Kalyanam Shivkumar

Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States

Are you Kalyanam Shivkumar?

Claim your profile

Publications (199)867.46 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Background Cocaine use is a known but rare cause of cardiac arrhythmias. Ventricular arrhythmias related to cocaine may not respond to antiarrhythmic drugs and may need treatment with radiofrequency ablation.Objectives We describe the clinical and electrophysiological characteristics of cocaine- related ventricular tachycardia (VT) from a multicenter registry.Methods Subjects presenting with VT related to cocaine use and being considered for radiofrequency ablation have been included in the study. Patients who were refractory to maximal medical therapy underwent radiofrequency ablation of the VT. Clinical, procedural variables, efficacy and safety outcomes were assessed.ResultsA total of 14 subjects met study criteria (age 44±13, range 18–68 year-old with 79% male, 71% Caucasian). MRI showed evidence of scar only in 43% of patients (6/14). The mechanism of VT was focal in 50% (n = 7) and scar related reentry in 50% (n = 7) based on 3D mapping. The mean VT cycle length was 429±96 msec. The site of origin was epicardial in 16% (3/18) of VTs. Most clinical VTs were hemodynamically stable (75%). Mean ejection fraction at the time of admission was 44±14%. Duration of procedure was 289±50 minutes. One subject developed pericardial tamponade requiring drainage. At 18±11 months follow-up, freedom from arrhythmia was seen in 86% (one case lost to follow-up and 2 died).Conclusion Radiofrequency ablation is not only feasible but also safe and effective in patients who have drug refractory VT related to chronic cocaine use.This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 04/2014; · 3.48 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: -Data on relative safety, efficacy and role of different percutaneous left ventricular assist devices (pLVADs) for hemodynamic support during the ventricular tachycardia (VT) ablation procedure are very limited. -We performed a multicenter, observational study from a prospective registry including all consecutive patients (N=66) undergoing VT ablation with a pLVAD in 6 centers in United States. Patients with intra aortic balloon pump (IABP group; N=22) were compared with patients with either an Impella or a TandemHeart deivce (Non-IABP group; N=44). There were no significant differences in the baseline characteristics between both the groups. In Non-IABP group a) more patients could undergo entrainment/activation mapping (82% vs 59%; p=0.046), b) more number of unstable VTs could be mapped and ablated per patient (1.05±0.78 vs 0.32±0.48; p<0.001), c) more number of VTs could be terminated by ablation (1.59±1.0 vs 0.91±0.81; p=0.007) and d) fewer VTs were terminated with rescue shocks (1.9±2.2 vs 3.0±1.5; p=0.049) when compared to IABP group. Complications of the procedure trended to be more in the Non-IABP group when compared to the IABP group (32% vs 14%; p=0.143). Intermediate term outcomes (mortality and VT recurrence) during 12±5 month follow-up were not different between both the groups. Left ventricular ejection fraction ≤ 15% was a strong and independent predictor of in-hospital mortality (53% vs 4%; p<0.001). -Impella and TandemHeart use in VT ablation facilitates extensive activation mapping of several unstable VTs and requires fewer rescue shocks during the procedure when compared to using IABP.
    Circulation Arrhythmia and Electrophysiology 02/2014; · 5.95 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: We report here, for the first time, two cases demonstrating a synergistic application of bilateral cardiac sympathetic decentralization and multimodal psychiatric treatment for the assessment and management of anxiety following recurrent Implantable Cardioverter Defibrillator (ICD) shocks. In a first case the combination of bilateral cardiac sympathetic decentralization (BCSD), cognitive behavioral psychotherapy and anxiolytic medication was sufficient to attenuate the patient's symptoms and maladaptive behaviors, with a maintained benefit at 1 year. Among the more prominent subjective changes in the post-lesion state we observed a decrease in aversive interoceptive sensations, particularly of the heartbeat. The patient continued to experience cognitive threat appraisals on a frequent basis, although these were no longer incapacitating. In a second case, we report the effect of BCSD on autonomic tone and subjective state. In the post-lesion state we observed attenuated sympathetic responses to the valsalva maneuver, isometric handgrip and mental arithmetic stressor, including decreased systolic and diastolic blood pressure and, decreased skin conductance. Collectively, these preliminary findings suggest that an integrative, multidisciplinary approach to treating anxiety disorders in the setting of ventricular arrhythmias and recurrent ICD shocks can result in sustained improvements in physical, psychological, and functional status. These findings raise the possibility of a potential role for the stellate ganglion in the modulation of emotional experience and afferent transmission of interoceptive information to the central nervous system.
