Sundt, Thoralf M.

Background— Proposed advantages to the Ross procedure included presumed increased freedom from reoperation and simpler reoperation for pulmonary conduit replacement if needed. It is increasingly apparent, however, that reoperations are frequent after the Ross procedure and that when required, they may be more complex than previously thought. Methods and Results— Between September 1991 and August 2008, 56 patients underwent reoperation at our institution after a Ross procedure performed by ourselves (n=13) or elsewhere (n=43). Median age at first reoperation at our institution was 26 years (range 1 to 69 years). The 4 most common indications for reoperation were isolated autograft (neoaortic) regurgitation in 11 cases (20), isolated pulmonary conduit regurgitation/stenosis in 9 (16), combined autograft regurgitation/dilatation in 8 (14), and combined autograft regurgitation and pulmonary conduit regurgitation/stenosis in 6 (11). A total of 144 procedures were performed in these 56 patients during first reoperation at our institution. The autograft valve required replacement in 21 cases (38) and aortic root replacement in 21 (38), with ascending aortic/arch reconstruction in 13 (23) and mitral valve surgery in 5 (9). The pulmonary valve was replaced in 33 cases (59) and the tricuspid valve was repaired/replaced in 10 (18). Early mortality was 1.8 (1 of 56 patients), and morbidity included 6 patients with respiratory failure and 3 who required postcardiotomy extracorporeal membrane oxygenation. There were 4 late deaths during the median follow-up of 8 months (range 1 to 179 months). Conclusions— A broad spectrum of complex reoperations may be required after the Ross procedure. Patients and family members considering the procedure should be informed of the potential for associated morbidity should reoperation be necessary.

Abstract Three cases are described of infants who developed malignant brain swelling (and in one case hemorrhage) after surgery for vein of Galen malformations. The cause for the brain swelling was felt to be due to hyperperfusion, or the “normal perfusion pressure breakthrough” syndrome. Although well-described for cerebral parenchymal arteriovenous malformations, cases of this complication occurring in vein of Galen malformations have not previously been reported. It is concluded from these cases that infants with large arteriovenous shunts, as attested by cardiac failure and cerebral atrophy, have an increased risk of developing this complication.

Abstract The alterations in metabolism and cerebral blood flow that occur following transient focal ischemia were studied in rabbits anesthetized with halothane and subjected to transient occlusion of an M2 segment of the middle cerebral artery (MCA). The parameters measured included intracellular brain pH and focal cortical blood flow (fCBF)—assessed by the umbelliferone technique—electrocorticograms, and cortical microcirculatory changes. A gradient of ischemia developed in the cortex between the patent and occluded vessels. Cortical sites with moderate and severely diminished flow were examined as a function of time before and after occlusion. Mean preocclusion fCBF was 50.8 ± 2.1 ml/100 g/min, and brain pH was 6.99 ± 0.04. Following occlusion, fCBF fell to 14.6 ± 2.3 ml/100 g/min, with an intracellular pH of 6.53 ± 0.03 in sites of severe ischemia in the territory of the occluded vessel. Sites between the patent and occluded branches revealed moderate changes in fCBF and intracellular pH of 26.7 ± 3.6 ml/100 g/min and 6.74 ± 0.03 ml/100 g/min, respectively. Sites adjacent to the patent M2 branch remained similar to baseline. Pretreatment intravenously with nimodipine, a dihydropyridine class of Ca2+ channel antagonist, improved flow in the territory of the occluded segment of the middle cerebral artery to 30.6 ± 2.2 ml/100 g/min, while maintaining the brain pH at 6.83 ± 0.03. Similarly, at sites intermediate between the patent and occluded M2 segments of the MCA, cortical blood flow remained at 53.5 ± 4.0 ml/100 g/min, and the pH at 6.95 ± 0.04, in 10 animals pretreated with nimodopine. This effect was apparently achieved by blocking the secondary, ischemia-induced vasoconstriction known to occur in areas of focal incomplete ischemia. The diphenylalkylamine class Ca2+ channel blockers was examined using verapamil. This was found to be without significant effect. The vehicle carrying nimodopine was also without effect. To authenticate further the reliability of MCA occlusion, a separate group of animals was examined with cautery occlusion of the M2 segment of the MCA. Nimodopine had an effect in this group of animals identical to that caused by occlusion of the vessel with a clip. Visual inspection of the cortex in control and treated animals revealed a marked difference in the development of cortical pallor and microcirculatory changes. We conclude that nimodopine protects the conducting vessels against the secondary vasoconstriction known to occur in areas of focal incomplete ischemia, and thus increases collateral flow. This agent may have the potential for brain protection in areas of incomplete focal ischemia from occlusion of a single major vessel.

Abstract The natural history of postirradiation extracranial cerebrovascular disease is uncertain. Previous reported cases spanning 20 years of carotid surgery are difficult to evaluate, because patients may sometimes have unspecified symptoms, physical examinations, postoperative results, and follow-up. Also, the evolution of carotid surgery over the past two decades makes it impossible to compare earlier operative technique with the state-of-the-art technique of today. Our series of 7 patients underwent 9 carotid endarterectomies with an average follow-up period of 46 months. The number of patients is small, and although technically this is a more difficult operation, we feel the results are favorable and may be comparable with endarterectomy procedures in nonirradiated patients. These patients should be approached as if radiation changes are not a major factor when they are considered for reconstructive arterial surgery.

