Jin-Long Huang

Changes of autonomic tone before the onset of paroxysmal atrial fibrillation

The relationship between autonomic nerve system and the onset of paroxysmal atrial fibrillation (PAF) is still controversial. Furthermore, no prior studies have compared heart rate variability (HRV) between PAF patients with (organic) or without (idiopathic) underlying cardiac diseases. The purpose of this study was to assess the alteration of autonomic tone by analyzing HRV immediately before the onset of atrial fibrillation. This study included 57 patients (M/F: 34/23, 66+/-22 years) with frequent attacks of PAF. All cases underwent 24-h ambulatory Holter monitoring; each patient had one or more episodes of sustained PAF (>30 s). A period of sinus rhythm 40 min was allowed for accurate assessment of HRV over these periods. Spectral HRV was expressed as low (0.04-0.15 Hz) and high (0.15-0.40 Hz) frequency components (LF, HF), and L/H ratio at 2-min intervals over a 40-min period before the onset of PAF. According to HRV, three subtypes were classified; onset of PAF accompanied with increased HF component and decreased L/H ratio was designated as vagal type; decreased HF component and increased L/H ratio was designated as sympathetic type, and the other episodes which did not belong to vagal or sympathetic type were designated as non-related type. In group I (idiopathic PAF, n=30): 63 episodes of PAF were found and vagal type was predominant (41/63, 63.5%); HF increased significantly before the onset of AF. In group II (organic PAF, n=27): 58 episodes of PAF were found and sympathetic type was predominant (39/58, 67.2%); L/H ratio increased before AF onset. None of the three subtypes showed significant circadian distributions in group I and II patients. Changes of HRV before the onset of PAF were not universal; most of the patients with idiopathic PAF were vagal dependent and most of the patients with organic PAF were sympathetic dependent.

Role of autonomic tone in facilitating spontaneous onset of typical atrial flutter.

OBJECTIVESnThis study sought to study the change in autonomic tone that precedes the initiation of paroxysmal atrial flutter.nnnBACKGROUNDnAn abrupt change in the autonomic tone of the heart is an important initiating factor in the pathogenesis of ventricular tachyarrhythmias and paroxysmal atrial fibrillation. Whether the autonomic tone has a role in the initiation of paroxysmal atrial flutter has not been reported.nnnMETHODSnHolter electrocardiographic recording was used to investigate the changes in heart rate variability before the onset of paroxysmal atrial flutter.nnnRESULTSnA total of 12 patients with paroxysmal atrial flutter were analyzed. An increase in the normalized value of the low frequency (LF) component and the LF/high frequency (HF) ratio and a decrease in the normalized value of the HF component began at 6 min before the onset of episodes of paroxysmal atrial flutter, which indicated that sympathovagal balance had shifted to more sympathetic predominance.nnnCONCLUSIONSnAn increase in sympathetic modulation or vagal withdrawal, or both, may facilitate the initiation of atrial flutter.

Effect of atrial dilatation on electrophysiologic properties and inducibility of atrial fibrillation

Abstract.Introduction: Atrial dilatation may play an important role in the occurrence of atrial fibrillation (AF) in clinical situations. However, the electrophysiologic characteristics of dilated atria are still unclear. Methods and results: In 18 isolated Langendorff-perfused canine hearts (14.6 ± 2.2 kg), we measured atrial effective refractory periods (ERPs) at four different sites, conduction velocity and percentage of slow conduction on the right atrium (using a high-density electrode plaque), and assessed the inducibility of AF at the baseline (0 cm H2O) and high (15 cm H2O) atrial pressure. The atrial ERPs did not change significantly, but the dispersion of ERP increased significantly (40 ± 18 vs 25 ± 9 vs ms, p = 0.01) during high atrial pressure. The percentage of slow conduction (< 25 cm/s) over the mapping area, and the inducibility of AF increased during high atrial pressure (23.7 ± 10.2 % vs 32.1 ± 12.5 %, p = 0.02). The AF inducibility significantly correlated with the ERP dispersion (R = 0.75, p < 0.001) and maximal percentage of slow conduction (R = 0.88, p < 0.001). Furthermore, ERPs were significantly shorter in the induced AF group than those without induced AF (68 ± 17 vs 84 ± 16 ms, P < 0.05). Conclusions: The increased inhomogenity in atrial electrophysiological properties during atrial dilatation contributed to the inducibility of AF.