    Frontiers in Integrative Neuroscience 01/2014; 7:98.
  • Olujimi A Ajijola, Roderick Tung, Kalyanam Shivkumar
    [show abstract] [hide abstract]
    ABSTRACT: Advances in the treatment of myocardial infarction (MI) have improved survival after ischemic cardiac injury. Post-infarct structural and functional remodeling results in electrophysiologic substrates at risk for monomorphic ventricular tachycardia (MMVT). Characterization of this substrate using a variety of clinical and investigative tools has improved our understanding of MMVT circuits, and has accelerated the development of device and catheter-based therapies aimed at identification and elimination of this arrhythmia. This review will discuss the central role of the ischemic heart disease substrate in the development MMVT. Electrophysiologic characterization of the post-infarct myocardium using bipolar electrogram amplitudes to delineate scar border zones will be reviewed. Functional electrogram determinants of reentrant circuits such as isolated late potentials will be discussed. Strategies for catheter ablation of reentrant ventricular tachycardia, including structural and functional targets will also be examined, as will the role of the epicardial mapping and ablation in the management of recurrent MMVT.
    Indian heart journal 01/2014; 66S1:S24-S34.
  • Pradeep S. Rajendran, Eric Buch, Kalyanam Shivkumar
    Journal of the American College of Cardiology 01/2014; · 14.09 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Objectives The objective of this study was to determine whether premature ventricular contractions (PVCs) arising from the aortic sinuses of Valsalva (SOV) and great cardiac vein (GCV) have coupling interval (CI) characteristics that differentiate them from other ectopic foci. Background PVCs occur at relatively fixed CI from the preceding normal QRS in most patients. However, we observed patients with PVCs originating in unusual areas (SOV and GCV) in whom the PVC CI was highly variable. We hypothesized that PVCs from these areas occur seemingly randomly due to lack of electrotonic effects of surrounding myocardium. Methods 73 consecutive patients referred for PVC ablation were assessed. Twelve consecutive PVC coupling intervals were recorded. The ΔCI (max-min CI) was measured. Results We studied 73 patients (age 50±16 years, 47% male). PVC origin was right ventricular (RV) in 29 (40%), left ventricular (LV) in 17 (23%), SOV 21 (29%) and GCV in 6 (8%). There was a significant difference between the mean ΔCI of RV/LV compared to SOV/GCV PVCs (33±15 ms vs 116±52 ms, p<0.0001). A ΔCI of>60 ms demonstrated a sensitivity of 89%, specificity of 100%, positive predictive value of 100% and negative predictive value of 94%. Cardiac events were more common in the SOV/GCV vs the RV/LV group (7/27 [26%] vs 2/46 [4%], p<0.02). Conclusions ΔCI is more pronounced in PVCs originating from the SOV or GCV. ΔCI of 60 ms helps discriminate the origin of PVCs prior to diagnostic electrophysiologic study and may be associated with increased frequency of cardiac events.
