Acute Hemodynamic Effects of Biventricular Pacing After Left Ventricular Assist Device.

BACKGROUND: Despite cardiac resynchronization therapy (CRT), some patients with heart failure progress and undergo left ventricular assist device (LVAD) implantation. Management of CRT after LVAD implantation has not been well studied. The purpose of this study was to determine whether RV pacing or biventricular pacing measurably affects acute hemodynamics in patients with an LVAD and a CRT device. METHODS AND RESULTS: Seven patients with CRT and LVAD underwent right heart catheterization. Pressures and oximetry were measured and LVAD parameters were recorded during 3 different conditions: RV pacing alone, biventricular pacing, and intrinsic atrioventricular conduction. Paired t tests were used to evaluate changes within subjects. There were no significant changes in right atrial pressure, pulmonary arterial pressures, pulmonary capillary wedge pressure, cardiac index, or any LVAD parameter (P > .05). CONCLUSIONS: Our data suggest that CRT probably has no acute hemodynamic effect in patients with LVADs, but further study is needed.

Significant Discrepancy Between Estimated and Actual Longevity in St. Jude Medical Implantable Cardioverter-Defibrillators.

BACKGROUND: Real-time estimated longevity has been reported in pacemakers for several years, and was recently introduced in implantable cardioverter-defibrillators (ICDs). OBJECTIVE: We sought to evaluate the accuracy of this longevity estimate in St. Jude Medical (SJM) ICDs, especially as the device battery approaches depletion. METHODS: Among patients with SJM ICDs who underwent generator replacements due to reaching elective replacement indicator (ERI) at our institution, we identified those with devices that provided longevity estimates and reviewed their device interrogations in the 18 months prior to ERI. Significant discrepancy was defined as a difference of more than 12 months between estimated and actual longevity at any point during this period. RESULTS: Forty-six patients with Current/Promote devices formed the study group (40 cardiac resynchronization therapy [CRT] and 6 single/dual chamber). Of these, 34 (74%) had significant discrepancy between estimated and actual longevity (28 CRT and all single/dual). Longevity was significantly overestimated by the device algorithm (mean maximum discrepancy of 18.8 months), more in single/dual than CRT devices (30.5 vs. 17.1 months). Marked discrepancy was seen at voltages ≥2.57 volts, with maximum discrepancy at 2.57 volts (23 months). The overall longevity was higher in the discrepant group of CRT devices than in the nondiscrepant group (67 vs. 61 months, log-rank P = 0.03). CONCLUSIONS: There was significant overestimation of longevity in nearly three-fourths of Current/Promote SJM ICDs in the last 18 months prior to ERI. Longevity estimates of SJM ICDs may not be reliable for making clinical decisions on frequency of follow-up, as the battery approaches depletion.

Prevalence and Electrocardiographic and Electrophysiological Characteristics of Idiopathic Ventricular Arrhythmias Originating From Intramural Foci in the Left Ventricular Outflow Tract.

BACKGROUNDS: Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) sometimes require catheter ablation from both the endocardial and epicardial sides for their elimination, suggesting the presence of intramural VA foci. This study investigated the prevalence and electrocardiographic and electrophysiological characteristics of these idiopathic intramural LVOT VAs when compared with the idiopathic endocardial and epicardial LVOT VAs. METHODS AND RESULTS: We studied 82 consecutive VAs with origins in the aortomitral continuity (n=30), LV summit (n=34), and intramural site (n=18). The maximum deflection index (the time to the maximum deflection in the precordial leads/QRS duration) was the largest in LV summit VAs (0.52±0.07), smallest in aortomitral continuity VAs (0.45±0.06), and midrange in intramural VAs (0.49±0.05). The electrocardiographic and electrophysiological characteristics of the intramural LVOT VAs were similar to those of the aortomitral continuity VAs. The intramural LVOT VAs exhibited a significantly smaller R-wave amplitude ratio in leads III to II, and ratio of the Q-wave amplitude in leads aVL to aVR, and a significantly earlier and later local ventricular activation time relative to the QRS onset at the His bundle and successful ablation sites than the LV summit VAs, respectively. CONCLUSIONS: Intramural sites account for a significant proportion of LVOT VAs. The electrocardiographic and electrophysiological characteristics of the idiopathic intramural LVOT VAs were midrange between those of the idiopathic endocardial and epicardial LVOT VAs, and more similar to those of the idiopathic endocardial LVOT VAs than those of the idiopathic epicardial LVOT VAs.

