Remaining longevity and evidence of failure of cardiac implantable electrophysiology devices recovered from funeral homes.

BACKGROUND: Given the prohibitive cost of pacemakers and defibrillators for medically underserved patients in low-income countries, these devices are sometimes recovered from funeral homes for charitable reimplantation. Many devices are implanted near the end of the patients' lives, meaning that recovered devices from funeral homes have the potential for significant remaining longevity. METHODS: After sending letters asking funeral directors in the Philadelphia area to donate explanted pacemakers and defibrillators, 78 devices were recovered. Sixty-seven of these devices were successfully interrogated, and 64 devices reported estimates of remaining battery life in years. Twenty-one defibrillators were also interrogated for evidence of failure. RESULTS: Twenty-two percent of the 64 devices had greater than 4 years of longevity. Fourteen percent of the devices had between 1 and 4 years of longevity, and the remaining 64% had less than 1 year of remaining battery life. We found no evidence from 21 recovered defibrillators that the patient's cause of death was because of defibrillator failure. In almost half (10/21) of the defibrillators, however, the arrhythmia logs were nondecipherable given the entire log was replaced by episodes of signal noise likely occurring after death. CONCLUSIONS: A significant percentage of devices explanted in funeral homes have suitable remaining battery life for reuse. While no evidence of defibrillator device failure could be found, the analysis was limited by postmortem signal artifact, which may preclude accurate assessment of rates of failure in devices explanted postmortem.

The ethics of unilateral implantable cardioverter defibrillators and cardiac resynchronization therapy with defibrillator deactivation: patient perspectives.

AIMS: Decisions about deactivation of implantable cardioverter defibrillators (ICDs) are complicated. Unilateral do-not-resuscitate (DNR) orders (against patient/family wishes) have been ethically justified in cases of medical futility. Unilateral deactivation of ICDs may be seen as a logical extension of a unilateral DNR order. However, the ethical implications of unilateral ICD deactivation have not been explored. METHODS AND RESULTS: Sixty patients who had an ICD or cardiac resynchronization therapy with defibrillator (CRT-D) were interviewed at a quaternary medical centre outpatient electrophysiology practice. Survey questions addressed whether deactivation of defibrillator function was included in advanced directives, whether deactivation constitutes physician-assisted suicide, and whether unilateral deactivation can be ethically justified. Responses were elicited to scenarios in which defibrillation function was deactivated in different contexts (including patient request to deactivate, existing DNR, and unilateral deactivation). Only 15% of respondents had thought about device deactivation if they were to develop a serious illness from which they were not expected to recover. A majority (53%) had advance directives, but only one mentioned what to do with the device. However, a majority (78%) did not consider deactivation of an ICD shocking function against patients' wishes to be ethical or moral. CONCLUSION: Management of ICDs and CRT-Ds as patients near the end of their lives creates ethical dilemmas. Few patients consider device deactivation at end-of-life, although a large majority believes that unilateral deactivation is not ethical/moral, even in the setting of medical futility. Advance care planning for these patients should address device deactivation.

Electrocardiogram voltage discordance: Interpretation of low QRS voltage only in the precordial leads.

OBJECTIVES: To define clinical correlates of low voltage isolated to precordial leads on the surface electrocardiogram (ECG). INTRODUCTION: Low voltage (V) on the ECG is defined as QRS V<5mm in all limb leads and <10mm in all precordial leads. The diagnostic use of ECGs with low voltage isolated to the precordial leads with normal limb lead voltages is unclear. METHODS: Twelve-lead ECGs with QRS V>5mm in one or more limb leads and <10mm in all precordial leads were collected. Associated clinical conditions were determined from clinical data, echocardiograms, and chest radiographs. RESULTS: Low precordial voltage was found in 256 of 150,000 ECGs (~0.2%). 50.4% of patients had discordant ECGs that correlated with classic etiologies, with a higher incidence of LV dilation in those with classic etiologies than those without. CONCLUSION: Low precordial voltage is associated with classic etiologies and LV dilation.

