Acute sleep deprivation is associated with increased QT dispersion in healthy young adults

Background: Sleep deprivation (SD) is known to be associated with worse cardiovascular outcome including mortality. We investigated the association between acute SD and electrocardiographic maximum QT interval (QTmax), QT, and corrected QT dispersion (QTd/cQTd), which are known to be among predictors of ventricular arrhythmias and sudden death.
Methods: We obtained electrocardiograms of 37 healthy young volunteers (age: 28.45 ± 7.97 years; 11 women) after a night with regular sleep and repeated after a night with sleep debt. We measured minimum QT interval (QTmin), QTmax, QTd, and cQTd in milliseconds.
Results: Average sleep time of the subjects were 7.7 ± 0.8 hours during regular sleep and 1.7 ± 1.6 hours during a night with sleep debt (P < 0.001). Subjects had similar values of QTmin in milliseconds after a night of sleep debt when compared to after regular sleep (347.56 ± 29.75 vs 344.59 ± 20.89; P = 0.51), whereas they had significantly higher values of QTmax, QTd, and cQTd (396.48 ± 30.11 vs 378.10 ± 23.90; P = 0.001, 49.45 ± 9.11 vs 33.51 ± 10.05; P < 0.001 and 54.92 ± 10.42 vs 37.23 ± 10.81; P < 0.001, respectively). In Pearson's correlation analysis, QTmax, QTd, and cQTd were inversely correlated with sleep time (P = 0.012, r =–0.291; P < 0.001, r =–0.625 and P < 0.001, r =–0.616, respectively)
Conclusions: In conclusion, we clearly demonstrated that even one night of SD is associated with significant increase in QTmax, QTd, and cQTd in healthy young adults despite remaining within normal limits. These electrocardiographic changes in acute SD might contribute to development and/or recurrence of arrhythmias. This implication deserves further studies for clarifying the possible linkage between SD and arrhythmias.     

The Effects of Trimetazidine on P-Wave Duration and Dispersion in Heart Failure Patients

Background: P-wave duration and dispersion (PWD) have been shown to be noninvasive predictors for development of atrial fibrillation. Thus, it may be possible to attenuate atrial fibrillation risk through normalization of P-wave duration and dispersion. Trimetazidine, a metabolic modulator, has been reported to improve cardiac function in heart failure (HF) patients.
Methods: Thirty-six HF patients being treated with angiotensin inhibitors, carvedilol, spironolactone, and furosemide were prescribed trimetazidine, 20 mg three times a day. Electrocardiographic and echocardiographic examinations were obtained before and 6 months after addition of trimetazidine in HF patients and 36 healthy control group patients having normal echocardiographic examination.
Results: Maximum P-wave duration (Pmax) (106.7 ± 15.8 vs. 91.7 ± 12.7 ms) and PWD (57.2 ± 15.4 vs. 37.9 ± 16.7 ms) were significantly longer in HF patients compared to the control group. There were significant correlations of Pmax and PWD with left atrial diameter (r = 0.508, P = < 0.001 and r = 0.315, P = 0.029), left ventricular ejection fraction (LVEF) (r = 0.401, p = 0.005 and r = 0.396, P = 0.005), deceleration time (r = 0.296, P = 0.032 and r = 0.312, P = 0.035), and isovolumetric relaxation time (r = 0.265, P = 0.038 and r = 0.322, P = 0.015). There were significant improvements in LVEF (32.7 ± 6.5% to 37.2 ± 5.5%, P = 0.036), left atrial diameter (41.5 ± 6.7 to 40.3 ± 6.1 mm, P < 0.001), and Pmax (106.7 ± 15.8 to 102.2 ± 11.5 ms, P = 0.006) and PWD (57.2 ± 15.4 to 48.9 ± 10.1 ms, P < 0.001) during follow-up.
Conclusions: Trimetazidine added to optimal medical therapy in HF may improve Pmax and PWD in association with improved left ventricular function. Longer-term and larger studies are necessary to evaluate whether these findings may have clinical implications on prevention of atrial fibrillation.     

