Biomedical subjects
Publications and source records attributed to Lawrence H Cohn.
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OBJECTIVES: The goal of this study was to determine if a "hybrid" approach to the treatment of complex combined coronary and valve disease is superior to the results predicted by a Society of Thoracic Surgeons' (STS) algorithm with conventional coronary artery bypass graft (CABG)/valve surgery in high-risk patients. BACKGROUND: With advancements in percutaneous coronary interventions (PCIs), some patients requiring coronary revascularization and valve surgery may benefit from a hybrid approach involving initial planned PCI followed by valve surgery, rather than conventional CABG/valve surgery. METHODS: We retrospectively analyzed 26 consecutive patients with coronary artery and valve disease who underwent planned initial PCI followed by valve surgery during the same hospital stay between September 1997 and August 2003. We calculated the predicted mortality at the time of PCI and compared it with the observed mortality. RESULTS: There were 12 male and 14 female patients with a median age of 72 years (range 53 to 91 years). Balloon angioplasty was performed in all patients, followed by stenting in 22 (85%) patients. Within a median of 5 days (range 0 to 14 days), 15 patients (58%) underwent primary and 11 patients (42%) underwent re-operative valve surgery. Operative mortality was 1 of 26 patients (3.8%), dramatically lower than the STS-predicted mortality of 22%. Median blood loss was 900 ml, and 22 patients (85%) required blood transfusions. Survival at 1, 3, and 5 years was 78%, 56%, and 44%, respectively. CONCLUSIONS: Hybrid initial PCI followed by staged valve surgery represents an excellent alternative to conventional CABG/valve surgery in some high-risk patients, particularly those who present in shock after myocardial infarction. Lower mortality rates come at the cost of more bleeding and transfusion requirements.
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BACKGROUND: We sought to analyze the risk factors and natural history associated with post-cardiac surgery acute pancreatitis. METHODS: Retrospective analysis of all patients having undergone cardiac surgery at our hospital between January 1, 1992, and October 1, 2001. RESULTS: A total of 10,249 cardiac operations were performed. Thirty-nine (0.4%) patients developed postoperative pancreatitis. There was a higher incidence during the period spanning 1992 through 1996 than 1997 through 2001 (0.6% versus 0.2%, P< .05). Patients with pancreatitis had longer postoperative length of stay (51+/-5 days versus 10+/-1 days, P<.05) and a greater in-hospital mortality rate (28% versus 4%, P<.05) than patients who did not develop pancreatitis. A history of alcohol abuse, cardiac surgery performed during 1992 to 1996, increased cardiopulmonary bypass time, and increased cross-clamp time were independent risk factors for the development of pancreatitis. Multiple-organ failure was an independent predictor for death among patients with pancreatitis. CONCLUSIONS: Although the frequency of post-cardiac surgery pancreatitis is diminishing, it is still associated with significant mortality.
BACKGROUND: The presence of lymph node metastases is an important prognostic marker with regard to non-small-cell lung cancer (NSCLC). Assessment of the sentinel lymph node (SLN) for the presence of tumor may improve staging. Our objective was to develop an optical noninvasive imaging tool that would permit intraoperative SLN mapping and provide real-time visual feedback for image-guided localization and resection. METHODS: Invisible near-infrared (NIR) light penetrates relatively deeply into tissue and background autofluorescence is low. We have developed a NIR fluorescence imaging system that simultaneously displays color video and NIR images of the surgical field. We recently engineered 15 nm nonradioactive NIR fluorescent quantum dots (QDs) as optimal lymphotrophic optical probes. The introduction of these QDs into lung tissue allows real-time visualization of draining lymphatic channels and nodes. RESULTS: In 12 Yorkshire pigs (mean weight 35 kg) we demonstrated that 200 pmol of NIR QDs injected into lobar parenchyma accurately maps lymphatic drainage and the SLN. All SLNs were strongly fluorescent and easily visualized within 5 minutes of injection. In 14 separate injections QDs localized to a mediastinal node, whereas in 2 injections QDs localized to a hilar intraparenchymal node. Histologic analysis in all cases confirmed the presence of nodal tissue. CONCLUSIONS: We report a highly sensitive rapid technique for SLN mapping of the lung. This technique permits precise real-time imaging and therefore overcomes many limitations of currently available techniques.