Defibrillator Deactivation against a Patient's Wishes: Perspectives of Electrophysiology Practitioners.

BACKGROUND: Unilateral do-not-resuscitate (DNR) orders (against patient/family wishes) have been ethically justified in cases of medical futility. We investigated whether electrophysiology practitioners believe medical futility justifies unilateral implantable cardioverter defibrillator (ICD) deactivation. METHODS AND RESULTS: Email invitations to take an online survey were sent to 1,894 electrophysiology practitioners. A total of 384 responses were collected (response rate 20.6%). Though the sample included respondents from Europe, Asia, Australia, South America, and Africa, the majority were from North America (78%), were academically affiliated (64%), and practiced in an urban setting (67.8%). Deactivation of ICD shock function in agreement with patient wishes and a preexisting DNR were not considered physician-assisted suicide (93.2%, 358/384). However, a majority of the sample responded that it was not ethical/moral for doctors to deactivate ICDs against patients' wishes (77.1%, 296/384) or against family/surrogates' wishes (72.4%, 278/384), even in the context of medical futility. A majority indicated that deactivating ICD shock function is not ethically/morally different than withholding cardiopulmonary resuscitation or external defibrillation in a code (72.7%, 277/381), but was different than deactivating pacing in a pacemaker-dependent patient (82.8%, 318/384). In the classification of interventions, a plurality (43.0%, 165/383) regarded ICDs to be unlike any other intervention. Concerning pacemakers, 50% (191/382) considered them to be like dialysis (a therapy that keeps patients alive). CONCLUSIONS: This international sample of electrophysiology practitioners considered ICD and pacemaker deactivation to be ethically distinct. While ICD deactivation was considered appropriate in the setting of patient/family agreement, unilateral deactivation was not.

Management of Atrial Fibrillation.

Atrial fibrillation remains the most prevalent cardiac arrhythmia, and its incidence is increasing as the population ages. Common conditions associated with an increased incidence include advanced age, hypertension, heart failure, and valvular heart disease. Patients with atrial fibrillation may complain of palpitations, fatigue, and decreased exercise tolerance or may be completely asymptomatic. Options for treating patients who experience atrial fibrillation include rate-controlling drugs such as digoxin, ß-blockers, and calcium channel blockers or a rhythm-controlling strategy with agents such as sodium channel blockers and potassium channel blockers. Atrial fibrillation increases the risk of stroke due to atrial thrombus formation and embolization. Anticoagulation with the vitamin K antagonist, warfarin, remains the most widely prescribed treatment option to decrease stroke risk. Several other antithrombotic agents have recently become available and offer excellent alternatives to warfarin. Catheter ablation can be undertaken as a nonpharmacologic rhythm control option with varying degrees of success depending on duration of atrial fibrillation and follow-up time from the procedure. This review article further describes the management options for patients presenting with atrial fibrillation.

Risk of stroke or transient ischemic attack after atrial fibrillation ablation with oral anticoagulant use guided by ECG monitoring and pulse assessment.