胺碘酮转复阵发性房颤前后P波离散度的变化

目的观察心房颤动（AF）患者胺碘酮复律前后P波最大时限（Pmax）和P波离散度（Pd）的变化,探讨Pmax、Pd对AF胺碘酮复律后复发的预测价值。方法 45例阵发性AF转复为窦性心律房颤者行心电图检查测量P波最大时限与最小时限,计算Pd,观察6个月后心房颤动复发与未复发组Pd差异。按AF是否复发分为AF复发组与AF未复发组,观察测量两组的Pmax和Pd,转复为窦性心律房颤者行心电图检查测量P波最大时限与最小时限,计算Pd,观察6个月后心房颤动复发与未复发组Pd差异。结果心房颤动复发组Pd较未复发组Pd明显延长（39±11）VS（27±13）（P〈0.01）。Pd≥40组心房颤动复发率较Pd〈40组明显为高（68%VS45%,P〈0.01）。结论 Pd延长可作为预测心房颤动复发的指标。     

The effects of surgical repair on P-wave dispersion in children with secundum atrial septal defect

INTRODUCTION: Atrial septal defect (ASD) is one of the most common congenital heart diseases in children. P-wave dispersion has been reported to be associated with non-homogeneous propagation of sinus impulses. The heterogeneity of atrial conduction time may predispose the atria to arrhythmias. The aim of this study was to determine the impact of surgical repair on P-wave indices in children with isolated secundum ASD. METHODS: Children with isolated secundum ASD undergoing surgical repair (n=50; mean age, 7.0+/-3.0 years) and healthy controls (n=51; mean age, 7.6+/-2.7 years) were compared. Maximum P-wave duration (Pmax), shortest duration (Pmin) and P-wave dispersion (Pd) were measured using 12-lead surface electrocardiography. RESULTS: Mean Pmax was found to be significantly higher in children with ASD compared with controls (95.2+/-10.8 vs 84.1+/-9.2 msec; P<0.001), and Pd before surgery was significantly higher compared with controls (47.4+/-12.0 vs 38.8+/-9.7 msec; P<0.001). Both P-wave indices were significantly decreased within the first year after surgical closure - the values decreased to those comparable to healthy controls (Pmax, 86.2+/-9.7 msec; Pd, 39.8+/-10.7 msec; P>0.05). CONCLUSION: Surgical closure of ASD in children decreases Pmax and P-wave conduction time. We speculate that earlier closure of the defect may play an important role in avoiding permanent changes in the atrial myocardium and atrial fibrillation in adulthood.     

Acute sleep deprivation is associated with increased atrial electromechanical delay in healthy young adults

Background: Sleep deprivation (SD) is known to be associated with an increased incidence of adverse cardiovascular outcome. Atrial electromechanical delay (AEMD) calculated from tissue Doppler imaging has been shown to detect atrial impairment in paroxysmal atrial fibrillation. The aim of the study was to investigate whether AEMD would increase in otherwise healthy young adults with acute SD. Methods: Twenty‐seven healthy volunteers were included into the study (mean age: 26 ± 3 years). The participants underwent an echocardiographic examination after a night with SD. AEMD defined as the interval from the onset of P wave to the onset of late diastolic Am wave (PA) was calculated from the lateral and septal mitral annulus, and lateral tricuspid annulus (PA lateral, PA septum, and PA tricuspid, respectively). Results: Subjects had similar values of PA tricuspid duration in milliseconds after the night of sleep debt when compared after regular sleep, whereas they had significantly higher values of PA lateral and PA septal durations (69.05 ± 10.64 ms vs 51.31 ± 11.32 ms, P < 0.001 and 51.75 ± 7.15 ms vs 41.37 ± 8.52 ms, P < 0.001; respectively). Moreover, participants had higher inter‐AEMD and intra‐AEMD values after the night of sleep debt when compared after regular sleep [30.19 ± 9.84 ms vs 14.72 ± 6.81 ms, P < 0.001 and 12.82 ± 7.09 ms vs 4.41 ± 3.60 ms, P < 0.001; respectively]. Pearson's correlation analyses suggest that inter‐AEMD and intra‐AEMD were inversely correlated with sleep time (r =?0.628, r =?0.499, r =?0.696, and r =?0.572, respectively [all P < 0.001]). Conclusion: In conclusion, in this cross‐sectional study, we clearly found that even one night of SD is associated with higher values of inter‐AEMD and intra‐AEMD in healthy young adults. (PACE 2011; 34:1645–1651)     

