David J. Caparrelli

Aortic root replacement in 271 Marfan patients: a 24-year experience.

BACKGROUND The introduction of composite graft repair of aortic root aneurysm by Hugh Bentall in 1968 promised Marfan patients the choice for a normal life expectancy. We performed our first Bentall composite graft procedure in 1976 and herein report our 24-year experience with 271 Marfan patients. METHODS Between September 1976 and August 2000, 232 Marfan patients had a composite graft replacement of the aortic root, 15 patients received a homograft, and 24 had a valve-sparing procedure. RESULTS Two hundred thirty-five Marfan patients underwent elective aortic root replacement with no 30-day mortality. Two early deaths occurred among 36 patients who underwent urgent or emergent operation. Eighty-three percent of patients in this series are currently alive. The actuarial freedom from thromboembolism, endocarditis, and reoperation on the residual aorta 20 years postoperatively was 93%, 90%, and 74%. Twenty-four patients have undergone valve-sparing procedures with encouraging results. CONCLUSIONS Elective aortic root replacement for Marfan patients can be performed with low operative risk. Elective repair before the aortic root reaches 6 cm in diameter is recommended to minimize risk of dissection and rupture.

Pharmacological preconditioning ameliorates neurological injury in a model of spinal cord ischemia

BACKGROUND Pharmacological openers of mitochondrial ATP-sensitive potassium (mitoKATP) channels have been shown to mimic ischemic preconditioning (IPC) in both the brain and myocardium. We hypothesized that similar endogenous mechanisms exist in the spinal cord and that diazoxide, a potent mitoKATP opener, could reduce neurologic injury after aortic cross-clamping in a model of spinal cord ischemia. METHODS The infra-renal aorta was cross-clamped in 45 male New Zealand white rabbits for 20 minutes. Control animals received no pretreatment. Diazoxide-treated animals were dosed (5 mg/kg) 15 minutes before cross-clamp. A third group underwent 5 minutes of IPC 30 minutes before cross-clamp. Two groups received KATP antagonists, 5-hydroxydecanoic acid (5-HD, 20 mg/kg) or glibenclamide (1.0 mg/kg), before diazoxide administration. Systemic hypotension was induced in a final group with excess isoflurane. Tarlov Scoring was used to assess neurologic function at 24 and 48 hours, after which, the spinal cords were procured for histopathological analysis. RESULTS Tarlov scoring demonstrated marked improvement in the Diazoxide group compared with control at 24 hours (p < 0.02) and 48 hours (p < 0.009). Moreover, no further neurologic injury occurred in this group at 7 days. IPC-treated animals showed neurologic improvement but were not significantly different from controls. Further, administration of glibenclamide was effective in antagonizing diazoxides protective effect. CONCLUSIONS Administration of diazoxide resulted in significant improvement in neurologic outcome in this model. This protective effect improved outcome at both early and late time points. Further, the antagonistic effect of glibenclamide implicates diazoxides ATP-dependent potassium channel agonism as the mechanism of protection. Overall, this study suggests that diazoxide may be useful in the prevention of neurologic injury after thoracic aneurysm surgery.