INTRODUCTION: We sought to gain insight into stroke risk after atrial fibrillation (AF) ablation. METHODS AND RESULTS: We followed 1,990 patients for >1 year (49 ± 29 months) who underwent AF ablation. Prior to stopping oral anticoagulants (OAC), we performed 3-week transtelephonic ECG monitoring (TTM) and taught patients heart rate and pulse assessment. Documented AF or inability to do monitoring or assess pulse precluded stopping OAC in CHADS2 ≥1 patients. OAC was stopped in 546/840 (65%) with CHADS2  = 0; 384/796 (48%) with CHADS2  = 1 and 101/354 (40%) with CHADS2 ≥ 2. Sixteen strokes or TIAs occurred (0.2%/patient-year); 5 in CHADS2  = 0 patients (all off OAC); 5 in CHADS2  = 1 (1 off and 4 on OAC); and 6 in CHADS2 ≥2 (2 off and 4 on OAC). Twelve of 16 patients (75%) with stroke or TIA had documented AF. In patients "off " OAC, stroke rate/year stratified by the CHADS2 score was similar (CHADS2  = 0: 0.28%; CHADS2  = 1: 0.07%; CHADS2 ≥2: 0.50%; P = NS). There was no difference in stroke risk "on" versus "off " OAC in CHADS2  = 1 (0.48% vs. 0.07%) or CHADS2 ≥2 (0.39% vs. 0.50%). Risk of major bleeding per patient year "on" OAC was > "off " OAC (13/1,138 (1.14%) versus 1/832 (0.1%); P<0.016). CONCLUSIONS: Post-AF ablation with OAC guided by TTM and pulse assessment: (1) Overall stroke or TIA rate risk is low and risk is due to recurrent AF and (2) OAC can be stopped in 40% of CHADS2 ≥2 patients with low stroke and hemorrhagic risk.

Assessing arrhythmia burden after catheter ablation of atrial fibrillation using an implantable loop recorder: the ABACUS study.

INTRODUCTION: Arrhythmia monitoring in patients undergoing atrial fibrillation (AF) ablation is challenging. Transtelephonic monitors (TTMs) are cumbersome to use and provide limited temporal assessment. Implantable loop recorders (ILRs) may overcome these limitations. We sought to evaluate the utility of ILRs versus conventional monitoring (CM) in patients undergoing AF ablation. METHODS AND RESULTS: Forty-four patients undergoing AF ablation received ILRs and CM (30-day TTM at discharge and months 5 and 11 postablation). Over the initial 6 months, clinical decisions were made based on CM. Subjects were then randomized for the remaining 6 months to arrhythmia assessment and management by ILR versus CM. The primary endpoint was arrhythmia recurrence. The secondary endpoint was actionable clinical events (change of antiarrhythmic drugs [AADs], anticoagulation, non-AF arrhythmia events, etc.) due to either monitoring strategy. Over the study period, 6 patients withdrew. In the first 6 months, AF recurred in 18 patients (7 noted by CM, 18 by ILR; P = 0.002). Five patients in the CM (28%) and 5 in the ILR arm (25%; P = NS) had AF recurrence during the latter 6 months. AF was falsely diagnosed frequently by ILR (730 of 1,421 episodes; 51%). In more patients in the ILR compared with the CM arm, rate control agents (60% vs 39%, P = 0.02) and AADs (71% vs 44%, P = 0.04) were discontinued. CONCLUSION: In AF ablation patients, ILR can detect more arrhythmias than CM. However, false detection remains a challenge. With adequate oversight, ILRs may be useful in monitoring these patients after ablation.

Innovative P-wave detection for discrimination between ventricular and supraventricular tachycardia in single-chamber ICDs: is the P-wave invisible during tachycardia?

AIMS: Differentiation between supraventricular tachycardia (SVT) and ventricular tachycardia (VT) remains a substantial clinical challenge in patients with single-chamber implantable cardioverter-defibrillators (ICDs) due to absence of visible P waves. Innovative optimization of intrathoracic electrogram (EGM) configuration will facilitate P-wave detection and rhythm differentiation during tachycardia. METHODS AND RESULTS: Innovative optimization of EGM configuration was originally performed to improve patient care. In this retrospective cohort study, we examined our database for records of 140 consecutive patients undergoing single-chamber ICD implantation. During the follow-ups of 61 included patients with optimized EGM configuration, 27 patients were identified to have VT and/or SVT. EGMs in the Can (generator) to superior vena cava (Can-SVC) configuration were compared with those conventionally from the Can to right ventricular coil (Can-RV coil) source in the same patients. In Can-SVC EGMs, the ratio of P/QRS amplitude was 14-fold higher (0.57 ± 0.08 vs. 0.04 ± 0.00, P < 0.001) compared with those in Can-RV coil EGMs during sinus rhythm. With Can-SVC configuration, the odds of atrioventricular dissociation detection in patients with VT was increased 15-fold (61.9% vs. 9.5% with Can-RV coil; odds ratio, 15.4; 95% confidence interval, 2.8 to 84.7; P = 0.0009). In patients with SVT, P-waves or retrograde P-waves were markedly more identifiable in Can-SVC configuration compared with Can-RV coil (odds ratio, 40; 95% confidence interval, 3.6 to 447.1; P = 0.0010). CONCLUSION: P-wave recognition by optimizing EGM configuration provides a novel diagnostic tool for differentiation between VT and SVT in single-chamber ICDs. A potential discrimination algorithm would provide a cost-effective approach to improving the qualitative outcomes.