P-Wave Duration and Dispersion in Patients with Metabolic Syndrome

Background: Metabolic syndrome (MS) has been reported to be associated with an increased risk of atrial fibrillation (AF). The aim of this study was to investigate P-wave dispersion (PWD) in patients with MS.
Methods: The study population included 66 patients with MS (21 men, 45 women; mean age, 49.7 ± 9.1 years) and 63 control subjects without MS (26 men, 37 women; mean age, 47.0 ± 10.6 years). The diagnosis of MS was based on the National Cholesterol Education Program Adult Treatment Panel III criteria. A 12-lead electrocardiogram was recorded for each subject. The difference between maximum and minimum P-wave duration was calculated and defined as PWD. An echocardiographic examination was also performed for each subject.
Results: Maximum P-wave duration and PWD were found to be significantly higher in patients with MS compared with the control subjects (Maximum P-wave duration: 113.5 ± 9.7 ms vs 101.0 ± 8.1 ms, PWD: 37.8 ± 7.6 vs 23.3 ± 5.9, respectively, P < 0.001 for both). However, there was no statistically significant difference between two groups regarding minimum P-wave duration (75.6 ± 6.9 ms vs 77.6 ± 7.8 ms, respectively, P = 0.18). In addition, PWD was positively correlated with age, body mass index, waist circumference, systolic and diastolic blood pressure, triglyceride level, deceleration time, isovolumetric relaxation time and negatively correlated with high-density lipoprotein cholesterol level and early-to-late diastolic velocity ratio .
Conclusion: We have shown that patients with MS have higher PWD, indicating increased risk for AF, compared to the control subjects without MS.     

Assessment of P-wave dispersion on 12-lead electrocardiography in students who exercise regularly

Background: P-wave dispersion, an electrocardiographic marker, is an independent predictor of atrial fibrillation. P-wave dispersion is associated with inhomogeneous and discontinuous propagation of sinus impulses. The aim of this study was to investigate P-wave dispersion in students who apply for registration to School of Physical Education and Sports.
Methods: Totally 984 students (810 boys [mean age: 19.8 ± 2.0 years] and 174 girls [mean age: 19.0 ± 1.8 years]) who applied for registration to School of Physical Education and Sports with a training history of some years were included in the study. P-wave duration was calculated in all 12 leads of the surface electrocardiography, which were simultaneously recorded. The difference between P maximum and P minimum durations was defined as P-wave dispersion.
Results: Age, body mass index (BMI), systolic blood pressure, diastolic blood pressure, P-wave maximal duration, and P-wave dispersion were increased in boys as compared with girls. Of age (P = 0.53), systolic blood pressure (P = 0.42), diastolic blood pressure (P = 0.50), pulse pressure (P = 0.73), gender, heart rate, and BMI tested with univariate linear regression analysis in all subjects; only gender (P < 0.001), BMI (P = 0.01), and heart rate (P = 0.02) were associated with P-wave dispersion (F = 5.16, P < 0.001, R²= 0.03).
Conclusions: P-wave dispersion was increased in boys as compared with girls who exercise regularly. P-wave dispersion is affected by gender, BMI, and heart rate in healthy students.     

