Chapter 82: Invasive Diagnostic Electrophysiology
All of the following are reasonable indications for a diagnostic electrophysiology study (EPS) except:
A. Evaluation of sinus node function in patients with suspected sick sinus syndrome
B. Delineation of the mechanism of wide-complex tachycardia
C. Evaluation of syncope in an airline pilot
D. Patient with coronary artery disease with a preserved left ventricular ejection fraction and a 5-beat run of non-sustained ventricular tachycardia
E. Wolff-Parkinson-White (WPW) syndrome when pre-excitation persists with exercise on stress testing
The answer is D. (Hurst’s The Heart, 14th Edition, Chap. 82). Electrophysiology study may be indicated in patients with coronary artery disease, depressed left ventricular ejection fraction (< 40%), and nonsustained ventricular tachycardia, where the induction of sustained VT or VF is an indication for an implantable cardioverted defibrillator (ICD). Evaluation of sinus node function in patients with suspected sick sinus syndrome is an indication for testing. A diseased sinus node is suggested by the presence of a prolonged sinus node recovery time (SNRT) > 1500 ms and inappropriate sinus bradycardia (option A). EPS is indicated for the evaluation of tachyarrhythmias, including the delineation of narrow- and wide-complex tachycardias, for diagnosis and/or for tachycardia mechanism prior to ablation (option B). EPS may be performed for the evaluation of syncope, including evaluation in high-risk occupations (airline pilots, bus drivers, etc.) (option C) as well as for syncope of unclear etiology and in patients with structural heart disease. Risk stratification for WPW syndrome may be performed when pre-excitation persists with exercise on stress testing (option E).
After a complete workup is performed in a 55-year-old woman with syncope, the etiology remains unclear. You decide to send her for an EPS. She wants to know the possible complications of EPS. All of the following are complications of EPS alone, without catheter ablation, except:
B. Cardiac perforation (0.2%)
C. Vascular access complications (0.4%)
D. Thromboembolic events (≈0.5%)
The answer is A. (Hurst’s The Heart, 14th Edition, Chap. 82). Pneumothorax is not a complication of an EPS. Options B through E represent possible complications and their present-day rates of occurrence. Thrombophlebitis (0.6%) is an additional potential complication. Patients should not be exposed even to this minimal risk if there is no benefit expected from EPS.
During EPS, intracardiac electrograms from various locations in the heart, along with the 12-lead surface electrocardiogram (ECG), are recorded and displayed. Which of the following is correct regarding intracardiac electrogram measurements?
A. The AH interval is measured between the atrial and ventricular electrograms on the His catheter
B. The AH interval varies with autonomic ...