Coupling Intervals and Polymorphic QRS Morphologies. Introduction: Premature ventricular contractions (PVCs) arising from the right ventricular outflow tract (RVOT) can trigger polymorphic ...ventricular tachycardia (PVT) or ventricular fibrillation (VF) in patients with no structural heart disease. We aimed to clarify the ECG determinants of the polymorphic QRS morphology in idiopathic RVOT PVT/VF.
Methods and Results: The ECG parameters were compared between 18 patients with idiopathic PVT/VF (PVT‐group) and 21 with monomorphic VT arising from the RVOT (MVT‐group). The coupling interval (CI) of the first VT beat was comparable between the 2 groups. However, the prematurity index (PI) of the first VT beat was smaller in the PVT‐group than in the MVT‐group (P < 0.001). Furthermore, the QT index, defined as the ratio of the CI to the QT interval of the preceding sinus complex, was also smaller for the PVT/VF in the PVT‐group than that for the VT in the MVT‐group (P < 0.01). In the PVT‐group, the CI of the first VT beat was comparable between that of VT and isolated PVCs, but the PI of the first VT beat was shorter for VT than isolated PVCs (P < 0.05). The PI was the only independent determinant of the polymorphic QRS morphology (odd ratio = 2.198; 95% confidence interval = 1.321–3.659; P = 0.002).
Conclusion: The smaller PIs of the first VT beat may result in a polymorphic QRS morphology. (Cardiovasc Electrophysiol, Vol. 23, pp. 521‐526, May 2012)
Background
Circulatory dynamics change during pulmonary vein (PV) isolation using cryoballoons. This study sought to investigate the circulatory dynamics during cryoballoon‐based PV isolation ...procedures and the contributing factors.
Methods and Results
This study retrospectively included 35 atrial fibrillation patients who underwent PV isolation with 28‐mm second‐generation cryoballoons and single 3‐minute freeze techniques. Blood pressures were continuously monitored via arterial lines. The left ventricular function was evaluated with intracardiac echocardiography throughout the procedure in 5 additional patients. Overall, 126 cryoapplications without interrupting freezing were analyzed. Systolic blood pressure (SBP) significantly increased during freezing (138.7±28.0 to 148.0±27.2 mm Hg, P<0.001) and sharply dropped (136.3±26.0 to 95.0±17.9 mm Hg, P<0.001) during a mean of 21.0±8.0 seconds after releasing the occlusion during thawing. In the multivariate analyses, the left PVs (P=0.008) and lower baseline SBP (P<0.001) correlated with a larger SBP rise, whereas a higher baseline SBP (P<0.001), left PVs (P=0.017), lower balloon nadir temperature (P=0.027), and female sex (P=0.045) correlated with larger SBP drops. These changes were similarly observed regardless of preprocedural atropine administration and the target PV order. PV occlusions without freezing exhibited no SBP change. PV antrum freezing without occlusions similarly increased the SBP, but the SBP drop was significantly smaller than that with occlusions (P<0.001). The SBP drop time‐course paralleled the left ventricular ejection fraction increase (66.8±8.1% to 79.3±6.7%, P<0.001) and systemic vascular resistance index decrease (2667±1024 to 1937±513 dynes‐sec/cm2 per m2, P=0.002).
Conclusions
With second‐generation cryoballoon‐based PV isolation, SBP significantly increased during freezing owing to atrial tissue freezing and dropped sharply after releasing the occlusion, presumably because of the peripheral vascular resistance decrease mainly by circulating chilled blood.
Background
Cardiac tamponade is a serious complication of catheter ablation for atrial fibrillation (AF). However, the outcomes of catheter ablation in patients of cardiac tamponade are unknown.
...Methods
We performed catheter ablation in 2467 sessions of AF or a recurrence of AF between January 2007 and January 2016. Of these, 29 events in 27 patients (1.18%: 22 men; 64.5 ± 10.4 years; 17 with paroxysmal AF) of cardiac tamponade during or after the procedure were recorded. The clinical characteristics and outcomes of these 29 events were studied in detail.
Results
Of the 19 events where the ablation procedure was completed, seven events developed acute recurrence of AF (36.8%). Of the 10 events with an incomplete procedure, 10 exhibited AF recurrence (100.0%). Direct oral anticoagulants were used in seven events, and clinical outcomes were not significantly different compared to the remaining 21 events that were prescribed warfarin. Pericarditis occurred in 10 events (34.5%) after the procedure, and the incidence rate was lower in patients receiving prophylactic nonsteroidal anti‐inflammatory drugs or steroids (2/15, 13.3% vs 8/14, 57.1%; P = 0.013). Repeated sessions were performed in 12 events (two with a complete initial procedure, 10 with an incomplete initial procedure). Freedom from atrial arrhythmias was observed in 27 events (93.1%, 9 with antiarrhythmic drugs) over midterm follow‐up (3.1 ± 2.6 years).