Reversal of Atrial Remodeling after Cardioversion of Persistent Atrial Fibrillation Measured with Magnetocardiography

Background : Atrial fibrillation (AF) causes electrical, functional, and structural changes in the atria. We examined electrophysiologic remodeling caused by AF and its reversal noninvasively by applying a new atrial signal analysis based on magnetocardiography (MCG).
Methods : In 26 patients with persistent AF, MCG, signal-averaged electrocardiography (SAECG), and echocardiography were performed immediately after electrical cardioversion (CV), and repeated after 1 month in 15 patients who remained in sinus rhythm (SR). Twenty-four matched subjects without history of AF served as controls. P-wave duration (Pd) and dispersion (standard deviation of Pd values in individual channels) and root mean square amplitudes of the P wave over the last 40 ms portions (RMS40) were determined.
Results : In MCG Pd was longer (122.8 ± 18.2 ms vs 101.5 ± 14.6 ms, P < 0.01) and RMS40 was higher (60.4 ± 28.2 vs 46.9 ± 19.1 fT) in AF patients immediately after CV as compared to the controls. In SAECG Pd dispersion was increased in AF patients. Mitral A-wave velocity and left atrial (LA) contraction were decreased and LA diameter was increased (all P < 0.01). After 1 month, Pd in MCG still remained longer and LA diameter greater (both P < 0.05), while RMS40 in MCG, Pd dispersion in SAECG, mitral A-wave velocity, and LA contraction were recovered.
Conclusions : Magnetocardiographically detected atrial electrophysiologic alterations in persistent AF diminish rapidly although incompletely during maintained SR after CV. This might be related to the known early high and late lower, but still existent tendency to AF relapses.     

P波时限及离散度在慢性充血性心力衰竭并阵发性心房颤动的预测价值

目的探讨P波时限及离散度在慢性充血性心力衰竭（CHF）并阵发性心房颤动患者的预测价值。方法对确诊65例患者采用12导联同步体表心电图记录（纸速50mm／s），4次／月，记录的心电图取基线平稳，图形清晰的心动周期进行采样测量，12导联P波宽度测量后，取最大P波时限（Pmax）及最小P波时限（P～），两者的差为P波离散度（Pd）（即Pd=Pmax-Pmin）。以Pmax≥110ms、Pd〉t40ms为阳性标准，随访1年，并对所有数据作统计学分析。结果患者阵发性心房颤动发作时，P波离散度（Pd）和P～明显增大（P〈0．01），当患者心电图Pmax≥110ms时，其预测充血性心力衰竭患者伴发心房颤动的灵敏度最高，但特异性却不如Pdt〉40ms及（Pmax≥110ms）＋（Pdt〉40ms），而且阳性预测值也明显低于后两者。其中以（Pmax≥110ms）联合（Pd≥40ms）的特异性和阳性预测值均最高。另外患者心房颤动发作前后左心房内径（LAD）和左心室射血分数（LVEF）变化有统计学意义（P〈0．05）。结论Pmax联合Pd在CHF患者中并发心房颤动具有较高的预测价值。联合利用这两项指标来预测房性心律失常，特别是那些未被体表心电图证实的阵发性心房颤动患者，具有重要的临床意义。     

The electrical substrate of vagal atrial fibrillation as assessed by the signal-averaged electrocardiogram of the P wave

Background: The autonomic nervous system is thought to be involved in the initiation of atrial fibrillation (AF). However, there is a distinct entity of vagal AF characterized by episodes occurring at rest, postprandially, or during sleep. The purpose of this study was to compare intraatrial conduction in patients with vagally mediated AF to those with nonvagal AF, using the signal-averaged electrocardiogram (SAECG) of P wave.
Methods: SAECG of P wave was performed in 58 patients with AF using the Marquette Medical System, and the mean filtered P-wave duration (SAPW) was measured. Nine patients were categorized as having pure vagal AF (Group I), and 42 patients as having nonvagal AF (Group II); the remaining seven patients were excluded from analysis because of incomplete data.
Results: The patients in Group I were significantly younger and more likely to have paroxysmal lone AF, as compared to those in Group II. There was no significant difference in left atrial size and left ventricular function in the two groups. The mean SAPW was significantly shorter in Group I when compared to Group II (118 ± 5 ms vs 149 ± 39 ms, P < 0.001). Whereas all patients in Group I had a normal SAPW, 79% of patients in Group II had an abnormal SAPW (P < 0.001). A normal SAPW was significantly predictive of vagal AF independent of other co-variables.
Conclusions: (1) Patients with vagal AF are younger, and invariably have paroxysmal lone AF. (2) SAPW is normal and significantly shorter in vagal AF when compared to patients with nonvagal AF. (3) This suggests that those in the vagal AF population have normal intraatrial conduction, which has implications for AF ablation in these patients.     

