Intracardiac electrocardiographic assessment of precordial TASER shocks in human subjects: A pilot study.

BACKGROUND: Case reports of cardiac arrest in temporal proximity to Conducted Electrical Weapon(CEW) exposure raise legitimate concerns about this as a rare possibility. In this pilot study, we respectfully navigate the oversight and regulatory hurdles and demonstrate the intra-shock electrocardiographic effects of an intentional transcardiac CEW discharge using subcutaneous probes placed directly across the precordium of patients with a previously implanted intracardiac EKG sensing lead. METHODS: Adults scheduled to undergo diagnostic EP studies or replacement of an implanted cardiac device were enrolled. Sterile subcutaneous electrodes were placed at the right sternoclavicular junction and the left lower costal margin at the midclavicular line. A standard police issue TASER Model X26 CEW was attached to the subcutaneous electrodes and a 5 s discharge was delivered. Continuous surface and intracardiac EKG monitoring was performed. RESULTS: A total of 157 subjects were reviewed for possible inclusion and 21 were interviewed. Among these, 4 subjects agreed and completed the study protocol. All subjects tolerated the 5 s CEW discharge without clinical complications. There were no significant changes in mean heart rate or blood pressure. Interrogation of the devices after CEW discharge revealed no ventricular pacing, dysrhythmias, damage or interference with the implanted devices. CONCLUSIONS: In this pilot study, we have successfully navigated the regulatory hurdles and demonstrated the feasibility of performing intracardiac EKG recording during intentional precordial CEW discharges in humans. While no CEW-associated dysrhythmias were noted, the size of this preliminary dataset precludes making conclusions about the risk of such events. Larger studies are warranted and should consider exploring variations of the CEW electrode position in relation to the cardiac silhouette.

Exercise training improves heart rate variability in older patients with heart failure: a randomized, controlled, single-blinded trial.

Reduced heart rate variability (HRV) in older patients with heart failure (HF) is common and indicates poor prognosis. Exercise training (ET) has been shown to improve HRV in younger patients with HF. However, the effect of ET on HRV in older patients with HF is not known. Sixty-six participants (36% men), aged 69±5 years, with HF and both preserved ejection fraction (HFPEF) and reduced ejection fraction (HFREF), were randomly assigned to 16 weeks of supervised ET (ET group) vs attention-control (AC group). Two HRV parameters (the standard deviation of all normal RR intervals [SDNN] and the root mean square of successive differences in normal RR intervals [RMSSD]) were measured at baseline and after completion of the study. When compared with the AC group, the ET group had a significantly greater increase in both SDNN (15.46±5.02 ms in ET vs 2.37±2.13 ms in AC, P=.016) and RMSSD (17.53±7.83 ms in ET vs 1.69±2.63 ms in AC, P=.003). This increase was seen in both sexes and HF categories. ET improved HRV in older patients with both HFREF and HFPEF.

Psychological effects of implantable cardioverter-defibrillator leads under advisory.

BACKGROUND: Automatic implantable cardioverter-defibrillators (ICDs) are standard therapy for patients at high risk of sudden cardiac death. Device implantation is a stressful event that has been associated with patient and anticipatory anxiety. While the psychological effects of normally functioning ICDs are known, only a dearth of literature evaluates how a warning about the potential for malfunction of an ICD lead, related to a device advisory, influences the degree of psychological distress. These effects are evaluated in a patient population with the Medtronic Sprint Fidelis defibrillation lead 6949 (Medtronic, Minneapolis, MN, USA). METHODS: A sample of 413 patients were studied. Groups included 158 with an advisory Medtronic 6949 and 255 with an ICD that had no current advisories. Patients were administered a validated disease-specific metric assessing concerns over ICDs, as well as a demographics questionnaire. The primary outcome was the total score on the ICD concerns (ICDC). Analysis was with one-way Analysis of Variance with preplanned orthogonal contrasts and multivariate regression. RESULTS: The advisory group tended to have higher numbers of high school and college graduates. The average length of device implant in the nonadvisory group was higher at 4.29 years versus 3.99 years in the advisory group (t = 0.901, P ≤ 0.5). A higher percentage of those with an advisory experienced more shocks (39% vs 32%; z =-1.51, P ≤ 0.5). Average ICDC scores in the advisory group with previous shock were significantly higher than in the nonadvisory group with prior shock ([27.7 standard deviation (SD) ± 14.5] vs [18.5 SD ± 12.5], P = 0.0001) . Average ICDC score in the advisory group without shock was also significantly elevated compared to the nonadvisory group (18.5 SD ± 14.5 vs 10.8, SD ± 12.5, P = 0.0001). There was a significant effect of having an advisory on total ICDC scores (F = 21.32, P ≤ 0.0001). History of shock also significantly increased total ICDC scores (F = 20.07, P ≤ 0.0001). In multivariate regression, presence of Fidelis lead and history of shock were predictors for increased ICDC scores (R(2) = 0.158, F = 38.88, P = 0.0001). When controlling for shock history, presence of Fidelis lead remained an independent predictor of elevated ICDC scores (R(2) = 0.125, F = 59.30, P ≤ 0.0001). CONCLUSIONS: Our study attempts to address some of the psychological differences between participants with advisory and nonadvisory leads. Higher scores on the ICDC were found in our advisory group. While statistically significant, it is entirely unclear if these scale elevations are clinically significant or if directed counseling at this stage may reduce these elevations. This raises the suspicion that directed counseling be undertaken for patients with future advisories.

