Pulmonary Embolism Complicated by Acute Limb Ischemia Managed by Surgical Pulmonary Embolectomy.

Acute pulmonary embolism (PE) is a manifestation of venous thromboembolic disease with potential serious and life-threatening complications. Management options for acute PE have drastically improved over the last 15 years with the introduction of multidisciplinary pulmonary embolism response teams throughout the world. We present the case of an 18-year-old woman diagnosed with acute PE complicated by near-complete occlusion of her left common femoral artery from a paradoxical embolus in the setting of patent foramen ovale (PFO), managed with surgical pulmonary embolectomy and surgical PFO repair.

Vitamin D and Postoperative Vasopressor Use in Cardiopulmonary Bypass.

The use of cardiopulmonary bypass (CPB) in cardiac surgery often leads to a systemic inflammatory response. Up to 25% of patients undergoing CPB for cardiac surgery are reported to develop vasoplegic syndrome in the acute postoperative period, in which the patients are refractory to vasopressors. The purpose of this study is to assess vitamin D deficiency as a risk factor for vasoplegia after using CPB. We performed a retrospective review of 1322 patients undergoing adult cardiac surgery requiring CPB. Forty-six patients with previously recorded 25-hydroxy vitamin D (25(OH)D) levels within 6 months of surgery met the conditions of this study. The mean level of 25(OH)D was 32.7 ng/mL (standard deviation [SD] = 15.1). The mean age of patients was 67 (SD = 10.1) years old, most were male (63%) and white (78%). Average CPB time was 140 ± 44 minutes. Postoperative vasopressor use was compared to individual preoperative 25(OH)D levels. As a secondary end point, postoperative vasopressor use and vasoplegia were analyzed between 3 groups: Vitamin D deficient defined as 25(OH)D ≤20 ng/mL (n = 7), vitamin D insufficient defined as 25(OH)D between 20 and 29 ng/mL (n = 15), and vitamin D sufficient defined as 25(OH)D ≥30 ng/mL (n = 24). There was no correlation between vitamin D levels and postoperative vasopressor use. The mean doses of postoperative vasopressor use were 0.088 µg/kg/min (standard error of the mean [SEM] = 0.032), 0.085 µg/kg/min (SEM = 0.037), and 0.072 µg/kg/min (SEM = 0.024) of norepinephrine equivalents for the vitamin D deficient, insufficient, and sufficient groups, respectively. Incidence of vasoplegia for each group was the following: 0.143 for vitamin D deficient, 0.067 for vitamin D insufficient, and 0.125 for vitamin D sufficient. In this pilot study, there does not appear to be a relationship between vitamin D and vasopressor use following cardiac surgery utilizing CPB; however, there appears to be a trend toward an increased vasopressor usage in patients with decreased vitamin D levels. A larger sample size and a prospective analysis are warranted to further assess the significance of the relationship between vasoplegia and vitamin D deficiency. With further investigation, vitamin D has the potential to become a low-cost, low-risk therapeutic for improving outcomes in CPB surgery.

Respiratory responses to stimulation of abdominal and upper-thorax intercostal muscles using multiple Permaloc electrodes.

Stimulation of abdominal and upper-thoracic muscles was studied with the long-term goal of improved respiratory care for spinal cord injury (SCI) patients. A 12-channel stimulator and multiple surface and implanted Permaloc electrodes were evaluated in five anesthetized canines. Abdominal stimulation with 100 mA using four bilateral sets of surface electrodes placed on the midaxillary line at the 7th through 13th intercostal spaces and with a closed airway at a large lung volume produced an expiratory tracheal pressure of 109 +/- 29 cm H2O (n = 2, mean +/- standard error of the mean). Similar high pressures were induced with implanted electrodes at the same locations. Upper-thoracic stimulation with 40 mA and four sets of implanted electrodes ventral to the axilla induced inspiratory pressures of -12 +/- 2 cm H2O (n = 5). Combined extradiaphragmatic pacing with an open airway produced a tidal volume of 440 +/- 45 mL (n = 4). The robust respiratory volumes and pressures suggest applications in SCI respiratory care.

Aberrant right subclavian artery-esophageal fistula and severe gastrointestinal bleeding after surgical correction of scimitar syndrome.

Scimitar syndrome and gastrointestinal bleeding from an aberrant right subclavian artery-esophageal fistula are each extremely rare. Although scimitar syndrome and aberrant right subclavian artery are typically asymptomatic in adults, fistulous connection between the aberrant artery and the esophagus is associated with a poor prognosis. Outcomes are contingent upon timely diagnosis and prompt surgical repair. Prolonged nasogastric and endotracheal intubation can lead to gastrointestinal bleeding in patients who have an aberrant right subclavian artery or other vascular ring. We recommend neither embolization nor the use of endovascular stents as anything other than a temporizing measure in the management of aberrant right subclavian artery injury. These methods can stop acute hemorrhage; however, sentinel bleeding will eventually occur and require definitive ligation. We report the case of a 57-year-old woman in whom an aberrant right subclavian artery-esophageal fistula developed after surgical correction of symptomatic scimitar syndrome. Massive gastrointestinal bleeding resulted from prolonged nasogastric and endotracheal intubation. To our knowledge, this is the first report of aberrant right subclavian artery and scimitar syndrome in the same patient, and the 4th report of a patient's surviving a fistula between the aberrant artery and the esophagus.