Radiofrequency catheter ablation of idiopathic ventricular arrhythmias originating from intramural foci in the left ventricular outflow tract: efficacy of sequential versus simultaneous unipolar catheter ablation.

BACKGROUNDS: Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) sometimes require catheter ablation from the endocardial and epicardial sides for their elimination, suggesting the presence of intramural VA foci. This study investigated the efficacy of sequential and simultaneous unipolar radiofrequency catheter ablation from the endocardial and epicardial sides in treating intramural LVOT VAs. METHODS AND RESULTS: Fourteen consecutive LVOT VAs, which required sequential or simultaneous irrigated unipolar radiofrequency ablation from the endocardial and epicardial sides for their elimination, were studied. The first ablation was performed at the site with the earliest local ventricular activation and best pace map on the endocardial or epicardial side. When the first ablation was unsuccessful, the second ablation was delivered on the other surface. If this sequential unipolar ablation failed, simultaneous unipolar ablation from both sides was performed. The first ablation was performed on the epicardial side in 9 VAs and endocardial side in 5 VAs. The intramural LVOT VAs were successfully eliminated by the sequential (n=9) or simultaneous (n=5) unipolar catheter ablation. Simultaneous ablation was most likely to be required for the elimination of the VAs when the distance between the endocardial and epicardial ablation sites was >8 mm and the earliest local ventricular activation time relative to the QRS onset during the VAs of <-30 ms was recorded at those ablation sites. CONCLUSIONS: LVOT VAs originating from intramural foci could usually be eliminated by sequential unipolar radiofrequency ablation and sometimes required simultaneous ablation from both the endocardial and epicardial sides.

A novel electrocardiographic criterion for differentiating a left from right ventricular outflow tract tachycardia origin: the V2S/V3R index.

INTRODUCTION: Although several ECG criteria have been proposed for differentiating between left and right origins of idiopathic ventricular arrhythmias (VA) originating from the outflow tract (OT-VA), their accuracy and usefulness remain limited. This study was undertaken to develop a more accurate and useful ECG criterion for differentiating between left and right OT-VA origins. METHODS AND RESULTS: We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 207 patients who underwent successful catheter ablation in the right (RVOT; n = 154) or left ventricular outflow tract (LVOT; n = 53). The surface ECGs during the OT-VAs and during sinus beats were analyzed with an electronic caliper. The V2S/V3R index was defined as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT-VA. The V2S/V3R index was significantly smaller for LVOT origins than RVOT origins (P < 0.001). The area under the curve (AUC) for the V2S/V3R index by a receiver operating characteristic analysis was 0.964, with a cut-off value of ≤1.5 predicting an LVOT origin with an 89% sensitivity and 94% specificity. In the AUC and accuracy, the V2S/V3R index was superior to any previously proposed ECG criteria in an analysis of all OT-VAs. This advantage of the V2S/V3R index over the V2 transition ratio and other indices also held true for a subanalysis of 77 OT-VAs with a lead V3 precordial transition. CONCLUSION: The V2S/V3R index outperformed other ECG criteria to differentiate left from right OT-VA origins independent of the site of the precordial transition.

Prevalence and clinical, electrocardiographic, and electrophysiologic characteristics of ventricular arrhythmias originating from the noncoronary sinus of Valsalva.