The best way of preventing device-device interactions may be avoiding implanting 2 devices in the first place.

Extensive testing during the second device implantation was required to best program the devices in order to decrease these negative interactions. Unfortunately, these programming changes were not always successful at preventing device-device interactions during clinical follow-up.

Recovery of pacemakers and defibrillators for analysis and device advance directives: electrophysiologists' perspectives.

BACKGROUND: Following high-profile device failures, the Heart Rhythm Society emphasized the need for postmarketing surveillance by recommending that physicians return all explanted devices to the manufacturer for analysis. METHODS: We conducted a national survey of electrophysiologists (EPs) regarding recovery for analysis of explanted pacemakers and implantable cardioverter defibrillators (devices), and attitudes toward device-specific advance directives to facilitate return of devices. Online survey invitations were sent in four waves from December 2008 to June 2009 to 300 e-mail addresses from the Heart Rhythm Society member database. RESULTS: From 250 invitations, there were 95 responses (38%). Demographics included average age 50 years (range, 31-87); 95% male; 81% Caucasian. Only 23% reported returning all explanted devices to the manufacturers. Of all the respondents, 32% discarded >10 devices/year as medical waste, 42% stored devices in a box in the electrophysiology lab, and 10% donated at least 1 device/year to charity for reuse overseas. Sixty-seven percent felt that it would not be helpful to have an advance directive specifying what the patient would want done with their device postmortem. CONCLUSIONS: Few EPs return all explanted devices or send interrogation reports to the manufacturers, though nearly all said it was easy to do so. A majority either dispose of explanted devices as medical waste or store them in laboratories or offices, and a small percentage donate for reuse in underserved nations or to veterinary hospitals. This study suggests a need for initiatives such as educational campaigns to increase the retrieval and return of devices, either for analysis or reuse.

Ventricular tachycardia storm after initiation of biventricular pacing: incidence, clinical characteristics, management, and outcome.

INTRODUCTION: Cardiac resynchronization therapy (CRT) or biventricular pacing (BVP) is becoming an important treatment option in patients with severe congestive heart failure (CHF) and electrical dyssynchrony. When combined with implantable cardioverter-defibrillator (ICD) therapy, cardiac resynchronization therapy with a defibrillator (CRT-D) has been shown to improve quality of life, functional class, and, most recently, survival. However, left ventricular (LV) stimulation in the form of BVP in patients at high risk of developing ventricular tachyarrhythmias has raised concerns that BVP may be proarrhythmic. We describe the incidence, clinical characteristics, and management in a series of patients who developed ventricular tachycardia storm (VTS) after initiation of BVP. METHODS AND RESULTS: Clinical data on all patients undergoing CRT-D were collected prospectively. VTS occurred in eight of 191 (4%) patients and was characterized by recurrent sustained monomorphic ventricular tachycardia (MMVT) with a single morphology. All patients with VTS were men (seven with ischemic heart disease, one with nonischemic cardiomyopathy) with a remote (5 +/- 2 years) history of MMVT. VTS developed a mean of 16 +/- 12.5 days after initiation of BVP. All patients presented with palpitations and/or decompensated CHF. VTS was refractory to intravenous antiarrhythmic medication and was managed by turning off LV pacing and/or radiofrequency catheter ablation and long-term oral antiarrhythmic therapy. Despite elimination of VT, presenting with VTS carried a poor prognosis in that all eight patients subsequently developed refractory CHF. CONCLUSIONS: VTS with recurrent MMVT can occur after initiation of BVP. Patients present with decompensated CHF and are best managed by either turning off LV pacing or radiofrequency catheter ablation (RFA) in combination with long-term antiarrhythmic medication. Despite eliminating MMVT, most patients have poor outcomes.

