To assess optimal hemodynamics in relation to stimulation site during right ventricular pacing, 17 consecutive patients who underwent cardiac catheterization were studied. In all patients, right ventricular apex and right ventricular outflow tract stimulation was performed at 85, 100, and 120 beats/min. Cardiac index at both pacing sites was compared using the left ventricular outflow tract continuous wave Doppler technique. Comparison of the two stimulation sites demonstrated that right ventricular outflow tract pacing resulted in a higher cardiac index at 85 beats/min (2.42 +/- 1.2 vs 2.04 +/- 1.0 L/min per m2, P < 0.002) at 100 beats/min (2.78 +/- 1.4 vs 2.35 +/- 1.1 L/min per m2, P < 0.001) and 120 beats/min (3.00 +/- 1.5 vs 2.61 +/- 0.9 L/min per m2, P < 0.001). From a total of 51 paired observations, 45 showed an increase in cardiac index during outflow tract pacing as compared to apex pacing. Right ventricular outflow tract pacing at 120 beats/min resulted in a lower cardiac index than right ventricular apex pacing in patients with significant coronary artery disease and/or impaired left ventricular function (ejection fraction < or = 50%), whereas right ventricular outflow tract pacing produced higher cardiac indices in the absence of these abnormalities. Right ventricular outflow tract pacing resulted in higher cardiac indices as compared to apex pacing in all other subgroups at all other pacing sites tested. It is concluded that stimulation of the right ventricular outflow tract offers a significant hemodynamic benefit during single chamber pacing as compared to conventional apex pacing, particularly in the absence of significant coronary artery disease and/or left ventricular dysfunction.

Thus, segmented magnetic resonance angiography is capable of non-invasive imaging of proximal coronary anatomy. Its good accuracy in detecting left main coronary artery disease, intermediate accuracy in detecting right coronary artery and left anterior descending coronary artery stenoses, and low accuracy in detecting left circumflex lesions fit within a range of sensitivities and specificities found by others. Further technical advances are necessary to make the technique clinically robust.

The Clinical and Angiographic analysis with a Cobalt Alloy Coronary Stent (Driver) (CLASS) study was a prospective, nonrandomized, multicenter study designed to assess the safety and efficacy of a cobalt-chromium alloy-based stent in patients with stable or unstable angina pectoris. A total of 203 lesions were treated in 202 enrolled patients. The percentage of major adverse cardiac event-free patients was 87.6% (177 of 202) at 6 months (primary safety end point; major adverse cardiac events were defined as death, myocardial infarction, emergency bypass surgery, or target lesion revascularization [percutaneous transluminal coronary angioplasty or coronary artery bypass grafting]). The angiographic success rate (primary efficacy end point) was 100%, and the procedural success rate was 98%. The binary in-stent restenosis rate at 6 months was 12.6%. Our results have demonstrated that the Driver cobalt-chromium alloy stent can be used with a low 6-month incidence of major adverse cardiac events, a low 6-month binary restenosis rate, and high angiographic and procedural success rates. The Medtronic Driver stent (Medtronic Vascular, Santa Rosa, California) is composed of a cobalt-chromium alloy and is similar in design to the Medtronic S7 stent. The design is based on elements 1.0 mm in length with an elliptical-rectangular strut cross section and a strut thickness of 0.0036 in. (91 m). The cobalt-chromium alloy has superior mechanical properties compared with traditional 316L stainless steel, including greater strength and increased density. These properties have allowed the development of stents with thinner struts, offering increased flexibility and ease of delivery, without compromising radial strength or radiopacity. The strut thickness has been shown to be an important determinant of the long-term restenosis rate. [1][2][3][4] This prospective, nonrandomized, multicenter study was designed to assess the safety and efficacy of the Medtronic Driver stent.• • • Patients with clinical evidence of stable or unstable angina pectoris, or positive functional study findings, with a planned percutaneous transluminal coronary angioplasty procedure of a single de novo lesion in a native coronary artery were considered for inclusion. Lesions (Յ13 mm) situated in a major coronary artery or major branch with estimated stenosis of 50% to 100% and a diameter suitable for implantation of a single stent with a diameter of 3.0 to 4.0 mm were considered eligible for enrollment.Preprocedural antiplatelet therapy was administered according to local routine with the following recommendations: aspirin (minimum 75 mg/day) and ticlopidine (500 mg loading dose followed by 250 mg twice daily) or aspirin and clopidogrel (300 mg loading dose followed by 75 mg/ day). It was initiated Ն24 hours before the procedure or before the conclusion of the catheterization. Ticlopidine or clopidogrel were discontinued after 14 to 28 days, and aspirin (Ն75 mg/day) was maintained indefinitely (Ն6 months after implantation).After introduction of the arterial...

Stimulation from the RAA was superior to stimulation from the right atrial free wall with respect to left ventricular filling and cardiac output. Compared with stimulation from the right atrial free wall, RAA pacing resulted in an increase of 10-15% in cardiac output.

A man with a history of bilateral pectoral pocket infection and subsequent pacemaker implantation with a screw-in epicardial lead was referred because of increasing lead impedance. Venography revealed bilateral total occlusion of the subclavian and innominate veins with extensive collateral formation in this asymptomatic patient. Both internal jugular veins were also totally occluded. Because repeated pacemaker implantation using epicardial leads resulted in increasing lead impedance of the ventricular lead within 1 year after implant, an alternative approach was found using the superior caval vein with minimal invasive thoracotomy for single lead VDD pacing.