BACKGROUND: Idiopathic ventricular arrhythmias (VAs) can be rarely ablated from the noncoronary cusp (NCC) of the aorta. OBJECTIVE: The purpose of this study was to investigate the prevalence and the clinical, electrocardiographic, and electrophysiologic characteristics of idiopathic NCC VAs. METHODS: We studied 90 consecutive patients who underwent successful catheter ablation of idiopathic aortic root VAs (left coronary cusp [LCC] 33, right coronary cusp [RCC] 32, junction between LCC and RCC 19, NCC = 6). RESULTS: NCC VAs occurred in significantly younger patients (all <40 years old) and exhibited a shorter QRS duration (all but one <150 ms), smaller R-wave amplitude ratio in leads II and III (III/II), earlier ventricular activation in the His bundle (HB) region (all but one preceded QRS onset by >25 ms), and larger atrial to ventricular electrogram amplitude ratio (A/V) at the successful ablation site (all but one >1) than the other VAs. QRS morphology of the NCC VAs was similar to that of RCC VAs, but NCC VAs always exhibited a left bundle branch block and left superior (n = 1) or inferior axis (n = 5). All NCC VAs exhibited ventricular tachycardias, although premature ventricular contractions were dominant in the other VAs. CONCLUSION: NCC VAs were very rare (7%) and occurred in significantly younger patients than those among the other aortic root VAs. In a limited set of six patients, the ECG and electrophysiologic characteristics of NCC VAs were similar to those of RCC VAs but were characterized by narrower QRS duration, smaller III/II ratio, earlier ventricular activation in the HB region, and A/V ratio >1 at the successful ablation site.

Cardiovascular implantable electronic device implantation with uninterrupted dabigatran: comparison to uninterrupted warfarin.

BACKGROUND: While continuation of oral anticoagulation (OAC) with warfarin may be preferable to interruption and bridging with heparin for patients undergoing cardiovascular implantable electronic device (CIED) implantation, it is uncertain whether the same strategy can be safely used with dabigatran. OBJECTIVE AND METHODS: To determine the risk of bleeding and thromboembolic complications associated with uninterrupted OAC during CIED implantation, replacement, or revision, the outcomes of patients receiving uninterrupted dabigatran (D) were compared to those receiving warfarin (W). RESULTS: D was administered the day of CIED implant in 48 patients (age 66 ± 12.4 years, 13 F and 35 M, 21 ICDs and 27 PMs), including new implant in 25 patients, replacement in 14 patients, and replacement plus lead revision in 9 patients. D was held the morning of the procedure in 14 patients (age 70 ± 11 years, 4 F and 10 M, 5 ICDs and 9 PMs). W was continued in 195 patients (age 60 ± 14.4 years, 54 F, and 141 M), including new implant in 122 patients, replacement in 33 patients, and replacement plus lead revision or upgrade in 40 patients. Bleeding complications occurred in 1 of 48 patients (2.1%) with uninterrupted dabigatran (a late pericardial effusion), 0 of 14 with interrupted D, and 9 of 195 patients (4.6%) on W (9 pocket hematomas), P = 0.69. Fifty percent of bleeding complications were associated with concomitant antiplatelet medications. CONCLUSIONS: The incidence of bleeding complications is similar during CIED implantation with uninterrupted D or W. The risks are higher when OAC is combined with antiplatelet drugs.

Dabigatran versus warfarin therapy for uninterrupted oral anticoagulation during atrial fibrillation ablation.

BACKGROUND: Uninterrupted oral anticoagulant (OA) therapy with warfarin has become the standard of care at many centers performing catheter ablation of atrial fibrillation (AF). Compared with warfarin, dabigatran, a direct thrombin inhibitor, has been demonstrated to reduce the risk of stroke in nonvalvular AF with similar bleeding risk. Few data exist on the safety profile of uninterrupted dabigatran therapy during AF ablation. METHODS: We compared the safety and efficacy of uninterrupted OA therapy with either warfarin or dabigatran in all patients undergoing AF catheter ablation at the University of Alabama at Birmingham between November 1, 2010 and January 31, 2012. All patients underwent a transesophageal echocardiogram (TEE) on the day of their ablation procedure to assess for the presence of intracardiac thrombi. All complications were identified and classified as bleeding, thromboembolic events, or other. RESULTS: There were 212 patients in the dabigatran group and 251 patients in the warfarin group. The groups were well matched. There were 3 complications in the dabigatran group and 6 in the warfarin group (P = 0.45). There were 2 bleeding complications in the dabigatran group and 6 in the warfarin group (P = 0.23). There was one thromboembolic complication (a possible TIA) in the dabigatran group and none in the warfarin group (P = 0.28). CONCLUSION: The administration of dabigatran is as safe and effective as warfarin for uninterrupted OA therapy during catheter ablation of AF.

Arrhythmias in Fabry cardiomyopathy.