Idiopathic monomorphic ventricular tachycardia: clinical outcome, electrophysiologic characteristics and long-term results of catheter ablation

Ventricular tachycardia (VT) without structural heart disease or any identifiable predisposing causes for arrhythmia is an uncommon but well-recognized clinical entity. The purpose of this study is to assess the results of catheter ablation therapy and the long-term outcome of patients with idiopathic monomorphic VT in a large patient group. Sixty-one consecutive patients (male/female=40/21; mean age 38+/-16 years) with idiopathic VT underwent electrophysiologic study and an attempt of catheter ablation therapy. The left VT group included 31 patients with QRS morphology of right bundle branch block during VT suggestive of the VT originating from the left ventricle (LV), and the right VT group consisted of 30 patients with QRS morphology of left bundle branch block with normal or right frontal axis deviation suggestive of VT arising from right ventricular outflow tract (RVOT). Idiopathic left VT has sustained VT during the clinical attacks, baseline electrophysiologic study or after isoproterenol infusion; it can be entrained by overdrive ventricular pacing, terminated by verapamil, but not by adenosine (except one case with VT focus at left ventricular free wall). Catheter ablation was successful in 22 (84%) of 26 patients, with recurrence rate of 9%. The successful ablation sites were located at LV inferior-apical septum (16 patients), mid-septum (three patients), high septum (two patients) and high anterior wall (one patient). In the right VT group, 20 (67%) of 30 patients presented clinically repetitive monomorphic VT. Most of the idiopathic right VT (22/30) required isoproterenol to facilitate induction of VT, and were sensitive to both verapamil and adenosine. Successful catheter ablation was achieved in 21 (84%) of 25 patients, with recurrence rate 19%. The successful ablation sites were located at RVOT-septum in 18 patients, and RVOT-free wall in three patients. During a mean follow-up period of 29.2+/-21.7 months (range 1-76 months) after hospital discharge, all patients were alive but one left VT case died of non-cardiovascular cause. We concluded that idiopathic left side and right side VTs have their distinct clinical, electrophysiologic and electropharmacological characteristics suggestive of different underlying mechanisms, and both have a benign prognosis. Furthermore, catheter ablation can be effective in eliminating idiopathic VT originating from the right ventricular outflow tract and left ventricle.

Determinants of successful ablation of idiopathic ventricular tachycardias with left bundle branch block morphology from the right ventricular outflow tract.

LEE, S.‐H., et al.: Determinants of Successful Ablation of Idiopathic Ventricular Tachycardias with Left Bundle Branch Block Morphology from the Right Ventricular Outflow Tract. The aim of the study was to define the factors that may predict the outcomes of radiofrequency ablation from the right ventricular outflow tract (RVOT) in patients with idiopathic VT with a QRS morphology of LBBB. Endocardial mapping and RF ablation from the RVOT were performed in 35 patients (14 men, mean age 41 ± 14 years), and VT was successfully ablated in 30 patients. There was no significant difference with regard to clinical characteristics and electrophysiological findings between patients with successful and failed ablation. The VTs with successful ablation showed an rS (n = 16) or QS (n = 14) pattern in lead V1, and all five VTs with failed ablation showed an rS pattern in lead V1. Although the absence of an R wave in lead V1 did not differ between patients with successful and failed ablation (P = 0.13), the absence of an R wave in lead V1 predicted VT successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 24%). The VTs with successful ablation had a median precordial transitional zone at lead V4 (range V3–V6), whereas all five VTs with failed ablation had precordial transition zones at lead V3 (P = 0.004). Furthermore, a presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 predicted VT not successfully ablated from the RVOT (positive predictive value 100%; negative predictive value 100%). In conclusion, some VTs with LBBB and inferior or normal axis cannot be ablated from the RVOT. The presence of an R wave in lead V1 associated with a precordial transition zone at lead V3 suggest that some VTs may not arise from the RVOT.

Prognostic Significance of Premature Atrial Complexes Burden in Prediction of Long‐Term Outcome

Background The prognostic significance of premature atrial complex (PAC) burden is not fully elucidated. We aimed to investigate the relationship between the burden of PACs and long-term outcome. Methods and Results We investigated the clinical characteristics of 5371 consecutive patients without atrial fibrillation (AF) or a permanent pacemaker (PPM) at baseline who underwent 24-hour electrocardiography monitoring between January 1, 2002, and December 31, 2004. Clinical event data were retrieved from the Bureau of National Health Insurance of Taiwan. During a mean follow-up duration of 10±1 years, there were 1209 deaths, 1166 cardiovascular-related hospitalizations, 3104 hospitalizations for any reason, 418 cases of new-onset AF, and 132 PPM implantations. The optimal cut-off of PAC burden for predicting mortality was 76 beats per day, with a sensitivity of 63.1% and a specificity of 63.5%. In multivariate analysis, a PAC burden >76 beats per day was an independent predictor of mortality (hazard ratio: 1.384, 95% CI: 1.230 to 1.558), cardiovascular hospitalization (hazard ratio: 1.284, 95% CI: 1.137 to 1.451), new-onset AF (hazard ratio: 1.757, 95% CI: 1.427 to 2.163), and PPM implantation (hazard ratio: 2.821, 95% CI: 1.898 to 4.192). Patients with frequent PAC had increased risk of mortality attributable to myocardial infarction, heart failure, and sudden cardiac death. Frequent PACs increased risk of PPM implantation owing to sick sinus syndrome, high-degree atrioventricular block, and/or AF. Conclusions The burden of PACs is independently associated with mortality, cardiovascular hospitalization, new-onset AF, and PPM implantation in the long term.