Single procedure efficacy of isolating all versus arrhythmogenic pulmonary veins on long-term control of atrial fibrillation: a prospective randomized study.

BACKGROUND: Current atrial fibrillation (AF) ablation involves isolation of all pulmonary veins (PVs) with or without additional linear lesions. However, whether such extensive ablation is necessary is unclear. OBJECTIVE: The purpose of this study was to assess the efficacy of different ablation strategies on long-term AF control. METHODS: We prospectively randomized patients to undergo isolation of all versus arrhythmogenic PVs (identified by standardized stimulation protocol). PV isolation was guided by circular mapping catheter. The endpoint was entry/exit block persisting for > or = 20 minutes. Patients were evaluated at three clinic visits (at 6 weeks, 6 months, and 1 year) and multiple transtelephonic monitoring periods. Antiarrhythmic drugs were discontinued at 6 weeks. Primary study endpoint was long-term AF control (freedom or >90% reduction in AF burden off or on previously ineffective antiarrhythmic drugs at 1 year after a single ablation procedure). RESULTS: Over a 20-month period, 105 patients (76 men and 29 women, age 57 +/- 9 years; paroxysmal AF = 77) were randomized, and 103 patients completed 1-year follow-up (51 patients in all-PV arm, 52 patients in arrhythmogenic PV arm). The primary endpoint was achieved in 75 (73%) patients and was similar in patients randomized to all-PV arm versus arrhythmogenic PV arm [38 (75%) patients vs 37 (71%) patients, respectively; odds ratio 1.18, 95% confidence interval 0.50, 2.83, P = .70]. Secondary study endpoints, including freedom from AF off antiarrhythmic drugs, total procedure/fluoroscopy times, and occurrence of serious adverse events, were not different between the two groups. CONCLUSION: In a randomized comparison, isolation of arrhythmogenic veins was as efficacious as empiric isolation of all veins in achieving long-term AF control.

Electrocardiogram voltage discordance: interpretation of low QRS voltage only in the limb leads.

INTRODUCTION: Low voltage on the surface electrocardiogram (ECG) is defined as QRS voltage less than 5 mm in all limb leads and less than 10 mm in all precordial leads. The clinical correlate of an ECG with low voltage in the limb leads but normal precordial QRS amplitudes is unclear. METHODS: Twelve-lead ECGs with QRS voltage less than 5 mm in all limb leads and more than 10 mm in at least 2 contiguous precordial leads were collected. Presence of clinical conditions associated with low voltage was determined from clinical data and chest imaging. RESULTS: Fifty-one of 100 patients had voltage discordant ECGs that correlated with conditions known to cause diffuse low voltage. Among those without associated conditions, 63% had dilated ventricles, with an average ejection fraction of 33%. CONCLUSIONS: Low voltage isolated to the limb leads is associated with the same conditions that cause diffuse low voltage in only half of patients. In the remainder, more than 60% have dilated cardiomyopathies.

Incidence and predictors of very late recurrence of atrial fibrillation after ablation.

