Use of aortic wall patches as leaflet replacement material during aortic valve repair.

Objectives: Aortic valve repair can be limited by inadequate leaflet tissue for proper coaptation. Various kinds of pericardium have been used for cusp augmentation, but most have failed because of tissue degeneration. A more durable leaflet substitute is needed. Methods: In this report, 8 consecutive cases are presented in which autologous ascending aortic tissue was used to augment inadequate native cusps during aortic valve repair. Biologically, aortic wall is a living autologous tissue that could have exceptional durability as a leaflet substitute. Techniques for insertion are described in detail, along with procedural videos. Results: Early surgical outcomes were excellent, with no operative mortalities or complications, and all valves were competent with low valve gradients. Patient follow-up and echocardiograms to a maximum of 8 months' postrepair remain excellent. Conclusions: Because of superior biologic characteristics, aortic wall has the potential to provide a better leaflet substitute during aortic valve repair and to expand patient categories amenable to autologous reconstruction. More experience and follow-up should be generated.

Aortic valve repair for isolated right coronary leaflet prolapse.

Objectives: Isolated right coronary leaflet prolapse is a common cause of nonaneurysmal aortic insufficiency, but can rarely occur in patients with proximal aortic aneurysms. Standardized techniques for routine autologous repair of this disorder are presented. Methods: Most aortic valve leaflet prolapse is isolated to the right coronary leaflet, with hypertension and annular dilatation being contributory. Echocardiographically, a posteriorly eccentric aortic insufficiency jet together with "fracture" of the right leaflet tip are diagnostic. Primary repair includes internal geometric ring annuloplasty to downsize and reshape the annulus, together with central plication of the prolapsing leaflet. Thickened, scarred, or retracted noduli are released using an ultrasonic aspirator. The goal is to achieve equivalent coaptation heights of ≥8 mm for all 3 leaflets. Results: Three videos of 6 cases are provided to illustrate these techniques. In the first, 3 patients are shown with classic isolated right leaflet prolapse. In the second and third videos, alternative pathologies are presented for contrast. Applying the reconstructive approaches of geometric ring annuloplasty, leaflet plication, and ultrasonic nodular release, excellent early and late repair outcomes are obtainable in most patients. Conclusions: The combination of aortic ring annuloplasty, central leaflet plication, and ultrasonic nodular release allows routine and standardized repair of right coronary leaflet prolapse, either isolated or concomitant with aneurysm surgery.

Thoracic injuries in US combat casualties: a 10-year review of Operation Enduring Freedom and Iraqi Freedom.

BACKGROUND: Mortality from thoracic injuries has declined significantly from 63% in the Civil War to 3% in Vietnam. We reviewed the injury patterns, procedures, blood products, and mortality of US soldiers sustaining a thoracic injury during Operation Enduring Freedom and Iraqi Freedom (OEF/OIF). METHODS: Data on US soldiers with a thoracic injury during OEF/OIF from January 2003 to May 2011 was collected from the Joint Theater Trauma Registry. Coalition forces, civilians, and soldiers killed in action were excluded. Injuries and procedures were identified using DRG International Classification of Diseases-9th Rev. and Abbreviated Injury Scale (AIS) codes. Data are presented as mean (SD). Statistical analysis used χ analysis and t test where appropriate. RESULTS: Thoracic injuries occurred in 2,049 of 23,797 wounded US military personnel for a prevalence of 8.6%. Mean (SD) age was 26 (6.6) years, and mean (SD) chest AIS score was 2.9 (0.9). Penetrating trauma was the most common mechanism of injury (61.5%), and explosive devices were the most common cause of injury (61.9%). Of 6,030 thoracic injuries identified, pneumothorax and pulmonary contusions were most common (51.8% and 50.2%, respectively). Of 1,541 surgical procedures performed in theater, the most common was tube thoracostomy (47.1%). Most patients with penetrating fragmentation injuries (84%) were managed with tube thoracostomy as sole therapeutic intervention. The fresh frozen plasma-to-packed red blood cells ratio was 0.86. Overall mortality was 8.3%. Acute respiratory distress syndrome and inhalation injury were associated with mortality (p < 0.006). CONCLUSION: Most penetrating fragmentation injuries can be managed with tube thoracostomy. Mortality of patients with chest injury in OEF/OIF is higher than in Korea and Vietnam. This most likely represents advances in prehospital care, personal protective equipment, and rapid transport that have resulted in more severely injured patients arriving alive to a medical facility. LEVEL OF EVIDENCE: Epidemiologic study, level IV.