AbstractBackgroundMany researchers have previously explored the correlation between surgical flow disruptions and adverse events in cardiac surgery; however, there is no reliable tool to prospectively categorize surgical flow disruptions and the conditions that predispose a surgical team to adverse events.MethodsTwo independent raters of different medical and human factors expertise observed 12 cardiovascular operations and iteratively designed a surgical flow disruption tool (SFDT) to characterize surgical flow disruptions and the latent factors that contribute to adverse events. Categories to characterize surgical flow disruptions were created based on human factors models of human error. After the design period, both raters observed ten surgical cases using the tool to assess validity and inter‐rater reliability.ResultsRating agreement (weighted kappa) for each category across the ten surgeries was moderate to very high, resulting in strong inter‐rater reliability for each category on the surgical flow disruption tool. Use of the SFDT was simple and clear for observers of diverse backgrounds, including human factors experts and medical personnel.ConclusionsThis research depicts the development and utility of a tool to analyze surgical flow disruptions in the cardiovascular operating room with satisfactory inter‐rater reliability. This tool is an important first step in systematically categorizing and measuring surgical flow disruptions and their impact on patient safety in the operating room.

Background— Bicuspid aortic valve is frequent and is reported to cause numerous complications, but the clinical outcome of patients diagnosed with normal or mildly dysfunctional valve is undefined. Methods and Results— In 212 asymptomatic community residents from Olmsted County, Minn (age, 32±20 years; 65% male), bicuspid aortic valve was diagnosed between 1980 and 1999 with ejection fraction ≥50% and aortic regurgitation or stenosis, absent or mild. Aortic valve degeneration at diagnosis was scored echocardiographically for calcification, thickening, and mobility reduction (0 to 3 each), with scores ranging from 0 to 9. At diagnosis, ejection fraction was 63±5% and left ventricular diameter was 48±9 mm. Survival 20 years after diagnosis was 90±3%, identical to the general population ( P =0.72). Twenty years after diagnosis, heart failure, new cardiac symptoms, and cardiovascular medical events occurred in 7±2%, 26±4%, and 33±5%, respectively. Twenty years after diagnosis, aortic valve surgery, ascending aortic surgery, or any cardiovascular surgery was required in 24±4%, 5±2%, and 27±4% at a younger age than the general population ( P <0.0001). No aortic dissection occurred. Thus, cardiovascular medical or surgical events occurred in 42±5% 20 years after diagnosis. Independent predictors of cardiovascular events were age ≥50 years (risk ratio, 3.0; 95% confidence interval, 1.5 to 5.7; P <0.01) and valve degeneration at diagnosis (risk ratio, 2.4; 95% confidence interval, 1.2 to 4.5; P =0.016; >70% events at 20 years). Baseline ascending aorta ≥40 mm independently predicted surgery for aorta dilatation (risk ratio, 10.8; 95% confidence interval, 1.8 to 77.3; P <0.01). Conclusions— In the community, asymptomatic patients with bicuspid aortic valve and no or minimal hemodynamic abnormality enjoy excellent long-term survival but incur frequent cardiovascular events, particularly with progressive valve dysfunction. Echocardiographic valve degeneration at diagnosis separates higher-risk patients who require regular assessment from lower-risk patients who require only episodic follow-up.

Background— Renal insufficiency is associated with increased morbidity and mortality after cardiopulmonary bypass cardiac surgery. B-type natriuretic peptide is a cardiac hormone that enhances glomerular filtration rate and inhibits aldosterone. Cystatin has been shown to be a better endogenous marker of renal function than creatinine. Methods and Results— We performed a double-blinded placebo-controlled proof of concept pilot study in patients (n=40) with renal insufficiency preoperatively (defined as an estimated creatinine clearance of <60 mL/min determined by the Cockroft-Gault formula), undergoing cardiopulmonary bypass cardiac surgery. Patients were randomized to placebo (n=20) or IV low dose nesiritide (n=20; 0.005 μg/Kg/min) for 24 hours started after the induction of anesthesia and before cardiopulmonary bypass. Patients in the nesiritide group had an increase of plasma B-type natriuretic peptide and its second messenger cGMP with a decrease in plasma cystatin levels at the end of the 24-hour infusion. These changes were not observed in the placebo group. There was a significant activation of aldosterone in the placebo group at the end of the 24-hour infusion, but not in the nesiritide group. At 48 and 72 hours, there was a decrease in estimated creatinine clearance and an increase in plasma cystatin as compared with end of the 24-hour infusion in the placebo group. In contrast, renal function was preserved in the nesiritide group with no significant change in estimated creatinine clearance and a trend for plasma cystatin to increase as compared with end of the 24-hour infusion. Conclusion— This proof of concept pilot study supports the conclusion that perioperative administration of low dose nesiritide is biologically active and decreases plasma cystatin in patients with renal insufficiency undergoing cardiopulmonary bypass cardiac surgery. Further studies are warranted to determine whether these physiological observations can be translated into improved clinical outcomes.