皮肤黏膜淋巴结综合征患儿QT间期离散度和P波离散度变化

目的　探讨用预测可能发生心律失常的心电学指标QT间期离散度 (QTd)和P波离散度 (Pd)来研究皮肤黏膜淋巴结综合征 (MCLS)患儿发生心律失常的可能性。方法　MCLS患儿 6 2例 (13例伴有冠脉扩张 ) ,随机匹配 79例健康儿童为对照。采用广东中山SR - 10 0 0A心电综合自动分析仪描记 12导联同步体表心电图 (12ECG) ,选择波形清晰的 3个心动周期 ,在人工干预下自动测量窦性节律时心率 (HR)、QTmax、QTmin、Pmax、Pmin ,计算QTd及Pd ,连测 3次后取其平均值。结果　与对照组比较 ,MCLS组急性期心率增快 (P <0 0 1) ,QTmax、QTmin缩短 ,QTd增大 ,Pmax增加 ,Pmin缩短 ,Pd增大 ;恢复期QTd、Pmax、Pd延长 ,其差异均有显著性 (P <0 0 1或P <0 0 5 )。伴有冠脉扩张与不伴有冠脉扩张的MCLS患儿之间QTmax、QTmin、QTd、Pmax、Pmin、Pd差异无显著性 (P >0 0 5 )。结论　MCLS能引起QTd及Pd增加 ,有可能发生严重心律失常 ,临床上不容忽视     

不同剂量替米沙坦对急性心肌梗死患者P波离散度的影响

目的探讨不同剂量的替米沙坦对急性心肌梗死患者P波离散度(Pd)、最大P波时限(Pmax)及住院期间心房颤动(Af)发生率的影响。方法选择我院2006年1月至2009年1月间因急性心肌梗死住院治疗的患者共261例,采用替米沙坦干预,小剂量组予20~40 mg/d,大剂量组予60~80 mg/d,观察不同剂量组患者治疗前后Pd、Pmax的变化及住院期间Af的发生情况。结果治疗后与小剂量治疗组相比,大剂量治疗组患者Pmax、Pd均明显降低,差异有统计学意义(P<0.05);治疗后大剂量组较治疗前Pmax及Pd明显降低,差异有统计学意义(P<0.05);而在小剂量治疗组中,治疗后Pmax及Pd有下降的趋势,但差异无统计学意义(P>0.05);大剂量组住院期间AF的发生比例较小剂量组低,差异有统计学意义(P<0.05)。结论大剂替米沙坦较小剂量替米沙坦能更明显减小Pd及Pmax,同时减少住院期间Af的发生。     

Segmental Wall Motion Abnormality Analyzed by Equilibrium Radionuclide Angiography and Improvement in Ventricular Function by Cardiac Resynchronization Therapy

Introduction: The purpose of this study was to determine the impact of the left ventricular (LV) segmental wall motion abnormalities detected by equilibrium radionuclide angiography (ERNA) on the improvement in LV and right ventricular (RV) function during biventricular (BIV) stimulation .
Results: We studied 28 patients in NYHA functional classes III or IV and QRS duration >150 ms on resting electrocardiogram. ERNA was performed before and during BIV stimulation at a 6-month follow-up. A significant shortening of QRS duration was observed during BIV stimulation (165 ± 5 ms before vs 133 ± 6 ms during, P < 0.01). Wall motion abnormalities (WMA) were observed in 16 patients (10 with nonischemic cardiomyopathies). In this group, LV and RV ejection fractions (EF) did not increase during BIV stimulation (LVEF = 22 ± 2% vs 20 ± 1.6%, ns; RVEF = 34 ± 3% vs 37 ± 3.8%, ns). Significant increases in RVEF (23 ± 3.2 %→ 38 ± 2.9%, P = 0.001) and LVEF (20 ± 2.5 %→ 30 ± 3%, P = 0.01) were observed in the group of patients without segmental WMA and with global hypokinesia (GH). In this group, a significant decrease in the dispersion in the phase of RV contraction was observed (SD = 39 ± 5 vs 26 ± 2 ms; P < 0.01). WMA predicted an increase in LVEF, in contrast to a baseline 6-minute-walk test, maximal oxygen consumption and LVEF, or amount of QRS shortening.
Conclusions: BIV stimulation increased in LV and RV EF in patients with ventricular dyssynchrony in absence of segmental WMA. ERNA was reliable in the selection of candidates for CRT.     