A bovine hemoglobin-based oxygen carrier as pump prime for cardiopulmonary bypass: reduced systemic lactic acidosis and improved cerebral oxygen metabolism during low flow in a porcine model.

OBJECTIVES: Cerebral ischemia can occur during cardiopulmonary bypass, especially during low flow. HBOC-201 (OPK Biotech, Cambridge, Mass) is a hemoglobin-based oxygen-carrying solution that enhances oxygen delivery. This project evaluated the benefits on total body and cerebral oxygen delivery and consumption using HBOC-201 during cardiopulmonary bypass. METHODS: Twelve immature swine were assigned to one of 2 groups. One group used HBOC-201 in pump prime, and the other used donor porcine blood. Cardiopulmonary bypass was initiated and then flow was serially decreased from 100% to 75%, to 50%, and then back to full flow. At each interval, (15)O positron emission tomographic analysis was performed, and blood was collected. Total body and cerebral oxygen delivery and consumption were calculated. Statistical analysis was performed with a Tukey-Kramer adjusted P value based on a repeated measures linear model on log-transformed data. RESULTS: Total and plasma hemoglobin levels were higher in the HBOC-201 group. Oxygen delivery and consumption were not statistically different but did tend to be higher in the HBOC-201 group. Mixed venous saturation was lower in the HBOC-201 group but not significant. Mild metabolic acidosis with increased lactate levels developed in the blood group. Mean cerebral blood flow decreased in both groups when total flow was 50%. In the HBOC-201 group cerebral oxygen metabolism was maintained. CONCLUSIONS: The addition of HBOC-201 for cardiopulmonary bypass appears to improve oxygen use and minimize anaerobic metabolism. Cerebral oxygen use was preserved in the HBOC-201 group, even during decrease in blood flow. These findings support the reported improved oxygen-unloading properties of HBOC-201 and might provide a benefit during cardiopulmonary bypass.

Hybrid endovascular pseudoaneurysm and pulmonary stenosis repair in bovine arch.

This case report details the endovascular management of a large aortic pseudoaneurysm in a high-risk patient with a complicated history using a multi-disciplinary, hybrid approach. The pseudoaneurysm compressed the main pulmonary artery to 5 mm with near complete obstruction of the left main pulmonary artery, while also compromising the lumens of the left superior pulmonary vein and left main bronchus. Furthermore, the patient's left upper extremity arteriovenous dialysis fistula and bovine arch anatomy required a hybrid approach of repair that preserved the fistula while treating the aortic, pulmonary, and bronchial pathology.

Wartime thoracic injury: perspectives in modern warfare.

BACKGROUND: Thoracic injury represents a major source of combat morbidity and mortality. The overall killed-in-action rate has decreased, whereas the died-of-wounds rate has increased; the creation of the Joint Theater Trauma Registry allows for improved documentation. This report seeks to provide a realistic contemporary look at thoracic injury sustained by military forces and civilian casualties during the current wartime experience. METHODS: The Joint Theater Trauma Registry was queried between 2002 and 2008. Patients receiving treatment for thoracic injuries were identified using International Classification of Diseases, 9th edition, diagnosis and procedure codes. All US soldiers, coalition forces, and local civilians were included in the analysis. RESULTS: There were 33,755 casualties identified during the study period, of which 1,660 patients (4.9%) sustained thoracic injury. Blast mechanism was the most prominent mode of injury, accounting for 45.8%. The mean Injury Severity Score in this cohort of patients was 14.9. A total of 4,232 procedures were performed, resulting in an average of 2.5 thoracic procedures per patient. Fifty percent of casualties were civilian, and 34% were US troops, with the remainder occurring in coalition forces. Overall mortality was 12%. CONCLUSIONS: This report provides a realistic account of current wartime thoracic injury. In contrast to previous wars, the majority of thoracic injury is secondary to blast injury as opposed to penetrating trauma, and the resultant mortality rate is higher. This report breaks down thoracic injuries to both US troops and civilian personal and provides realistic expectations for thoracic injury during future combat planning.

