Menekhem M. Zviman
Johns Hopkins University
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Featured researches published by Menekhem M. Zviman.
Circulation | 2005
Saman Nazarian; David A. Bluemke; Albert C. Lardo; Menekhem M. Zviman; Stanley Watkins; Timm Dickfeld; Glenn Meininger; Ariel Roguin; Hugh Calkins; Gordon F. Tomaselli; Robert G. Weiss; Ronald D. Berger; João A.C. Lima; Henry R. Halperin
Background— Patients with left ventricular dysfunction have an elevated risk of sudden cardiac death. However, the substrate for ventricular arrhythmia in patients with nonischemic cardiomyopathy remains poorly understood. We hypothesized that the distribution of scar identified by MRI is predictive of inducible ventricular tachycardia. Methods and Results— Short-axis cine steady-state free-precession and postcontrast inversion-recovery gradient-echo MRI sequences were obtained before electrophysiological study in 26 patients with nonischemic cardiomyopathy. Left ventricular ejection fraction was measured from end-diastolic and end-systolic cine images. The transmural extent of scar as a percentage of wall thickness (percent scar transmurality) in each of 12 radial sectors per slice was calculated in all myocardial slices. The percentages of sectors with 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100% scar transmurality were determined for each patient. Predominance of scar distribution involving 26% to 75% of wall thickness was significantly predictive of inducible ventricular tachycardia and remained independently predictive in the multivariable model after adjustment for left ventricular ejection fraction (odds ratio, 9.125; P=0.020). Conclusions— MR assessment of scar distribution can identify the substrate for inducible ventricular tachycardia and may identify high-risk patients with nonischemic cardiomyopathy currently missed by ejection fraction criteria.
Circulation | 2006
Albert C. Lardo; Marco A. S. Cordeiro; Caterina Silva; Luciano C. Amado; Richard T. George; Anastasios Saliaris; Karl H. Schuleri; Veronica Fernandes; Menekhem M. Zviman; Saman Nazarian; Henry R. Halperin; Katherine C. Wu; Joshua M. Hare; Joao A.C. Lima
Background— The ability to distinguish dysfunctional but viable myocardium from nonviable tissue has important prognostic implications after myocardial infarction. The purpose of this study was to validate the accuracy of contrast-enhanced multidetector computed tomography (MDCT) for quantifying myocardial necrosis, microvascular obstruction, and chronic scar after occlusion/reperfusion myocardial infarction. Methods and Results— Ten dogs and 7 pigs underwent balloon occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion. Contrast-enhanced (Visipaque, 150 mL, 325 mg/mL) MDCT (0.5 mm × 32 slice) was performed before occlusion and 90 minutes (canine) or 8 weeks (porcine) after reperfusion. MDCT images were analyzed to define infarct size/extent and microvascular obstruction and compared with postmortem myocardial staining (triphenyltetrazolium chloride) and microsphere blood flow measurements. Acute and chronic infarcts by MDCT were characterized by hyperenhancement, whereas regions of microvascular obstruction were characterized by hypoenhancement. MDCT infarct volume compared well with triphenyltetrazolium chloride staining (acute infarcts 21.1±7.2% versus 20.4±7.4%, mean difference 0.7%; chronic infarcts 4.15±1.93% versus 4.92±2.06%, mean difference −0.76%) and accurately reflected morphology and the transmural extent of injury in all animals. Peak hyperenhancement of infarcted regions occurred ≈5 minutes after contrast injection. MDCT-derived regions of microvascular obstruction were also identified accurately in acute studies and correlated with reduced flow regions as measured by microsphere blood flow. Conclusions— The spatial extent of acute and healed myocardial infarction can be determined and quantified accurately with contrast-enhanced MDCT. This feature, combined with existing high-resolution MDCT coronary angiography, may have important implications for the comprehensive assessment of cardiovascular disease.