BACKGROUND: Prior studies suggest that the incidence of ventricular arrhythmias is high in patients with Fabry cardiomyopathy. This study evaluated the incidence of significant arrhythmias in a series of patients with Fabry cardiomyopathy. HYPOTHESIS: Arrhythmias are important causes of morbidity and mortality in Fabry Cardiomyopathy. METHODS: This study was a retrospective chart review of 19 patients with known Fabry cardiomyopathy. Device interrogation reports were reviewed for those who had implantable devices. Electrocardiogram, Holter monitor, and event monitors were reviewed in those who did not have implantable devices. RESULTS: Eighteen of nineteen patients were on enzyme replacement therapy (ERT). Nine (47%) out of 19 patients had implantable devices. Implant indications included symptomatic bradycardia, nonsustained ventricular tachycardia, conduction abnormalities, palpitations, and syncope. Mean follow-up in the patients with devices was 50 ± 23 months. Two patients received implantable cardioverter-defibrillator (ICD) shocks, 1 of which was inappropriate for atrial fibrillation. Patients were paced in the atrium 71% ± 37% of the time and paced in the ventricle 49% ± 52% of the time. Four patients with devices were paced more than 95% of the time. Patients with an ICD had lower heart rates prior to ICD implant than the group that did not have devices (60 ± 10 vs 78 ± 16, P = 0.03). Of the patients without devices, only 1 had sudden cardiac death. Patients with implanted devices had higher left ventricular (LV) mass indices compared to patients without implanted devices (136 ± 40 g/m(2) vs 93 ± 19 g/m(2), P = 0.008). CONCLUSIONS: Significant ventricular arrhythmias are uncommon in patients with Fabry cardiomyopathy on ERT, but utilization of pacing is high. Sudden cardiac death in Fabry cardiomyopathy may be related to bradycardia.

Successful reduction of a high defibrillation threshold by a combined implantation of a subcutaneous array and azygos vein lead.

A 72-year-old man with nonischemic cardiomyopathy was referred because his implantable cardioverter defibrillator had failed to terminate spontaneous ventricular fibrillation (VF). Defibrillation threshold (DFT) testing confirmed that 830-V shocks failed to defibrillate VF despite optimization of the biphasic waveform and reversal of shock polarity. The placement of a new right ventricular lead and the addition of a subcutaneous array failed to defibrillate VF at 830 V. The combination of a subcutaneous array and azygos vein coil successfully defibrillated VF. The mechanism for successful DFT reduction was likely greater current supplied to the posterior basal left ventricle by the azygos vein lead.

Successful epicardial catheter ablation of a septal ventricular tachycardia after myocardial infarction.

A 55-year-old man underwent catheter ablation of ventricular tachycardia (VT) after anterior myocardial infarction. Although electrophysiological study suggested that the VT originated from the septum, biventricular endocardial irrigated radiofrequency ablation failed to interrupt the VT. Epicardial ablation at the site located halfway between the lesions in the right and left ventricles via a pericardial approach eliminated the VT, suggesting that the VT likely originated from the top of the septum. When VTs originating from the upper septum are refractory to endocardial ablation, epicardial mapping and ablation may be considered because only that site may be accessible with an epicardial approach.

Demonstration of a right ventricular substrate of ventricular tachycardia after myocardial infarction.

A 57-year-old man with prior anteroseptal myocardial infarction underwent catheter ablation of ventricular tachycardia (VT) exhibiting a left bundle branch block QRS morphology. After failed left ventricular ablation, catheter ablation from the right ventricle (RV) eliminated the VT. An RV voltage map demonstrated an area of low voltage around the successful ablation site that likely allowed for a VT substrate.

Idiopathic ventricular arrhythmias originating from the left ventricular summit: anatomic concepts relevant to ablation.

BACKGROUND: The summit of the left ventricle (LV) is the most superior portion of the epicardial LV bounded by an arc from the left anterior descending coronary artery, superior to the first septal perforating branch to the left circumflex coronary artery. Ventricular arrhythmias (VAs) originating from this region may present challenges for catheter ablation. METHODS AND RESULTS: We studied 27 consecutive patients with VAs originating from the LV summit. The great cardiac vein (GCV) divides this region between an inferior area accessible to ablation and a superior, inaccessible area. Successful ablation was achieved within the GCV in 14 patients and on the epicardial surface in 4. Ventricular prepotentials were recorded at the successful ablation site in 80% of these patients. In 5 patients, ablation was abandoned because of inaccessibility of the catheter to the myocardium or high impedance with radiofrequency application within the GCV. In the remaining 4 patients, epicardial mapping suggested VA origins in a region of low voltage that was located superior to the GCV (inaccessible area), and ablation was abandoned because of close proximity to the coronary arteries or high impedance. A right bundle-branch block, transition zone, R-wave amplitude ratio in leads III to II, Q-wave amplitude ratio in leads aVL to aVR, and S waves in lead V(6) accurately predicted the site of origin. CONCLUSIONS: LV summit VAs may be ablated within the GCV or inferior to the GCV on the epicardial surface, though sites superior to the GCV are usually inaccessible to ablation.