Placement of a Pacing Lead at the Inferior Portion of the Interatrial Septum Without Special Tools

Introduction: Previous studies have suggested that, among septal sites, the inferior portion of the interatrial septum (IAS) is the most likely to prevent atrial fibrillation, though inserting an active fixation lead at this site can be tedious and time consuming. We describe a relatively straightforward technique to insert a lead at this site without special tools .
Method: We studied 117 consecutive patients (mean age = 76 ± 8 years, 69% men) with ACC/AHA class I and II pacing indications and histories of paroxysmal or permanent atrial fibrillation, undergoing implantation of a dual chamber pacing system. A technique using the "preshaped" stylet and fluoroscopic guidance is described.
Results: The insertion was successful in 111 patients (95%). Acute dislodgement occurred in six patients (5%). The intrinsic P-wave duration was 117 ± 22 ms, and the paced P-wave duration was 90 ± 20 ms (23% shortening, P < 0.001). The mean time required to insert the atrial lead was 12 ± 8 minutes. No complications occurred.
Conclusions: Insertion of an active fixation lead at the inferior portion of the interatrial septum was safe and highly successful in the majority of patients with this technique.     

Cavotricuspid Isthmus Ablation with Large-Tip Gold Alloy Versus Platinum-Iridium-Tip Electrode Catheters

Background: Gold has excellent electrical conductive properties and creates deeper and wider lesions than platinum-iridium during radiofrequency (RF) ablation in vitro . We tested the maximum voltage-guided technique (MVGT) of cavotricuspid isthmus (CTI) ablation using two 8-mm tip catheters containing gold (group G) or platinum-iridium (group PI).
Methods: We enrolled 31 patients who underwent CTI ablation. In group G (n = 15) CTI ablation was performed with a gold-tip ablation catheter, while in group PI (n = 16) a platinum-iridium tip was used. Ablation was guided by CTI potentials with the highest amplitude until achievement of bidirectional block (BIB). If BIB was not achieved after 10 RF applications, RF was delivered via a 3.5-mm irrigated-tip catheter. Success rate, procedure duration, duration of fluoroscopic exposure, and number of RF applications were measured.
Results: BIB was achieved in all patients in group G, while in group PI an irrigated tip was used in four patients (0% vs 25%, P < 0.001). These four patients required a total of 21 additional RF applications (5.25 ± 2.22). Procedure time (56.4 ± 12 vs 73.1 ± 15 minutes P < 0.05) and fluoroscopic explosure (4.9 ± 2.3 vs 7.1 ± 3.8 minutes, P < 0.01) were shorter in group G than in group PI. Mean number of RF applications was lower (4.6 ± 1.9 vs 6.6 ± 3.1 P < 0.001) and total RF duration shorter (280 ± 117 vs 480 ± 310 seconds) in group G than in group PI. No difference was observed in the number of recurrences at a 6 month-follow up (1 in group G vs 1 in group PI).
Conclusion: Using the MVGT of CTI ablation, gold-tip catheters were associated with shorter procedural and fluoroscopic times, and fewer RF applications.     

Early Experience with Robotic Navigation for Catheter Ablation of Paroxysmal Atrial Fibrillation