Circulation | 2004
Ariel Roguin; Menekhem M. Zviman; Glenn Meininger; E. Rene Rodrigues; Timm M. Dickfeld; David A. Bluemke; Albert C. Lardo; Ronald D. Berger; Hugh Calkins; Henry R. Halperin
Background—MRI has unparalleled soft-tissue imaging capabilities. The presence of devices such as pacemakers and implantable cardioverter/defibrillators (ICDs), however, is historically considered a contraindication to MRI. These devices are now smaller, with less magnetic material and improved electromagnetic interference protection. Our aim was to determine whether these modern systems can be used in an MR environment. Methods and Results—We tested in vitro and in vivo lead heating, device function, force acting on the device, and image distortion at 1.5 T. Clinical MR protocols and in vivo measurements yielded temperature changes <0.5°C. Older (manufactured before 2000) ICDs were damaged by the MR scans. Newer ICD systems and most pacemakers, however, were not. The maximal force acting on newer devices was <100 g. Modern (manufactured after 2000) ICD systems were implanted in dogs (n=18), and after 4 weeks, 3- to 4-hour MR scans were performed (n=15). No device dysfunction occurred. The images were of high quality with distortion dependent on the scan sequence and plane. Pacing threshold and intracardiac electrogram amplitude were unchanged over the 8 weeks, except in 1 animal that, after MRI, had a transient (<12 hours) capture failure. Pathological data of the scanned animals revealed very limited necrosis or fibrosis at the tip of the lead area, which was not different from controls (n=3) not subjected to MRI. Conclusions—These data suggest that certain modern pacemaker and ICD systems may indeed be MRI safe. This may have major clinical implications for current imaging practices.
Circulation | 2006
Saman Nazarian; Ariel Roguin; Menekhem M. Zviman; Albert C. Lardo; Timm Dickfeld; Hugh Calkins; Robert G. Weiss; Ronald D. Berger; David A. Bluemke; Henry R. Halperin
Background— Magnetic resonance imaging (MRI) is an important diagnostic modality currently unavailable for millions of patients because of the presence of implantable cardiac devices. We sought to evaluate the diagnostic utility and safety of noncardiac and cardiac MRI at 1.5T using a protocol that incorporates device selection and programming and limits the estimated specific absorption rate of MRI sequences. Methods and Results— Patients with no imaging alternative and with devices shown to be MRI safe by in vitro phantom and in vivo animal testing were enrolled. Of 55 patients who underwent 68 MRI studies, 31 had a pacemaker, and 24 had an implantable defibrillator. Pacing mode was changed to “asynchronous” for pacemaker-dependent patients and to “demand” for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored. Efforts were made to limit the system-estimated whole-body average specific absorption rate to 2.0 W/kg (successful in >99% of sequences) while maintaining the diagnostic capability of MRI. No episodes of inappropriate inhibition or activation of pacing were observed. There were no significant differences between baseline and immediate or long-term (median 99 days after MRI) sensing amplitudes, lead impedances, or pacing thresholds. Diagnostic questions were answered in 100% of nonthoracic and 93% of thoracic studies. Clinical findings included diagnosis of vascular abnormalities (9 patients), diagnosis or staging of malignancy (9 patients), and assessment of cardiac viability (13 patients). Conclusions— Given appropriate precautions, noncardiac and cardiac MRI can potentially be safely performed in patients with selected implantable pacemaker and defibrillator systems.