Myocardial protection of insulin and potassium in a porcine ischemia-reperfusion model.

BACKGROUND: We previously evaluated cardioprotective effects of glucose-insulin-potassium (GIK) in a porcine ischemia-reperfusion model; our results showed less myocardial pH decrease during ischemia and reperfusion and faster normalization of ATP and glucose during reperfusion. The proposed protective mechanism was facilitation of glucose transport for myocardial metabolism. The objective of this study was to assess the impact of insulin-potassium (IK) alone on myocardial metabolism. METHODS: Male swine received continuous infusion of IK (IK group, n = 10), GIK (GIK group, n = 10), or standard lactated Ringer's (LR) solution (controls, n = 10). Induction of 20 minutes of ischemia in the left anterior descending (LAD) artery distribution was followed by 20 minutes of reperfusion. Real-time biosensors recorded pH and glucose levels in ischemic and nonischemic beds. Myocardial biopsies in the distribution of the LAD assessed ATP levels. Groups were compared using the Kruskal-Wallis and Mann-Whitney tests. RESULTS: Real-time data are presented as percent change from baseline. At less than 10 minutes of ischemia, the average pH change was less for the IK group than the LR group (0.03% +/- 0.21% vs -2.06% +/- 1.23%; P = .001), and the pH change in the IK group was similar to the GIK group. After 10 minutes of ischemia and during the first 10 minutes of reperfusion, the IK group experienced pH changes that were similar to the LR group. Biopsies after 20 minutes of ischemia and 20 minutes of reperfusion showed less of a decline in ATP levels for the IK group compared to the LR group. Glucose at all time points demonstrated no statistically significant differences. CONCLUSION: IK infusion alone demonstrates cardioprotective effects during early ischemia; however, compared to GIK infusion after 20 minutes of ischemia and reperfusion, myocardial pH and glucose levels were not sustained. Although insulin may facilitate glucose transport during ischemia, additional glucose in combination with IK enhances myocardial protection during reperfusion. This finding suggests that GIK enhancement during acute ischemia-reperfusion may improve myocardial protection.

Postoperative hyperbilirubinemia is an independent predictor of longterm outcomes after cardiopulmonary bypass.

BACKGROUND: Two decade-old studies of cardiopulmonary bypass (CPB) patients documented a 25% to 35% incidence of postoperative hyperbilirubinemia, associated with increased in-hospital morbidity and mortality. Longterm consequences of this complication are unknown. STUDY DESIGN: Medical records of CPB patients were reviewed. Mortality was ascertained through the National Death Index. Proportional hazards determined important factors in post-CPB survival. Logistic regression delineated predictors of hyperbilirubinemia. Kaplan-Meier and Mantel-Cox log-rank survival analyses compared hyperbilirubinemia groups. RESULTS: Bilirubin levels were followed in 826 (59.7%) patients. Bilirubin was normal in 570 (69.0%) patients (group 1), it was 1.4 to 2.8 mg/dL in 184 (22.3%) patients (group 2), and it exceeded 2.8 mg/dL in 72 (8.7%) patients (group 3). Elevated bilirubin was associated with decreased body mass index, congestive heart failure, heparin before operation, postoperative transfusion requirement, bleeding, and renal failure. In-hospital mortality was 4.3% in group 2 and 25.0% in group 3, compared with 0.9% in group 1 (p<0.001). Two-year crude survival was 95.8% in group 1, 84.8% in group 2, and 62.5% in group 3 (p<0.001). Multivariable predictors of longterm mortality were older age, history of stroke, emergency operation, increased duration of cardiopulmonary bypass, respiratory failure, and elevated bilirubin. Compared with survival in group 1, there was a 1.7-fold decrease in group 2 2-year survival (95% CI 0.9 to 3.0; p=0.09) and a 3.8-fold decrease in group 3 survival (95% CI 2.0 to 7.2; p<0.001). CONCLUSIONS: Postoperative bilirubin elevation in CPB patients is common and deadly. The predictive power of hyperbilirubinemia is similar to that of respiratory failure. The cause of postbypass hyperbilirubinemia is unknown and is probably multifactorial. Additional prospective studies are warranted.

Real-time myocardial glucose measurement using biosensors.