INTRODUCTION: Radiofrequency catheter ablation can effectively treat patients with refractory atrial fibrillation (AF). Very late AF recurrence (> or = 12 months post-ablation) is uncommon and may represent a unique patient cohort. METHODS AND RESULTS: A nested case-control study was performed in the cohort who underwent AF ablation at the University of Pennsylvania to characterize patients who develop very late AF recurrence after ablation. The procedure consisted of isolation of pulmonary veins (PVs) demonstrating triggers and elimination of non-PV triggers initiating AF. Twenty-seven (7.9%) patients with very late recurrence were compared to 219 patients without recurrence and > or = 12 months of follow-up. The mean age was 54.6 +/- 11.3 years and 79% were men. Very late recurrence patients more likely weighed >200 lbs (70% vs 55%, P = 0.01); during initial ablation had fewer PVs isolated (2.8 +/- 1.1 vs 3.3 +/- 1.0, P = 0.03); and were less likely to have right inferior PV isolation (37% vs 61%, P = 0.02), less likely to have isolation of all PVs (30% vs 56%, P = 0.01), and more likely to have non-PV triggers (30% vs 11% OR 3.4(95% CI, 1.3-8.7), P = 0.01). PV reconnectivity and new triggers were found in the majority of patients with very late recurrence of AF who underwent repeat ablation. CONCLUSION: Very late recurrence of AF more likely occurred in patients >200 lbs who demonstrated non-PV triggers and did not undergo right inferior PV isolation. The majority of patients undergoing repeat ablation for very late recurrence demonstrated PV reconnectivity and new non-PV and PV triggers not observed during the initial ablation.

Proper management of pericardial tamponade as a late complication of implantable cardiac device placement.

Cardiac tamponade as a late complication of device placement is exceedingly rare, with only several case reports previously published. We sought to characterize our institution's experience with cardiac tamponade occurring >30 days after permanent pacemaker or implantable cardioverter-defibrillator placement. From January 2000 to June 2003, 2,535 patients received an implantable cardiac device at our institution. Four patients (0.17%) presented with cardiac tamponade>30 days after the procedure. A fifth patient who had undergone implantation at another institution but was referred to our group with tamponade was also included in the analysis. The baseline characteristics varied widely with respect to age, gender, device type, and anticoagulation status. Lead parameters were altered in 2 of 5 patients. Two patients were treated with pericardiocentesis, 1 patient had pericardiocentesis followed by lead extraction, and 2 patients required cardiac surgical intervention. Pericardial fluid culture and cytologic findings were negative in all patients. All patients had normal recovery and were well at a mean follow-up of 31 months. In conclusion, cardiac tamponade is a rare, but serious late complication of permanent pacemaker and implantable cardioverter-defibrillator placement. The patient characteristics and mode of presentation vary widely. Once tamponade is recognized and treated, these patients appear well at long-term follow-up, with no other device-related problems. A role for lead manipulation does not appear to exist in the standard treatment of these patients.

Comparison of cool tip versus 8-mm tip catheter in achieving electrical isolation of pulmonary veins for long-term control of atrial fibrillation: a prospective randomized pilot study.

OBJECTIVE: To compare safety and efficacy of 8-mm versus cooled tip catheter in achieving electrical isolation (EI) of pulmonary veins (PV) for long-term control of atrial fibrillation (AF). BACKGROUND: There is paucity of studies comparing safety/efficacy of 8-mm and cooled tip catheters in patients undergoing AF ablation. METHODS AND RESULTS: This was a randomized and patient-blinded study. Subjects were followed by clinic visits (at 6 weeks and 6 months) and transtelephonic monitoring (3-week duration) done around each visit. Primary endpoints were: (1) long-term AF control (complete freedom and/or >90% reduction in AF burden on or off antiarrhythmic drugs at 6 months after a single ablation), and (2) occurrence of serious adverse events (cardiac tamponade, stroke, LA-esophageal fistula, and/or death). Eighty-two patients (age 56 +/- 9 years, 60 males, paroxysmal AF = 59) were randomized (42 patients to 8-mm tip and 40 patients to cooled tip). EI of PVs was achieved in shorter time by the 8-mm tip as compared with cooled tip catheter (40 +/- 23 minutes vs 50 +/- 30 minutes; P < 0.05) but long-term AF control was not different between the two (32 patients [78%] vs 28 patients [70%], respectively; P = NS). One serious adverse event occurred in each group (LA-esophageal fistula and stroke, respectively) and no significant PV stenosis was observed in either. CONCLUSION: EI of PVs using either 8-mm or cooled tip catheter results in long-term AF control in the majority after a single ablation procedure, with comparable efficacy and safety.

