Biomedical subjects
Publications and source records attributed to K E Sommers.
Thoracic complications of solid organ transplantation are common and can arise from the implantation surgical procedure or can be secondary to the need for lifelong immunosuppression. Problems that arise can be general to cardiothoracic surgery or unique to transplant patients. This article provides an overview of these complications and some approaches to their avoidance and management.
BACKGROUND: Aortic annulus enlargement has long been advocated for the placement of valve prostheses larger than otherwise would have been possible. Little information exists, however, on the short- and long-term outcome of this surgical procedure. METHODS: We performed a retrospective review of 530 patients enrolled in a registry for patients who underwent aortic valve replacement using the Hancock II bioprosthesis and were followed up prospectively over the course of 11 years at a single institution. In an effort to avoid prosthetic valve-patient mismatch, the aortic annulus was enlarged in 98 patients (18%). Short- and long-term outcome was analyzed. RESULTS: Enlargement of the aortic annulus during aortic valve replacement increased the operative mortality rate from 3.5% to 7.1%, but this difference did not reach statistical significance (p = 0.10). The long-term survival of patients who had annulus enlargement was similar to that of patients who did not. Because there were differences in the clinical profile of patients who had annulus enlargement and those who did not, a case-control study was carried out. This study showed similar long-term survival, freedom from valve-related and cardiac death, and combined end points in the two groups of patients. CONCLUSION: Aortic annulus enlargement increased the operative mortality of aortic valve replacement. However, patients who underwent enlargement of a small aortic annulus had long-term survival and freedom from cardiac and valve-related death comparable to those of patients who received larger aortic prostheses.
BACKGROUND: We have developed a safe, simple, and easily performed standardized exercise oximetry outpatient test to assess patients undergoing lung resections. We studied its ability to predict outcome after pneumonectomy in 46 consecutive patients over a 5-year period. METHODS: Room air oximetry is initially performed at rest. The patient then begins to exercise on a stair-stepper apparatus (Stamina Stepper), which provides uniform resistance to stepping. Oxygen saturation values are noted at 10, 20, and 30 steps, equivalent to climbing three flights of stairs. Group 1 consisted of the patients who either had a resting saturation less than 90%, or desaturation greater than or equal to 4% during exercise. Group 2 consisted of all patients who had a preoperative forced expiratory volume in 1 second of 60% or less. Group 3 consisted of all patients who had a predicted postoperative forced expiratory volume in 1 second of 40% or less. Group 4 consisted of patients who had a predicted postoperative diffusing capacity of 40% or less. RESULTS: There were four deaths (8.6%), 12 patients (26%) remained in the intensive care unit 4 or more days, and 11 patients (23%) suffered major morbidity. Desaturation during exercise (group 1) significantly predicted longer intensive care unit stay (p = 0.0002) and incidence of major morbidity (p < 0.0001). Groups 2, 3, and 4 were not significantly predictive of either longer intensive care unit stay or major morbidity. CONCLUSIONS: Standardized exercise oximetry performed in the outpatient facility is highly predictive of major morbidity and prolonged intensive care unit stay after pneumonectomy.
We present a case of primary cardiac lymphoma in a patient with dyspnea and hypoxemia. Transesophageal echocardiography reveals a large right atrial mass and an atrial septal aneurysm with right-to-left shunting through a patent foramen ovale. The patient underwent resection and atrial reconstruction. Pathology was a B cell lymphoma with diffuse large cell histology. There was no evidence of extracardiac involvement, and the patient is well 3 months postoperatively with a normal transthoracic echocardiogram.
A 66-year-old woman presented with a bronchoesophagopleural fistula 10 weeks after thoracic photodynamic therapy for malignant mesothelioma. This is the third reported case of an esophagopleural fistula developing subsequent to photodynamic therapy for mesothelioma. We review the literature on this topic and report our successful management of this complication.
BACKGROUND: Transplantation of lung allografts from the same donor into 2 recipients ("twinning") provides an opportunity to study recipient and donor factors that influence early allograft function. METHODS: Twenty-seven pairs of recipients were identified and evaluated using multivariate logistic regression analysis (p < 0.05). Four measures of early graft function were analyzed: alveolar-arterial gradient in the operating room, first alveolar-arterial gradient in the intensive care unit, alveolar-arterial gradient at 24 hours, and days of mechanical ventilation. RESULTS: Analysis of the pooled data without regard to pairing showed that alveolar-arterial gradient in the operating room was influenced by donor age, length of donor hospitalization, recipient mean pulmonary artery (PA) pressure at unclamping, and transplantation of a left lung. The alveolar-arterial gradient in the intensive care unit was correlated with donor age, donor cause of death, and mean PA pressure on arrival in that unit. Only mean PA pressure remained significant at 24 hours. Days of mechanical ventilation was determined by mean PA pressure on arrival in the intensive care unit, drop in mean PA pressure during operation, and diagnosis of the recipient. In the paired analysis, receiving a left lung, recipient diagnosis (pulmonary hypertension worse than others), and need of cardiopulmonary bypass were significantly associated with immediate graft dysfunction, although these influences did not persist beyond the immediate postoperative period. Donor arterial oxygen tension and time of ischemia were not significant predictors in any analysis. CONCLUSIONS: Immediate allograft function was associated with donor-related characteristics initially, but these lost importance over the ensuing 24 hours. Recipient PA pressure was an immediate and persisting influence. In the analysis of differences in function between the members of each pair, transplantation of the left lung, recipient diagnosis, and cardiopulmonary bypass were identified, but their influence did not persist beyond the first 6 hours.
