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The first results of a new, single lead DDD pacing system consisting of two bipolar combinations of floating atrial ring electrodes, with the proximal ring at the vena cava superior junction, and which can be used separately for atrial sensing and pacing (VECATS) are reported. Uncomplicated implantation of the pacing system was performed in 78 patients with VDD indications. Pacing and sensing parameters were measured at implantation, before discharge (days 1-3), at 1 and 3 months in various positions and during activity. Atrial pacing threshold (AT) and diaphragmatic stimulation threshold (DT) were 3.3 +/- 1.1 V and 7.2 +/- 2.2 at implant, and 4.3 +/- 0.5 and 7.9 +/- 1.1 V at 3 months, respectively, in the European group. In the Canadian group AT increased and DT decreased during follow-up, leaving a safety margin of 1 V. Reliable intraoperative atrial pacing was possible in 93% of patients. Failures were caused by no capture (3%) or AT > DT (4%). At 3 months, 54% of the atria were consistently paced. Atrial pacing failures were due to no atrial capture (8%), and AT > DT (38%). We conclude that atrial pacing was safe and initially possible in the majority of patients with the VECATS pacing system, though diaphragmatic stimulation became more prevalent over time, due to an increase in AT threshold and a decrease in DT.

The first results of a new, single lead DDD pacing system consisting of two bipolar combinations of floating atrial ring electrodes, with the proximal ring at the vena cava superior junction, and which can be used separately for atrial sensing and pacing (VECATS) are reported. Uncomplicated implantation of the pacing system was performed in 78 patients with VDD indications. Pacing and sensing parameters were measured at implantation, before discharge (days 1-3), at 1 and 3 months in various positions and during activity. Atrial pacing threshold (AT) and diaphragmatic stimulation threshold (DT) were 3.3 +/- 1.1 V and 7.2 +/- 2.2 at implant, and 4.3 +/- 0.5 and 7.9 +/- 1.1 V at 3 months, respectively, in the European group. In the Canadian group AT increased and DT decreased during follow-up, leaving a safety margin of 1 V. Reliable intraoperative atrial pacing was possible in 93% of patients. Failures were caused by no capture (3%) or ATDT (4%). At 3 months, 54% of the atria were consistently paced. Atrial pacing failures were due to no atrial capture (8%), and ATDT (38%). We conclude that atrial pacing was safe and initially possible in the majority of patients with the VECATS pacing system, though diaphragmatic stimulation became more prevalent over time, due to an increase in AT threshold and a decrease in DT.

Immediate PTCA following thrombolysis with streptokinase was performed in 46 out of 533 patients enrolled in a multicentre randomized trial of early reperfusion in patients with acute myocardial infarction. Additional effects of PTCA in patients with a residual diameter stenosis in the infarct-related coronary artery of 70% or more after thrombolysis were compared with successful thrombolysis alone in a matched pair analysis. Thirty six pairs of patients were formed identical with respect to the infarct related coronary artery, presence or absence of previous myocardial infarction, total ST segment elevation on the ECG at admission to the trial, and delay between onset of symptoms and hospital admission. PTCA after thrombolysis did not lead to additional limitation of infarct size, nor to further preservation of left ventricular function. Infarction rate during the three-year follow-up was 14% after PTCA versus 30% after thrombolysis alone (P = 0.05). Similarly, patients had less angina or heart failure after PTCA, since on average 128 out of 156 weeks follow-up were symptom free, while this was only 102 weeks after thrombolysis alone (P = 0.03). Immediate PTCA after thrombolysis with intracoronary streptokinase seems to prevent recurrent ischemia and reinfarction. Further studies should address the proper indication and timing of PTCA after thrombolysis.

The acute haemodynamic effects of endralazine, a new hydralazine-like vasodilating agent, were studied in 6 patients with stable angina pectoris and proven coronary artery disease. Twenty minutes after intravenous administration of 5 mg endralazine heart rate and cardiac index increase, while mean arterial blood pressure and total systemic resistance were significantly reduced. Three patients developed symptoms of typical angina pectoris 15 to 20 minutes after drug administration, probably caused by reflex tachycardia. We conclude that intravenous administration of endralazine causes marked haemodynamic effects for the drug is a potent arterial vasodilator, but it may precipitate anginal chest pain in patients with coronary artery disease.