Faculty Bibliography

PURPOSE: To evaluate gadolinium-enhanced three-dimensional magnetic resonance (MR) angiography for thoracic aortic disease and to compare this technique with conventional thoracic MR imaging. MATERIALS AND METHODS: One hundred eight consecutive patients underwent 122 thoracic MR examinations, including conventional MR imaging followed by enhanced three-dimensional MR angiography. A gradient-echo sequence was used at 1.5 T (116 examinations) and 1.0 T (6 examinations) during infusion of 0.2 mmol/kg gadopentetate dimeglumine. Two independent readers (A and B), with varied experience in thoracic MR angiography, retrospectively evaluated the images for presence of aortic dissection, aneurysm, arch vessel disease, and protruding atheroma. Correlation with findings of surgery or other imaging modalities was available in 98 cases. RESULTS: Enhanced MR angiography was sensitive (92%-96%) and specific (100%) for acute and chronic aortic dissection (n = 26) and was as useful as conventional MR imaging in the diagnosis of aneurysm (n = 43) and arch vessel disease (n = 7). One of two intramural hematomas were overlooked at MR angiography by reader A, and both were overlooked by reader B. CONCLUSION: Enhanced three-dimensional MR angiography is a rapid and accurate imaging modality in diagnosis of thoracic aortic disease but is insensitive to intramural hematoma

Thoracoscopic cardiac surgery is presently under intense investigation. This study examined the feasibility and efficacy of closed chest cardiopulmonary bypass and cardioplegic arrest in comparison with standard open chest methods in a dog model. The minimally invasive closed chest group (n = 6) underwent percutaneous cardiopulmonary bypass and cardiac venting, as well as antegrade cardioplegic arrest through use of a specially designed percutaneous endovascular aortic occluder and cardioplegic solution delivery system. The control group (n = 6) underwent standard sternotomy and conventional open chest cardiopulmonary bypass, aortic crossclamping, and antegrade cardioplegia. Ischemic arrest time was 1 hour in each group. Ventricular pressures and sonomicrometer segment lengths were recorded before bypass and at 30 and 60 minutes after bypass. Left ventricular function did not differ significantly between the two groups, as demonstrated by measurements of elastance and end-diastolic stroke work. Also, the preload recruitable work area was 69% and 60% of baseline at 30 and 60 minutes after bypass in the minimally invasive group versus 65% and 62% in the conventional control group (p = not significant); the stroke work end-diastolic length relationship was 78% and 71% of baseline in the minimally invasive group at these intervals versus 77% and 74% in the conventional control group (p = not significant). Myocardial temperatures were similar throughout bypass in the two groups, and ultrastructural examination of prebypass and postbypass biopsy specimens showed no differences between groups. These results demonstrate that minimally invasive cardiopulmonary bypass with cardioplegic arrest is as feasible, safe, and effective as conventional open chest cardiopulmonary bypass. Thus current technology may allow wider clinical application of closed chest cardiac surgery

BACKGROUND: A variety of surgical techniques has been developed to attempt to minimize the risk of paraplegia after descending thoracic aortic aneurysm repair. This study reviews our institutional experience with several basic techniques over a period of 10 years. METHODS: Seventy-eight consecutive patients underwent repair of descending thoracic aortic aneurysm between 1983 and 1993. Two basic repair strategies were used: (1) distal perfusion with somatosensory evoked potential monitoring (n = 54) and (2) cross-clamping (n = 24), alone (n = 6) or with controlled distal exsanguination (n = 18). RESULTS: The operative mortality rate was 6.5% for elective repair (n = 62), 25.0% for emergent repair (n = 16), and 10.3% overall. Univariate predictors of increased operative risk were emergent operation, rupture, and shock. Neither death nor paraplegia was related to the operative technique used. The incidence of paraplegia was 3.7% in perfused patients and 4.2% in cross-clamping patients (p > 0.05). Paraplegia did not occur after any elective operation (zero of 62) but occurred in 18.6% of emergent cases (p < 0.01). In perfused patients, paraplegia did not occur when the distal pressure was maintained above 55 mm Hg and somatosensory evoked potentials remained intact. When somatosensory evoked potentials were lost (n = 7) in perfused patients, the operative technique was altered successfully in 5 patients, whereas in 2 patients (28.6%), paraplegia developed. CONCLUSIONS: The risks associated with elective descending thoracic aortic aneurysm repair were extremely low using an operative strategy that was flexible but skewed toward perfusion with somatosensory evoked potential monitoring. In perfused patients, paraplegia did not occur when distal pressure was greater than 55 mm Hg and somatosensory evoked potentials remained intact. However, the risks of death and paraplegia were primarily related to emergent presentation, not to technique, and the technique of cross clamping with controlled distal exsanguination was found to be valuable in unstable or in anatomically complicated subsets of patients