Warren M Jackman

University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States

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Publications (248)1601.12 Total impact

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    ABSTRACT: Ripple Mapping (RM) is designed to overcome the limitations of existing isochronal 3D mapping systems by representing the intracardiac electrogram as a dynamic bar on a surface bipolar voltage map that changes in height according to the electrogram voltage-time relationship, relative to a fiduciary point. We tested the hypothesis that standard approaches to atrial tachycardia CARTO™ activation maps were inadequate for RM creation and interpretation. From the results, we aimed to develop an algorithm to optimize RMs for future prospective testing on a clinical RM platform. CARTO-XP™ activation maps from atrial tachycardia ablations were reviewed by two blinded assessors on an off-line RM workstation. Ripple Maps were graded according to a diagnostic confidence scale (Grade I - high confidence with clear pattern of activation through to Grade IV - non-diagnostic). The RM-based diagnoses were corroborated against the clinical diagnoses. 43 RMs from 14 patients were classified as Grade I (5 [11.5%]); Grade II (17 [39.5%]); Grade III (9 [21%]) and Grade IV (12 [28%]). Causes of low gradings/errors included the following: insufficient chamber point density; window-of-interest<100% of cycle length (CL); <95% tachycardia CL mapped; variability of CL and/or unstable fiducial reference marker; and suboptimal bar height and scar settings. A data collection and map interpretation algorithm has been developed to optimize Ripple Maps in atrial tachycardias. This algorithm requires prospective testing on a real-time clinical platform. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    No preview · Article · Jul 2015 · International journal of cardiology
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    ABSTRACT: Transcutaneous low-level tragus electrical stimulation (LLTS) suppresses atrial fibrillation (AF) in canines. This study examined the antiarrhythmic and anti-inflammatory effects of LLTS in humans. Patients with paroxysmal AF who presented for AF ablation were randomized to either 1 h of LLTS (n = 20) or sham control (n = 20). Attaching a flat metal clip onto the tragus produced LLTS (20 Hz) in the right ear (50% lower than the voltage slowing the sinus rate). Under general anesthesia, AF was induced by burst atrial pacing at baseline and after 1 h of LLTS or sham treatment. Blood samples from the coronary sinus and the femoral vein were collected at those time points and then analyzed for inflammatory cytokines, including tumor necrosis factor alpha and C-reactive protein, using a multiplex immunoassay. There were no differences in baseline characteristics between the 2 groups. Pacing-induced AF duration decreased significantly by 6.3 ± 1.9 min compared with baseline in the LLTS group, but not in the control subjects (p = 0.002 for comparison between groups). AF cycle length increased significantly from baseline by 28.8 ± 6.5 ms in the LLTS group, but not in control subjects (p = 0.0002 for comparison between groups). Systemic (femoral vein) but not coronary sinus tumor necrosis factor (TNF)-alpha and C-reactive protein levels decreased significantly only in the LLTS group. LLTS suppresses AF and decreases inflammatory cytokines in patients with paroxysmal AF. Our results support the emerging paradigm of neuromodulation to treat AF. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
    Full-text · Article · Mar 2015 · Journal of the American College of Cardiology