    Journal of the American College of Cardiology 01/2014; · 14.09 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Objectives To determine if ablation that targets patient-specific AF-sustaining substrates (rotors or focal sources) is more durable than trigger ablation alone at preventing late AF recurrences. Background Late recurrence substantially limits the efficacy of pulmonary vein (PV) isolation for AF, and is associated with PV reconnection and the emergence of new triggers. Methods We performed 3 year follow-up of the CONFIRM trial, in which 92 consecutive AF patients (70.7% persistent) underwent novel computational mapping to reveal a median of 2 (IQR 1-2) rotors or focal sources in 97.7% of patients during AF. Ablation comprised source (Focal Impulse and Rotor Modulation, FIRM) then conventional ablation in n=27 (FIRM-guided), and conventional ablation alone in n=65 (FIRM-blinded). Patients were followed with implanted ECG monitors when possible (85.2% FIRM guided, 23.1% FIRM-blinded). Results On 890 days follow-up (median; IQR 224–1563) compared FIRM-blinded therapy, patients receiving FIRM-guided ablation maintained higher freedom from AF after 1.2±0.4 procedures (median 1, IQR 1-1) (77.8% vs 38.5%; p=0.001) and a single procedure (p>0.001), and higher freedom from all atrial arrhythmias (p=0.003). Freedom from AF was higher when ablation directly or coincidentally passed through sources than when it missed sources (p>0.001). Conclusions FIRM-guided ablation is more durable than conventional trigger-based ablation at preventing 3 year AF recurrence. Future studies should investigate how ablation of patient-specific AF-sustaining rotors and focal sources alters the natural history of arrhythmia recurrence. Clinical trial info NCT01008722
    Journal of the American College of Cardiology 01/2014; · 14.09 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Left and bilateral CSD have been shown to reduce burden of ventricular arrhythmias acutely in a small number of patients with VT storm. The effects of this procedure beyond the acute setting are unknown. The purpose of this study was to evaluate the intermediate and long-term effects of left and bilateral cardiac sympathetic denervation (CSD) in patients with cardiomyopathy and refractory ventricular tachy-arrhythmias (VT) or VT storm. Retrospective analysis of medical records for patients who underwent either left or bilateral cardiac sympathetic denervation for VT storm or refractory VT between April 2009 and December 2012 was performed. Forty one patients underwent CSD (left CSD: n = 14; bilateral CSD: n = 27). There was a significant reduction in the burden of ICD shocks during follow up as compared to the 12 months prior to the procedure. The number of ICD shocks was reduced from a mean of 19.6±19 pre-procedure to 2.3±2.9 post-procedure, P<0.001, with 90% of patients experiencing a reduction in ICD shocks. At a mean follow up of 367±251 days post-procedure, survival free of ICD shock was 30% of in the left CSD group and 48% in the bilateral CSD group. Shock free survival was greater in the bilateral group than in the left CSD group, P=0.04. In patients with VT storm, bilateral CSD is more beneficial than left CSD. The beneficial effects of bilateral CSD extend beyond the acute post-sympathectomy period, with continued freedom from ICD shocks in 48% of patients and a significant reduction in ICD shocks in 90% of patients.
    Heart rhythm: the official journal of the Heart Rhythm Society 11/2013; · 4.56 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The aim of this study was to determine the pertinent anesthetic considerations for patients undergoing surgical sympathectomy for electrical storm (incessant ventricular tachycardia (VT) refractory to traditional therapies). This is a retrospective review of a prospective database. This single-center study took place in a university hospital setting. Twenty-six patients were enrolled. Fifteen patients underwent left-sided sympathectomy, whereas 11 patients underwent bilateral sympathectomy. Anesthetic management of these patients was quite complex, requiring invasive monitoring, transesophageal echocardiography, one-lung ventilation, programming of cardiac rhythm management devices, and titration of vasoactive medications. Paired t test of hemodynamic data before, during, and after surgery showed no significant difference between preoperative and postoperative blood pressure values, regardless of whether the patient underwent unilateral or bilateral sympathectomy. Eight patients remained free of VT, three patients responded well to titration of oral medications, and one patient required 2 radiofrequency ablations after sympathectomy to control his VT. Three patients continued to have VT episodes, although reduced in frequency compared with before the procedure. Four patients were lost to followup. Overall, five patients within the cohort died within 30 days of the procedure. No patients developed any anesthetic complications or Horner's syndrome. The overall perioperative mortality (within the first 7 days of the procedure) was 2 of 26, or 7.7%. The anesthetic management of patients undergoing surgical sympathectomy for electrical storm can be quite complex, because these patients often present in a moribund and emergent state and cannot be optimized using current ACC/AHA guidelines. Expertise in invasive monitoring, transesophageal echocardiography, one-lung ventilation, cardiac rhythm device management, and pressor management is crucial for optimal anesthetic care.
