Electroanatomic Mapping of Cardiac Resynchronization Therapy
A 51-year-old man with a history of dilated cardiomyopathy presented with New York Heart Association Class III congestive heart failure. Despite optimal medical management, he continued to experience symptoms consistent with low-output failure: exertional dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. He was hospitalized 3 times in the previous 4 months for congestive heart failure management. The baseline ECG revealed a left bundle-branch block with a QRS width of 172 ms, and the echocardiogram revealed an ejection fraction of 28%. He was referred to the cardiac arrhythmia service for cardiac resynchronization therapy. A biventricular pacemaker was implanted in the left prepectoral region. A transvenous approach was utilized to position both the standard right-sided leads, and the left ventricular lead was positioned via the coronary sinus (Figure 1).
Two months after implantation of the biventricular pacing system, the patient underwent electroanatomic mapping of both ventricles during an electrophysiological study. Electroanatomic mapping revealed a significant change in the electrical activation pattern during either right ventricular (Figure 2) or biventricular (Figure 3) pacing. As compared with right ventricular pacing alone (Figure 2), biventricular pacing resulted in a concomitant reduction in the width of the QRS complex (Figure 3): 211 ms versus 157 ms, respectively. At 9-month follow-up, the patient experienced a significant improvement of his clinical symptoms (from Class III to Class II) and no hospitalizations for congestive heart failure. A repeat echocardiogram revealed an ejection fraction of 34%.
In patients with congestive heart failure and significant cardiac conduction system disease, dramatic clinical improvement can be realized by cardiac resynchronization therapy. This case graphically illustrates the consequent electrophysiological changes that occur with this emerging therapeutic modality.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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