A prospective analysis of the incidence and risk factors associated with junctional ectopic tachycardia following surgery for congenital heart disease.

This study was designed to evaluate the incidence and risk factors associated with the occurrence of junctional ectopic tachycardia (JET) in patients after congenital heart surgery. We prospectively analyzed cardiac rhythm status in 336 consecutive patients undergoing surgery for congenital heart disease at our institution during a 1-year period. The incidence of JET was 8% (27/336). Repairs with the highest incidence of JET were arterial switch operation (3/13, 23%), atrioventricular (AV) canal repair (4/19, 21%), and Norwood repair (2/10, 20%). Compared to patients with no arrhythmias, patients with JET were more likely to be younger (2.75 +/- 2.44 vs 5.38 +/- 7.25 years, p < 0.01), have had longer cardiopulmonary bypass times (126 +/- 50 vs 85 +/- 73, p < 0.01), and have a higher inotrope score (6.26 +/- 7.55 vs 2.41 +/- 8.11, p < 0.01). By multivariate analysis, ischemic time was the only factor associated with JET [odds ratio, 1.01 (confidence interval, 1.005-1.02); p = 0.0014). The presence of JET did not correlate with electrolyte abnormalities. JET is not necessarily related to surgery near the His bundle or hypomagnesemia. Longer ischemic time is the best predictor of JET. Patients undergoing arterial switch operation, AV canal repair, and Norwood repair are at highest risk of postoperative JET and should be considered for prophylactic therapy.

Serial exercise performance in children with surgically corrected congenital aortic stenosis.

We examined serial exercise test performance in children with congenital aortic stenosis (AS) treated surgically compared to that of nonoperated children with mild to moderate AS. Maximal treadmill exercise data were assessed in 21 children 5.5 +/- 3.8 years after aortic valve (AO) surgery. Patients had undergone the Ross procedure (n = 6) or previous aortic valvotomy, balloon valvuloplasty, or neonatal aortic valvotomy (n = 15). Follow-up treadmill tests were conducted 3.7 +/- 2.8 years later. Data were compared to those of 19 nonoperated AS patients (mean gradient by echocardiogram <50 mmHg). These patients were exercised 3.6 +/- 3.2 years apart. Endurance time, heart rate, systemic blood pressure, and electrocardiogram were compared as repeated measures between tests and to age- and sex-matched normative data. Postsurgical children with AS had normal endurance times despite low peak heart rates on the initial test, and they maintained endurance over time. Nonoperated children with mean AO gradients <50 mmHg also had normal endurance times on the initial test but increased endurance over 3.6 years. Children with operated and nonoperated AS were able to reach or exceed normal endurance times, which may make it difficult to achieve compliance to imposed activity restrictions in this population.

Effect of radiofrequency catheter ablation of accessory pathways on autonomic tone in children.

BACKGROUND: Radiofrequency catheter ablation is standard treatment for children with re-entrant supraventricular tachycardias. Autonomic changes have been noted after such ablation for atrioventricular nodal re-entry tachycardia, but not as well documented with atrioventricular re-entry over an accessory pathway. METHODS AND RESULTS: In 10 normal paediatric volunteers and 12 children referred for electrophysiologic testing and radiofrequency ablation of supraventricular tachycardia, non-invasive autonomic function tests and tilt-table testing were performed, and the variability in 24-h heart rate was analysed. Patients with supraventricular tachycardia underwent these tests both 24-72 h before and 24 h after ablation. Patients with tachycardia underwent additional autonomic testing to assess the sensitivity of baroreceptors and the intrinsic heart rate with autonomic blockade immediately before and after ablation. One non-invasive autonomic function test, namely handgrip, demonstrated significant differences (p < 0.05) in diastolic blood pressure before and after ablation, though these values did not differ from controls. Significant decreases were noted in two indexes of the variability of heart rate before and after ablation (p < 0.05). Certain tilt test variables also demonstrated significant differences between controls and those with tachycardia subsequent to ablation. Intracardiac testing demonstrated changes (p < 0.05) in sinus cycle lengths, effective refractory periods and/or blood pressures at baseline and during testing of the sensitivity of baroreceptors before and after ablation. These changes were consistent with increased sympathetic or decreased parasympathetic tone. With autonomic blockade, these differences were abolished. CONCLUSIONS: Catheter ablation of accessory pathways in children was associated with changes consistent with increased sympathetic or decreased parasympathetic tone. These autonomic changes persisted 24 h after the ablation procedure.

