Continuous vectorcardiographic monitoring of ischemia during coronary angioplasty in patients with bundle-branch block.

Abstract

Patients with the combination of bundle-branch block and ischemic heart disease have a poor outcome. There is no established criterion for detection of transient ischemia when bundle-branch block is present. To elucidate vectorcardiographic changes during coronary angioplasty of patients with bundle-branch block. The QRS complex and ST-segment changes of 29 patients with bundle-branch block were studied during elective coronary angioplasty using continuous vectorcardiography. Data for the patients with bundle-branch block were compared with data for narrow-QRS-complex controls, matched for the vessel dilated, sex, and age. Patients with bundle-branch block were found to have more pronounced changes in the QRS-vector difference as a response to coronary occlusion than did controls. ST-vector magnitude responded in a similar way during coronary occlusion of patients with and without bundle-branch block but from different baselines. ST change-vector magnitude was found to be the most sensitive parameter for detection of ischemia in patients with bundle-branch block as well as for controls. Monitoring of transient ischemia during coronary angioplasty for patients with bundle-branch block is feasible using continuous vectorcardiography. A change in ST vector magnitude > 100 microV is suggested to indicate significant ischemia in the presence of bundle-branch block.