Introduction: Pulmonary venous antra isolation (PVAI) is the cornerstone of catheter ablation procedure for drug refractory paroxysmal atrial fibrillation (AF). However, the procedure is technically challenging. Robotic navigation has a potential to expedite and facilitate the procedure.
Methods: A robotic catheter control system was used for remote navigation-supported PVAI in 22 patients (mean age = 55 ± 9 years, 16 males, study group). An irrigated-tip catheter with estimate of catheter force on the tissue was used. This was compared in nonrandomized fashion with conventional hand-controlled catheter ablation in 16 patients (mean age = 55 ± 9 years, 13 males, control group). The procedures were performed under guidance of Ensite NavX navigation system (St. Jude Medical, St. Paul, MN, USA) and intracardiac echocardiography.
Results: Robotic navigation was associated with significantly shorter overall duration of radiofrequency delivery (1,641 ± 609 vs 2,188 ± 865 seconds, P < 0.01), shorter total procedural time (207 ± 29 vs 250 ± 62 minutes, P = 0.007), fluoroscopy exposure (15 ± 5 vs 27 ± 9 minutes, P < 0.001), and lower radiation dose (1,119 ± 596 vs 3,048 ± 2,029 mGy/m², P < 0.001). No complication was observed in either the study or the control group. During the 5 ± 1 months follow-up in the study group and 9 ± 3 months in the control group, 91% and 81% of patients, respectively, were AF free.
Conclusions: In our early clinical experience, PVAI using a remote robotic catheter navigation was effective, safe, and associated with shorter procedural and fluoroscopic times than conventional PVAI.     

Effects of Autonomic Manipulation on Ventricular Fibrillation and Internal Cardiac Defibrillation Thresholds in Pigs

Autonomic tone may contribute to cardiac arrhythmogenesis and influence the efficacy of implantable defibrillators. Fifty-two anesthetized pigs were randomized to: (1) methacholine (n = 12); (2) nitroprusside (n = 12); (3) phenylephrine (n = 12); (4) carbachol (n = 8); and (5) saline (n = 8). Ventricular fibrillation threshold (VFT) and triplicate defibrillation thresholds (DFT) were obtained before and during each intervention. Mean (± SE) VFT was increased with: methacholine (76 ± 10.6 V vs 39 ± 7.1 V, P < 0.001); phenylephrine (68 ± 10.5 V vs 38 ± 6.2 V, P < 0.001); and carbachol (106 ± 11.5 V vs 30 ± 6.5 V, P < 0.0001). Nitroprusside and saline failed to alter VFT. Mean (± SE) DFT was decreased with: methacholine (7.7 ± 0.8 J vs 9.7 ± 0.8 J, P < 0.001); phenylephrine (9.8 ± 0.9 J vs 11.3 ± 1.0 1, P < 0.05); and carbachol (9.2 ± 0.7 J vs 12.2 ± 0.8), P < 0.0001), remaining unchanged following nitroprusside and saline infusion. Thus, modulation of autonomic tone modified arrhythmia susceptibility and the energy necessary for defibrillation, increased parasympathetic tone, increased VFT, and decreased DFT. Evaluation of autonomic balance, particularly parasympathetic tone, may be useful with the implantation of automatic defibrillators.     

High incidence of diabetes in men with sleep complaints or short sleep duration: a 12-year follow-up study of a middle-aged population

OBJECTIVE: The aim of this study was to investigate the possible relationship among sleep complaints, sleep duration, and the development of diabetes prospectively over a 12-year period in a middle-aged Swedish population. RESEARCH DESIGN AND METHODS: A random sample of 2,663 subjects aged 45-65 years living in mid-Sweden were sent a postal questionnaire including questions about sleep complaints, sleep duration, sociodemographic characteristics, behavioral risk factors, medical conditions, and depression (response rate 70.2%). Twelve years later, a new questionnaire with almost identical questions was sent to all the survivors (n = 1,604) in 1995, and the questionnaire was answered by 1,244 subjects (77.6%). RESULTS: Men reporting new diabetes at follow-up more often reported short sleep duration (< or =5 h per night) (16.0 vs. 5.9%, P < 0.01), difficulties initiating sleep (16.0 vs. 3.1%, P < 0.001), and difficulties maintaining sleep (28.0 vs. 6.3%, P < 0.001) at baseline than men who did not develop diabetes. Women reporting new diabetes at follow-up reported long sleep duration (> or =9 h per night) more often at baseline than women not developing diabetes (7.9 vs. 2.4%, P < 0.05). In multiple logistic regression models, the relative risk (95% CI) for development of diabetes was higher in men with short sleep duration (2.8 [1.1-7.3]) or difficulties maintaining sleep (4.8 [1.9-12.5]) after adjustment for age and other relevant risk factors. Short or long sleep duration or sleep complaints did not influence the risk of new diabetes in women. CONCLUSIONS: Difficulties maintaining sleep or short sleep duration (< or =5 h) are associated with an increased incidence of diabetes in men.     