BACKGROUND: We examined the impact of concomitant coronary artery bypass grafting (CABG) on hospital survival after aortic root replacement. We sought to determine whether CABG procedures that were not originally planned but rather added after the aortic root procedure was completed (CABG/bailout) skewed the results to shift patients with bad outcomes to the CABG group, making the non-CABG group appear undeservedly low risk. METHODS: Between May 1992 and January 2001, 369 consecutive patients underwent aortic root replacement. Concomitant CABG was required in 95 patients (26%). Indications for CABG were significant coronary artery disease in 73 patients (20%), active endocarditis or acute aortic dissection involving the coronary orifices in 14 patients (4%), and difficulty weaning from bypass because of regional wall motion abnormality from presumed but unconfirmed coronary artery disease or technical error at coronary ostial reimplantation (CABG/bailout) in 8 patients (2%). RESULTS: Operative mortality for the entire cohort was 5.7% (21 patients). The operative mortality rate for the non-CABG group was 0.4% (1 of 274 patients), and for the CABG group, 21% (20 of 95 patients; p < 0.001). Independent predictors of operative mortality in the CABG group were New York Heart Association functional class III or IV (odds ratio, 3.9; 95% confidence interval, 1.07 to 14.5), active endocarditis (odds ratio, 9.2; 95% confidence interval, 2.06 to 41.5), acute aortic dissection (odds ratio, 7.6; 95% confidence interval, 1.81 to 32.0), and failure to use retrograde cardioplegia (odds ratio, 6.4; 95% confidence interval, 1.06 to 38.8). The use of CABG/bailout was not a predictor. CONCLUSIONS: Adding CABG at the end of an aortic root procedure is a rare event, and because it is rare, there is no significant shift of risk as a result of the CABG/bailout patients on the overall CABG group.
BACKGROUND: Regardless of the indication, tricuspid valve replacement (TVR) has historically been associated with high mortality and morbidity. We report the results of our experience in a high-risk patient population with an emphasis on operative mortality, long-term survival, and valve related events according to the type of prosthesis. METHODS: Between 1985 and 1999 TVR was performed in 81 patients (isolated n = 25, combined with valve surgery n = 44, combined with CABG or other n = 12). The mean age was 61 years old (range 19-83 years old). Risk factors included New York Heart Association functional class III/IV (n = 73, 90%), reoperation (n = 58, 72%), urgent/emergent indication (n = 62, 76%), and hepatic dysfunction (n = 13, 16%). Mean pulmonary artery pressure was 34 mmHg. Etiology of tricuspid regurgitation was classified as functional (n = 18, 22%) or organic (n = 52, 64%), or failed previous tricuspid valve surgery (n = 11, 14%). RESULTS: Tricuspid valve replacement was performed with either a bioprosthetic (n = 34, 42%) or mechanical valve (n = 47, 58%). The overall operative mortality was 22% (n = 18). Risk factors for mortality included urgent/emergent status, age greater than 50 years old, functional etiology, and elevated pulmonary artery pressure. Of the 60 survivors, 26 (43%) died during follow up. After univariate analysis, organic etiology was the only predictor of late death (p = 0.01). Kaplan-Meier survival at 2.5, 5, and 10 years was 80%, 60%, and 45% for bioprosthetic, and 84%, 69%, and 59% for mechanical valves, respectively. CONCLUSIONS: Patients requiring TVR are typically high-risk with a high-percentage of reoperations, concomitant cardiac procedures, and end-stage functional class. Operative and overall mortality remains high. Heart failure was the predominant cause of early and late deaths, emphasizing importance of timely referral before the development of end-stage cardiac impairment.