Focal ventricular arrhythmias originating from the left ventricle adjacent to the membranous septum.

AIMS: We report the features of focal ventricular arrhythmias (VAs) arising from the left ventricle (LV) adjacent to the membranous septum. METHODS AND RESULTS: We studied eight patients (five men, 65 ± 10 years) with (n = 2) or without structural heart disease (n = 6) who had ventricular tachycardia (n = 4) or premature ventricular contractions (n = 4) originating from the LV septum underneath the aorta. Ventricular arrhythmias exhibited a focal activation pattern, left (n = 4) or right bundle branch block (n = 4), respectively, left superior (n = 4) or inferior axis QRS morphology (n = 4), negative QRS polarity in lead III and early or no precordial transition in all. During all of these VAs, far-field electrograms in the His bundle (HB) region preceded the QRS onset. In all patients, ventricular pre-potentials were recorded during VAs while late potentials were recorded in sinus rhythm at the border of a localized low-voltage area underneath the aorta. Radiofrequency catheter ablation at the presumed sites of origin successfully eliminated VAs in five patients and was abandoned in the remaining three because the HB electrogram was recorded at that site. CONCLUSION: Focal VAs may arise from the LV adjacent to the membranous septum as a part of the LV ostium, and broadens the spectrum of LV ostium VAs.

Electrocardiographic and electrophysiological characteristics in idiopathic ventricular arrhythmias originating from the papillary muscles in the left ventricle: relevance for catheter ablation.

BACKGROUND: Idiopathic ventricular arrhythmias (VAs) can originate from the left ventricular papillary muscles (PAMs). This study investigated the electrophysiological characteristics of these VAs and their relevance for the results of catheter ablation. METHODS AND RESULTS: We studied 19 patients who underwent successful catheter ablation of idiopathic VAs originating from the anterior (n=7) and posterior PAMs (n=12). Although an excellent pace map was obtained at the first ablation site in 17 patients, radiofrequency ablation at that site failed to eliminate the VAs, and radiofrequency lesions in a relatively wide area around that site were required to completely eliminate the VAs in all patients. Radiofrequency current with an irrigated or nonirrigated 8-mm-tip ablation catheter was required to achieve a lasting ablation of the PAM VA origins. During 42% of the PAM VAs, a sharp ventricular prepotential was recorded at the successful ablation site. In 9 (47%) patients, PAM VAs exhibited multiple QRS morphologies, with subtle, but distinguishable differences occurring spontaneously and after the ablation. In 7 (78%) of those patients, radiofrequency lesions on both sides of the PAMs where pacing could reproduce an excellent match to the 2 different QRS morphologies of the VAs were required to completely eliminate the VAs. CONCLUSIONS: Radiofrequency catheter ablation of idiopathic PAM VAs is challenging probably because the VA origin is located relatively deep beneath the endocardium of the PAMs. PAM VAs often exhibit multiple QRS morphologies, which may be caused by a single origin with preferential conduction resulting from the complex structure of the PAMs.

Idiopathic ventricular tachycardia originating from the left ventricle near the His bundle.

A 62-year-old man with idiopathic ventricular tachycardia (VT) exhibiting left bundle branch block and left inferior axis QRS morphology with a Qr in lead III underwent electrophysiological testing. Successful ablation was achieved in the left ventricle (LV) at a site with an excellent pace map, adjacent to the His bundle electrogram recording site. At that site, the sequence of the ventricular electrogram and late potential recorded during sinus rhythm reversed during spontaneous premature ventricular contractions with the same QRS morphology as the VT. This case shows that VT can arise from the LV ostium adjacent to the membranous septum.