  • No preview · Article · Mar 2015 · Journal of the American College of Cardiology
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    ABSTRACT: Recent experimental and clinical studies have shown that the epicardial autonomic ganglia play an important role in the initiation and maintenance of atrial fibrillation (AF). In this review, we present the current data on the role of the autonomic ganglia in the pathogenesis of AF and discuss potential therapeutic implications. Experimental studies have demonstrated that acute autonomic remodeling may play a crucial role in AF maintenance in the very early stages. The benefit of adding ablation of the autonomic ganglia to the standard pulmonary vein (PV) isolation procedure for patients with paroxysmal AF is supported by both experimental and clinical data. The interruption of axons from these hyperactive autonomic ganglia to the PV myocardial sleeves may be an important factor in the success of PV isolation procedures. The vagus nerve exerts an inhibitory control over the autonomic ganglia and attenuation or loss of this control may allow these ganglia to become hyperactive. Autonomic neuromodulation using low-level vagus nerve stimulation inhibits the activity of the autonomic ganglia and reverses acute electrical atrial remodeling during rapid atrial pacing and may provide an alternative non-ablative approach for the treatment of AF, especially in the early stages. This notion is supported by a preliminary human study. Further studies are warranted to confirm these findings.
    Full-text · Article · Mar 2015
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    ABSTRACT: Endocardial mapping for scars and abnormal electrograms forms the most essential component of ventricular tachycardia ablation. The utility of ultra-high resolution mapping of ventricular scar was assessed using a multielectrode contact mapping system in a chronic canine infarct model. Chronic infarcts were created in five anesthetized dogs by ligating the left anterior descending coronary artery. Late gadolinium-enhanced magnetic resonance imaging (LGE MRI) was obtained 4.9 ± 0.9 months after infarction, with three-dimensional (3D) gadolinium enhancement signal intensity maps at 1-mm and 5-mm depths from the endocardium. Ultra-high resolution electroanatomical maps were created using a novel mapping system (Rhythmia Mapping System, Rhythmia Medical/Boston Scientific, Marlborough, MA, USA) Rhythmia Medical, Boston Scientific, Marlborough, MA, USA with an 8.5F catheter with mini-basket electrode array (64 tiny electrodes, 2.5-mm spacing, center-to-center). The maps contained 7,754 ± 1,960 electrograms per animal with a mean resolution of 2.8 ± 0.6 mm. Low bipolar voltage (<2 mV) correlated closely with scar on the LGE MRI and the 3D signal intensity map (1-mm depth). The scar areas between the MRI signal intensity map and electroanatomic map matched at 87.7% of sites. Bipolar and unipolar voltages, compared in 592 electrograms from four MRI-defined scar types (endocardial scar, epicardial scar, mottled transmural scar, and dense transmural scar) as well as normal tissue, were significantly different. A unipolar voltage of <13 mV correlated with transmural extension of scar in MRI. Electrograms exhibiting isolated late potentials (ILPs) were manually annotated and ILP maps were created showing ILP location and timing. ILPs were identified in 203 ± 159 electrograms per dog (within low-voltage areas) and ILP maps showed gradation in timing of ILPs at different locations in the scar. Ultra-high resolution contact electroanatomical mapping accurately localizes ventricular scar and abnormal myocardial tissue in this chronic canine infarct model. The high fidelity electrograms provided clear identification of the very low amplitude ILPs within the scar tissue and has the potential to quickly identify targets for ablation. ©2015 The Authors. Pacing and Clinical Electrophysiology Published by Wiley Periodicals, Inc.
    No preview · Article · Feb 2015 · Pacing and Clinical Electrophysiology
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    Full-text · Article · Feb 2015 · Journal of Cardiovascular Magnetic Resonance

  • No preview · Chapter · Dec 2014
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    ABSTRACT: Background: Electrode-tissue contact force (CF) is believed to be a major factor in radiofrequency lesion size. The purpose of this study was to determine, in the beating canine heart, the relationship between CF and radiofrequency lesion size and the accuracy of predicting CF and lesion size by measuring electrogram amplitude, impedance, and electrode temperature. Methods and results: Eight dogs were studied closed chest. Using a 7F catheter with a 3.5 mm irrigated electrode and CF sensor (TactiCath, St. Jude Medical), radiofrequency applications were delivered to 3 separate sites in the right ventricle (30 W, 60 seconds, 17 mL/min irrigation) and 3 sites in the left ventricle (40 W, 60 seconds, 30 mL/min irrigation) at (1) low CF (median 8 g); (2) moderate CF (median 21 g); and (3) high CF (median 60 g). Dogs were euthanized and lesion size was measured. At constant radiofrequency and time, lesion size increased significantly with increasing CF (P<0.01). The incidence of a steam pop increased with both increasing CF and higher power. Peak electrode temperature correlated poorly with lesion size. The decrease in impedance during the radiofrequency application correlated well with lesion size for lesions in the left ventricle but less well for lesions in the right ventricle. There was a poor relationship between CF and the amplitude of the bipolar or unipolar ventricular electrogram, unipolar injury current, and impedance. Conclusions: Radiofrequencylesion size and the incidence of steam pop increase strikingly with increasing CF. Electrogram parameters and initial impedance are poor predictors of CF for radiofrequency ablation.
    Preview · Article · Nov 2014 · Circulation Arrhythmia and Electrophysiology
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    Hiroshi Nakagawa · Warren M Jackman