Abnormal Nocturnal Heart Rate Variability and QT Dynamics in Patients with Brugada Syndrome

Background: In Brugada syndrome (BSY), most of the ventricular arrhythmic events are nocturnal, suggesting an influence of the autonomic nervous system.
Methods: In 46 patients (mean age = 41 ± 14 years, 43 men) with electrocardiograms (ECG) consistent with BSY and structurally normal hearts, we measured heart rate variability (HRV) and QT dynamics (QT/RR slopes) on 24-hour ambulatory ECG. Type 1 BSY-ECG was spontaneous in 23 (50%) and induced in 23 patients.
Results: History of syncope was present in 23 patients (50%). Programmed ventricular stimulation induced ventricular tachyarrhythmias (VTA) in 13 patients (28%). A single patient developed ventricular tachycardia during a mean follow-up of 34 months. Compared to a control group matched for age and sex, HRV was decreased over 24 hours and during nighttime in patients with BSY (SDNN 122 ± 44 vs 93 ± 36 ms, P = 0.0008 and SDANN 88 ± 39 vs 54 ± 24 ms, P < 0.0001). QTend /RR slopes were decreased over 24 hours in patients with BSY (0.159 ± 0.05 vs 0.127 ± 0.05, P = 0.003) and particularly at night (0.123 ± 0.04 vs 0.089 ± 0.04, P = 0.0001). QTend /RR slopes were significantly decreased during nighttime in patients with spontaneous versus provoked BSY-ECG patterns. By contrast, HRV and QT/RR slopes were similar in symptomatic and asymptomatic patients, whether VTA were induced or not.
Conclusions: Patients with a BSY-ECG pattern had lower HRV and QT/RR slopes than control subjects during nighttime. High-risk patients with spontaneous BSY-ECG patterns had the lowest nocturnal QTend/RR slopes. These unique repolarization dynamics might be related to the frequent nocturnal occurrence of VTA in BSY.     

Role of Pulmonary Veins Isolation in Persistent Atrial Fibrillation Ablation:

Background: The role of pulmonary veins (PV) isolation in patients with persistent atrial fibrillation (AF) is still debated. The aim of this study was to evaluate the adjunctive role of PV isolation in patients with persistent AF who underwent circumferential PV ablation (anatomical approach).
Methods: We treated 97 consecutive patients presenting with drug-refractory persistent AF by an anatomical approach (group A, n = 36, mean age = 60 ± 8 years, 29 males) or an integrated approach (group B, n = 61, mean age 59 ± 10 years, 48 males). In all patients, radiofrequency (RF) ablation was performed by means of a nonfluoroscopic navigation system, in order to anatomically create circumferential lines around the PV. In group B, the persistence of PV potentials was ascertained with a multipolar circular catheter. If PV potentials persisted, RF energy targeting the electrophysiological breakthroughs was delivered to disconnect the PV. Past a 2-month period of observation, success was defined as absence of any atrial tachyarrhythmia recurrence lasting >30 seconds.
Results: Total procedure duration (220 ± 62 minutes vs 140 ± 43 minutes, P < 0.001), fluoroscopy time (35 ± 15 minutes vs 17 ± 9 minutes, P < 0.001), and RF delivery time (48 ± 22 minutes vs 27 ± 9 minutes, P < 0.001) were significantly longer in group B than in group A. One cardiac perforation occurred in group A. After 15 ± 9.1 months, 21 patients in group A (58%) and 34 patients in group B (56%) were free of atrial tachyarrhythmia recurrence (P = 0.9).
Conclusions: In patients with persistent AF, who underwent an anatomical approach, electrophysiological confirmation of PV disconnection significantly increased the fluoroscopy and procedural times, without effect on the long-term outcomes.