European Heart Journal | 2009
Karl H. Schuleri; Gary S. Feigenbaum; Marco Centola; Eric S. Weiss; Jeffrey M. Zimmet; Jennifer Turney; Joshua Nathan Kellner; Menekhem M. Zviman; Konstantinos E. Hatzistergos; Barbara Detrick; John V. Conte; Ian McNiece; Charles Steenbergen; Albert C. Lardo; Joshua M. Hare
AIMS The ability of mesenchymal stem cells (MSCs) to heal the chronically injured heart remains controversial. Here we tested the hypothesis that autologous MSCs can be safely injected into a chronic myocardial infarct scar, reduce its size, and improve ventricular function. METHODS AND RESULTS Female adult Göttingen swine (n = 15) underwent left anterior descending coronary artery balloon occlusion to create reproducible ischaemia-reperfusion infarctions. Bone-marrow-derived MSCs were isolated and expanded from each animal. Twelve weeks post-myocardial infarction (MI), animals were randomized to receive surgical injection of either phosphate buffered saline (placebo, n = 6), 20 million (low dose, n = 3), or 200 million (high dose, n = 6) autologous MSCs in the infarct and border zone. Injections were administered to the beating heart via left anterior thoracotomy. Serial cardiac magnetic resonance imaging was performed to evaluate infarct size, myocardial blood flow (MBF), and left ventricular (LV) function. There was no difference in mortality, post-injection arrhythmias, cardiac enzyme release, or systemic inflammatory markers between groups. Whereas MI size remained constant in placebo and exhibited a trend towards reduction in low dose, high-dose MSC therapy reduced infarct size from 18.2 +/- 0.9 to 14.4 +/- 1.0% (P = 0.02) of LV mass. In addition, both low and high-dose treatments increased regional contractility and MBF in both infarct and border zones. Ectopic tissue formation was not observed with MSCs. CONCLUSION Together these data demonstrate that autologous MSCs can be safely delivered in an adult heart failure model, producing substantial structural and functional reverse remodelling. These findings demonstrate the safety and efficacy of autologous MSC therapy and support clinical trials of MSC therapy in patients with chronic ischaemic cardiomyopathy.
Annals of Internal Medicine | 2011
Saman Nazarian; Rozann Hansford; Ariel Roguin; Dorith Goldsher; Menekhem M. Zviman; Albert C. Lardo; Brian Caffo; Kevin D. Frick; Michael A. Kraut; Ihab R. Kamel; Hugh Calkins; Ronald D. Berger; David A. Bluemke; Henry R. Halperin
BACKGROUND Magnetic resonance imaging (MRI) is avoided in most patients with implanted cardiac devices because of safety concerns. OBJECTIVE To define the safety of a protocol for MRI at the commonly used magnetic strength of 1.5 T in patients with implanted cardiac devices. DESIGN Prospective nonrandomized trial. (ClinicalTrials.gov registration number: NCT01130896) SETTING: One center in the United States (94% of examinations) and one in Israel. PATIENTS 438 patients with devices (54% with pacemakers and 46% with defibrillators) who underwent 555 MRI studies. INTERVENTION Pacing mode was changed to asynchronous for pacemaker-dependent patients and to demand for others. Tachyarrhythmia functions were disabled. Blood pressure, electrocardiography, oximetry, and symptoms were monitored by a nurse with experience in cardiac life support and device programming who had immediate backup from an electrophysiologist. MEASUREMENTS Activation or inhibition of pacing, symptoms, and device variables. RESULTS In 3 patients (0.7% [95% CI, 0% to 1.5%]), the device reverted to a transient back-up programming mode without long-term effects. Right ventricular (RV) sensing (median change, 0 mV [interquartile range {IQR}, -0.7 to 0 V]) and atrial and right and left ventricular lead impedances (median change, -2 Ω [IQR, -13 to 0 Ω], -4 Ω [IQR, -16 to 0 Ω], and -11 Ω [IQR, -40 to 0 Ω], respectively) were reduced immediately after MRI. At long-term follow-up (61% of patients), decreased RV sensing (median, 0 mV, [IQR, -1.1 to 0.3 mV]), decreased RV lead impedance (median, -3 Ω, [IQR, -29 to 15 Ω]), increased RV capture threshold (median, 0 V, IQR, [0 to 0.2 Ω]), and decreased battery voltage (median, -0.01 V, IQR, -0.04 to 0 V) were noted. The observed changes did not require device revision or reprogramming. LIMITATIONS Not all available cardiac devices have been tested. Long-term in-person or telephone follow-up was unavailable in 43 patients (10%), and some data were missing. Those with missing long-term capture threshold data had higher baseline right atrial and right ventricular capture thresholds and were more likely to have undergone thoracic imaging. Defibrillation threshold testing and random assignment to a control group were not performed. CONCLUSION With appropriate precautions, MRI can be done safely in patients with selected cardiac devices. Because changes in device variables and programming may occur, electrophysiologic monitoring during MRI is essential.