Autonomic changes and heart rate variability in children with neurocardiac syncope.

This study evaluated resting autonomic function and autonomic responses to head-up tilt-table testing in children who experienced neurocardiac syncope to determine whether predictable differences existed between these patients and normal volunteers. Neurocardiac syncope is a common cause of syncope in children. The mechanism, though related to abnormalities in autonomic function, has not been fully elucidated, particularly in pediatric patients. This study evaluated resting autonomic tone using noninvasive autonomic function tests (i.e., Valsalva, handgrip, and deep breathing) and 24-hour heart rate variability (HRV). In addition, heart rate and blood pressure were evaluated during head-up tilt examination. Values from patients who experienced neurocardiac syncope were compared to those from age-matched normal volunteers. No significant differences were noted during noninvasive testing. Some time domain HRV variables demonstrated a trend toward significant difference (p < 0.10). Tilt testing data were significantly different in sinus beat to sinus beat (RR) intervals between controls and syncope patients at 2, 5, and 10 minutes after tilting. In addition, significant differences were noted in RR interval and the standard deviation of RR interval 1 or 2 minutes prior to syncope when compared to controls at 5 and 10 minutes after tilting. Children with syncope exhibited abnormalities during tilt testing indicating an increased sympathetic or decreased parasympathetic tone, particularly prior to syncope. Some measures of HRV might constitute noninvasive parameters that correlate with the positive tilt table test.

Perioperative management of children with third degree heart block undergoing pacemaker placement: a ten year review.

It has been suggested that children with third degree heart block require insertion of a temporary pacemaker prior to general anaesthesia. This recommendation needs to be reevaluated with the availability of noninvasive transcutaneous cardiac pacing. We undertook a retrospective ten-year chart review of anaesthesia in children with third degree heart block undergoing pacemaker insertion or revision. Forty-eight children with complete heart block underwent seventy anaesthetics of which fifty three were in children without pacemakers or with nonfunctioning pacemakers. One child had a temporary pacemaker placed preoperatively following asystole in the emergency room. In children who were not being paced, 60% had baseline heart rates less than 60 bpm. Complications seen in this study, including hypotension, would not have been prevented by temporary pacemaker placement. We conclude that there is no benefit to routine preoperative temporary pacing in children with third degree heart block.

Outcome measures of a chronic pain program: a prospective statistical study.

OBJECTIVE: To provide outcome data measuring objective and subjective variables of an individualized, multidisciplinary, comprehensive pain management program. DESIGN: The study is a prospective evaluation of 50 consecutive patients who completed the pain management program. Objective measures were medication use and return to work. Subjective measures included self-reports of pain levels and completion of a Personal Concerns and Goals Assessment (PCGA) examining issues of lifestyle and emotional well-being. These measures were compared at program onset and completion by using appropriate statistical analyses. RESULTS: Objective measures: Medication use by the study subjects decreased overall by 72% within all drug categories. Opioid use was eliminated. Regarding return to work, the study subjects increased their work hours by twofold overall. Of patients working fewer than 30 h per week at program onset, representing 62% of the study population, a fivefold return to work was observed. Subjective measures: Overall pain levels improved by 33%, with an 18 to 47% improvement in all descriptors (average pain levels on good or bad days, average number of good or bad days). Of the PCGA factors, patients improved 24 to 46% in all categories concerning lifestyle and emotional well-being. Correlative analysis of the data produced prognostic information as well as insights into chronic pain development. CONCLUSIONS: This study of objective and subjective outcome measures demonstrates that a comprehensive program employing specific principles and methods produces an effective approach for the management of chronic pain. Patients disabled by chronic pain regain a quality of life that allows them to resume a functioning, productive role.