Elevated defibrillation thresholds in patients undergoing biventricular defibrillator implantation: incidence and predictors.

BACKGROUND: The biventricular implantable cardioverter-defibrillator (ICD) is an important therapy for select patients with severe heart failure. Given reported risk factors for elevated defibrillation thresholds (DFTs), patients undergoing biventricular ICD placement would be suspected of having a higher incidence of elevated DFT. OBJECTIVES: The purpose of this study was to examine the clinical predictors and mortality risk of elevated DFTs in patients receiving a biventricular ICD. METHODS: Characteristics of patients undergoing biventricular ICD placement with an elevated DFT were compared to those without an elevated DFT. RESULTS: An elevated DFT was found in 14 (12%) of 121 patients. Mean QRS duration was 210 +/- 50 ms in the elevated DFT group and 171 +/- 36 ms in the normal DFT group (P = .01). Patients with a QRS duration >or=200 ms were more likely to have an elevated DFT than those with a duration <200 ms (odds ratio 13.4, 95% confidence interval 3.1-66.7, P <.01). No other clinical characteristics were associated with an elevated DFT. More than 90% of patients with an elevated DFT achieved an adequate safety margin through system modification or manipulation of their drug regimen. An elevated DFT did not have an impact on 2-year mortality. CONCLUSION: Patients with a biventricular ICD had a 12% incidence of elevated DFT in our sequential patient cohort. QRS duration prior to biventricular ICD placement is the most powerful predictor of patients at risk for an elevated DFT. An elevated DFT does not have an impact on mortality, perhaps because of successful implementation of system modifications to ensure an adequate defibrillation safety margin.

The evolution of atrial fibrillation ablation from triggers to substrate.

The surgical approach to treat atrial fibrillation involves compartmentalizing the atrium. By dividing the atrium into discrete segments, the surgeon prevents the arrhythmia's ability to sustain by decreasing the required atrial substrate for propagation of the fibrillatory wavelets. Endocardial catheter ablation techniques used to replicate the surgical procedure were fraught with long procedure times and unacceptably high thromboembolic complications. The realization that the initiation of atrial fibrillation is often caused by triggers within the pulmonary veins has changed the focus from preventing the arrhythmia's ability to maintain itself to preventing the arrhythmia from ever being initiated. Early focal catheter ablation of atrial fibrillation used activation mapping and pace mapping to identify sites of spontaneous firing that led to bursts of atrial fibrillation. Although acute success rates were quite high, recurrences were unacceptably common. When investigators reattempted ablation of these patients, triggers were often found in other areas of the vein initially targeted and/or in remote veins. Because it appeared that either new triggers could arise in nonablated areas of veins or these areas were arrhythmogenic but not realized during initial ablation, the technique of complete isolation of the pulmonary vein was developed. A circular mapping catheter was placed at the funnel-shaped opening of each vein to map electrical exit sites of the vein into the atrium. Early attempts at electrical isolation of the veins occasionally caused pulmonary vein stenosis, on occasion necessitating angioplasty or stenting of the vein. This phenomenon has caused investigators to isolate the veins by using much larger circles with far greater diameters along the posterior left atrium. Many investigators now also have added ablation lines along the roof of the left atrium as well as down to the mitral valve annulus. The technique appears to be more analogous to the surgical model, now isolating triggers as well as preventing arrhythmia propagation.