Electrophysiological effects of contrast media. Dynamic vectorcardiographic monitoring of patients during coronary angiography

Objective: The aims of this work were to study, by means of dynamic vectorcardiography (VCG), the electrophysiological effects of contrast media (CM) injected into the coronary arteries and to evaluate which VCG variables are most suitable for comparing different CM. We also studied if CM-induced VCG changes differ from those seen after myocardial ischaemia. The clinical significance of the VCG changes was evaluated by comparing the frequency of cardiac adverse events (CAE) during cardioangiography in an unselected patient population.Methods: The VCG recordings were carried out using the MIDA 1000 system. This system provides on-line information about changes in the different phases of the ECG-complex by means of continuously calculated VCG variables, such as QRS-vd, QRSC-va, STC-vm and TC-vm. This technique was used in three coronary angiography studies where changes induced by CM (iohexol, iohexol/Na, iodixanol and ioxaglate) were analysed and compared. In another study CM related changes (iohexol) were compared with those from acetated Ringer injections and ischaemia during percutaneous transluminal angioplasty. The clinical relevance of the VCG changes induced by iohexol and iodixanol was assessed by registering the frequency of CAE up to 24 hours after cardioangiography in a total of 1020 patients receiving either of these two CM.Results: All CM induced changes in several VCG variables, in particular QRS-vd, QRSC-va and TC-vm were affected. Iodixanol caused significantly less VCG changes than both iohexol and ioxaglate. Ioxaglate induced the largest relative change in TC-vm. QRS-vd was more affected by iohexol injections in the left coronary artery than by ischaemia in the left anterior descending artery, while ischaemia induced the largest change in STC-vm. Both iohexol and iodixanol were well tolerated when used in an unselected patient population, but there was a trend that iodixanol induced fewer CAE. Conclusions: Dynamic vectorcardiography makes it easy to follow and quantitate CM induced electrophysiological changes. QRS-vd, QRSC-va and TC-vm seem best suited to monitor CM effects. Patients with unstable angina pectoris, old age and female gender might benefit from the use of iodixanol, the CM that affected VCG variables the least