    Journal of cardiothoracic and vascular anesthesia 11/2013; · 1.06 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: -The extent to which channels within scar are inter-connected is not known. The objective of the study was to evaluate the impact of local ablation of LPs on adjacent and remote areas of slow conduction with simultaneous multipolar mapping. -Analysis was performed on consecutive patients referred for ablation of scar-mediated VT with double ventricular access. Ablation was performed targeting the earliest of LPs visualized on the multipolar catheter and the impact on later LPs was recorded. In 21 patients, a multipolar catheter placed within scar visualized spatially distinct LPs. Among 39 RF applications, ablation at earlier LPs had an effect on neighboring and remote LPs in 31 (80%), with delay in 8 (21%), partial elimination in 9 (23%), and complete elimination in 14 (36%). The mean distance where an ablation impact was detected was 17.6±14.7mm (range 2mm-50mm). Among all patients, 9.7±7.8 RF applications were delivered to homogenize the targeted scar region with a mean number of 23±12 LPs targeted. -Ablation can eliminate neighboring and remote areas of slow conduction, suggesting that channels within scar are frequently inter-connected. This is the first mechanistic demonstration to show that ablation can modify electrical activity in regions of scar outside of the known radius of an RF lesion. The targeting of relatively earlier LPs can expedite scar homogenization without the need for extensive ablation of all LPs.
    Circulation Arrhythmia and Electrophysiology 10/2013; · 5.95 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Late Gadolinium Enhancement (LGE) MRI of ventricular scar has been shown to be accurate for detection and characterization of arrhythmia substrates. However, the majority of patients referred for ventricular tachycardia (VT) ablation have an implantable cardioverter defibrillator (ICD), which obscures image integrity and the clinical utility of MRI. To develop and validate a wideband LGE MRI technique for device artifact removal. A novel wideband LGE MRI technique was developed to allow for improved scar evaluation on patients with ICDs. The wideband technique and the standard LGE MRI were tested on 18 patients with ICDs. VT ablation was performed in 13 of 18 patients with either endocardial and/or epicardial approach and the correlation between the scar identified on MRI and electroanatomical mapping was analyzed. Hyper-intensity artifact was present in 16/18 of patients using standard MRI, which was eliminated using the wideband LGE and allowed for MRI interpretation in 15/16 patients. All patients had ICD lead characteristics confirmed as unchanged post- MRI and had no adverse events. LGE scar was seen in 11/18 patients. Among the 15 patients where wideband LGE allowed visualization of myocardium, 10 had LGE scar and 5 had normal myocardium in the regions with image artifacts when using the standard LGE. The left ventricular scar size measurements using wideband MRI and EAM were correlated with R(2)=0.83, P=0.00003. The wideband LGE-MRI improves the ability to visualize myocardium for clinical interpretation, which correlated well with EAM findings during VT ablation.
    Heart rhythm: the official journal of the Heart Rhythm Society 10/2013; · 4.56 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Purpose:To propose and test a modified wideband late gadolinium enhancement (LGE) magnetic resonance (MR) imaging technique to overcome hyperintensity image artifacts caused by implanted cardiac devices.Materials and Methods:Written informed consent was obtained from all participants, and the HIPAA-compliant study protocol was approved by the institutional review board. Studies in phantoms and in a healthy volunteer were performed to test the hypothesis that the hyperintensity artifacts that are typically observed on LGE images in patients with implanted cardiac devices are caused by insufficient inversion of the affected myocardial signal. The conventional LGE MR imaging pulse sequence was modified by replacing the nonselective inversion pulse with a wideband inversion pulse. The modified LGE sequence, along with the conventional LGE sequence, was evaluated in 12 patients with implantable cardioverter defibrillators (ICDs) who were referred for cardiac MR imaging.Results:The ICD causes 2-6 kHz in frequency shift at locations 5-10 cm away from the device. This off-resonance falls outside the typical spectral bandwidth of the nonselective inversion pulse used in conventional LGE, which results in the hyperintensity artifact. In 10 of the 12 patients, the conventional LGE technique produced severe, uninterpretable hyperintensity artifacts in the anterior and lateral portions of the left ventricular wall. These artifacts were eliminated with use of the wideband LGE sequence, thereby enabling confident evaluation of myocardial viability.Conclusion:The modified wideband LGE MR imaging technique eliminates the hyperintensity artifacts seen in patients with cardiac devices. The technique may enable LGE MR imaging in patients with cardiac devices, in whom LGE MR imaging otherwise could not be used for diagnosis.© RSNA, 2013Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130942/-/DC1.