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BACKGROUND: Atheroembolic complications associated with clamping a severely diseased ascending aorta during aortic valve replacement may result in unacceptable mortality and morbidity. Different management options include hypothermic circulatory arrest to replace the aortic valve, an aortic endarterectomy, or tube graft replacement of the aorta to allow safe application of cross-clamp before aortic valve replacement. METHODS: From 1998 to 2004, 70 patients who underwent aortic valve replacement had an aorta that was unclampable. Median age was 76 years; 33 (47%) were women; 46 (66%) had concomitant coronary artery bypass grafting; 9 (13%) had concomitant mitral valve surgery; and 4 (6%) were reoperations. Hypothermic circulatory arrest was used to replace the aortic valve alone, to do an aortic endarterectomy, or replace the ascending aorta with a tube graft. RESULTS: Operative mortality was 4%. There were 8 (11%) strokes and 1 (1.4%) transient ischemic attack. Statistical analysis showed no association between circulatory arrest period and occurrence of adverse cerebral events. There was no significant difference among the three groups when operative mortality and cerebral events were compared. CONCLUSIONS: Hypothermic circulatory arrest is an important adjunct that allows aortic valve replacement to be performed with an acceptable mortality but with an increased risk of cerebral event in this high-risk and elderly group of patients.
OBJECTIVE: In esophageal cancer, selective removal of involved lymph nodes could improve survival and limit complications from extended lymphadenectomy. Mapping with vital blue dyes or technetium Tc-99m often fails to identify intrathoracic sentinel lymph nodes. Our purpose was to develop an intraoperative method for identifying sentinel lymph nodes of the esophagus with high-sensitivity near-infrared fluorescence imaging. METHODS: Six Yorkshire pigs underwent thoracotomy and received submucosal, esophageal injection of quantum dots, a novel near-infrared fluorescent lymph tracer designed for retention in sentinel lymph nodes. Six additional pigs underwent thoracotomy and received submucosal esophageal injection of CW800 conjugated to human serum albumin, another novel lymph tracer designed for uptake into distant lymph nodes. Finally, 6 pigs received submucosal injection of the fluorophore-conjugated albumin with an endoscopic needle through an esophagascope. These lymph tracers fluoresce in the near-infrared, permitting visualization of migration to sentinel lymph nodes with a custom intraoperative imaging system. RESULTS: Injection of the near-infrared fluorescent lymph tracers into the esophagus revealed communicating lymph nodes within 5 minutes of injection. In all 6 pigs that received quantum dot injection, only a single sentinel lymph node was identified. Among pigs that received fluorophore-conjugated albumin injection, in 5 of 12 a single sentinel lymph node was revealed, but in 7 of 12 two sentinel lymph nodes were identified. There was no dominant pattern in the appearance of the sentinel lymph nodes either cranial or caudal to the injection site. CONCLUSION: Near-infrared fluorescence imaging of sentinel lymph nodes is a novel and reliable intraoperative technique with the power to assist with identification and resection of esophageal sentinel lymph nodes.
OBJECTIVES: This study retrospectively reviews an aggressive multidisciplinary approach to the treatment of massive pulmonary embolism, centering on rapid diagnosis with contrast-enhanced computed tomography of the chest to define the location and degree of clot burden and transthoracic echocardiography to document right ventricular strain followed by immediate surgical intervention when appropriate. METHODS: Between October 1999 through February 2004, 47 patients (30 men and 17 women; median age, 58 years; age range, 24-86 years) underwent emergency surgical embolectomy for massive central pulmonary embolism. The indications for surgical intervention were (1) contraindications to thrombolysis (21/47 [45%]), (2) failed medical treatment (5/47 [10%]), and (3) right ventricular dysfunction (15/47 [32%]). Preoperatively, 12 (26%) of 47 patients were in cardiogenic shock, and 6 (11%) of 47 were in cardiac arrest. RESULTS: There were 3 (6%) operative deaths, 2 with preoperative cardiac arrest; 2 of these 3 patients required a right ventricular assist device. In 38 (81%) patients a caval filter was placed intraoperatively. Median length of stay was 11 days (range, 3-75 days). Median follow-up was 27 months (range, 2-50 months); follow-up was 100% complete in surviving patients. There were 6 (12%) late deaths, 5 of which were from metastatic cancer. Actuarial survival at 1 and 3 years' follow-up was 86% and 83%, respectively. CONCLUSION: An aggressive approach to large pulmonary embolus, including rapid diagnosis and prompt surgical intervention, has improved results with surgical embolectomy. We now perform surgical pulmonary embolectomy not only in patients with large central clot burden and hemodynamic compromise but also in hemodynamically stable patients with right ventricular dysfunction documented by means of echocardiography.