Elimination of AV nodal reentrant tachycardia with 2:1 VA block by posteroseptal ablation.

AV nodal reentry capable of VA block during tachycardia was successfully eliminated using a posteroseptal ablation pulse delivered well away from the site of earliest atrial activation during tachycardia. A possible explanation is that the arrhythmia represented typical AV nodal reentrant tachycardia with transient intra-atrial conduction block during tachycardia.

Multiple accessory pathways in the permanent form of junctional reciprocating tachycardia.

The permanent form of junctional reciprocating tachycardia (PJRT) has been successfully eliminated by ablation of the accessory pathway responsible for the tachycardia. The coexistence of multiple accessory pathways responsible for different, long RP-interval tachycardias was not documented previously. Five patients with PJRT underwent radiofrequency catheter ablation of accessory pathways. Three of 5 patients had 2 accessory pathways each: 1 had 2 left free wall accessory pathways, another had a right posterior free wall and right posteroseptal pathway, whereas the third had 2 right posteroseptal pathways approximately 1 cm apart. The remaining 2 patients each had 1 right posteroseptal accessory pathway. Seven of 8 pathways were successfully ablated with a median of 3 radiofrequency pulses. No patient developed complications. Peak serum creatine kinase ranged from 131 to 311 IU/liter, with peak MB fraction 7 to 17 IU/liter, or 5 to 11%. Follow-up electrophysiologic study, 29 to 70 days after ablation, revealed no inducible tachycardia and no evidence of accessory pathway conduction, except for the 1 pathway not ablated. All patients remained asymptomatic 17 to 29 months after ablation. Thus, patients with PJRT can have several accessory pathways that can be safely and effectively eliminated with radiofrequency catheter ablation.

Preoperative and postoperative "aneurysm" associated with coarctation of the aorta.

The reported incidence of aortic aneurysm after surgical repair or balloon angioplasty for aortic coarctation varies widely. To determine the incidence of aneurysm formation after surgery, preoperative and postoperative cineangiograms from 65 patients who underwent operation at age 1.5 +/- 3.4 years were examined. Repair included a prosthetic patch in 14 patients, end to end anastomosis in 28 and subclavian flap in 23. Aneurysm was documented by change in contour or irregularities in contour at the repair site or by abnormal dimensions at the repair site, defined by the ratio of the widest measurement at the repair site to the measurement of the aorta at the diaphragm. An aneurysmal bulge above the ductus diverticulum was identified in 14 (23%) of 60 patients preoperatively; the area showed no change 4.72 +/- 4.07 years after surgery. Significant changes at the repair site were seen in only three patients, all of whom had Dacron patch repair. One patient had a change in contour at the repair site, one had an abnormally high repair site to diaphragmatic aorta ratio and one had a progressive increase in this ratio. Thus, during childhood years, 3 (5%) of 65 patients were diagnosed as having aneurysm at the surgical repair site. In conclusion, 1) comparison with preoperative cineangiograms, especially for aneurysmal bulges above the ductus arteriosus, is essential before an aneurysm can be attributed to coarctation repair by any technique, and 2) aneurysm developed only in patients subjected to Dacron patch repair.

Tolerance development to the arousal effects of nicotine.

To determine if repeated daily doses of nicotine induces tolerance to both its EEG and behavioral activating effects, rats implanted with sets of bipolar cortical elecrodes and carotid cannulae received intracarotid injections of either (1) 6 daily doses of nicotine (as tartrate, 30 mug/kg) (Group 1) or (2) 3 daily doses of saline followed by 4 days of nicotine (Group 2). From an exercise-induced resting state, nicotine produced immediate EEG and behavioral arousal, both of which disappeared in Group 1 by Day 6. Saline administered to Group 2 rats produced little or no response but subsequent nicotine resulted in responses similar to those produced by Group 1 animals. It is concluded that tolerance development to nicotine activation is reflected not only in behavior, but also in the EEG.