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Biomedical subjects

G A Serwer

Publications and source records attributed to G A Serwer.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1987

Evaluation of pacemaker pulse generator and patient longevity in patients aged 1 day to 20 years.

The longevity of pediatric patients requiring pacemakers and the survival rates of the implanted generators were evaluated. From January 1970 to December 1985, 96 patients aged 1 day to 20 years underwent 162 pulse generator implantation procedures. Indication for initial implantation was surgically induced heart block in 52 patients, sick sinus syndrome in 20, congenital complete heart block with symptoms of low cardiac output in 19 and tachydysrhythmia control in 5. Modal age at initial implantation was less than 1 year; median age was 5 years. During this period 90 generators were removed from service: 49 (54%) because of generator failure, 22 (24%) because the patient died, 12 (13%) because of elective upgrade at the time of lead failure or cardiac surgery, 5 (6%) because of generator pocket infection and 2 (2%) because of manufacturer's recall. Pulse generators were separated into 4 groups based upon generator technology. Group I (n = 16) were asynchronous units with mercury-zinc batteries; group II (n = 18) were single-chamber demand units with mercury-zinc batteries; group III (n = 14) were single-chamber demand units with rechargeable batteries; and group IV (n = 114) were single- or dual-chamber demand units with lithium batteries. Patient survival rate was 84% at 6 months and 70% by 109 months. There was no further decrease to the end of the study period. Six-month generator survival rate was 82% for all groups, mostly a reflection of patient deaths.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
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↗
PubMed1986

Factors affecting use of the Doppler-determined time from flow onset to maximal pulmonary artery velocity for measurement of pulmonary artery pressure in children.

Measurement of the time from onset to maximal or peak velocity (TPV) of pulmonary artery (PA) flow has been proposed as a noninvasive means of determining PA pressure. The effects of age, heart rate, increased PA pressure and flow, pulmonary valve obstruction and altered PA vascular resistance on this measurement were evaluated. In 84 children, aged 1 day to 18 years, TPV was measured using continuous-wave Doppler echocardiography. The children were separated into 3 groups. Group I (n = 33) consisted of children with no cardiovascular abnormalities. Group II (n = 33) consisted of children with a variety of cardiovascular diseases producing varying PA pressures and flows. Group III (n = 18) consisted of children who had valvular pulmonic stenosis with PA to right ventricular gradients greater than 40 mm Hg. Doppler studies of group II and III patients were performed in conjunction with measurement of PA pressures and flows at the time of cardiac catheterization. In group I TPV showed a significant negative linear correlation with heart rate (r = -0.86, p less than 0.001). The ratio of observed TPV to predicted TPV (TPVN) determined using the regression equation for TPV vs heart rate or TPV/TPVN was heart rate- and age-independent (p greater than 0.1) and ranged from 0.81 to 1.31 (mean 1.005). In group II TPV/TPVN was inversely related to the natural log of the PA pressures (systolic, r = -0.91; mean, r = -0.87; diastolic, r = -0.82; all p less than 0.01), whether pressure elevation was due to increased flow, resistance or left atrial hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Physiological rationale for a bidirectional cavopulmonary shunt. A versatile complement to the Fontan principle.

The original Fontan procedure included a classic superior vena cava-to-right pulmonary artery (Glenn) shunt. Subsequent experience demonstrated that this anastomosis was not essential and was an unnecessary commitment of the larger right pulmonary circulation to the smaller blood volume of the superior vena caval return. With application of the Fontan principle to more complex cardiac malformations, there has been a reconsideration of possible benefits of a cavopulmonary shunt in selected patients. A modified shunt from the divided end of the superior vena cava to the side of the undivided right pulmonary artery utilized in 21 patients is described. This shunt is designed to allow bidirectional pulmonary arterial distribution of both superior vena caval inflow and right atrial outflow after completion of the Fontan procedure. Twelve patients had the bidirectional shunt performed prior to a Fontan operation; five of these had a subsequent atriopulmonary connection and seven await operation. Eight patients had construction of this shunt at the time of their Fontan procedure. One patient had a bidirectional shunt constructed following atriopulmonary anastomosis to help relieve right atrial outflow obstruction. Two patients with univentricular heart undergoing simultaneous Fontan procedure and a bidirectional shunt died while in the hospital. The remaining 19 patients have been followed up for 2 months to 9 years with one late sudden death at 9 years. There have been no bidirectional cavopulmonary shunt failures, stenoses, kinks, or recognized pulmonary arteriovenous malformations. Postoperatively, eight patients had assessment of pulmonary distribution of shunt blood flow by angiography. Seven of these patients were also evaluated by radionuclide angiography. Superior vena caval blood flow via the bidirectional cavopulmonary shunt tended to be greater to the right lung, but bilateral pulmonary flow was documented in all but one patient. After Fontan operation, six of seven patients tested also demonstrated bilateral distribution of atriopulmonary flow. We concluded from our experience that this modified shunt provides excellent relief of cyanosis, allows bidirectional pulmonary distribution of both superior vena caval return and also the right atrial blood flow after atriopulmonary connection, and may be done before, with, or after a Fontan procedure and is compatible with all currently recommended modifications. Perioperative hemodynamic adjustments to the Fontan procedure may be improved by reducing atrial volume, and this may also be of potential benefit in the long-term adaptation to Fontan physiology by minimizing atrial distention.

