Comparison of electrocardiograms recorded with standard leads and derived from the vectorcardiographic frank leads in high risk patients.

Dynamic vectorcardiography (VCG) is increasingly employed for ischaemia monitoring with the use of a computerized method for recording and on-line analysis by the calculation of trend parameters. To elucidate how well the derived electrocardiogram (dECG), calculated from the VCG, compares with the simultaneously registered standard ECG (sECG), dECGs from 17 postoperative cardiac-risk patients and 36 subjects with acute myocardial infarction (AMI) were compared to sECGs, both quantitatively in leads II, III, V2 and V5 and qualitatively. Despite small, but some significant differences, mainly in the amplitudes of precordial leads, the qualitative interpretation by two independent cardiologists showed good agreement between the methods (kappa = 0.72 and 0.67, respectively) for the diagnosis of AMI/ischaemia. The dECG seems to be reliable and can be used clinically in these groups of patients during VCG recordings.

Computerized vectorcardiography for improved perioperative cardiac monitoring in vascular surgery.

BACKGROUND: Postoperative cardiac complications occur frequently after noncardiac operations in high-risk patients. Routine cardiac monitoring is usually done by electrocardiographic (ECG) methods. The present analysis shows that computerized vectorcardiography (VCG) is superior to traditional ECG monitoring in predicting postoperative cardiac complications. STUDY DESIGN: Thirty-eight patients scheduled for abdominal aortic operations were monitored intraoperatively and for 48 hours postoperatively using VCG. These data were analyzed in a blinded fashion, and compared to cardiac outcome and regularly calculated 12-lead ECGs. RESULTS: Thirteen patients suffered from cardiac events: myocardial infarction (n = 3), cardiac death (n = 1), recurrent myocardial ischemia (n = 1), arrhythmias (n = 2), congestive heart failure (n = 2), and arrhythmias combined with congestive heart failure (n = 4). Thirty of 38 patients had ischemia recorded on their VCG, including all 13 patients with cardiac events. Only seven of the 13 patients had ischemic changes on the V5-lead alone and ten on the three leads II, V4, V5, yielding a sensitivity of 54 percent (V5), 77 percent (II, V4, V5) and 100 percent (VCG). Signs of ischemia appeared 400 +/- 690 (mean plus or minus standard deviation) minutes earlier (median 78 minutes, with a range of zero to 2,284 minutes), and never later on the VCG compared to the three leads II, V4, V5. CONCLUSIONS: Vectorcardiography in this risk group shows increased sensitivity in predicting perioperative cardiac complications and earlier ischemia detection than the most sensitive scalar leads. Vectorcardiography substantially improves the possibility of earlier intervention, potentially reducing the incidence of postoperative cardiac complications.