Aortoesophageal fistula is a rare complication after thoracic aortic aneurysm repair. Six previously reported cases of aortoesophageal fistula management have been uniformly fatal. We present our successful management and review the literature of this topic.
Myocardial preservation for prolonged ischemia has traditionally centered around deep hypothermia with metabolic arrest. This approach is limited in tolerable ischemic time by the state of energy reserves at the onset of ischemia, because anaerobic glycolysis during ischemia is limited by end-product accumulation (lactate, alanine, and H+). In this study we evaluated a novel preservation solution containing the basic amino acid histidine to buffer H+, glucose as substrate, and low sodium and calcium concentrations to mimic the intracellular ionic environment. Isolated rabbit hearts were subjected to hypothermic ischemia for 8 and 16 hours at 4 degrees and 21 degrees C followed by reperfusion. The buffered solution was compared to University of Wisconsin solution (high potassium). Intracellular pH was maintained at preischemic levels in the buffered solution hearts at 21 degrees C, and this was associated with better preservation of high energy stores and recovery of contractile function. Developed pressure recovered to 90% +/- 3% of preischemic values after 16 hours of 21 degrees C ischemia with the buffered solution as compared with 79% +/- 2% in the University of Wisconsin group at 4 degrees C (contracture occurred in the University of Wisconsin hearts at 21 degrees C). The optimal temperature in the buffered solution hearts was 13 degrees C, and with this temperature acceptable recovery of contractile function was seen after 24 hours of ischemia. On the basis of these results, we conclude that promoting anaerobic glycolysis during ischemia achieves superior prolonged preservation of energetic and contractile function of the heart.
The buffering capacity of histidine in cardioplegia was analyzed from a viewpoint of anaerobic glycolysis and its end-products (lactate and alanine) by the myocardium. Isolated rabbit hearts were subjected to 3 hours multidose cardioplegic arrest by histidine (195 mM)-buffered or control solution at 21 degrees C and 30 minutes reperfusion. Diastolic pressure (DP) and recovery of developed pressure (DevP%) were measured with an intracavitary balloon filled to a pre-ischemic DP of 8-10 mmHg. Lactate and alanine in tissue and effluent were measured after ischemia by HPLC. The buffered solution group showed lower DP and higher DevP%, production of more lactate and alanine with diffusion of larger part of them into effluent than control group. We conclude that histidine in cardioplegia stimulates production of anaerobic glycolysis-derived high energy phosphate-compounds not only by proton buffering but also by removal of detrimental end-products out of the cell.
BACKGROUND: The biochemical basis for postischemic myocardial stunning is not fully elucidated. Magnesium is an important regulator of cellular energetic processes and excitation-contraction coupling. We hypothesized that the decrease in function in the postischemic period may be the result of an alteration in magnesium regulation. METHODS: In a Langendorf perfused rabbit heart model, we used 31P nuclear magnetic resonance spectroscopy to noninvasively determine intracellular Mg2+ and high-energy phosphate levels in the preischemic period and after a 30-minute period of normothermic ischemia. We measured adenosine triphosphate (ATP), phosphocreatine, and the phosphocreatine/inorganic phosphate ratio and calculated the free energy of ATP hydrolysis (delta GATP). On reperfusion, hearts were divided into three groups (n = 7 per group)--those receiving unmodified Krebs-Henseleit (control), 192 ng/ml dobutamine, or 5 mmol/L pyruvate. RESULTS: Function (expressed as the rate-pressure product) was approximately 77% of preischemic values in the control group, whereas in both dobutamine and pyruvate groups it returned to preischemic levels. ATP was decreased similarly in all groups in the postischemic period. Phosphocreatine/inorganic phosphate ratio and delta GATP were higher in the pyruvate group compared with the other groups. Intracellular Mg2+ was elevated significantly in the unmodified control postischemic group compared with preischemic, postischemic dobutamine, and pyruvate groups (1.0 +/- 0.12 vs 0.80 +/- 0.08, 0.64 +/- 0.08, and 0.70 +/- 0.05 mmol/L, respectively; p less than 0.05). CONCLUSIONS: We conclude that (1) postischemic "stunned" hearts have elevated Mg2+ levels in association with impaired contractile function, (2) inotropic agents improve contractile function in association with a decline in Mg2+ to preischemic levels despite differing effects on intracellular energetics, and (3) Mg2+ may play an important regulatory role in the heart after ischemia.
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