Hysterectomy and weight gain.

OBJECTIVE: To investigate whether overweight women are more likely to have a hysterectomy and whether hysterectomy leads to increased weight gain. METHODS: Survey data of middle-aged women participating in the Australian Longitudinal Study on Women's health in 1996 (ages 45-50 y; n = 13,125), 1998 (n = 10,612), 2001 (n = 10,293), and 2004 (n = 9309) included self-reported height, weight, and hysterectomy. First, we conducted a cohort analysis, comparing body mass index (BMI) of women categorized according to hysterectomy status. Second, we used a nested case-control analysis to compare weight gain between women who underwent hysterectomy and women who did not have a hysterectomy, matched for prehysterectomy weight, height, menopause status, and educational level. RESULTS: At survey 1, the mean BMI of women who subsequently had a hysterectomy was greater than that of women without a hysterectomy by survey 2 (difference, 1.1 kg/m; 95% CI, 0.5-1.6). Results were similar for surveys 2 to 3 (BMI difference, 0.8 kg/m; 95% CI, 0.3-1.3) and surveys 3 to 4 (BMI difference, 0.8 kg/m; 95% CI, 0.1-1.4). Having a hysterectomy between surveys 1 and 2 was not associated with percentage of weight gain over the 3 or 6 years after survey 2 (odds ratio, 0.98 [95% CI, 0.96-1.01] and 0.99 [95% CI, 0.97-1.01], respectively). Having a hysterectomy between surveys 2 and 3 was weakly associated with percentage of weight gain over 3 years (odds ratio, 1.03 [95% CI, 1.00-1.05]). CONCLUSIONS: Among women older than 45 to 50 years, hysterectomy did not lead to greater weight gain but was more likely to be performed in heavier women.

Rate-dependent slow conduction velocity in the cavo-tricuspid isthmus and septum in patients with atrial flutter.

PURPOSE: To evaluate and compare the effects of heart rate on conduction velocity in the cavotricuspid isthmus (CTI) and septum in patients with and without typical atrial flutter (AF) using electro-anatomic mapping (EAM) of the right atrium (RA). METHODS: Ten patients (age 53+/-10 yrs, 7M/3F) with AF and 13 patients (age 51+/-11 yrs, 5M/8F) with atrioventricular nodal reentrant tachycardia (AVNRT) underwent conventional electrophysiological study, electro-anatomic mapping and radiofrequency ablation. Using EAMs obtained during coronary sinus pacing at pacing cycle length (PCL) 600 ms, 400 ms, and 300 ms, we evaluated conduction velocities in the CTI and septum of RA in 10 patients with AF and compared EAMs to 13 patients with AVNRT to determine whether the conduction slowing required to maintain AFL was related to changes in volume alone or altered RA electrophysiology. RESULTS: Conduction velocities in CTI and septum were significantly slower at all PCL when AF was compared to AVNRT (*P<0.05). Additionally, in the AF group, septal conduction velocities were slower at PCL 600 ms and 400 ms, but not at 300 ms compared to CTI (*P<0.05). In AF, during PCL 300, conduction in CTI slowed significantly compared to PCL 600 and 400 ms such that there was no difference between CTI and septum at PCL 300. CONCLUSIONS: There is slower conduction in the septum compared to the CTI in all patients. However, in patients with AF, there is significant slowing of conduction in the CTI and septum as well as decremental rate-dependent slowing of conduction in the CTI. These findings indicate that in addition to RA enlargement, changes in atrial electrophysiology distinguish AF patients from patients with AVNRT.

Electro-anatomic mapping of the right atrium: anatomic abnormality is an important substrate.

OBJECTIVE: To map and compare the right atrium in patients with AF to those with atrioventricular nodal reentrant tachycardias (AVNRT, as control group) and to investigate the anatomical and electrophysiological abnormality of the right atrium in AF. METHODS: The anatomy and electrophysiology of right atrium and cavotricuspid isthmus were evaluated in 20 patients with AF (16 M/4 F, mean age 55.9 +/- 10.68 years) and 26 patients with AVNRT (9 M/17 F, mean age 47.50 +/- 19.56 years) during coronary sinus pacing at 600 ms prior to ablation with electro-anatomical mapping system. Right atrial volume (RAV), the length and width of cavotricuspid isthmus (IsL, IsW), unipolar and bipolar voltage in the right atrium (UniV-RA, BiV-RA) were measured and compared between patients with AF and those with AVNRT. RESULTS: RAV, IsL, IsW, UniV-RA, and BiV-RA were 143.22 +/- 40.72 vs 104.35 +/- 21.06 ml, 39.31 +/- 8.10 vs 32.42 +/- 9.77 mm, 30.54 +/- 7.48 vs 23.15 +/- 6.61 mm, 1.96 +/- 1.24 vs 1.53 +/- 0.91 mv and 1.47 +/- 1.47 vs 1.29 +/- 1.12 mv in AF and AVNRT respectively. CONCLUSION: The right atrial volume is larger; both the length and width of cavotricuspid isthmus are greater. Unipolar and bipolar voltages in the right atrium are higher in AF than in AVNRT, suggesting that the enlarged right atrium, increased length and width of cavotricuspid isthmus, and concomitant atrial hypertrophy are important substrates for initiation and perpetuation of typical AF.