Jens Seiler

Loss of pace capture on the ablation line: a new marker for complete radiofrequency lesions to achieve pulmonary vein isolation.

BACKGROUND Catheter ablation procedures for atrial fibrillation (AF) often involve circumferential antral isolation of pulmonary veins (PV). Inability to reliably identify conduction gaps on the ablation line necessitates placing additional lesions within the intended lesion set. OBJECTIVE This pilot study investigated the relationship between loss of pace capture directly along the ablation line and electrogram criteria for PV isolation (PVI). METHODS Using a 3-dimensional anatomic mapping system and irrigated-tip radiofrequency (RF) ablation catheter, lesions were placed in the PV antra to encircle ipsilateral vein pairs until pace capture at 10 mA/2 ms no longer occurred along the line. During ablation, a circular mapping catheter was placed in an ipsilateral PV, but the electrograms were not revealed until loss-of-pace capture. The procedural end point was PVI (entrance and exit block). RESULTS Thirty patients (57 +/- 12 years; 15 male [50%]) undergoing PVI in 2 centers (3 primary operators) were included (left atrial diameter 40 +/- 4 mm, left ventricular ejection fraction 60 +/- 7%). All patients reached the end points of complete PVI and loss of pace capture. When PV electrograms were revealed after loss of pace capture along the line, PVI was present in 57 of 60 (95%) vein pairs. In the remaining 3 of 60 (5%) PV pairs, further RF applications achieved PVI. The procedure duration was 237 +/- 46 minutes, with a fluoroscopy time of 23 +/- 9 minutes. Analysis of the blinded PV electrograms revealed that even after PVI was achieved, additional sites of pace capture were present on the ablation line in 30 of 60 (50%) of the PV pairs; 10 +/- 4 additional RF lesions were necessary to fully achieve loss of pace capture. After ablation, the electrogram amplitude was lower at unexcitable sites (0.25 +/- 0.15 mV vs. 0.42 +/- 0.32 mV, P < .001), but there was substantial overlap with pace capture sites, suggesting that electrogram amplitude lacks specificity for identifying pace capture sites. CONCLUSION Complete loss of pace capture directly along the circumferential ablation line correlates with entrance block in 95% of vein pairs and can be achieved without circular mapping catheter guidance. Thus, pace capture along the ablation line can be used to identify conduction gaps. Interestingly, more RF ablation energy was required to achieve loss of pace capture along the ablation line than for entrance block into PVs. Further study is warranted to determine whether this method results in more durable ablation lesions that reduce recurrence of AF.

Steam pops during irrigated radiofrequency ablation: Feasibility of impedance monitoring for prevention

BACKGROUND Steam pops are a risk of irrigated radiofrequency catheter ablation (RFA) and may cause cardiac perforation. Data to guide radiofrequency (RF) energy titration to avoid steam pops are limited. OBJECTIVE This study sought to assess the frequency and consequence of audible pops and to determine the feasibility of using the magnitude of impedance change to predict pops. METHODS We reviewed consecutive endocardial open-irrigated RFA for ventricular tachycardia (VT) with continuously recorded ablation data in 142 patients with structural heart disease. Steam pops were defined as an audible pop associated with a sudden spike in impedance. Ablation lesions before or after pops served as controls. RESULTS From a total of 4,107 ablation lesions, 62 (1.5%) steam pops occurred in 42 procedures in 38 patients. Perforation with tamponade occurred with 1 of 62 (2%) pops. Applications with pops had a greater impedance decrease (22 +/- 7 Omega vs. 18 +/- 8 Omega, P = .001) and a higher maximum power (45 +/- 5 W vs. 43 +/- 6 W, P = .011), but did not differ in maximum catheter tip temperature (40 degrees C +/- 4 degrees C vs. 40 degrees C +/- 4 degrees C, P = .180) from applications without pops. Eighty percent of pops occurred after impedance decreased by at least 18 Omega. CONCLUSION During VT ablation with open irrigation, audible pops are infrequent and do not usually cause perforation. Limiting RF power to achieve an impedance decrease of <18 Omega is a feasible method of reducing the likelihood of a pop when perforation risk is of concern.

Substrate characterization and catheter ablation for monomorphic ventricular tachycardia in patients with apical hypertrophic cardiomyopathy

VT Ablation in Apical Hypertrophic Cardiomyopathy. Introduction: Monomorphic ventricular tachycardia (VT) is uncommon in apical hypertrophic cardiomyopathy (HCM). The purpose of this study was to define the substrate and role of catheter ablation for VT in apical HCM.