Circulation | 2008
Saman Nazarian; Aravindan Kolandaivelu; Menekhem M. Zviman; Glenn Meininger; Ritsushi Kato; Robert C. Susil; Ariel Roguin; Timm Dickfeld; Hiroshi Ashikaga; Hugh Calkins; Ronald D. Berger; David A. Bluemke; Albert C. Lardo; Henry R. Halperin
Background— Compared with fluoroscopy, the current imaging standard of care for guidance of electrophysiology procedures, magnetic resonance imaging (MRI) provides improved soft-tissue resolution and eliminates radiation exposure. However, because of inherent magnetic forces and electromagnetic interference, the MRI environment poses challenges for electrophysiology procedures. In this study, we sought to test the feasibility of performing electrophysiology studies with real-time MRI guidance. Methods and Results— An MRI-compatible electrophysiology system was developed. Catheters were targeted to the right atrium, His bundle, and right ventricle of 10 mongrel dogs (23 to 32 kg) via a 1.5-T MRI system using rapidly acquired fast gradient-echo images (≈5 frames per second). Catheters were successfully positioned at the right atrial, His bundle, and right ventricular target sites of all animals. Comprehensive electrophysiology studies with recording of intracardiac electrograms and atrial and ventricular pacing were performed. Postprocedural pathological evaluation revealed no evidence of thermal injury to the myocardium. After proof of safety in animal studies, limited real-time MRI-guided catheter mapping studies were performed in 2 patients. Adequate target catheter localization was confirmed via recording of intracardiac electrograms in both patients. Conclusions— To the best of our knowledge, this is the first study to report the feasibility of real-time MRI-guided electrophysiology procedures. This technique may eliminate patient and staff radiation exposure and improve real-time soft tissue resolution for procedural guidance.
Circulation Research | 2007
Hiroshi Ashikaga; Tetsuo Sasano; Jun Dong; Menekhem M. Zviman; Robert Evers; Bruce Hopenfeld; Valeria Castro; Robert H. Helm; Timm Dickfeld; Saman Nazarian; J. Kevin Donahue; Ronald D. Berger; Hugh Calkins; M. Roselle Abraham; Eduardo Marbán; Albert C. Lardo; Elliot R. McVeigh; Henry R. Halperin
In catheter ablation of scar-related monomorphic ventricular tachycardia (VT), substrate voltage mapping is used to electrically define the scar during sinus rhythm. However, the electrically defined scar may not accurately reflect the anatomical scar. Magnetic resonance–based visualization of the scar may elucidate the 3D anatomical correlation between the fine structural details of the scar and scar-related VT circuits. We registered VT activation sequence with the 3D scar anatomy derived from high-resolution contrast-enhanced MRI in a swine model of chronic myocardial infarction using epicardial sock electrodes (n=6, epicardial group), which have direct contact with the myocardium where the electrical signal is recorded. In a separate group of animals (n=5, endocardial group), we also assessed the incidence of endocardial reentry in this model using endocardial basket catheters. Ten to 12 weeks after myocardial infarction, sustained monomorphic VT was reproducibly induced in all animals (n=11). In the epicardial group, 21 VT morphologies were induced, of which 4 (19.0%) showed epicardial reentry. The reentry isthmus was characterized by a relatively small volume of viable myocardium bound by the scar tissue at the infarct border zone or over the infarct. In the endocardial group (n=5), 6 VT morphologies were induced, of which 4 (66.7%) showed endocardial reentry. In conclusion, MRI revealed a scar with spatially complex structures, particularly at the isthmus, with substrate for multiple VT morphologies after a single ischemic episode. Magnetic resonance–based visualization of scar morphology would potentially contribute to preprocedural planning for catheter ablation of scar-related, unmappable VT.
