be allowed to pursue a normal, active life-style.

Activities of Daily Living↗