Dual-loop circuits in postoperative atrial macro re-entrant tachycardias

Background: Patients may develop dual-loop re-entrant atrial arrhythmias late after open-heart surgery, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques. Objectives: The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop re-entrant arrhythmias, and to define the optimal mapping and ablation strategy. Methods: 40 consecutive patients (mean (SD) age 52 (12) years) with intra-atrial re-entrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. After an abrupt tachycardia change during radiofrequency ablation, electrical disconnection of the targeted re-entry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localised using electroanatomical mapping and/or entrainment mapping. Results: Dual-loop IART was demonstrated in eight (20%, 5 patients with congenital heart disease, 3 with acquired heart disease) patients. Dual-loop IART included an isthmus-dependant atrial flutter combined with a re-entry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardia modification. Overall, 35 patients had successful radiofrequency ablation (88%). Success rates were lower in patients with dual-loop IART than in patients without dual-loop IART. Ablation failures in three patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall. Conclusions: Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping manoeuvres demonstrate these circuits. Electroanatomical mapping appears to be important to assist catheter ablation of periatriotomy circuits.

Atrial fibrillation in congestive heart failure

Atrial fibrillation (AF) and heart failure (HF) are common and interrelated conditions, each promoting the other, and both associated with increased mortality. HF leads to structural and electrical atrial remodeling, thus creating the basis for the development and perpetuation of AF; and AF may lead to hemodynamic deterioration and the development of tachycardia-mediated cardiomyopathy. Stroke prevention by antithrombotic therapy is crucial in patients with AF and HF. Of the 2 principal therapeutic strategies to treat AF, rate control and rhythm control, neither has been shown to be superior to the other in terms of survival, despite better survival in patients with sinus rhythm compared with those in AF. Antiarrhythmic drug toxicity and poor efficacy are concerns. Catheter ablation of AF can establish sinus rhythm without the risks of antiarrhythmic drug therapy, but has important procedural risks, and data from randomized trials showing a survival benefit of this treatment strategy are still lacking. In intractable cases, ablation of the atrioventricular junction and placement of a permanent pacemaker is a treatment alternative; and biventricular pacing may prevent or reduce the negative consequences of chronic right ventricular pacing.

Mortality and safety of catheter ablation for antiarrhythmic drug-refractory ventricular tachycardia in elderly patients with coronary artery disease

BACKGROUND As the population ages, recurrent ventricular tachycardia (VT) is increasingly encountered in elderly patients with ischemic heart disease. Radiofrequency catheter ablation is useful for reducing VT therapy in patients with an implantable defibrillator. The utility of radiofrequency catheter ablation in the elderly is not well defined. OBJECTIVE The purpose of this study was to evaluate the prognosis and safety of radiofrequency catheter ablation of postinfarct VT in elderly patients. METHODS Radiofrequency catheter ablation was performed in 285 consecutive patients with recurrent postinfarct VT refractory to antiarrhythmic drugs. Mortality and outcomes were compared for an elderly group (age >or=75 years, n = 72) and a younger group (age <75 years, n = 213). RESULTS The groups were similar with regard to baseline characteristics, except for a greater number of females in the elderly group (20.8% vs 10.8%, P = .03). Inducible VTs were abolished or modified in 79.2% of the elderly group and 87.8% of the younger group (P = .12). Major complications occurred in 5.6% of elderly patients and 2.3% of younger patients (P = .48). Periprocedural mortality was similar between both groups (2/72 in elderly and 9/213 in younger group, P = .74). During mean follow-up of 42 +/- 33 months, 50.0% of the elderly group and 35.2% of the younger group died (P = .08). No VT was observed in 63.9% of the elderly patients and 60.1% of the younger patients, respectively (mean follow-up 18 +/- 24 months, P = .80). CONCLUSION Outcomes of catheter ablation are similar for selected elderly and younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival.

Percutaneous Access of the Epicardial Space for Mapping Ventricular and Supraventricular Arrhythmias in Patients With and Without Prior Cardiac Surgery

Percutaneous Epicardial Access. Introduction: There is a paucity of data on the success rates of achieving percutaneous epicardial access in different groups of patients.

Is 7-day event triggered ECG recording equivalent to 7-day Holter ECG recording for atrial fibrillation screening?