    Preview · Article · Oct 2014 · Circulation Arrhythmia and Electrophysiology
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    Benjamin J Scherlag · Warren M Jackman

    Preview · Article · Aug 2014 · Circulation Arrhythmia and Electrophysiology
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    ABSTRACT: -Ablation of epicardial posteroseptal accessory pathways (EpiPSAP) requires ablation within the coronary venous system. We assessed the risk of coronary artery (CA) injury with radiofrequency ablation (RFA) within the coronary venous system as a function of the distance between the CA and ablation site. We also examined the efficacy and safety of cryoablation close to a CA. -Two-hundred-forty patients underwent ablation for EpiPSAP. Coronary angiography was performed prior to ablation in the last 169 patients and was repeated after ablation if performed in the coronary venous system within 5mm of a significant CA. The distance between the ideal ablation site and closest CA was <2mm in 100 (59%), 3-5mm in 28 (16%) and >5mm in 41 of 169 (25%) patients. CA injury was observed in 11 of 22 (50%) and 1 of 15 (7%) patients when RFA was performed within 2mm and 3-5mm of a CA, respectively. Cryoablation was performed in 26 patients with a significant CA located within 5mm. Cryoablation alone eliminated EpiPSAP conduction in 17 of 26 (65%) patients and in 8 patients with additional RFA without CA narrowing in any patient. Over a follow-up period of 3-6 months, single procedure success rates were 90% and 77% for RFA and cryoablation at the ideal site, respectively. -The risk of CA injury with RFA is correlated inversely with the distance from the ablation site. Cryoablation is a safe and reasonably effective alternative when a significant CA is located close to the ideal ablation site.
    Preview · Article · Dec 2013 · Circulation Arrhythmia and Electrophysiology
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    ABSTRACT: Iron deposition has been shown to occur following myocardial infarction (MI). We investigated whether such focal iron deposition within chronic MI lead to electrical anomalies. Two groups of dogs (ex-vivo (n = 12) and in-vivo (n = 10)) were studied at 16 weeks post MI. Hearts of animals from ex-vivo group were explanted and sectioned into infarcted and non-infarcted segments. Impedance spectroscopy was used to derive electrical permittivity ([Formula: see text]) and conductivity ([Formula: see text]). Mass spectrometry was used to classify and characterize tissue sections with (IRON+) and without (IRON-) iron. Animals from in-vivo group underwent cardiac magnetic resonance imaging (CMR) for estimation of scar volume (late-gadolinium enhancement, LGE) and iron deposition (T2*) relative to left-ventricular volume. 24-hour electrocardiogram recordings were obtained and used to examine Heart Rate (HR), QT interval (QT), QT corrected for HR (QTc) and QTc dispersion (QTcd). In a fraction of these animals (n = 5), ultra-high resolution electroanatomical mapping (EAM) was performed, co-registered with LGE and T2* CMR and were used to characterize the spatial locations of isolated late potentials (ILPs). Compared to IRON- sections, IRON+ sections had higher[Formula: see text], but no difference in[Formula: see text]. A linear relationship was found between iron content and [Formula: see text] (p<0.001), but not [Formula: see text] (p = 0.34). Among two groups of animals (Iron (<1.5%) and Iron (>1.5%)) with similar scar volumes (7.28%±1.02% (Iron (<1.5%)) vs 8.35%±2.98% (Iron (>1.5%)), p = 0.51) but markedly different iron volumes (1.12%±0.64% (Iron (<1.5%)) vs 2.47%±0.64% (Iron (>1.5%)), p = 0.02), QT and QTc were elevated and QTcd was decreased in the group with the higher iron volume during the day, night and 24-hour period (p<0.05). EAMs co-registered with CMR images showed a greater tendency for ILPs to emerge from scar regions with iron versus without iron. The electrical behavior of infarcted hearts with iron appears to be different from those without iron. Iron within infarcted zones may evolve as an arrhythmogenic substrate in the post MI period.