Cardiopulmonary effects of continuous negative pressure wound therapy in swine.

BACKGROUND: Negative pressure wound therapy (NPWT) has been used for complex sternotomy wounds. Some reports describe foam placement below the posterior sternal table. We compared the hemodynamic and pulmonary effects of foam location during NPWT after median sternotomy. METHODS: Swine were randomized into four groups (n = 6 per group). A polyurethane open cell foam dressing was placed either within or below the sternal table. In one-half, a silicone mesh barrier was placed between the heart and the foam. The NPWT was applied at -125 mm Hg and then released to ambient pressure. This cycle was repeated two more times, and the foam was removed. Heart rate, mean arterial pressure, cardiac output, mixed venous oxygenation, central venous pressure, and pulmonary artery wedge pressure were measured. Peak inspiratory pressure, mean airway pressure, work of breathing, and intrathoracic pressure measurements were recorded. RESULTS: Intersternal placement of foam did not affect hemodynamic parameters. Substernal placement resulted in depression of hemodynamic variables which improved when negative pressure was applied. Pulmonary mechanics were not affected by foam location. CONCLUSIONS: Initial placement of the foam dressing below the posterior sternal table caused reversible depression of cardiac function which appears to be consistent with direct cardiac compression. NPWT therapy had no clinically significant impact on pulmonary parameters. The use of a protective barrier does not alter hemodynamic or pulmonary parameters but continues to be recommended when NPWT is used for sternotomy wounds.

Selective cerebral perfusion: real-time evidence of brain oxygen and energy metabolism preservation.

BACKGROUND: Deep hypothermic circulatory arrest (DHCA) is commonly used for complex cardiac operations in children, often with selective cerebral perfusion (SCP). Little data exist concerning the real-time effects of DHCA with or without SCP on cerebral metabolism. Our objective was to better define these effects, focusing on brain oxygenation and energy metabolism. METHODS: Piglets undergoing cardiopulmonary bypass were assigned to either 60 minutes of DHCA at 18 degrees C (n = 9) or DHCA with SCP at 18 degrees C (n = 8), using pH-stat management. SCP was administered at 10 mL/kg/min. A cerebral microdialysis catheter was implanted into the cortex for monitoring of cellular ischemia and energy stores. Cerebral oxygen tension and intracranial pressure also were monitored. After DHCA with or without SCP, animals were recovered for 4 hours off cardiopulmonary bypass. RESULTS: With SCP, brain oxygen tension was preserved in contrast to DHCA alone (p < 0.01). Deep hypothermic circulatory arrest was associated with marked elevations of lactate (p < 0.01), glycerol (p < 0.01), and the lactate to pyruvate ratio (p < 0.001), as well as profound depletion of the energy substrates glucose (p < 0.001) and pyruvate (p < 0.001). These changes persisted well into recovery. With SCP, no significant cerebral microdialysis changes were observed. A strong correlation was demonstrated between cerebral oxygen levels and cerebral microdialysis markers (p < 0.001). CONCLUSIONS: Selective cerebral perfusion preserves cerebral oxygenation and attenuates derangements in cerebral metabolism associated with DHCA. Cerebral microdialysis provides real-time metabolic feedback that correlates with changes in brain tissue oxygenation. This model enables further study and refinement of strategies aiming to limit brain injury in children requiring complex cardiac operations.

Combat casualty care in an air force theater hospital: perspectives of recently deployed cardiothoracic surgeons.

Current military operations have generated a large number of casualties and have led to the establishment of the first Air Force Theater Hospital since Vietnam. Located at Balad Airbase, Iraq, this hospital is a busy trauma center. Thoracic injuries are relatively infrequent but highly lethal. The cardiothoracic surgeon is uniquely trained to provide sophisticated surgical management to some of the most severely injured patients. The operative experiences of four recently deployed cardiothoracic surgeons are described. Mortality from combat injury in this conflict is lower than in prior wars. Body armor may prevent some fatal injuries. Several features of military medical care process are helping to improve our outcomes-specifically, the development of a trauma care system modeled on successful civilian centers, the expanded use of damage control concepts, and utilization of early transportation out of the theater of operations using Critical Care Air Transport Teams (CCATT).