Arteriovenous Shunt, Surgical↗
PubMed1982

Heart block in children. Evaluation of subsidiary ventricular pacemaker recovery times and ECG tape recordings.

To evaluate subsidiary ventricular pacemaker function in 20 children with congenital or surgically induced complete heart block, we measured recovery times following overdrive ventricular pacing. Long-term ECG tape recordings were performed in eight of these children. Ages ranged from 1 month to 17 years. The resting R-R intervals ranged from 595 to 1,740 msec. The ventricles were paced at various cycle lengths of 400 to 1,000 msec with either transvenous electrode catheters or surgically implanted epicardial electrodes. His bundle recordings showed that the site of block did not allow separation of patients with symptoms from those without symptoms. Prolonged recovery times were present in patients with block above the His bundle recording site who had symptoms of syncope or dizziness, as well as in patients who had a wide QRS. However, some asymptomatic patient with heart block above the His bundle recording site also had long recovery times. None of the asymptomatic patients who had ECG tape recordings had paroxysmal tachycardia in more than 300 hours of recordings. However, one symptomatic patient with congenital heart block and a prolonged recovery time had brief episodes of paroxysmal ventricular tachycardia that produced no symptoms at the time of recording. The results suggest that the coexistence of prolonged recovery times and paroxysmal tachycardia may be predisposing factors to the development of symptoms in patients with complete heart block. We believe that further electrophysiologic investigation of this possibility is warranted in patients with heart block.

Adolescent↗
PubMed1982

Indomethacin and the preterm infant with a patent ductus arteriosus: relationship between plasma concentration and ductus closure.

The relationship of indomethacin pharmacokinetics to clinical and echocardiographic evidence of closure of the patient ductus arteriosus (PDA) is described in 9 preterm infants. PDA closures occurred in 4 infants when peak indomethacin plasma concentrations were 0.71-1.10 micrograms/ml, mean 0.93 +/- 0.16 microgram/ml. With partial or no PDA response to oral treatment, the peak concentrations were 0.20-0.69 microgram/ml, mean 0.57 +/- 0.08 microgram/ml, p less than 0.01. The left atrial size in the study infants correlated inversely with the indomethacin peak concentrations, r = 0.75. The plasma apparent terminal half-life correlated with postnatal age, r = 0.75. All patients with peak concentrations greater than 0.50 microgram/ml had transient oliguria. This study suggests that a minimum indomethacin concentration may be needed to promote PDA constriction.

Bacterial Infections↗
PubMed1982

Abnormal cerebral hemodynamics in preterm infants with patent ductus arteriosus.

Blood flow patterns in the anterior cerebral arteries were studied in eight preterm infants with patent ductus arteriosus and left-to-right shunts. A noninvasive Doppler technique was used to obtain the blood flow patterns and to calculate a pulsatility index. Advancing diastolic blood flow was decreased in all eight infants, and two demonstrated retrograde anterior cerebral artery flow during diastole. Following ductal closure, the diastolic flow in the anterior cerebral arteries increased significantly, reaching levels seen in normal infants. These observations demonstrate that infants with patent ductus arteriosus and left-to-right shunts may have abnormal cerebral hemodynamics which return to normal following ductal closure.

Blood Flow Velocity↗
PubMed1981

Left atrial myxoma. Is cardiac catheterization essential?

Although uncommon in children, primary cardiac tumors, especially left atrial myxomas, can be cured with surgery. We present our experience with a 12-year old boy with a left atrial myxoma diagnosed by two-dimensional echocardiography who underwent successful surgical resection without prior catheterization. We recommend that all patients suspected of having cardiac tumors undergo echocardiographic evaluation. As this case illustrates, the essential information for surgical management of myxomas can be obtained from two-dimensional echocardiograms, which obviates cardiac catheterization.

Cardiac Catheterization↗
PubMed1980

Nonivasive detection of retrograde descending aortic flow in infants using continuous wave doppler ultrasonography. Implications for diagnosis of aortic run-off lesions.

Continuous wave Doppler ultrasonography was utilized to detect and characterize descending aortic blood flow velocity patterns in 27 preterm and term infants with or without an aortic run-off lesion proximal to the descending aorta. The effects of coexistent intracardiac defects on the velocity time profiles were evaluated by comparing records from patients with no intracardiac defects or systemic run-off lesions to those with a variety of intracardiac defects but no systemic run-off lesion. No significant alterations were noted. In all patients, the velocity tracing in systole was triangular in shape. During diastole, however, there were qualitative and quantitative differences between patients with and without a proximal run-off lesion. In those without a run-off lesion, retrograde descending aortic flow was present only in early diastole, and aortic flow velocity oscillated around the zero baseline during mid and late diastole. In those with a run-off lesion, retrograde flow present in early diastole continued throughout diastole. Quantitatively, the ratio of the area under the retrograde flow portion of the tracing to the forward flow portion was significantly greater in those with a run-off lesion. The velocity time profiles obtained with CW Doppler were similar to those previously obtained invasively with electromagnetic flow probes of catheter-mounted velocitometers. CW Doppler ultrasonograpy provides a reliable, noninvasive method for describing descending aortic blood flow velocity in infants.

Aorta, Thoracic↗