Faculty Bibliography

The purpose of this study was to determine the effects of the addition of amino acids to blood cardioplegic solution and the value of terminal cardioplegia enhancement techniques in routine myocardial protection. Forty-five open-chest adult dogs were instrumented with sonomicrometry crystals to measure left ventricular long axis, midequatorial short axis, and wall thickness. The aorta was clamped for 120 minutes of cardiopulmonary bypass. Animals were randomly separated into four myocardial protection groups: (1) blood cardioplegic solution with amino acids and no terminal cardioplegia (n = 12); (2) blood cardioplegic solution with amino acids and warm amino acid terminal cardioplegia (n = 11); (3) blood cardioplegic solution with amino acids and cold amino acid terminal cardioplegia (n = 12); and (4) blood cardioplegic solution plus cold terminal cardioplegia (no amino acids, n = 10). Data for preload recruitable stroke work were obtained by inflow occlusion before bypass (baseline) and at 30 and 60 minutes after reperfusion and analyzed for changes in x-intercept and slope. A significant rightward shift in x-intercept did not occur in any group. When cardiac function was expressed as a percentage of baseline preload recruitable stroke work slope, improved functional recovery was seen at both 30 and 60 minutes in groups 2 (88.6% and 91.8%), 3 (85.8% and 86.9%), and 4 (88.6% and 92.6%) compared with group 1 (77.3% and 79.2%, p < 0.05). No significant difference was found in the degree of functional recovery among groups 2, 3, and 4. These results suggest that for myocardial protection of 2 hours in nonischemic hearts, a terminal dose of blood cardioplegic solution before unclamping is beneficial, but this positive effect is independent of amino acid supplementation and temperature

In two patients undergoing open heart operations, electrochemical burns developed at the sites of connection to an external pacing system. Investigation revealed that failure of the pacing generator caused a small, continuous, direct current to pass through the patients, resulting in electrolysis at the sites of contact with the pacing and grounding wires. This electrolytic reaction was recreated in a mock pacing system and resulted in tissue injury and disintegration of the pacing wire. Guidelines to help recognize and prevent this complication are presented

During an 8-year period (1984 to 1991) 66 patients (mean age 59 years, range 26 to 84 years) with type A aortic dissection (60 ascending aorta tears, 6 arch tears; 35 acute, 31 chronic) had surgical repair by a continuous suture-graft inclusion technique. Hypothermic circulatory arrest (16 degrees C) was used in 58 patients (35/35 acute, 23/31 chronic; mean arrest time 26 minutes, range 10 to 55 minutes). Fifty-two patients had hemiarch repair and 6 had total arch replacement. Aortic valve disease necessitated treatment in 38 patients (1 valved conduit, 20 valve replacements, 17 valve repairs). Recently 11 patients had valve repair by reconstruction of the native aortic root, by means of techniques similar to those used for homograft valve insertion. Operative mortality was 9% (14% acute, 3% chronic). Stroke occurred in 2 patients (3%) and was fatal in both. Variables suggestive of increased operative risk by univariate analysis were acuteness (p = 0.12), visceral ischemia (p = 0.12), and preoperative shock (p = 0.13). No variable was significant by multivariate analysis. Overall actuarial survival at 48 months was 77%, with 3 late deaths from a ruptured distal aneurysm. Late computed tomography or magnetic resonance imaging scan was done in 28 patients at a mean interval of 33 months. These studies identified 1 patient with a pseudoaneurysm requiring reoperation and 3 patients with contained flow between the graft and the wrap. Three patients required late operation: 1 for pseudoaneurysm, 1 for arch dissection, and 1 for repair of a distal aneurysm

A wide variety of carotid shunts are available for use in extracranial carotid surgery. Since it is commonly assumed that when properly positioned all shunts are equal in ability to protect the brain from cerebral ischemia, the choice of shunt is usually based on handling characteristics. However, after an intraoperative stroke occurred in a patient, we compared shunt flow rates using a simple and reproducible method of measurement. A mock circuit was created using a saline-filled fluid reservoir connected to the particular shunt being tested via 1/2-inch tubing. Hydrostatic pressure across the shunt was varied by changing the height of the reservoir, and the flow was collected over 30-second intervals. Multiple flow rate measurements were performed for each shunt with pressure gradients varying from 25 to 150 cm H2O. The data show significant hemodynamic differences among commercially available carotid shunts. A pressure gradient of 75 cm H2O produced a 2.8-fold variation in the amount of fluid delivered by various shunts. Minimal cerebral blood flow requirements and the possibility of underperfusion require that the surgeon consider such data in choosing an appropriate carotid shunt

The normal range of postoperative imaging findings are described in 34 asymptomatic patients studied 5-66 months (mean, 28 months) after undergoing the continuous-suture graft-inclusion technique for repair of aortic aneurysms (n = 20) and dissections (n = 14) involving the ascending aorta. All 34 patients underwent magnetic resonance (MR) imaging, and 24 patients also underwent computed tomography (CT). Perigraft thickening was seen in 19 patients (56%) with MR imaging and in eight patients (33%) with CT. Flow outside the graft but contained within the native wrap was noted in five patients (15%) with MR imaging and in four patients (17%) with contrast material-enhanced CT. Thrombus was identified outside the graft and within the wrap in seven patients (21%) with MR imaging and in six patients (25%) with CT. Mass effect on the graft was depicted in four patients (12%) with MR imaging and in three patients (13%) with CT. Of the 14 patients who underwent repair of aortic dissections, an intimal flap was seen distal to the graft in seven of the 14 (50%) evaluated with MR imaging and in four of the 10 (40%) evaluated with contrast-enhanced CT. An accurate postoperative imaging evaluation requires precise knowledge of the surgical technique performed and its anatomic consequences