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.
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ABSTRACT: Patients with right bundle branch block comprise 5-9% of all patients with acute myocardial infarction. In spite of this, limited data exist on early diagnosis or the usefulness of continuous electrocardiographic monitoring in these patients. A prospective multicenter study with 14 Swedish coronary care units. Patients with right bundle branch block and suspicion of acute myocardial infarction with less than 6 hours symptom duration were included. All patients were monitored with continuous vectorcardiography for 12-24 hours. Seventy-nine patients were included, 43% had acute myocardial infarction. Patients with acute myocardial infarction had significantly higher initial ST-vector magnitude values (P = 0.0014) compared to patients without acute myocardial infarction. Patients with acute myocardial infarction also showed gradual regression of ST-vector magnitude over time that was not seen for patients without acute myocardial infarction (P = 0.005). ST-vector magnitude measured at the J-point differentiated best between patients with and without acute myocardial infarction. A cutoff value of 125 microV for initial ST-vector magnitude resulted in 55% sensitivity and 87% specificity for the diagnosis of acute myocardial infarction. Over time, patients with acute myocardial infarction showed greater changes in QRS-vector difference compared to patients without acute myocardial infarction (P = 0.052). Vectorcardiographic monitoring shows good diagnostic abilities for patients with right bundle branch block and clinical suspicion of acute myocardial infarction and could be useful for continuous monitoring of these patients.Annals of Noninvasive Electrocardiology 05/2005; 10(2):161-8. · 1.08 Impact Factor