Circulation
-
We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL.100 g-1.min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB. ⋯ This information, along with our previous data shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.
-
A low cardiac output state can complicate the postoperative course of patients undergoing Fontan-type operations and tetralogy of Fallot repair. ⋯ Negative-pressure ventilation improves cardiac output in children after total cavopulmonary connection and tetralogy of Fallot repair and may prove to be an important therapeutic option in children with the low cardiac output state.
-
It is known that supravalvular pulmonary artery stenosis can occur in patients with d-transposition of the great arteries (TGA) after arterial switch operation (ASO). However, little is known about the growth of the neopulmonary valve annulus after the ASO. This study investigated the growth potential of the neopulmonary (old aortic) valve annulus. ⋯ These data indicate that not only supravalvular pulmonary stenosis but also pulmonary valvular stenosis due to a small annulus can occur in TGA, especially in patients with a history of pulmonary artery banding and in patients with ventricular septal defect.
-
Historically, the majority of pulse generators implanted in the United States remain at the nominal programmed settings from the time of implant. While these nominal settings typically allow a sufficient safety margin to prevent later loss of capture with potential chronic threshold rise, the pulse generator with significant use would not be expected to last longer than that predicted by the manufacturer. However, improvements in lead technology have resulted in significantly lower chronic capture thresholds, which would permit lower programmable output settings while still allowing acceptable safety margins. Such changes could result in a significant reduction in long-term battery drain and translate into longer generator life. ⋯ Reprogramming of permanent pacemakers is efficacious and cost-effective.