Conclusion
Although cardiac tamponade caused by catheter ablation led to a high rate of acute AF recurrence and pericarditis, the midterm recurrence rates of AF are unaffected if the procedure can be completed.
Background: Hyperthyroidism is usually regarded as a reversible cause of atrial fibrillation (AF); however, one-third of patients remain in AF despite euthyroid restoration. We hypothesized that a ...significant number of AF patients with hyperthyroidism (Hyperthyroid-AF) as well as those without (Non-thyroid-AF) would benefit from catheter ablation of AF (AF ablation). This study aimed to clarify the prevalence of hyperthyroidism in candidates for AF ablation and to compare the long-term outcome of AF ablation between the Hyperthyroid-AF and Non-thyroid-AF groups. Methods and Results: This study enrolled 337 consecutive patients with AF who underwent a first AF ablation that mainly involved extensive encircling pulmonary vein isolation. Sixteen (4.7%) patients had hyperthyroidism; the remaining 321 (95.3%) did not. In the Hyperthyroid-AF patients, a euthyroid state had been restored for at least 3 months before the ablation. During a mean follow-up period of 4±1 years after ablation, AF recurred in 7 patients (44%) with Hyperthyroid-AF and in 139 patients (43%) with Non-thyroid-AF (P=0.91 by the log-rank test). In the multivariate Cox regression models, the presence of hyperthyroidism was not associated with a higher risk of AF recurrence (hazard ratio, 0.87; 95% confidence interval, 0.40–1.88; P=0.73). Conclusions: In the AF ablation candidates without structural heart disease, hyperthyroidism was not rare. After euthyroid restoration on pharmacological treatment, hyperthyroidism was not associated with a higher risk of AF recurrence. (Circ J 2012; 76: 2546–2551)
Background: The aim of this study was to propose modified tissue Doppler imaging (TDI) parameters derived from the first active wall motion and to assess them for the better prediction of cardiac ...resynchronization therapy (CRT) responders in comparison with to original TDI parameters. Methods and Results: In 61 patients with CRT, time from QRS onset to peak velocities by TDI (Ts), which were derived from active wall motion identified by longitudinal strain rate (LSR) value, were assessed. Time from QRS onset to the negative peak of LSR (TLSR) was also assessed. Modified standard deviation of Ts in 12 left ventricular (LV) segments (Ts-SD), that of TLSR (TLSR-SD), differences of Ts between septum and lateral wall (Ts-SL), and that of TLSR (TLSR-SL) were calculated. Original Ts-SD and Ts-SL were calculated by previously described methods. Responders were defined as patients with LV end-systolic volume reduction (>15%) at 6 months after CRT: 35 patients (57%) were identified as CRT responders. Area under the receiver-operating characteristics curve (AUC) of modified Ts-SD (0.87) was significantly higher than that of Ts-SD (0.65), Ts-SL (0.62), and TLSR-SL (0.69). AUC of modified Ts-SL was significantly higher than those of Ts-SD, and Ts-SL. AUC of TLSR-SD (0.82) also was significantly higher than that of Ts-SD. Conclusions: Modified TDI dyssynchrony parameters derived from the first active wall motion improve the ability to predict responders to CRT. (Circ J 2012; 76: 689-697)
AF Rat Model Induced by Transvenous Catheter Pacing. Introduction: Large animal models of atrial fibrillation (AF) are well established, but limited experimental reports exist on small animal models. ...We sought to develop an in vivo rat model of AF using a transvenous catheter and to evaluate the model's underlying characteristics.
Methods and Results: Echocardiogram, surface electrocardiogram (ECG), and atrial effective refractory period (AERP) were recorded at baseline in young (3 months) and middle‐aged (9 months) Wistar rats. AF inducibility and duration were measured through transvenous electrode catheter in young (n = 11) and middle‐aged rats (n = 11) and middle‐aged rats treated with either pilsicainide (1 mg/kg iv, n = 7) or amiodarone (10 mg/kg iv, n = 9). Degrees of interstitial fibrosis and cellular hypertrophy in the atria were assessed histologically. The P‐wave duration and AERP were significantly longer and echocardiographic left atrial dimension significantly larger in middle‐aged versus young rats. AF was inducible in >90% of all procedures in both untreated rat groups, whereas AF inducibility was reduced by the antiarrhythmic drugs. The AF duration was significantly longer in middle‐aged than in young rats and was significantly shortened by treatment with either pilsicainide or amiodarone. Histologic analysis revealed significant increases in atrial interstitial fibrosis and cellular diameter in middle‐aged versus young rats.
