Carmine Sorbera

Heart Rate Variability and the Outcome of Head-Up Tilt in Syncopal Children

Neurocardiogenic syncope may be caused by enhanced sympathetic activity evoking a vasodepressor-cardioinhibitory reflex. Heart rate variability (HRV) methods can be used to assess the modulation of sympathetic and parasympathetic activity. To determine whether HRV measurements are related to the outcome of head-up tilt testing (HUT), we studied 29 syncopal patients aged 7-19 y. After 30 min supine, patients were tilted to 80 ° for 30 min or until syncope occurred. Sequential beats free from ectopy were analyzed. Time domain indices included SD (SDNN), root mean square successive differences (RMSSD), percent exceeding 50 ms (pNN50). An autoregressive model was used to calculate power spectra. Low frequency power (LFP, 0.05-0.15 Hz), high frequency power (HFP, 0.15-0.40 Hz), and total power (TP, 0.01-0.40 Hz) were compared before and after tilt. Data were obtained supine before tilt(baseline), within 5 min after HUT (early), 5-10 min after HUT (mid), and 15 min after HUT or presyncope (late). Seventeen patients fainted (HUT+), and 12 patients did not (HUT-). Variability indices were different for HUT- and HUT+ at baseline: SDNN was 123 ± 17versus 78 ± 6, RMSSD was 127 ± 23 versus 64± 6 ms, pNN50 was 51 ± 6 versus 31 ± 4, respectively. Spectral data demonstrated decreased HFP and TP in HUT+(834 ± 133 and 2855 ± 420 ms2) versus HUT- (3433 ± 840 and 7062 ± 1500). With tilt, SDNN, RMSSD, and pNN50 decreased proportionately in HUT- and HUT+. However, sympathovagal balance, measured by the ratio LFP/HFP and by normalized LFP, was markedly increased in HUT+ (2.2 ± 0.7 and 0.43 ± 0.03) compared with HUT- (0.8 ± 0.2 and 0.31± 0.02) at baseline and differences increased with tilt. With syncope, sympathetic activity decreased, and parasympathetic activity increased. Decreased RR variability with decreased parasympathetic activity and increased indices of sympathovagal balance before HUT predict a positive tilt test in children referred for evaluation of neurocardiogenic syncope.

Prospective Evaluation of Heart Block Complicating Early Lyme Disease

Lyme disease is a recognized cause of heart block/carditis. The incidence of heart block complicating early Lyme disease has not been prospectively evaluated. In this study, 61 patients with early Lyme disease documented by the rash of erythema migrans were prospectively evaluated for carditis. Fifty five of 61 patients had a repeat examination 3 to 4 weeks after initiation of antibiotic therapy. Only one of 61 patients (1.6%) presented with heart block, which resolved with antibiotics. None of the 54 patients without heart block on initial presentation had a change in any measured electrocardiographic parameter or progressed to heart block after antibiotics. Therefore, early Lyme disease appears to be infrequently complicated by heart block. Early administration of antibiotics may prevent the development of heart block fcarditis.

Effect of Beta Blockers, Angiotensin-Converting Enzyme Inhibitors or Angiotensin Receptor Blockers, and Statins on Mortality in Patients With Implantable Cardioverter-Defibrillators

Nine hundred sixty-five patients (mean age 70 years) with implantable cardioverter-defibrillator were followed for 32 +/- 33 months for all-cause mortality. Death occurred in 73 of 515 patients (13%) treated with beta blockers (group 1), in 84 of 494 patients (17%) treated with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (group 2), in 56 of 402 patients (14%) treated with statins (group 3), in 40 of 227 patients (18%) treated with amiodarone (group 4), in 5 of 26 patients (19%) treated with sotalol (group 5), and in 64 of 265 patients (24%) treated with no beta blocker, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, statin, amiodarone, or sotalol (group 6) (p <0.001 for group 1 vs group 6 and group 3 vs group 6, p <0.02 for group 2 vs group 6). In conclusion, patients with implantable cardioverter-defibrillators should be treated with beta blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and statins to reduce mortality.

Statins Reduce Appropriate Cardioverter-Defibrillator Shocks and Mortality in Patients With Heart Failure and Combined Cardiac Resynchronization and Implantable Cardioverter-Defibrillator Therapy

Of 209 patients with heart failure treated with combined cardiac resynchronization therapy and implantable cardioverter-defibrillator therapy, appropriate cardioverter-defibrillator shocks occurred at 34-month follow-up in 22 of 121 patients (18%) on statins and in 30 of 88 patients (34%) not on statins (P = .009). Deaths occurred in 3 of 121 patients (2%) on statins and in 9 of 88 patients (10%) not on statins (P = .017). Stepwise Cox regression analysis showed that significant independent prognostic factors for appropriate shocks were use of statins (risk ratio = 0.46), smoking (risk ratio = 3.5), and diabetes (risk ratio = 0.34). Significant independent prognostic factors for the time to mortality were use of statins (risk ratio = 0.05), use of digoxin (risk ratio = 4.2), systemic hypertension (risk ratio = 14.2), diabetes (risk ratio = 4.3), and left ventricular ejection fraction (risk ratio = 1.1).

