Edwin C. McGough

Comparison of angioplasty and surgery for unoperated coarctation of the aorta.

BackgroundThe use of balloon coarctation angioplasty instead of surgery as treatment for unoperated coarctation of the aorta is controversial. The efficacy and complications of the two procedures have not been studied before in a prospective fashion. Methods and ResultsThirty-six patients were prospectively randomized to either angioplasty (20 patients) or surgery (16 patients). Immediate results and patient follow-up, including physical examination, angiograms, and magnetic resonance imaging, were compared between groups. Reduction in peak systolic pressure gradient across the coarctation was similar (86%) immediately after both balloon coarctation angioplasty and surgery. On follow-up, aneurysms were seen only in the angioplasty group (20%) and not in the surgery group (0%o). No aneurysms have shown progression or required surgery. The incidence of other complications was similar in both groups, although two patients experienced neurological complications after surgery. Although not statistically different, the incidence of restenosis (peak systolic pressure gradient 220 mm Hg) tended to be greater in the angioplasty group (25%) than in the surgery group (6%). Restenosis after angioplasty occurred more frequently in patients with an aortic isthmus/descending aorta diameter ratio <0.65 and was associated with an immediate catheterization residual peak systolic pressure gradient across the coarctation 212 mm Hg. ConclusionsImmediate gradient reduction is similar after balloon coarctation angioplasty and surgical treatment of unoperated coarctation of the aorta. The risks of aneurysm formation and possibly restenosis after angioplasty are higher than after surgery, although the risks of other complications are similar. Balloon coarctation angioplasty may provide an effective initial alternative to surgical repair of unoperated coarctation of the aorta in children beyond infancy, particularly in patients with a well-developed isthmus. Further follow-up is necessary to determine the long-term risks of postangioplasty aneurysms.

Mid-term results after bidirectional cavopulmonary shunts

Despite the increasing use of the bidirectional cavopulmonary shunt, little is known about the late results, the duration of palliation, and the frequency with which this procedure allows later successful conversion to a Fontan type of procedure. We reviewed our experience (1984 to 1992) in 38 consecutive children, ages 4 months to 16 years (mean, 4.0 years), who underwent a bidirectional cavopulmonary shunt procedure. All had a single functional ventricle and represented high risks for the performance of a Fontan procedure based on anatomic and hemodynamic criteria. The oxygen saturation in these patients improved from a preoperative value of 75% +/- 7% to 82% +/- 7% (p < 0.05) at late cardiac catheterization by a mean of 24 months after operation. The actuarial survival, including early deaths and that associated with all secondary procedures, was 86% at 1 year and 81% at 6 years. Early deaths occurred in 5.3% (2/38) and late deaths in 11% (4/36). Late follow-up ranged from 5 to 90 months (mean, 37 months). Conversion to a Fontan or fenestrated Fontan procedure was accomplished in 21 early survivors (21/36; 58%) by a mean of 26 months after the bidirectional cavopulmonary shunt procedure, with one operative and no late deaths (1/21; 4.8%). Three additional patients have undergone late reoperation, including 2 requiring cardiac transplantation and 1 undergoing the late creation of an axillary artery-to-vein fistula for the treatment of cyanosis. The midterm survival after a bidirectional cavopulmonary shunt procedure appears to be excellent, and it serves as a good staging procedure for patients who represent high risks for a Fontan procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Current results with intraaortic balloon pumping in infants and children

BACKGROUND Intraaortic balloon pumping (IABP) is useful for support in patients with moderate left ventricular dysfunction. IABP is usually timed with the R wave of the electrocardiogram. We have utilized M-mode echocardiography timed IABP in children with left-side heart failure since 1994. Electrocardiogram timing seems inappropriate for children, who have much higher heart rates. We describe our experience with children who underwent IABP therapy before and after 1994, when echocardiographic timing was instituted. METHODS We reviewed records of 29 children who underwent IABP for all indications at Primary Childrens Medical Center since 1988. RESULTS Overall survival was 62.1% (18 of 29) in this series. Survival was similar for infants (odds ratio = 2.0, 95% confidence interval = 0.29 to 14.31, p = 0.43) and older children. Survival was similar in the echocardiography era when compared with the electrocardiogram era (odds ratio = 2.4, 95% confidence interval = 0.56 to 10.4, p = 0.44). CONCLUSIONS IABP is a useful means of support in children with left ventricular dysfunction. M-mode echocardiography is effective in triggering IABP. The sample size in this study is too small to detect a mortality rate difference.

