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Thirty-two children with both ventricular septal defect (VSD) and aortic insufficiency (AI) were evaluated for progression in degree of AI as well as effectiveness of operation in reducing or eliminating regurgitation. At the time of initial study, AI was mild in 21, moderate in eight, and severe in three patients. Twenty-one patients were followed medically over a 2 year to 19 year period, during which the degree of AI progressed in five. One death occurred during an episode of endocarditis. A total of 24 patients underwent operation at ages ranging from 1 year to 23 years. Postoperative evaluations continued from a minimum of 1 year to 24 years in 19 patients, with residual AI noted in 63% of these. Children less than 5 years of age, even with little valvular involvement, exhibited minimal benefit from attempted correction compared with those in the latter part of the first decade of life (p

1. 1. A series of tests were conducted to determine whether or not the hemolymph of the crayfish, Orconectes virilis , contains a plasma coagulation factor analogous to mammalian fibrinogen. 2. 2. Anti-coagulated hemolymph free from cell material could not be induced to clot by the addition of calcium chloride, whereas clot formation proceeded when whole cells and/or cell debris was present. 3. 3. Thrombin and rabbit anti-human and anti-bovine fibrinogen antisera failed to react with any crayfish samples used. 4. 4. All hemolymph samples exhibited similar electrophoretic banding patterns. 5. 5. Prothrombin and partial thromboplastin time tests using human reagents yielded negative results with all hemolymph samples studied.

ObjectivesOur objective was to evaluate the short-term safety and efficacy of cardiac resynchronization therapy (CRT) in children.BackgroundCardiac resynchronization therapy has been beneficial for adult patients with poor left ventricular function and intraventricular conduction delay. The efficacy of this therapy in the young and in those with congenital heart disease (CHD) has not yet been established.MethodsThis is a multi-center, retrospective evaluation of CRT in 103 patients from 22 institutions.ResultsMedian age at time of implantation was 12.8 years (3 months to 55.4 years). Median duration of follow-up was four months (22 days to 1 year). The diagnosis was CHD in 73 patients (71%), cardiomyopathy in 16 (16%), and congenital complete atrioventricular block in 14 (13%). The QRS duration before pacing was 166.1 ± 33.3 ms, which decreased after CRT by 37.7 ± 30.7 ms (p < 0.01). Pre-CRT systemic ventricular ejection fraction (EF) was 26.2 ± 11.6%. The EF increased by 12.8 ± 12.7 EF units with a mean EF after CRT of 39.9 ± 14.8% (p < 0.05). Of 18 patients who underwent CRT while listed for heart transplantation, 3 improved sufficiently to allow removal from the transplant waiting list, 5 underwent transplant, 2 died, and 8 others are currently awaiting transplant.ConclusionsCardiac resynchronization therapy appears to offer benefit in pediatric and CHD patients who differ substantially from the adult populations in whom this therapy has been most thoroughly evaluated to date. Further studies looking at the long-term benefit of this therapy in this population are needed.

C'est le traitement employe dans les blocs auriculoventriculaires complets congenitaux pour eviter la mort subite des nourrissons

Sinus node (SN) and atrioventricular node (AVN) dysfunction after repair of atrial septal defect (ASD) may be caused by inherent nodal abnormalities and not related to altered hemodynamics. To assess the preoperative prevalence and postoperative persistence of nodal dysfunction, 21 consecutive children, mean age 5.4 years, underwent electrophysiologic evaluations before ASD repair. Preoperative SN recovery time was prolonged in 11 patients and was associated with abnormal AVN response to rapid atrial pacing in 5. There were no significant differences in age, hemodynamic values or shunt size between children with normal and those with abnormal nodal function. Atrial and AVN refractory periods were normal. The ASD was repaired in 9 children with SN dysfunction. Electrophysiologic studies performed 4 to 16 months after surgical correction showed improvement in all electrophysiologic values. However, SN function remained abnormal. Significant decreases were observed in atrial (p less than 0.05) and AVN (p less than 0.05) refractory periods, with increased atrial conduction velocity (p less than 0.01) and AVN Wenckebach response to atrial pacing (p less than 0.01). ASD repair improved nodal and atrial muscle electrophysiologic function, theoretically by relieving stress on atrial impulse propagation. SN and AVN dysfunction may persist as an inherent part of the ASD complex.

The files of 121 patients who presented to Children's 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.

Five children with severe, life-threatening tachydysrhythmias were treated successfully with surgery. Three had atrial ectopic automatic tachycardia (AET), one had AV junctional (His bundle) automatic ectopic tachycardia (JET), and one had ventricular reentry tachycardia (VT). The mechanism and site of the tachycardia were diagnosed preoperatively using intracardiac electrophysiologic studies (EPS). Medical management with all avaliable drugs failed to control the tachycardia in each patient. The two patients with left atrial AET underwent cryoabiation of the focus using cardiopulmonary bypass. The patient with right atrial AET had removal of the anterior one third of the right atrial appendage and cryoablation of the edges. The patient with AV JET first had incision and suture ligation of the bundle of His and implantation of a ventricular pacemaker, but the tachycardia recurred 2 weeks later. Cryoabiation of the bundle of His prevented further recurrences. Tachycardia stopped in the patient with VT during incision of a tumor in the apex of the left ventricle. No patient had tachycardia after surgery and none has required medical treatment.

KARPAWICH, P.P., ET AL.: A new low threshold platinized epicardial pacing electrode: comparative evaluation in immature canines. A prospective comparison of pacing and sensing capabilities between the conventional Medtronic Model 49S1 platinum-iridium epicardial pacing electrode and a new modifted "platinized" version of the' same electrode was performed in immature canines to determine if the new electrode design improves pacing in the immature myocardium. The conventional electrode was modifted by electroplating platinum black particles onto the surface to increase the effective or true microscopic surface area, yet essentially maintain the same overall geometric electrode size. Both epicardial electrodes were inserted into the right ventricular myocardium with the lead pad sutured to the epicardium, and externalized to the scruff in jive puppies (age 3 months). An additional left ventricular lead was implanted to permit chronic pacing following epicardially-induced atrioventricular block. Acute and chronic sensing and pacing capabilities of each externalized electrode were performed at implant and weekly up to 4 months. Histologic examination of each electrode implant site was performed at the end of the study period. At implant, both electrodes exhibited comparablevalues for sensed R waves, lead impedances, and pacing thresholds. During the study, the platinized electrode exhibited lower pacing thresholds. Analysis of all postimplant data demonstrated this threshold difference to be signiftcantly lower (P < .01) for the platinized version. Lead impedance and sensing capabilities remained comparable between the two de­ signs. Histologic study demonstrated less fibrotic injiltration at the platinized electrode site. This prelimi­ nary evaluation indicates that for the duration of the postimplant study period, the platinized epicardial electrode design was associated with signiftcantly lower thresholds and less ftbrosis as a function of time compared to the conventional smooth electrode surface design. The new platinized electrode limits exit block in the developing immature myocardium and permits safe pacing at lower pulse widths and voltages to increase battery life. (PACE, Vol. 11, August 1988) platinization, cardiac pacing, epicardial electrode