    Radiology 10/2013; · 6.34 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The precise localization of the site of origin of a premature ventricular contractions (PVC) prior to ablation would facilitate the planning and execution of the electrophysiological procedure. Current electrocardiographic imaging (ECGI) techniques require body surface maps, a costly and complex procedure, that requires as many as 256 leads to localize the PVC origin. We developed and tested a novel myocardial activation based ECGI technique utilizing the readily available 12-lead ECG to localize the PVC origin. The major components of the 12-lead ECGI method are: the source model, proximity effect and spatial orientation, volume conductor, and patient specific model of the heart, lungs, and thorax as derived from magnetic resonance imaging (MRI). For the PVC origin localization, the fastest route algorithm is used on patient specific models created by newly developed morphing software. PVC localization by the 12-lead ECGI was correlated to the site of successful ablation. Seven patients that underwent electrophysiological mapping and ablation of PVCs were studied. All patients (7/7) had accurate prediction of the PVC origin. However in two patients, no specific MRI was used for localization that resulted in an incorrect switch between the RV free wall and septum of the RVOT. With patient-specific models, these latter two cases would likely be localized correctly. This feasibility study of a novel myocardial activation-based ECGI using only the standard 12-lead ECG shows promise to localize the origin of PVC. This ECGI method yields activation estimates of isochrones on both ventricles from which the PVC origin location is derived. This method has the capability to localize the PVC from any part of the ventricular endocardium, intra-myocardium or epicardium.
    Journal of electrocardiology 09/2013; · 1.08 Impact Factor
  • Roderick Tung, Kalyanam Shivkumar
    Heart rhythm: the official journal of the Heart Rhythm Society 09/2013; · 4.56 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Left stellate or right stellate ganglia stimulation (L/R SGS) is associated with ventricular tachyarrhythmias(VT/VF); however, the electrophysiological mechanisms remain unclear. We assessed (1) regional dispersion of myocardial repolarization during RSGS and LSGS, and (2) regional electrophysiological mechanisms underlying T wave changes, including Tp-e, that are associated with VT/VF. In 10 pigs, a 56-electrode sock was placed around the heart and both stellate ganglia were exposed. Unipolar electrograms, to asses activation recovery interval (ARI) and repolarization time (RT), and 12-lead ECG were recorded pre and during RSGS and LSGS. Both LSGS and RSGS increased dispersion of repolarization; with LSGS, greatest regional dispersion occurred on the LV anterior wall and LV apex, while with RSGS, greatest regional dispersion occurred on RV posterior wall. Baseline, LSGS and RSGS dispersion correlated with Tp-e. The increase in RT dispersion, which was due to increase in ARI dispersion, correlated with the increase in Tp-e intervals (R(2)=0.92 LSGS, R(2)=0.96 RSGS). During LSGS, the ARIs and RTs on the lateral and posterior walls were shorter than the anterior LV wall (P<0.01), and on the apex versus base (P<0.05), explaining the T wave vector shift posteriorly/inferiorly. RSGS caused greater ARI and RT shortening on anterior versus lateral or posterior walls (P<0.01), and on base versus apex (P<0.05), explaining the T wave vector shift anteriorly/superiorly. LSGS and RSGS cause differential effects on regional myocardial repolarization, explaining the ECG T-wave morphology. Sympathetic stimulation, in line with its pro-arrhythmic effects, increases Tp-e interval, which correlates with increases in myocardial dispersion of repolarization.
