Author + information
- Received April 27, 2012
- Revision received July 31, 2012
- Accepted August 6, 2012
- Published online December 11, 2012.
- Ajit H. Janardhan, MD, PhD⁎,
- Wenwen Li, PhD†,
- Vadim V. Fedorov, PhD†,
- Michael Yeung, MD⁎,
- Michael J. Wallendorf, PhD‡,
- Richard B. Schuessler, PhD†,§ and
- Igor R. Efimov, PhD⁎,†,⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Igor R. Efimov, Department of Biomedical Engineering, 1 Brookings Drive, Washington University, St. Louis, Missouri 63130
Objectives The authors sought to develop a low-energy electrotherapy that terminates ventricular tachycardia (VT) when antitachycardia pacing (ATP) fails.
Background High-energy implantable cardioverter-defibrillator (ICD) shocks are associated with device failure, significant morbidity, and increased mortality. A low-energy alternative to ICD shocks is desirable.
Methods Myocardial infarction was created in 25 dogs. Sustained, monomorphic VT was induced by programmed stimulation. Defibrillation electrodes were placed in the right ventricular apex, and coronary sinus and left ventricular epicardium. If ATP failed to terminate sustained VT, the defibrillation thresholds (DFTs) of standard versus experimental electrotherapies were measured.
Results Sustained VT ranged from 276 to 438 beats/min (mean 339 beats/min). The right ventricular–coronary sinus shock vector had lower impedance than the right ventricular–left ventricular patch (54.4 ± 18.1 Ω versus 109.8 ± 16.9 Ω; p < 0.001). A single shock required between 0.3 ± 0.2 J to 5.9 ± 2.5 J (mean 2.64 ± 3.22 J; p = 0.008) to terminate VT, and varied depending upon the phase of the VT cycle in which it was delivered. By contrast, multiple shocks delivered within 1 VT cycle length were not phase dependent and achieved lower DFT compared with a single shock (0.13 ± 0.09 J for 3 shocks, 0.08 ± 0.04 J for 5 shocks, and 0.09 ± 0.07 J for 7 shocks; p < 0.001). Finally, a multistage electrotherapy (MSE) achieved significantly lower DFT compared with a single biphasic shock (0.03 ± 0.05 J versus 2.37 ± 1.20 J; respectively, p < 0.001). At a peak shock amplitude of 20 V, MSE achieved 91.3% of terminations versus 10.5% for a biphasic shock (p < 0.001).
Conclusions MSE achieved a major reduction in DFT compared with a single biphasic shock for ATP-refractory monomorphic VT, and represents a novel electrotherapy to reduce high-energy ICD shocks.
This study was supported by National Institutes of Health grants R01 HL-067322, R01 HL-082729, and T32 HL-007081. Dr. Li is an employee of Cardialen, Inc. Dr. Schuessler has received a research grant from Cardialen. Dr. Efimov is a cofounder, shareholder, member of the board of directors, and chairman of the scientific advisory board of Cardialen, Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Janardhan and Li contributed equally to this work.
- Received April 27, 2012.
- Revision received July 31, 2012.
- Accepted August 6, 2012.
- American College of Cardiology Foundation