Postoperative internal thoracic artery spasm after coronary artery bypass grafting.

Spasm of the left internal thoracic artery in the perioperative period represents a life-threatening complication after coronary artery bypass grafting. We present a case in which graft spasm was treated with the administration of intra-arterial nitroglycerin and verapamil. Although vasospasm is more often seen in radial artery grafts, this case demonstrates that left internal thoracic artery grafts are also prone to spasm.

Low-volume resuscitation with a polymerized bovine hemoglobin-based oxygen-carrying solution (HBOC-201) provides adequate tissue oxygenation for survival in a porcine model of controlled hemorrhage.

BACKGROUND: We have shown in a previous work that HBOC-201 is able to reverse anaerobic metabolism at low volumes in a porcine model of controlled hemorrhage. On the basis of these results, we hypothesize that low-volume resuscitation with HBOC-201 in a porcine model of controlled hemorrhage provides adequate tissue oxygenation to limit end-organ damage and allow for survival of the animal. METHODS: Twenty-four Yorkshire swine (55-65 kg) were rapidly hemorrhaged to a mean arterial pressure (MAP) of 30 mm Hg, maintained hypotensive for 45 minutes, and then divided into four groups. The first group, Shed Blood (BL), was resuscitated with shed blood to baseline MAP. A second group, Shed Blood (60), underwent resuscitation for four hours at an MAP of 60 mm Hg with shed blood. The third group, LR + Blood, was resuscitated with lactated Ringer's (maximum, 40 mL/kg) followed by shed blood to baseline MAP. The final group, HBOC (60), underwent resuscitation for 4 hours at an MAP of 60 mm Hg with HBOC-201. Hemodynamic variables, urine output, blood gas analyses, lactate levels, and jejunal oximetry were followed throughout the experiment. Animals were allowed to survive and underwent necropsy on postinjury day 3. Histologic comparisons were made. Data were analyzed using analysis of variance/Duncan's multiple range test. RESULTS: All animals survived the hemorrhage/resuscitation. One animal in the LR + Blood group died on postinjury day 1. Heart rate, MAP, and arterial pH were similar between groups. Cardiac output was significantly lower throughout resuscitation in the HBOC (60) group. Jejunal oximetry was similar throughout the experiment in all groups, revealing a decline in Po2 during hemorrhage and return to baseline or near baseline during resuscitation. There was no evidence of renal dysfunction. Histologically, one animal in the LR + Blood group and four of six animals in the HBOC (60) group demonstrated mild hepatocellular damage. All other tissues examined were found to have no significant abnormalities. Elevations in serum aspartate aminotransferase levels were noted when comparing the HBOC (60) group to the Shed Blood (BL) and Shed Blood (60) groups on day 2. Significant decreases in hemoglobin levels were noted in the HBOC (60) group compared with all other groups beginning on day 2. CONCLUSION: Low-volume resuscitation with HBOC-201 provides adequate tissue oxygenation for survival in a porcine model of controlled hemorrhagic shock with no long-term organ dysfunction identified. Although some animals did show mild hepatocellular damage with elevations of aspartate aminotransferase at day 2, these findings did not appear to have clinical relevance, and the enzyme elevations were trending toward normal by the third postoperative day. Decreases in hemoglobin levels at the later time points were expected, given the half-life of the product.

Successful endovascular therapy of a penetrating zone III internal carotid injury.

Penetrating injuries to the internal carotid artery in zone III of the neck can be a significant challenge to the operating surgeon. Direct surgical exposure and repair of the internal carotid artery at the skull base can be extremely difficult, and surgical options for treatment of a pseudoaneurysm at this location are limited. We present a case of an 18-year-old man who sustained a single gunshot wound to the distal cervical internal carotid artery that led to a pseudoaneurysm managed with endovascular exclusion. Recent literature on the surgical and endovascular management of distal carotid injuries is reviewed.