    AJP Heart and Circulatory Physiology 07/2013; · 3.63 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Background Myocardial infarction (MI) induces neural and electrical remodeling at the scar border zones. The impact of focal MI on global functional neural remodeling is not well understood. Methods and Results Sympathetic stimulation (SS) was performed in swine with antero-apical infarcts (MI) (n=9), and controls (n=9). A 56-electrode sock was placed over both ventricles to record electrograms (EGMs) at baseline (BL), and during left, right, and bilateral stellate ganglia (LSG, RSG, & BSG, respectively) stimulation. Activation recovery intervals (ARIs) were measured from EGMs. Global and regional ARI shortening, dispersion of repolarization (DOR), and activation propagation were assessed before and during SS. At BL, mean ARI was shorter in MI hearts than controls (365±8ms vs. 436±9ms, p<0.0001), DOR was greater in MI vs. control hearts (734±123ms(2) vs. 362±32ms(2), p=0.02), and the infarcted region in MI hearts showed longer ARIs than non-infarcted regions (406±14ms vs. 365±8ms p=0.027). In controls, percent ARI shortening was greater on anterior than posterior wall during RSG stimulation (p=0.0001), while, LSG stimulation showed the reverse (p=0.0003). In infarcted animals, this pattern was completely lost. In 50% of the animals studied, SS compared to baseline, significantly altered the direction of activation propagation emanating from intra-myocardial scar during pacing. Conclusion: Focal distal anterior MI alters regional and global pattern of sympathetic innervation, resulting in shorter ARIs in infarcted hearts, greater repolarization dispersion and altered activation propagation. These conditions may underlie the mechanisms by which arrhythmias are initiated when sympathetic tone is enhanced.
    AJP Heart and Circulatory Physiology 07/2013; · 3.63 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: -Radiofrequency ablation for ventricular tachycardia (VT) is an established therapy. Use of chemical agents for scar homogenization represents an alternative approach. The purpose of this study was to characterize the efficacy of collagenase (CLG) application on epicardial ventricular scar homogenization. -Myocardial infarcts were created in Yorkshire pigs (n=6) by intra-coronary microsphere injection. After 46.6±4.3 days, CLG type 2, type 4, and purified CLG were applied in vitro (n=1) to myocardial tissue blocks containing normal myocardium, border-zone (BZ) and dense scar (DS). Histopathological studies were performed to identify the optimal CLG subtype. In-vivo high-density electroanatomic mapping of the epicardium was also performed, and BZ and DS surface area, and LPs were quantified before and after CLG-4 application (n=5). Of the CLG subtypes tested in vitro, CLG-4 provided the best scar modification, and least damage to normal myocardium. During in vivo testing, CLG-4 application decreased BZ area (21.3±14.3mm(2) to 17.1±11.1 mm(2), p=0.043) and increased DS area (9.1±10.3 mm(2) to 22.0±20.6 mm(2), p=0.043). The total scar area before and after CLG application was 30.4±23.4mm(2) and 39.2±29.5 mm(2), respectively, p=0.08). LPs were reduced by CLG-4 application (28.8±21.8 to 13.8±13.1, p=0.043). During CLG-4 application (50.0±15.5 min), systolic blood pressure and heart rate were not significantly changed (68.0±7.7mmHg vs. 61.8±5.3mmHg, p=0.08; 77.4±7.3 beats per minute (BPM) vs. 78.8±6.0BPM, p=0.50, respectively). -Ventricular epicardial scar homogenization by CLG-4 application is feasible and effective. This represents the first report on bioenzymatic ablation of arrhythmogenic tissue as an alternative strategy for lesion formation.