Amrinone-associated thrombocytopenia : pharmacokinetic analysis

Amrinone‐associated thrombocytopenia is thought to result from nonimmune‐mediated peripheral platelet destruction. Platelet destruction may be a concentration‐dependent toxic effect of amrinone or its principal metabolite N‐acetylamrinone. Eighteen children receiving amrinone after heart surgery were prospectively evaluated to correlate the pharmacokinetics of amrinone and N‐acetylamrinone with thrombocytopenia. Amrinone and N‐acetylamrinone plasma concentrations were determined by HPLC during loading, infusion, and terminal elimination, with concurrent monitoring of platelet counts. Thrombocytopenia developed in eight patients (platelet count, 66 ± 17 x 109 platelets/L [mean ± SD]). Peak and steady‐state amrinone plasma concentration, amrinone total dose, duration of amrinone exposure, and amrinone area under curve (AUC) were similar between patients with and without thrombocytopenia. N‐Acetylamrinone peak concentration, steady‐state concentration, N‐acetylamrinone AUC, and ratio of N‐acetylamrinone to amrinone were greater in patients with thrombocytopenia. This association suggests that N‐acetylamrinone, and not amrinone, may be the mediator of thrombocytopenia in children receiving amrinone.

Surgical treatment of patent ductus arteriosus in preterm infants

SummarySeventy-nine consecutive patent ductus arteriosus (PDA) ligations were performed in our newborn intensive care unit (NBICU) over a four-year period. Seven infants (9%) died within one month after surgery. The deaths were not attributed to the surgery but were associated with preexisting medical complications or new intracranial hemorrhages. Significant surgical morbidity was rare. We conclude that ligation of the PDA in the premature infant can be a safe and effective procedure, when pharmacologic closure is ineffective or contraindicated. Furthermore, PDA ligation may be safely performed in the NBICU.

Estimation of timing errors for the intraaortic balloon pump use in pediatric patients.

The use of the intraaortic balloon pump (IABP) for managing acute left ventricular failure in pediatric patients is less successful than in adults. It is often reported that rapid pediatric heart rates make accurate timing difficult to achieve. Traditional IABP theory requires that the balloon inflate during diastole (after aortic valve closure), for optimum coronary pressure and flow augmentation, and deflate just before the next systole for optimal ventricular afterload reduction. Errors in timing balloon inflation and deflation may result in the reduced IABP efficacy seen in children. To investigate timing errors when using the traditional IABP inflation and deflation markers in pediatric patients, six patients (age, 2.2+/-1.4 years; weight, 11.5+/-3.9 kg) were studied intraoperatively. Radial artery pressure (RAP) waveforms from a standard, fluid-filled pressure monitoring system were recorded on an FM data tape recorder simultaneously with high-fidelity, aortic root pressure waveforms, aortic root flow waveforms, and M-mode echocardiography. For each patient, a sequence of five recorded waveforms was analyzed. The mean +/- standard deviation of the time delay between aortic root and RAP markers and percentage delay of the corresponding part of the cardiac cycle were determined. When compared with aortic root waveforms, the RAP waveform consistently showed a delay in the IABP timing markers. A 107+/-23 msec (53+/-11%) delay in diastolic inflation and a 92+/-11 msec (40+/-4%) delay in presystolic deflation was found. If IABP timing to the RAP markers were to be used, the delay in IABP inflation would result in reduced diastolic augmentation, and the delay in IABP deflation into the systolic period would increase afterload. M-mode echocardiography provided timing markers that were identical to those provided by high-fidelity aortic root pressure waveforms. The combined effect of these delays on IABP function could substantially reduce the efficacy of the IABP in pediatric patients, indicating the need for more accurate indices for IABP timing in this patient group.