Conclusions: Transvenous catheter‐based AF is significantly longer in middle‐aged than in young rats and is markedly reduced by treatment with antiarrhythmic drugs. This rat model of AF is simple, reproducible, and reliable for examining pharmacologic effects on AF and studying the process of atrial remodeling.
(J Cardiovasc Electrophysiol, Vol. 21, pp. 88–93, January 2010)
Background: Linear ablation of atrial flutter usually targets a 6 o’clock position on the cavotricuspid isthmus on left anterior oblique view, but the difficulty of the ablation often requires a ...variation in successful ablation line position from 5 to 7 o’clock. Methods and Results: This study included 94 patients without structural heart disease. A linear lesion was created in turn at the 6, 7, and 5 o’clock positions until bidirectional block of the isthmus was completed; the final lesion was defined as the successful ablation line. The degree of counterclockwise heart rotation (CCW-HR) was evaluated in a blinded fashion according to the angle between the vertical line crossing the His bundle catheter and the line connecting the His bundle catheter and coronary sinus ostium. Successful ablation lines were obtained at the 6 o’clock position in 59 patients (63%); the 7 o’clock position in 19 patients (20%; the oldest group with a moderate radiofrequency burden); and the 5 o’clock position in the remaining 16 (17%; the youngest group with the largest radiofrequency burden). Age-related increase in CCW-HR was the only independent predictor of a more septal successful ablation line (OR, 7.1; 95% CI: 3.3–14.3; P<0.01). Conclusions: Variation in successful ablation line position was affected by age-related CCW-HR; its evaluation might reduce radiofrequency burden, especially in the young and elderly. (Circ J 2014; 78: 859–864)
Abstract Background To determine an appropriate M-mode method in assessing left ventricular (LV) dyssynchrony in left bundle branch block (LBBB), and to assess feasibility of the method to predict ...cardiac resynchronization therapy (CRT) responses. Methods and results Fifty-one patients with LBBB were enrolled. Among them 31 patients underwent CRT. In addition to original septal to posterior wall motion delay (SPWMD), first peak-SPWMD was proposed as time of difference between the first septal displacement and the maximum displacement of the posterior. If an early septal point was not present, anatomical M-mode was used to visualize an early septal displacement spreading scan-area until inferoseptal wall. CRT responders were defined as LV end-systolic volume reduction (>15%) at 6 months after CRT. Twenty patients (65%) were identified as CRT responders. First peak-SPWMD in responders was significantly higher than those in nonresponders, although SPWMD did not differ between groups. Strong predicting ability of first peak-SPWMD was revealed (first peak-SPWMD: 80/90/83%; SPWMD: 35/100/58%), and area under the curve in receiver operating characteristic analysis of first peak-SPWMD (0.88) was significantly higher than that of SPWMD (0.61) ( p < 0.05). Conclusion In patients with LBBB, time differences between early septal and delayed displacement of posterolateral wall on M-mode images were the appropriate dyssynchrony parameter, and could improve the predictive ability for CRT responses.
The requirement for epicardial radiofrequency ablation (RFA) is still undefined in ventricular tachycardia (VT) late after myocardial infarction (MI).
The purpose of this study was to evaluate the ...correlation between the need for epicardial RFA and the clinical and electrophysiologic characteristics of VT late after MI.
Endocardial mapping and RFA were performed for VT late after MI, followed by epicardial mapping and RFA if no endocardial substrate was present or endocardial RFA failed.
Seventy patients with VT late after MI (30 anterior MI A-MI and 40 posteroinferior MI PI-MI) were included in the study. Forty-one VTs in patients with A-MI and 64 VTs in patients with PI-MI were targeted for RFA. Epicardial mapping and ablation were attempted in 6 patients and performed successfully in only 4 patients. All 6 (100%) patients requiring epicardial access had PI-MIs. Patients with epicardial RFA had endocardial low-voltage areas of smaller size compared to patients without epicardial RFA (21 ± 13 cm(2) vs 68 ± 40 cm(2); P <.01). During 25 ± 19 months of follow-up, recurrence after the initial procedure was noted in 12 of 30 patients (40%) with A-MI and in 18 of 40 patients (45%) with PI-MI. There was no significant difference between groups.
In the majority of patients, clinical and slower VTs late after MI can be abolished using endocardial RFA. Rarely indicated, epicardial RFA is more commonly required in patients with small-sized PI-MI. During follow-up, VT recurrence after successful RFA is common.
We describe a patient who underwent radiofrequency (RF) catheter ablation of cavo-tricuspid isthmus-dependent atrial flutter (AFL). Extensive ablation at the isthmus failed to terminate the AFL. A ...coronary sinus (CS) diverticulum arising from the proximal portion of the middle cardiac vein was found near the isthmus. An RF energy application at the bottom of the CS diverticulum resulted in completion of a bidirectional block line at the isthmus, as well as AFL termination.
PDF
