Burton L. Perry

Pacing in children and young adults with nonsurgical atrioventricular block: Comparison of single-rate ventricular and dual-chamber modes

A prospective comparison of physiologic response to single-rate ventricular and dual-chamber atrioventricular pacing was conducted in 14 pediatric patients (age 1 to 24 years, median 14) with symptomatic nonsurgical second- or third-degree atrioventricular block. All patients were studied acutely during cardiac catheterization before and after 1 hour of both pacing modes. Following pacemaker implant, eight patients were reevaluated after 1 month of each mode with symptom questionnaire, resting ECG, resting echocardiogram, and Doppler cardiac output measurement at rest and at peak treadmill exercise. Cardiac outputs (mean +/- standard error) increased acutely (n = 14) with both ventricular (32 +/- 12%) and dual-chamber (39 +/- 10%) pacing over intrinsic rhythm values (p less than 0.01 in both). During chronic pacing (n = 8), symptoms were reported only with the ventricular mode. Dual-chamber synchronous pacing was associated with improved mean resting shortening fraction and cardiac output, slower mean resting sinus rate (89 +/- 5 compared to 73 +/- 4 bpm (p less than 0.02), and a 23% increase in mean excerise cardiac output (4.2 +/- 0.4 compared to 3.4 +/- 0.3 L/min/m2) compared to single-rate ventricular pacing. Exercise-induced dysrhythmias occurred only with ventricular pacing. This study demonstrates that pediatric patients with nonsurgical atrioventricular block can compensate for loss of atrioventricular synchrony at rest but exhibit improved cardiac function with chronic dual-chamber atrioventricular compared to single-rate ventricular pacing.

Surgical and medical results of complete atrioventricular canal: A ten year review

The files of 121 patients who presented to Childrens Hospital of Michigan over the last 10 years with complete atrioventricular (AV) canal were reviewed to evaluate long-term management and overall outcome. Of 121 patients, 70 underwent corrective surgery, 21 (30%) of whom died perioperatively. The surgical mortality rate was 13% when patients with hypoplastic left or right ventricle (n = 6), double-orifice mitral valve or extreme deficiency of mitral tissue (n = 5), and pulmonary vascular obstructive disease (n = 5) were excluded. Of the 49 patients who survived operation, 36 are in New York Heart Association class I, 1 patient requires a pacemaker and 3 died late. In 34 of the 51 patients (28%) who did not undergo operation, pulmonary vascular obstructive disease developed; it occurred within 12 months in 10 patients (8%). Eight other patients who did not undergo operation died before planned surgery (age 1 to 9 months). Although surgical prognosis in good candidates is acceptable, the overall prognosis for children with complete AV canal is guarded because of the risk of early death or early pulmonary vascular obstructive disease and frequently unfavorable anatomy.

Growth hormone levels in children with congenital heart disease.

ology of the lesion and suggests infection, both of which are likely _either trauma or to subside. Hoefnagel and l’enry’ presented six cases of seventh nerve paresis, three of which spontaneously improved. Patient S. MC., whose facial nerve paresis has persisted, has associated left mild hemiparesis and minor motor seizures. Th,is suggests a more central etiology of his neurologic lesion. The purpose of this communication is not only to corroborate the findings of Dr. Cayler, but to caution against the assigning of a single etiology to this combination of lesions.

108 CALCIUM BLOCKERS AFTER B-BLOCKADE IN CONSCIOUS PUPPIES

Following reports of cardiac arrest, acute conversion therapy with verapamll is contralndicated in children on chronic propranlol for recurrent SVT. The exact hemodynamic changes produced by verapamil after β-blockade have not been shown in children or awake, instrumented immature animals. We proposed to document these alterations and compare them to those produced by a similarly effective calcium-blocking agent, diltiazem, potentially of use in pediatrlc patients. Fourteen puppies were chronically instrumented for: aortic flow(CO); regional LV shortenlng(SF); pressures--carotid(MBP), pulmonary(PAP), and left a trial(LAP); heart rate(HR) and P-R interval. Measurements during infusions of each agent at 5-125/μ/kg/min were repeated after a propranolol bolus (0.7-0.9mg/kg) lowered HR 10%, simulating p therapy. Results at maximal infusion (mean ± S.D.; *p (.01):Verapamlls effects before β-blockade were similar to those documented in other studies. Diltiazem produced significantly less decrease in cardiac output (p<.01) both before and after β-blockade. Throughout, LAP rose (p<.01) when CO decreased significantly, while PAP did not change. SF did not show significant changes. 7/14 animals progressed to severe bradycardia after V+P responsive only to Ca++ gluconate infusion with immediate Improvement in CO (p<.01). We have documented verapamlls profound depressant effect in the presence of B-blockade. We also conclude that diltiazem, with similar antlarrhythmlc properties, produces less negative inotropic effect than verapamll in unsedated immature animals.

156 EFFECTS OF COLD CARDIOPLEGIA IN TETRALOGY OF FALLOT REPAIR

The value of cold cardioplegia was studied in 196 successive patients receiving three different methods of myocardial preservation during intracardiac repair of Tetralogy of Fallot. Group A (n=100)were repaired normothermic using intermittent aortic arch clamping (IAAC). Group B (n=43) received moderate hypothermia (28°C)and IAAC. Group C (n=53) were given moderate hypothermia and cold cardioplegia fluid. There was no significant difference in sex, type of right ventricular outflow tract obstruction or pre-op hemoglobin between groups. More Group A patients had a previous shunt (p<01) and had higher pre-op systemic saturations (p<.01). Group B patients tended to be older and larger at repair though these patients had significantly higher incidence of early death (within 30 days post-op) ,(p<.01). Aortic cross clamp time was significantly longer in C patients than other groups (p<.01). Post-op pressures in the right ventricle (p<.01) and pulmonary artery (p<.01) were lower in C patients. The major difference between groups occurred in comparing duration of inotropic support. Group A patients required 33 ± 2.9 hours,Group B 39 ± 4.3 hours. Significantly, Group C patients required only 12.5 ± 2.9 hours (p<.001) of dopamine or isoproterenol to maintain clinically normal cardiac output in the post-operative period. In conclusion, cold cardioplegia offers markedly better myocardial preservation than previous methods, allowing longer operative time with less compromise of cardiac output in the post-operative period.