Mechanisms of ventricular fibrillation during coronary angioplasty: increased incidence for the small orifice caliber of the right coronary artery

BACKGROUNDnVentricular fibrillation (VF) is not an infrequent complication of percutaneous transluminal coronary angioplasty (PTCA). However, it is not clear why there is a marked discrepancy in the higher incidence of VF during right coronary artery (RCA) approach.nnnMETHODS AND RESULTSnWe analyzed in detail every case of VF occurring in 905 consecutive PTCA procedures to investigate possible mechanisms. Sixteen patients (M/F=15/1, mean age: 71 +/- 8 years) with VF during PTCA for the RCA as Group I. Those 51 patients (M/F=48/3, mean age: 70 +/- 9 years) without VF during PTCA for the RCA engagement were designated as Group II. Patients were equipped with cardiac event recorder (CardioCall, Reynolds Medical, UK) before the PTCA, and we set the time period 1 min before and after the event. The lead II was selected to check the QRS width, QTc interval, ST segment change and RR interval before and after event. A total of 905 PTCA procedures were included. There were 561 procedures for the left coronary artery and three events (0.5%) with spontaneous VF. However, there were 16 events (4.6%) of VF during 344 PTCA procedures for the right coronary artery. The incidence of VF for the right side PTCA was significantly higher than for the left side. The orifice of RCA in Group I was smaller than Group II (orifice of RCA in Group I vs. Group II - 2.7+/-0.8 vs. 4.1+/-1.2 mm, P<0.001). Most cases (68.7%) presented with ST segment depression before the onset of VF.nnnCONCLUSIONnA small caliber of RCA and associated ST segment changes played important roles in the patients with VF during the PTCA.

Heart rate variability parameters and ventricular arrhythmia correlate with pulmonary arterial pressure in adult patients with idiopathic pulmonary arterial hypertension

OBJECTIVEnThis aim of this study was to correlate heart rate variability (HRV) parameters to pulmonary arterial pressure (PAP) in patients with purely idiopathic pulmonary arterial hypertension (IPAH).nnnBACKGROUNDnHRV is decreased in patients with PAH. Whether HRV indices can be used to assess PAP in IPAH patients remains unclear.nnnMETHODSnHRV parameters obtained by 24-h ECG were evaluated in 26 IPAH patients and 51 controls.nnnRESULTSnTime-domain HRV parameters (SDNN, pxa0<xa00.0001; SDANN, pxa0<xa00.0001; RMSSD, pxa0=xa00.006) were lower in IPAH patients. Frequency-domain indices (high-frequency power, HFP, pxa0=xa00.001; low-frequency power, LFP, pxa0=xa00.003; total power, TP, pxa0=xa00.001) were also decreased in IPAH patients. In IPAH patients, RMSSD (pxa0=xa00.001), HFP (pxa0=xa00.015), and LFP (pxa0=xa00.027) were significantly correlated with PAP. IPAH patients had longer QTc intervals (pxa0<xa00.0001) and more premature ventricular contractions (pxa0<xa00.0001) than controls.nnnCONCLUSIONSnIPAH is associated with autonomic dysfunction. RMSSD, HFP, and LFP may be used as a supplemental tool to assess PAP in IPAH patients. IPAH patients with autonomic dysfunction are at high risk for ventricular arrhythmia.

Pedal Tc-99m phytate lymphoscintigraphy in primary chylopericardium

This paper describes a case of 65-year-old woman with primary chylopericardium. She received Tc-99m phytate lymphoscintigraphy after pericardial drainage and was managed with medium-chain triglycerides without surgical intervention. This was the first reported case of primary chylopericardium diagnosed with Tc-99m phytate lymphoscintigraphy.

Corrigendum to “Changes of autonomic tone before the onset of paroxysmal atrial fibrillation” [International Journal of Cardiology 66 (1998) 275–283]

“Division of Cardiology, Department of Medicience, National Yang-Ming University, Taichung, Veterans General Hospital, 201 Sec. 2, Shih-Pai Road, Taipei, Taiwan, Republic of China. ‘Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital, Taichung, Taiwan, Republic of China “Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China