During ischemia, myocardial fatty acid metabolism ceases, rapidly depleting the other primary fuel, glucose. No technique has existed to continuously monitor myocardial glucose. Needle-tip enzymatic glucose biosensors have been developed for subcutaneous use in diabetic management. To study the utility of these sensors for real-time myocardial glucose monitoring in clinically relevant applications, 40 kg Yorkshire swine were cannulated for cardiopulmonary bypass. Biosensors were placed in the left anterior descending artery distribution (LAD) and posterior descending artery distribution (PD), and a third in the liver. Selective ischemia was induced by ligation of the LAD artery. Glucose levels were monitored during ischemia and reperfusion in the setting of cardioplegic arrest (n = 7) and in the normal beating heart (n = 14). In the normal beating heart, glucose levels fall to 6.5% +/- 7.4% baseline at 1 minute and 29.0% +/- 23.0% at 5 minutes of ischemia. In both arrested and beating heart scenarios, biosensors show distinct metabolic states in specific regions of the heart and liver. Biosensors can track regional glucose metabolism in the beating and arrested heart. This novel application of these sensors allows real-time determination of myocardial glucose levels to guide cardioplegia administration and monitor ischemic states for clinical and experimental use.

Real-time monitoring of cardiac metabolism using biosensors shows myocardial protection during ischemia-reperfusion injury with glucose-insulin-potassium administration.

BACKGROUND: Systemic infusion of glucose-insulin-potassium (GIK) is thought to confer myocardial protection during ischemia-reperfusion injury. Our laboratory has experience with real-time monitoring of glucose and pH levels using needle-mounted biosensors. We tested the hypothesis that GIK enhances myocardial metabolism as displayed by real-time myocardial metabolic monitoring. METHODS: A total of 40 kg male swine were randomized to receive GIK (n = 7) or lactated Ringer's (n = 7) solution intravenously at 1.5 mL/kg/hour. Ischemia was induced in the left anterior distribution (LAD) by 20 minutes LAD occlusion, followed by 20 minutes reperfusion. Hearts were instrumented anteriorly and posteriorly with continuously recording myocardial pH and glucose biosensors. Biopsies from the LAD distribution were taken at baseline, maximum ischemia, and after reperfusion to assess cardiac adenosine triphosphate (ATP) levels. RESULTS: GIK animals had less myocardial pH decrease than controls during both ischemia (pH decrease -0.03 vs -0.37, P = .04) and reperfusion (pH decrease -0.10 vs -0.44, P = .05). Neither ATP (74% vs 73% decrease from baseline) nor glucose (27% vs 33% decrease from baseline) varied significantly between groups during ischemia. GIK animals had faster normalization of ATP (100% vs 79% increase from ischemia) and glucose (69% vs 28% increase from ischemia) during reperfusion. CONCLUSIONS: Real-time myocardial metabolic monitoring shows that cardiac pH is improved by GIK during ischemia-reperfusion injury; however, ATP and glucose levels were not significantly enhanced. GIK animals trended toward earlier recovery during reperfusion. Mediators of this metabolic enhancement need to be explored.

Use of both internal thoracic arteries in diabetic patients increases deep sternal wound infection.

BACKGROUND: Use of both internal thoracic arteries has been limited in diabetic patients fearing an increased incidence of deep sternal wound infection. We analyzed this concern by querying The Society of Thoracic Surgeons Database. METHODS: Diabetic patients who had isolated coronary artery bypass graft surgery during 2002 to 2004 were included if they had no prior bypass surgery, two or more distal bypasses, and a left internal thoracic artery bypass. Group B (both internal thoracic arteries) was compared with group L (left internal thoracic artery only). RESULTS: The incidence of deep sternal wound infection for all patients undergoing isolated first-time bypass surgery was less than 1%. Of these, 120,793 patients met criteria for inclusion: group B, 1.4% (1732); and group L, 98.6% (119,061). Group B had a higher crude (unadjusted) deep sternal wound infection rate of 2.8% (49) versus 1.7% (1969; p = 0.0005) in group L, with an estimated odds ratio of 2.23 (95% confidence interval, 1.69 to 2.96). Group B had a similar crude mortality rate of 1.7% (30) versus 2.3% (2785; p = NS) in group L, with an estimated odds ratio of 1.110 (95% CI, 0.78 to 1.59; p = NS). Patients in group B were younger, mostly male, had a lower serum creatinine level, and were more often current smokers; less commonly, they were insulin dependent, diagnosed with pulmonary or vascular disease, or on dialysis. Other risk factors for deep sternal would infection included female gender, insulin dependence, peripheral vascular disease, recent infarction, body mass index exceeding 35 kg/m2, and use of blood products. CONCLUSIONS: There is a significant increase in the incidence of deep sternal would infection in diabetic patients. This is further increased with the use of both internal thoracic arteries with no apparent short-term mortality difference.