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While cardiac arrhythmias are relatively uncommon in the neonatal period, their diagnosis and therapy may be challenging. Careful analysis of the ECG both during and after termination of an arrhythmia is essential in making the correct diagnosis. A knowledge of associated conditions may be especially helpful in recognizing and dealing with rhythm problems. With an increased understanding of arrhythmia mechanisms, new drugs and therapeutic techniques have increased our ability to effectively treat, and in fact, to cure, these infants.

Introduction of the automatic implantable cardioverter defibrillator (AICD) has dramatically affected the surgical treatment of malignant ventricular tachyarrhythmias. The authors continue to perform electrophysiologically directed subendocardial resection (SER) of left ventricular (LV) scars in selected patients, and we revascularize (CABG) those patients undergoing AICD implantation who have significant myocardial ischemia. In an attempt to define the optimal role of each procedure, this report analyzes our 8-year experience with 348 consecutive patients treated surgically for these arrhythmias (SER since 1983 and AICD since 1986). All patients undergoing SER had organized ventricular tachycardia (VT) as a result of myocardial infarction, and most had LV aneurysms; of those undergoing AICD or AICD/CABG, 60% had VT, 15% had ventricular fibrillation, and 25% had both or were noninducible. The thirty-day mortality rate was 1.5% (3/197) for AICD, 5.4% (5/93) for AICD/CABG, and 8.6% (5/58) for SER; these mortality figures are not significant different. Late deaths in all groups were predominantly due to congestive heart failure, and actuarial survival as well as freedom from sudden death was similar between the groups at 4 years. Recurrent VT occurred in 167 of 282 (59%) of long-term survivors of AICD or AICD/CABG during follow-up and in nine of 53 (17%) of those with SER. Forty-eight per cent of survivors of AICD or AICD/CABG required antiarrhythmic medications, whereas only 11% of those with SER required antiarrhythmics. Long-term survival in each group is much higher than that reported for comparable patients with severe LV dysfunction treated medically. In those patients with organized VT and LV aneurysm who are judged able to survive the procedure, SER offers a high likelihood of cure rather than simple prevention of sudden death.

A surgical approach is described for a more cosmetically acceptable placement of the automatic implantable cardioverter-defibrillator in young women. The transvenous sensing lead and the vena caval spring electrode are placed through a small subclavicular incision. The left ventricular patch electrode is placed through an anterior minithoracotomy in the crease under the left breast. A small transverse incision in the left lower quadrant is used to place the generator under the external oblique fascia in the low abdominal wall. Minimal cosmetic impairment from incisions and hardware results.

The advent of the automatic implantable cardioverter defibrillator (AICD), generally viewed as a safe and effective intervention, has in some measure discouraged the use of electrophysiologically directed endocardial resection for intractable ventricular arrhythmias. We reviewed the records of 127 patients undergoing either AICD procedures or resection over a 6-year period. Thirty-day mortality was 5.6% (5/89 patients) for all AICD procedures, 10.7% (3/28) for AICD placement plus coronary artery bypass grafting, and 11.8% (4/34) for resection. These mortality figures are not significantly different. Patients undergoing resection were less likely to require antiarrhythmic agents than patients given an AICD (33% versus 61%). Survival at 2 years was 78% in the resection group and 72% in the AICD group. Survival at 4 years was still 78% in the resection group. Only 1 late sudden death occurred in the AICD group and none in the resection group. We conclude that resection continues to be a valuable alternative, offering a greater overall benefit at only slightly increased risk.

