Images in Clinical Medicine

“R-on-T” Phenomenon

Paul Oupadia, M.D., and Krishnaswamy Ramaswamy, M.D.

N Engl J Med 1998; 338:1812June 18, 1998

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Figure 1 Ventricular fibrillation in an 83-year-old man after coronary angiography was caused by the “R-on-T” phenomenon, due to a sensing failure on the part of a temporary pacemaker with ventricular pacing, ventricular sensing, and an inhibition response. Paced beats (open arrows) are followed by four normal sinus beats (small arrows), and a paced beat then interrupts the downsloping portion of the T wave because of the failure of the pacemaker to sense the change (large arrow). This paced beat induces ventricular fibrillation. Immediate cardioversion was performed, and there were no sequelae. The patient, who had recently had a myocardial infarction, presented originally with syncope. A temporary pacemaker was placed after a seven-second sinus pause was documented. Cardiac catheterization revealed multivessel coronary artery disease. The patient underwent successful coronary-artery bypass surgery. Ventricular fibrillation following the R-on-T phenomenon is thought to occur as a result of dispersion of the duration of the action potential and electrical inhomogeneity in the myocardium.

Paul Oupadia, M.D.
Krishnaswamy Ramaswamy, M.D.
St. Elizabeth's Medical Center, Boston, MA 02135

Citing Articles (4)

Citing Articles

1. 1

   Jeffrey D. Ho, Donald M. Dawes, Robert F. Reardon, Seth R. Strote, Sebastian N. Kunz, Rebecca S. Nelson, Erik J. Lundin, Benjamin S. Orozco, James R. Miner. (2011) Human cardiovascular effects of a new generation conducted electrical weapon. Forensic Science International 204:1-3, 50-57
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2. 2

   Diego Chemello, Anandaraja Subramanian, Kumaraswamy Nanthakumar. (2010) Cardiac arrest caused by undersensing of a temporary epicardial pacemaker. Canadian Journal of Cardiology 26:1, e13-e14
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3. 3

   John L. Atlee, Alan D. Bernstein. (2002) Harm Associated with Reprogramming Pacemakers for Surgery. Anesthesiology 97:4, 1034
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