Objective Prolonged ECG monitoring is standard for atrial fibrillation (AF) screening. This study investigated whether 7-day event triggered (tECG) ECG recording is equivalent to 7-day continuous Holter (cECG) ECG recording for AF screening. Design Both a cECG (Lifecard CF) and a tECG (R.Test Evolution 3) were simultaneously worn for 7 days by patients with known or suspected paroxysmal AF. Results In 100 corresponding recordings, median effective duration of monitoring was 165 h (range 10–170 h) for cECG and 137 h (0–169 h) for tECG (p<0.001). Median number and total duration of arrhythmias (AF, atrial flutter or atrial tachycardia) of ≥30 s duration recorded by cECG were 10 (1–428) and 1030 min (≤1–10 020), respectively. An arrhythmia was recorded in 42 cECGs (42%) versus 37 tECGs (37%, p=0.56). Triggered ECG failed to record an arrhythmia in cECG positive cases because of interrupted monitoring in four cases and because of recording failure in one case. Sensitivity, specificity, and positive and negative predictive values of tECG therefore were 88%, 100%, 100%, and 92%, respectively. Quantitative cECG analysis required a median of 20 min (3–205 min) and qualitative tECG analysis 4 min (1–20 min; p<0.001). Skin irritation was a frequent side effect (42%) resulting in premature removal of devices in 16% of patients. Conclusion Sensitivity of tECG for AF screening as compared to cECG is lower, mainly because of shorter effective monitoring duration. Qualitative tECG analysis is less time consuming than quantitative cECG analysis. Skin irritation is a frequent side effect and reason for premature device removal.

Role of repeat procedures for catheter ablation of postinfarction ventricular tachycardia

BACKGROUND In patients with ischemic heart disease, ventricular tachycardia (VT) is associated with increased mortality and morbidity. Catheter ablation is useful for reducing VT therapies but remains challenging, and recurrences are common. OBJECTIVE The purpose of this study was to assess the prognosis and safety of repeat catheter ablation procedures for postinfarct VT and to determine clinical and procedural predictors of outcomes. METHODS From a total of 280 patients undergoing catheter ablation of postinfarct VT at one center, 107 consecutive patients having a repeat procedure after one or more prior failed catheter ablation procedures (PFCA group) were compared to 173 patients who underwent a single catheter ablation (SCA group) in the same study period. RESULTS Of the PFCA group, 75 (70.1%) had one procedure and 32 (29.9%) had two or more prior ablations. Ventricular function and age were similar between groups. Periprocedural complications occurred in 11.2% of patients in the PFCA group and 8.7% of patients in the SCA group (P = .484). The 1-year VT recurrence rate was higher in the PFCA group compared to the SCA group (32.6% vs 16.6%, P = .001). On multivariable analysis, prior ablation (hazard ratio [HR] 1.84, P = .018), left ventricular ejection fraction (HR 1.04, P = .019), and mean number of induced VTs (HR 1.17, P = .043) were independent predictors of VT recurrence. CONCLUSION Failure of initial ablation does not preclude subsequent successful ablation for postinfarct VT. Whether healing of prior lesions, change in arrhythmic substrate, or changes in antiarrhythmic therapy are factors that influence recurrence warrants further study.

Ventricular Tachycardia Arising From the Aortomitral Continuity in Structural Heart Disease: Characteristics and Therapeutic Considerations for an Anatomically Challenging Area of Origin

Background—The aortomitral continuity (AMC) has been described as a site of origin for ventricular tachycardias (VT) in structurally normal hearts. There is a paucity of data on the contribution of this region to VTs in patients with structural heart disease. Methods and Results—Data from 550 consecutive patients undergoing catheter ablation for VT associated with structural heart disease were reviewed. Twenty-one (3.8%) had a VT involving the peri-AMC region (age, 62.7±11 years; median left ventricular ejection fraction, 43.6±17%). Structural heart disease was ischemic in 7 (33%), dilated cardiomyopathy in 10 (47.6%), and valvular cardiomyopathy in 4 (19%) patients, respectively. After 1.9±0.8 catheter ablation procedures (including 3 transcoronary ethanol ablations) the peri-AMC VT was not inducible in 19 patients. The remaining 2 patients underwent cryosurgical ablation. Our first catheter ablation procedure was less often successful (66.7%) for peri-AMC VTs compared with that for 246 VTs originating from the LV free wall (81.4%, P=0.03). During a mean follow-up of 1.9±2.1 years, 12 (57.1%) patients remained free of VT, peri-AMC VT recurred in 7 patients, and 1 patient had recurrent VT from a remote location. Three patients died. Analysis of 50 normal coronary angiograms demonstrated an early septal branch supplying the peri-AMC area in 58% of cases that is a potential target for ethanol ablation. Conclusions—VTs involving the peri-AMC region occur in patients with structural heart disease and appear to be more difficult to ablate compared with VTs originating from the free LV wall. This region provides unique challenges for radiofrequency ablation, but cryosurgery and transcoronary alcohol ablation appear feasible in some cases.