    Full-text · Article · Sep 2013 · PLoS ONE
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    ABSTRACT: -During radiofrequency (RF) ablation, high electrode-tissue contact force (CF) is associated with increased risk of steam pop and perforation. The purpose of this study, in patients undergoing ablation of paroxysmal atrial fibrillation (AF), was to: 1) identify factors producing high CF during left atrial (LA) and pulmonary vein (PV) mapping; 2) determine the ability of atrial potential amplitude (Amp) and impedance to predict CF; and 3) explore the feasibility of controlling RF power based on CF. -A high-density map of LA/ PVs (median 328 sites) was obtained in 18 patients undergoing AF ablation using a 7.5F irrigated mapping/ablation catheter to measure CF. Average CF was displayed on the 3D map. For 5,682 mapped sites, CF ranged 1-144g (median 8.2g). High CF (≥35g) was observed at only 118/5,682 (2%) sites, clustering in 6 LA regions. The most common high CF site (48/113 sites in 17/18 patients) was located at the anterior/rightward LA roof, directly beneath the ascending aorta (confirmed by merging the CT image and map). Poor relationship between CF and either unipolar-Amp, bipolar-Amp or impedance was observed. During ablation, RF power was modulated based on CF. All PVs were isolated without steam pop, impedance rise, or pericardial effusion. -High CF often occurs at anterior/rightward roof, where the ascending aorta provides resistance to the LA. Atrial potential Amp and impedance are poor predictors of CF. Controlling RF power based on CF appears to prevent steam pop and impedance rise without loss of lesion effectiveness.
    Full-text · Article · Jul 2013 · Circulation Arrhythmia and Electrophysiology
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    ABSTRACT: The distal insertion of right atriofascicular pathways remains a source of debate. Moreover, there are various morphologies of preexcited QRS complexes involving atriofascicular pathways that have been poorly characterized. To characterize the distal insertion of atriofascicular accessory pathways and to provide a mechanism for the change in QRS morphology observed between short and long V-H antidromic AVRT in the same patient. 13 patients with atriofascicular pathways and preexcited AVRT with short V-H and long V-H intervals were studied. For each patient the tachycardia cycle length, V-H interval, QRS width, and axis were compared. A baseline H-V interval was also recorded. The baseline H-V interval was significantly longer than the V-H interval during antidromic AVRT (medial 50 msec vs. -10 msec, p<.0001). Retrograde RBBB increased the V-H interval (median -10 msec vs. 85 msec, p <.0001), the tachycardia CL (median of 302.5 msec vs. 350 msec, p <.0001) and the QRS width (median 120msec vs. 140msec, p<.0002). At least subtle changes in the QRS morphology, axis, or QRS width were seen in all patients. The distal insertion of right atriofascicular pathways fuses with the right bundle branch. The various QRS morphologies seen during the change from short V-H to long V-H antidromic AVRT can be explained by fusion, particularly over the left anterior fascicle.
    Full-text · Article · Jul 2013 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Vincent P Keating · Ryan Cooley · Warren M Jackman