Incidence of Appropriate Cardioverter-Defibrillator Shocks and Mortality in Patients With Heart Failure Treated With Combined Cardiac Resynchronization Plus Implantable Cardioverter-Defibrillator Therapy Versus Implantable Cardioverter-Defibrillator Therapy

Of 529 patients with heart failure and a mean left ventricular ejection fraction of 29%, 209 (40%) were treated with cardiac resynchronization therapy (CRT) plus an implantable cardioverter-defibrillator (ICD) and 320 (60%) with an ICD. Mean follow-up was 34 months for both groups. Stepwise logistic regression analysis showed that significant independent variables for appropriate ICD shocks were statins (risk ratio = 0.35, P < .0001), smoking (risk ratio = 2.52, P < .0001), and digoxin (risk ratio = 1.92, P = .0001). Significant independent variables for time to deaths were use of CRT (risk ratio = 0.32, P = .0006), statins (risk ratio = 0.18, P < .0001), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (risk ratio = 0.10, P < .0001), hypertension (risk ratio = 24.15, P < .0001), diabetes (risk ratio = 2.54, P = .0005), and age (risk ratio = 1.06, P < .0001). In conclusion, statins reduced and smoking and digoxin increased appropriate ICD shocks. Use of CRT, statins, and angiotensin-converting enzyme inhibitors/angiotensin receptor blockers reduced mortality and hypertension, diabetes, and older age increased mortality.

Symptomatic Atrioventricular Dual Pathway Double Responses: A Role for Slow Pathway Ablation

Two patients with symptomatic fast/slow pathway double responses were evaluated with electrophysiology studies. Chronic palpitations were resistant or worsened by medical therapy. No reentry tachycardias were induced. A nonreentrant paroxysmal supraventricular tachycardia was documented, Radiofrequency ablation of the slow pathway was safely and successfully performed. Patients remain asymptomatic for 16‐18 months. Ablation of the slow pathway for this substrate is a viable option.

Prevalence of appropriate cardioverter-defibrillator shocks in 1038 consecutive patients with implantable cardioverter-defibrillators.

During a 33-month follow-up of 1038 consecutive patients who had implantable cardioverter-defibrillators, appropriate shocks occurred in 329 of 1038 patients (32%). Appropriate shocks occurred in 101 of 380 patients (27%) treated with β-adrenergic blockers alone; in 31 of 95 patients (33%) treated with amiodarone alone; in 39 of 149 patients (26%) treated with β-blockers plus amiodarone; in 11 of 28 patients (39%) treated with sotalol alone; and in 147 of 386 patients (38%) treated with no β-blockers, amiodarone, or sotalol (P < 0.001 comparing patients treated with β-adrenergic blockers alone with patients treated with no β-blockers, amiodarone, or sotalol; and P < 0.01 comparing patients treated with β-blockers plus amiodarone with patients treated with no β-blockers, amiodarone, or sotalol). In conclusion, patients having implantable cardioverter-defibrillators should also be treated with β-adrenergic blockers to reduce the frequency of appropriate shocks.

Acute Reversible Diffuse Conduction System Disease due to Lyme Disease

During the acute phase of Lyme disease, a 56‐year‐old man without previous heart disease developed complete heart block with alternating left and right bundle branch block pattern QRS complexes. Electrophysiological study performed in the acute phase revealed marked HV prolongation, although the level of heart block was at the atrioventricular node. The heart block was mildly symptomatic and resolved (as did the bundle branch block) with antibiotic therapy. Lyme disease may cause reversible His‐Purkinje disease.

Prevalence of complications during implantation and during 38-month follow-up of 1060 consecutive patients with implantable cardioverter-defibrillators.

During implantation and during 38-month follow-up of 1060 consecutive patients who had implantable cardioverter-defibrillators, complications occurred in 60 (5.7%) of 1060 patients. These complications consisted of fractured leads requiring lead revision in 36 (3.4%) patients, lead infection requiring antibiotics in 5 (0.5%) patients, device replacement because of malfunction in 5 (0.5%) patients, repositioning of leads in 3 (0.3%) patients, a hematoma at the time of implantation in 3 (0.3%) patients, pneumothorax at the time of implantation in 2 (0.2%) patients, repair of a defective generator in 1 (0.1%) patient, replacement of the device because of atrophy of the skin over the device in 1 (0.1%) patient, a transient ischemic attack because of atrial fibrillation developing during implantation in 1 (0.1%) patient, device replacement because of a recall from Guidant in 1 (0.1%) patient, pocket revision because of pain when lying on the side of the pacemaker in 1 (0.1%) patient, and pacemaker infection in 1 (0.1%) patient.

Safety and Efficacy of Outpatient Transseptal Radiofrequency Ablation of Atrioventricular Accessory Pathways

A retrospective analysis of 60 consecutive patients who underwent outpatient transseptal radiofrequency ablation of left sided accessory pathways at Westchester County Medical Center/New York Medical College from September 1994 to December 1997 was performed. Patients were followed for a mean duration of 22 months. No complications either local or related to the transseptal method were observed. All patients had successful ablation of the accessory pathway. One patient had a recurrence of symptoms. This study suggests transseptal radiofrequency ablation of the left sided accessory pathways to be safe, feasible and an effective procedure when performed in an outpatient setting. These results were obtained at a high volume center with experience using the transseptal technique.