Thirty-three patients treated with an abbreviated oral amiodarone loading regimen for ventricular tachycardia underwent electrophysiologic testing in the control state, after 1 week of high-dose (1170 +/- 88 mg/day) inpatient therapy; and after an 8-week intermediate (669 +/- 129 mg/day) dosing phase. Serum levels of amiodarone and desethylamiodarone were measured by high-pressure liquid chromatography during follow-up electrophysiologic studies. Although the corrected sinus node recovery time, sinoatrial conduction time, and AH and HV intervals remained unchanged throughout the loading period, the sinus cycle length, Wenckebach cycle length, atrial and ventricular refractory periods, and ventricular tachycardia mean and return cycle lengths lengthened significantly by 1 week. They then remained stable for the remainder of the treatment period (control less than 1 and 8 weeks, p less than 0.05). In contrast, amiodarone and especially desethylamiodarone levels rose from 1 to 8 weeks: 1.29 +/- 0.56 to 1.97 +/- 0.90 micrograms/ml (p = 0.001) and 0.63 +/- 0.29 to 1.29 +/- 0.61 micrograms/ml (p less than 0.0001), respectively. Because this regimen produces relatively prompt electrophysiologic changes, which then stabilize, early outpatient management becomes feasible before pharmacologic steady state is attained.

The electrocardiographic, hemodynamic and surgical data of 30 patients who underwent a Fontan operation between 1977 and 1986 were retrospectively reviewed to identify the incidence and predictors of immediate and late postoperative arrhythmias and associated morbidity in long-term survivors. Of 4 patients who died less than 1 year after operation (mortality 13%), 1 death was related to an arrhythmia. Three patients were not in sinus rhythm before operation and were excluded from the statistical analysis that examined predictors of arrhythmias. The remaining 23 long-term survivors have been followed 6.3 +/- 2.6 years (mean +/- standard deviation) since surgery and all remain in New York Heart Association functional class I or II. Ten patients (43%) developed immediate postoperative arrhythmias (less than or equal to 30 days) whereas 11 (48%) had late arrhythmias. With up to 10.7 years of follow-up, the proportion of patients free from late arrhythmias continues to decline. Arrhythmias included bradyarrhythmias, atrial tachyarrhythmias, the tachy-brady syndrome and supraventricular ectopic activity. Immediate postoperative arrhythmias predicted late arrhythmias (p = 0.022). The preoperative electrocardiogram was the only variable useful in predicting both immediate and late postoperative arrhythmias. A more negative P-wave deflection in lead V1 (-2.4 +/- 0.7 vs -1.4 +/- 1.2 mV, p = 0.02) predicted patients with immediate postoperative arrhythmias, whereas both greater P-wave duration and a more negative deflection in this lead predicted late arrhythmias (103 +/- 14 vs 83 +/- 20 ms, p = 0.01, and -2.5 +/- 0.8 vs -1.3 +/- 1.0 mV, p = 0.005, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Programmed ventricular stimulation was performed at 10 mA with up to 3 extrastimuli in 15 patients studied for indications other than sustained ventricular tachycardia and with no sustained arrhythmias induced at twice diastolic threshold. Stimulation with 10 mA produced 6 new instances of ventricular fibrillation (VF), 1 of which may have been clinically relevant. No sustained ventricular tachycardia was induced. VF was induced with triple extrastimuli in 5 of 6 cases. The increased arrhythmogenicity of 10-mA stimulation was related to shortened ventricular refractory periods (S2 267 +/- 21 vs 231 +/- 22 ms, p less than 0.0001; S3 217 +/- 15 vs 178 +/- 15 ms, p less than 0.0005) and did not occur without at least 2 extrastimulus coupling intervals being less than was possible at twice diastolic threshold. Stimulation with 10 mA also resulted in greater increments in extrastimulus local conduction time (27 +/- 19 vs 54 +/- 15 ms, p less than 0.001) and intraventricular conduction time (27 +/- 17 vs 45 +/- 18 ms, p less than 0.005) as coupling intervals were shortened from 360 ms to just beyond ventricular refractoriness. VF was induced more frequently in patients with cardiomyopathy (p less than 0.05). Thus, the increase in arrhythmogenicity with 10-mA stimulation with triple extrastimuli is predominantly manifest as VF, which occurs with considerable frequency and is of uncertain clinical significance. This technique should be used with great caution, and only after other stimulation modalities have been attempted.