Hemodynamics and left ventricular mass regression following implantation of the Toronto SPV stentless porcine valve.

Stentless tissue valves may provide more favorable hemodynamics than conventional stented valves. Hemodynamic findings from a large multicenter trial have not been previously reported. The present report describes the hemodynamic findings from a multinational, multicenter study after implantation of the Toronto SPV valve. A total of 577 patients underwent aortic valve replacement with the Toronto SPV valve at 12 sites in 3 countries. Echocardiograms were recorded in the early postoperative period, 3 to 6 months after surgery, 1 year after surgery, and yearly thereafter, with follow-up to 3 years. Gradients decreased and effective orifice area increased in the months after surgery. One year after surgery, mean gradient for valve sizes 20 to 22, 23, 25, 27, and 29 mm was 7.3 +/- 4.4, 7.4 +/- 4.5, 6.1 +/- 3.3, 4.9 +/- 2.4, and 4.0 +/- 2.1 mm Hg, respectively; effective orifice area was 1.3 +/- 0.7, 1.5 +/- 0.5, 1.7 +/- 0.4, 2.0 +/- 0.4, and 2.4 +/- 0.6 cm2, respectively. There was a very low prevalence of significant aortic regurgitation at all time periods. There was significant left ventricular (LV) mass regression between the early and 3- to 6-month periods and between the 3- to 6-month and 1-year postoperative periods. The Toronto SPV valve has an excellent hemodynamic profile supported by significant regression of LV hypertrophy in the year after implantation. Data through 3 years demonstrates maintenance of low gradients and freedom from significant aortic regurgitation.

Contributions of a transient outward current to repolarization in human atrium.

Conventional microelectrode recordings combined with enzymatic cell dispersion methods and a single microelectrode voltage-clamp technique were used to record transmembrane action potentials and ionic currents in isolated single myocytes and in excised segments of human right atrium. Recordings of the outward current(s), which is responsible for the resting potential and early repolarization of the action potential in human right atrium, consistently showed that this tissue has 1) a relatively small inwardly rectifying background potassium current (IK1) which generates the resting potential in mammalian ventricular tissue and Purkinje fibers, and 2) a large time- and voltage-dependent, but Ca2(+)-independent, transient outward current. A somewhat similar K+ current was originally described in neurons and recently has also been identified in a variety of mammalian cardiac tissues. As expected from previous work, this transient outward current in human atrium is blocked by 4-aminopyridine (4-AP; 0.5 mM) and exhibits time- and voltage-dependent inactivation and reactivation. Measurements of action potential shape changes and phasic tension as a function of stimulus frequency, or after 4-AP application, show that in human atrium this current can produce pronounced changes in both the early repolarization of the action potential and force generation.

The outcome and complications of the DiaTAP bioCarbon button-graft vascular access device in haemodialysis patients: a two-year experience.

The outcome and complications which developed in 8 hemodialysis patients who received 12 DiaTAP bioCarbon button vascular-access devices were reviewed. All patients had a poor vascular access history. Three of twelve devices have been replaced because of thrombosis and two because of infection. Four patients have had 10 episodes of reduced blood flow. Streptokinase infusion into the DiaTAP button led to improved blood flow in 8 of 10 episodes. The 6-month survival rate of the DiaTAP access device was 67% and the average functioning life was 9.4 months. It was a valuable form of access when others had failed.