    No preview · Article · Jun 2013 · Heart rhythm: the official journal of the Heart Rhythm Society
  • Vasanth Vedantham · Warren M Jackman · Melvin M Scheinman

    No preview · Article · Mar 2013 · Journal of Cardiovascular Electrophysiology
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    ABSTRACT: Seminal experimental studies showing that prolonged periods of atrial fibrillation (AF) can induce electrophysiological remodeling of the atria so that “AF begets AF,” has become the basis for the understanding of the progression of AF in patients from paroxysmal to persistent to long-standing persistent forms of AF. Clinical studies which initially targeted pulmonary vein firing have refocused on the atrial substrate including the complex fractionated atrial electrograms (CFAEs) invariably found in all forms of AF. More recent experimental and clinical studies have shown that autonomic nerve elements on the heart may play a critical role in the initiation and maintenance of AF and the formation of CFAEs. In this chapter we used iso-potential mapping in the atrium as a starting point and a means of gaining insights into the autonomic factors underlying CFAEs and the substrate for AF.Subsequently we illustrated previous experimental findings to support the mapping evidence and suggested how these lines of experimental evidence correlate with clinical findings. In conclusion, we emphasize the role of the autonomic innervation of the atria in the pathophysiology of CFAEs and their association with the substrate for AF.
    No preview · Chapter · Dec 2012
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    ABSTRACT: Background: The open-irrigated catheter is used most frequently for atrial and ventricular radiofrequency ablation (RFA), and is often considered as the standard by which new ablation systems are compared. But few data have been published concerning its safety. This report provides a comprehensive safety analysis of the use of an open-irrigated catheter for RFA of atrial flutter, ventricular tachycardia, and atrial fibrillation in 1,275 patients in six rigorously monitored, prospective, multicenter studies. Methods: This analysis is of data from six studies conducted as part of both Food and Drug Administration-mandated investigational device exemption studies and postapproval studies. The six studies span a period of more than 10 years. All serious RFA complications and vascular access complications that occurred within seven days postprocedure were included. Results: The number of patients who experienced any acute serious RFA complication in these studies combined was 4.9% (63/1,275). The two earliest studies were conducted when the open-irrigated catheter was first introduced, and accounted for 55.6% of the complications. In the first atrial flutter ablation study, RFA complications decreased by 60% (15.4%-6.2%) after a proctoring program was initiated during the study. For all studies, vascular access complications ranged between from 0.5%-4.7%, and no stroke or transient ischemic attack was reported within 7 days postprocedure. No significant pulmonary vein stenosis was reported from the atrial fibrillation studies. Conclusion: A proctoring program, careful fluid management, and absence of char and coagulum contributed to the safe use of the open-irrigated RFA catheter.
    No preview · Article · Jul 2012 · Pacing and Clinical Electrophysiology

  • No preview · Article · Apr 2012 · Europace
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    ABSTRACT: There has been a long-standing controversy regarding the mechanism(s) to explain the irregular ventricular response during atrial tachycardia (AT) or atrial fibrillation (AF) and where the site of block, if any, resides in the atrioventricular (AV) junction. We studied 12 Langendorff preparations perfused with modified Tyrode's solution containing 5-10 mM diacetyl monoxime which suppressed contractility but allowed the use of intracellular action potential (AP) recordings. Octapolar catheters (2-mm rings, 2-mm spacing) were secured along the tricuspid annulus from the apex to the base of the triangle of Koch and along the anterior limbus of the fossa ovalis to record extracellular, slow pathway, fast pathway, His bundle (Hb) and AV nodal (AVN) extracellular potentials as well as intracellular action potentials. AT or AF induced by rapid atrial pacing showed a variety of irregular responses due to: (1) Wenckebach conduction showing decrement within the AVN and progressive diminution of extracellular AVN potentials (n = 5); (2) repetitive concealed conduction proximal to the AVN (n = 3); (3) ectopic beats arising within the AVN (n = 2); (4) ectopic beats arising at the Hb (n = 2). In this experimental preparation, extracellular and intracellular recordings provided presumptive evidence for the mechanisms causing the irregularities of the ventricular response such as repetitive concealed conduction, enhanced automaticity or electrotonically triggered activity. Also more definitive determinations of the site of block in the AV junction were also obtained.
    No preview · Article · Apr 2012 · Acta cardiologica

Publication Stats

16k Citations
1,601.12 Total Impact Points


  • 1988-2015
    • University of Oklahoma Health Sciences Center
      • • Heart Rhythm Institute (HRI)
      • • Department of Internal Medicine
      • • Section of Cardiovascular Diseases
      Oklahoma City, Oklahoma, United States
    • Johns Hopkins Medicine
      Baltimore, Maryland, United States
  • 1983-2015
    • Oklahoma City University
      Oklahoma City, Oklahoma, United States
  • 2011
    • University of Amsterdam
      • Department of Clinical and Experimental Cardiology
      Amsterdamo, North Holland, Netherlands
  • 2008
    • Renmin University of China
      Peping, Beijing, China
  • 2003-2005
    • Seattle Institute for Cardiac Research
      Seattle, Washington, United States
  • 1998
    • Mayo Clinic - Rochester
      Рочестер, Minnesota, United States
  • 1982-1983
    • Indiana University-Purdue University School of Medicine
      • Department of Medicine
      Indianapolis, IN, United States
    • Indianapolis Zoo
      Indianapolis, Indiana, United States
  • 1981-1983
    • Indiana University-Purdue University Indianapolis
      • Krannert Institute of Cardiology
      Indianapolis, Indiana, United States