Effects of homograft blood type and anatomic type on stenosis, regurgitation and calcium in homografts in the pulmonary position.

The use of both aortic and pulmonary homografts in the pulmonary position for treatment of right ventricular or pulmonary outflow tract obstruction has gained widespread popularity.1–3 Although this homograft tissue presents a potential allogeneic stimulus to the recipient, little is known about the effects of blood-type (ABO) compatibility or incompatibility on homograft function.4 This study retrospectively reviews the outcome of homografts in the pulmonary position in 39 consecutive children who had placement of an aortic or pulmonary homograft in the pulmonary position for treatment of pulmonary outflow tract obstruction.

Age-related amrinone pharmacokinetics in a pediatric population.

ObjectivesTo measure the plasma concentrations of amrinone and N-acetyl-amrinone achieved using current pediatric dosing recommendations. To examine the pharmacokinetics of amrinone in an extended age range of pediatric patients. To examine any age-related differences in the relative contribution of hepatic metabolism vs. renal elimination of amrinone. DesignProspective study. SettingA pediatric intensive care unit in a tertiary care teaching hospital. PatientsThirty-one patients aged 4 days to 15 yrs who required a constant infusion of amrinone. InterventionsBlood samples were obtained 15 mins after each 0.75 mg/kg loading dose, and every 6 hrs during a constant infusion of amrinone to measure plasma amrinone, N-acetyl-amrinone and N-glycolyl-amrinone concentrations by high-performance liquid chromatography. Blood samples to measure amrinone, N-acetyl-amrinone, and N-glycolyl-amrinone concentrations during elimination were also obtained at regular intervals after discontinuation of the infusion. Six-hour urine collections were obtained to measure amrinone renal clearance. Measurements and Main ResultsPlasma amrinone concentrations ≥2 μg/mL were obtained in 13 of 14 patients after a 3-mg/kg loading dose. There was a six-fold variability in steady-state plasma amrinone concentrations in patients receiving the same ordered infusion rate. There was a significant (p = .001) difference between the ordered and measured amrinone infusion rates. Six (19.4%) of 31 patients had steady-state plasma amrinone concentrations of ≤2 μg/mL. There was a large variability in the volume of distribution, clearance, and elimination half-life which did not appear to be age-related. Renal clearance of amrinone ranged between 0.4 and 2.18 mL/kg/min, and did not increase with age. There was no increase in the proportion of children with a high plasma steady-state N-acetyl-amrinone/amrinone ratio over time from 1 to 24 months of life. ConclusionsAdministering a 3-mg/kg amrinone loading dose in four divided doses over 1 hr resulted in relatively rapid therapeutic plasma concentrations without excessively high concentrations and good clinical tolerance. The wide interindividual variation in clearance and volume of distribution resulted in a variable dose-concentration relationship; children receiving lower amrinone infusion rates may have subtherapeutic plasma steady-state concentrations. There did not appear to be any age-related change in renal clearance or hepatic metabolism of amrinone in children aged 1 to 24 months. (Crit Care Med 1994; 22:1016–1024)

Separation of conjoined thoracopagous twins joined at the right atria

A case of conjoined thoracopagous twins with a shared atrial myocardium who were successfully surgically separated is described. Twin B had hypoplastic right heart syndrome and was dependent on Twin A for oxygenation of her blood. The twins were surgically separated by dilating Twin Bs ductus arteriosus with an infusion of prostaglandin E1 and creating an aortopulmonary shunt to increase her pulmonary blood flow; both twins survived the operation. However, 1 week after surgery Twin B had hepatic and renal failure and died.

Acute Traumatic Rupture of the Aorta: A Reemphasis of Repair Without a Vascular Prosthesis

Abstract The incidence of acute aortic rupture has paralleled the increasing number of high-speed vehicles on our highways. Repair of acute aortic rupture without a vascular prosthesis has been mentioned frequently but seldom applied. Three consecutive patients with acute rupture repaired without a vascular prosthesis are discussed. The advantages of this technique are reviewed, and technical factors of the operation are described.