    Circulation Arrhythmia and Electrophysiology 07/2013; · 5.95 Impact Factor
  • Heart rhythm: the official journal of the Heart Rhythm Society 04/2013; · 4.56 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: OBJECTIVES: To determine the availability of quinidine in the world. BACKGROUND: Quinidine is the only oral medication that is effective for preventing life-threatening ventricular arrhythmias due to Brugada syndrome and idiopathic ventricular fibrillation. However, because of its low price and restricted indication, this medication is not marketed in many countries. METHODS: We conducted a world survey of quinidine availability by contacting professional medical societies and arrhythmia specialists worldwide. Physicians were e-mailed questionnaires requesting information concerning the quinidine preparation available at their hospital. We also requested information concerning cases of adverse arrhythmic events resulting from quinidine unavailability. RESULTS: A total of 273 physicians from 131 countries provided information regarding quinidine availability: Quinidine is readily available in only 19 (14%) countries. In contrast, this medication is not accessible in 99 (76%) countries and is available but only through specific regulatory processes that require 4-30 days for completion in 13 (10%) countries. We were able to gather information concerning 22 patients who had serious arrhythmias probably related (10 cases) or possibility related (12 cases) to the absence of quinidine, including 2 fatalities possibly due to quinidine unavailability. CONCLUSIONS: The lack of quinidine accessibility is a serious medical hazard at the global level.
    Journal of the American College of Cardiology 04/2013; · 14.09 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: OBJECTIVE: We hypothesized that ablation of recently described stable AF sources, either directly by Focal Impulse and Rotor Modulation (FIRM) or coincidentally when anatomical ablation passes through AF sources, may explain long term freedom of AF. BACKGROUND: It is unclear why conventional anatomical AF ablation can be very effective in some patients yet ineffective in others with similar profiles. METHODS: The CONFIRM trial prospectively revealed stable AF rotors or focal sources in 98/101 subjects with AF at 107 consecutive ablation cases. In 1:2 fashion, subjects received targeted source ablation (FIRM) then conventional ablation, or conventional ablation alone. We determined if ablation lesions on electroanatomic maps passed through AF sources on FIRM maps. RESULTS: Subjects who completed followup (n=94, 71.2% persistent AF) each showed 2.3±1.1 concurrent AF rotors or focal sources, that lay near pulmonary veins (22.8%), left atrial roof (16.0%), and elsewhere in left (28.2%) and right (33.0%) atria. AF sources were ablated directly in 100% FIRM cases and coincidentally (e.g. left atrial roof) in 45% conventional cases (p<0.05). During 273 days (median, IQR 138-636) after 1 procedure, AF was absent in 80.3% of patients if sources were ablated but recurred in 81.8% of patients if sources were missed (p<0.001). Freedom from AF was highest if all sources were ablated, intermediate if some sources were ablated, and lowest if no sources were ablated (p<0.001). CONCLUSIONS: Elimination of stable AF rotors and focal sources may explain freedom from AF after diverse approaches to ablation. Patient-specific AF source distributions are consistent with the reported success of specific anatomical lesion sets, and of widespread ablation. These results support targeting AF sources to reduce unnecessary ablation, and motivate studies on FIRM-only ablation.
    Journal of the American College of Cardiology 04/2013; · 14.09 Impact Factor

Publication Stats

942 Citations
867.46 Total Impact Points


  • 2014
    • Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center
      Torrance, California, United States
  • 2004–2014
    • University of California, Los Angeles
      • Division of Cardiology
      Los Angeles, California, United States
  • 2012–2013
    • University of California, San Diego
      • Department of Medicine
      San Diego, California, United States
    • The Ohio State University
      Columbus, Ohio, United States
  • 2009–2013
    • University of Southern California
      Los Angeles, California, United States
    • UCLA Cardiovascular Research Laboratory
      Los Angeles, California, United States
  • 2009–2012
    • University of California, Davis
      • Department of Biomedical Engineering
      Davis, CA, United States
  • 2011
    • CSU Mentor
      Long Beach, California, United States
    • St. David's North Austin Medical Center
      Austin, Texas, United States
  • 2010
    • Concordia University Texas
      Austin, Texas, United States
  • 2007–2010
    • Stanford University
      • E. L. Ginzton Laboratory
      Stanford, CA, United States
  • 2007–2009
    • Oregon Health and Science University
      Portland, Oregon, United States
  • 2001–2002
    • University of Iowa
      Iowa City, Iowa, United States