Biventricular Pacing ECG
abstract & commentary
By Michael H. Crawford, MD
Synopsis: BiV capture can be accurately detected by observing the R/S ratio in leads V1 and I of the 12-lead ECG.
Source: Ammann P, et al. An Electrocardiogram-Based Algorithm to Detect Loss of Left Ventricular Capture During Cardiac Resynchronization Therapy. Ann Intern Med. 2005;142:968-973.
Without resorting to calling someone in with the programmer appropriate to your patient’s device, it is often difficult to tell if biventricular (biV) pacing is working correctly. Thus, Ammann and colleagues sought to develop 12-lead ECG criteria for loss of left ventricular capture, a frequent problem that could cause a deterioration of the patient’s symptoms. They started with 10 patients who they switched from right to biV pacing, and observed the 12-lead ECG changes. They developed an algorithm to detect left
ventricular (LV) capture: R/S amplitude in V1 > 1, yes, LV capture; no, look at lead I, R/S > 1, yes, LV capture,
no, means RV pacing only. Then they had 2 blinded, general cardiologists test the algorithm in 54 different patients with biV pacing, which was turned on and off. All patients had left bundle-branch block before pacing, the LV lead was placed in the coronary sinus and the RV
lead at the apex. The algorithm detected biV pacing 93% of the time and RV pacing 94% of the time. The
algorithm was 100% accurate for detecting biV pacing when the coronary sinus catheter was in the diagonal branches of the anterior interventricular vein or the middle cardiac vein, but only 90% of those in the posterior and left marginal veins. Ammann and colleagues concluded that biV capture can be accurately detected by observing the R/S ratio in leads V1 and I of the 12-lead
ECG.
Commentary
Loss of LV capture by dislodgement of the coronary sinus lead is a potential cause of heart failure decompensation in a biV-paced patient. The ability to detect it on the surface ECG without resorting to the programmer, which is often not readily available in a busy general cardiology or heart failure clinic, is of value. The algorithm described in this study is simple and works fairly well with sensitivities and specificities of 90% or better. It is based upon starting with lead V1 over the right ventricle. If there is LV activation, the R wave vector should be directed at V1 with an R/S > 1. Sometimes, the RV activation obscures LV activation in V1 so when the R/S in V1 is < 1, then lead I needs to be examined. With LV activation the vector should be away from lead I with an R/S > 1. There are some limitations. The algorithm only works if the underlying rhythm was left bundle-branch block. Also, certain programmed intervals and delays may obscure LV activation, but these will be detected by the programmer when you refer the patient for lack of LV pacing. In addition, this algorithm was developed in patients with RV apex pacing, as is usually done with an AICD-biV pacer device. Other RV lead placements may not be as accurate. With these limitations in mind, this algorithm seems to be a useful screening device for failure of LV capture in biV pacing, and should reduce the number of programmer checks required for managing heart failure patients.
By Michael H. Crawford, MD Synopsis: BiV capture can be accurately detected by observing the R/S ratio in leads V1 and I of the 12-lead ECG.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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