Circulation | 2009
Demetris Yannopoulos; Menekhem M. Zviman; Valeria Castro; Aravindan Kolandaivelu; Ravi Ranjan; Robert F. Wilson; Henry R. Halperin
Background— We investigated the effects of intra–cardiopulmonary resuscitation (CPR) hypothermia with and without volume loading on return to spontaneous circulation and infarction size in an ischemic model of cardiac arrest. Methods and Results— Using a distal left anterior descending artery occlusion model of cardiac arrest followed by resuscitation with a total of 120 minutes of occlusion and 90 minutes of reperfusion, we randomized 46 pigs into 5 groups and used myocardial staining to define area at risk and myocardial necrosis. Group A had no intervention. Immediately after return of spontaneous circulation, group B received surface cooling with cooling blankets and ice. Group C received intra-CPR 680±23 mL of 28°C 0.9% normal saline via a central venous catheter. Group D received intra-CPR 673±26 mL of 4°C normal saline followed by surface cooling after return of spontaneous circulation. Group E received intra-CPR and hypothermia after return of spontaneous circulation with an endovascular therapeutic hypothermia system placed in the right atrium and set at a target of 32°C. Intra-CPR volume loading with room temperature (group C) or iced saline (group D) significantly (P<0.05) decreased coronary perfusion pressure (group C, 12.8±4.78 mm Hg; group D, 14.6±9.9 mm Hg) compared with groups A, B, and E (20.6±8.2, 20.1±7.8, and 21.3±12.4 mm Hg). Return of spontaneous circulation was significantly improved in group E (9 of 9) compared with groups A plus B and C (10 of 18 and 1 of 8). The percent infarction to the area at risk was significantly reduced with intra-CPR hypothermia in groups D (24.3±4.2%) and E (4±3.4%) compared with groups A (72±5.1%) and B (67.3±4.2%). Conclusions— Intra-CPR hypothermia significantly reduces myocardial infarction size. Elimination of volume loading further improves outcomes.
Heart Rhythm | 2013
Hiroshi Ashikaga; Hermenegild Arevalo; Fijoy Vadakkumpadan; Robert C. Blake; Jason D. Bayer; Saman Nazarian; Menekhem M. Zviman; Harikrishna Tandri; Ronald D. Berger; Hugh Calkins; Daniel A. Herzka; Natalia A. Trayanova; Henry R. Halperin
BACKGROUND Previous studies suggest that magnetic resonance imaging with late gadolinium enhancement (LGE) may identify slowly conducting tissues in scar-related ventricular tachycardia (VT). OBJECTIVE To test the feasibility of image-based simulation based on LGE to estimate ablation targets in VT. METHODS We conducted a retrospective study in 13 patients who had preablation magnetic resonance imaging for scar-related VT ablation. We used image-based simulation to induce VT and estimate target regions according to the simulated VT circuit. The estimated target regions were coregistered with the LGE scar map and the ablation sites from the electroanatomical map in the standard ablation approach. RESULTS In image-based simulation, VT was inducible in 12 (92.3%) patients. All VTs showed macroreentrant propagation patterns, and the narrowest width of estimated target region that an ablation line should span to prevent VT recurrence was 5.0 ± 3.4 mm. Of 11 patients who underwent ablation, the results of image-based simulation and the standard approach were consistent in 9 (82%) patients, where ablation within the estimated target region was associated with acute success (n = 8) and ablation outside the estimated target region was associated with failure (n = 1). In 1 (9%) case, the results of image-based simulation and the standard approach were inconsistent, where ablation outside the estimated target region was associated with acute success. CONCLUSIONS The image-based simulation can be used to estimate potential ablation targets of scar-related VT. The image-based simulation may be a powerful noninvasive tool for preprocedural planning of ablation procedures to potentially reduce the procedure time and complication rates.