Interaction between beta-blockers and contrast media during intracoronary administration in rabbit heart.

The effects of ionic, meglumine sodium diatrizoate (Urografin 76) and nonionic, iohexol contrast media were examined in the absence and presence of propranolol, a beta-blocker having nonspecific membrane stabilizing action and atenolol, a beta-blocker lacking nonspecific membrane stabilizing action on Langendorff-perfused rabbit hearts. Contrast medium, 0.7 ml, was injected into the aortic root in the absence and presence of 10(-7) and 10(-5) M beta-blocker to observe the changes in resting tension, force of contraction, rate of contraction, heart rate and PR interval. Beta-blockers and contrast media interact in affecting myocardial contractility, heart rate and atrioventricular conduction. The interaction is milder when the beta-blocker lacks membrane stabilizing activity and the contrast medium is nonionic.

Analysis of high frequency QRS potentials observed during acute myocardial infarction.

The value of high frequency QRS potentials (HFQRS) during acute myocardial infarction (AMI) was assessed to define infarct size and prognosis. HFQRS were recorded by signal-averaged ECG with 150-250 Hz frequency ranges, using X, Y, Z orthogonal leads. Recordings were obtained in surviving AMI patients (n = 33, 12 inferior, 11 anterior, 10 anterior-inferior) on the first and tenth days, but in non-survived patients (n = 5, 2 inferior, 1 anterior, 2 anterior-inferior) only on the first day. Additionally, the frequency of ventricular tachycardia (VT) was evaluated by 24-h Holter monitoring in all patients at the same days. The control group consisted of 11 healthy people. In surviving AMI patients, RMS voltage of vector magnitude reduced in anterior and anterior-inferior MI but filtered QRS duration was longer in inferior MI than normals (P < 0.05, < 0.05, < 0.01, respectively). In nonsurvived patients, RMS voltages of leads X, Y, Z and vector magnitude were lower than normals (P < 0.01, < 0.05, < 0.01, < 0.01, respectively) and surviving AMI patients (P < 0.01, < 0.05, < 0.05, < 0.05, respectively), the filtered QRS duration was found to be longer than normals and survived patients (P < 0.01, < 0.01). In patients who had VT on Holter monitoring, filtered QRS duration was significantly longer than in patients without VT (P < 0.05). As a result, HFQRS was important for defining infarct size but not malignant ventricular arrhythmias. VT was related to filtered QRS duration. HFQRS may offer significant prognostic information and contribute to early risk stratification of AMI patients.

Permanent pacemaker implantation in a pregnant woman with the guidance of ECG and two-dimensional echocardiography.

A 30-year-old pregnant woman was admitted to the Cardiology Research Center with syncope, dizziness, and fatigue on exertion. On ECG complete atrioventricular block was diagnosed. Permanent pacemaker implantation was performed with the guidance of ECG and two-dimensional echocardiography and without the use of fluoroscopy.