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STUDY OBJECTIVES: Although the sentinel lymph node (SLN) concept has traditionally been applied to solid organs, we hypothesized that the pleural space might drain into a specific SLN group. The identification of such a nodal group could assist in the staging and treatment of pleural-based diseases, such as mesothelioma, or other lung cancers with visceral pleural invasion. The purpose of this study was to determine whether the pleural space has an SLN group. DESIGN: Sixteen rats underwent right or left pleural space injection of a novel lymph tracer, quantum dots (QDs), which have a hydrodynamic diameter of 15 nm and fluoresce in the near-infrared (NIR) spectrum. Nodal uptake of the entire thorax was imaged with a custom system that simultaneously acquired color video, NIR fluorescence of the QDs, and a merged picture of the two in real-time. Six pigs underwent right or left pleural space injection of QDs and similar imaging. MEASUREMENTS AND RESULTS: In the rat, the QDs drained solely to the highest superior mediastinal lymph node group, corresponding to lymph node station 1, according the regional lymph node classification for lung of the American Joint Committee on Cancer. In one rat, the injection of QDs in the left pleural space resulted in migration to the contralateral station 1 lymph node group. The injection of QDs in the right or left pleural space of the pig resulted in migration solely to the ipsilateral highest superior mediastinal lymph node group. CONCLUSIONS: NIR fluorescence imaging in two species demonstrated that the highest superior mediastinal lymph nodes of station 1 are the SLNs of the pleural space. This study also provides intraoperative feasibility and proof of the concept for identifying lymph nodes communicating with the pleural space on a patient-specific basis, in real-time, and with high sensitivity.
BACKGROUND AND AIM OF THE STUDY: Currently, there is no clear consensus on the optimal type of cardiac valve prosthesis that should be placed in women of childbearing age. The risks of reoperative surgery for bioprosthetic valves must be weighed against those of anticoagulation therapy required for mechanical valves. Bioprosthetic valves placed in women of childbearing age are not necessarily superior to mechanical valves in terms of maternal or fetal outcomes. METHODS: A retrospective analysis was performed of early and late outcome in 103 women of childbearing age (mean age 28.3 +/- 5.1 years; range: 18-35 years) who underwent mechanical (n = 63) or biological (n = 40) valve replacement between January 1982 and July 2002. RESULTS: Eleven of the 40 women (28%) with biological valves had 19 pregnancies (13 vaginal births; three caesarean sections). Twelve of the 63 women (19%) with mechanical valves had 37 pregnancies (nine vaginal births, four caesarean sections). All of the women with mechanical valves became pregnant while receiving warfarin, and were subsequently placed on heparin or enoxaparin. No bleeding complications or birth defects were observed in either group. The incidence of miscarriages (32% (12/37) versus 11% (2/19), p = 0.09) and therapeutic abortions (32.4% (12/37) versus 5.3% (1/19), p = 0.06) were greater in the group with mechanical valves than with bioprosthetic valves. Freedom from reoperation at five and 10 years for biological versus mechanical valves was 79% versus 90%, and 38% versus 82%, respectively (p < 0.01), with no reoperative mortality. CONCLUSION: Biological valves are recommended in women of childbearing age, despite the fact that no birth defects were seen in children born to women with mechanical valves on warfarin, because the teratogenic effects of warfarin may be masked by the high rate of miscarriages and therapeutic abortions in this group.
BACKGROUND AND AIM OF THE STUDY: Between January 1998 and March 2004, a total of 1,596 mitral valve repairs was performed at the authors' institution. Among these operations, 23 constituted re-repair of previously repaired mitral valves. The cases were analyzed retrospectively to ascertain the etiology of the failed repair, the technical considerations of re-repair, and outcome. METHODS AND RESULTS: Previous repairs were performed for myxomatous valve disease in 14 of 23 patients. In seven patients recurrence occurred within three months of the original procedure (two as a result of infective endocarditis and five after technical failure). Incorrect annuloplasty ring size or failure to use a ring, resulting in progressive annular dilatation with or without new valvular dysfunction, were the main causes of delayed recurrence of mitral regurgitation (i.e. more than one year after the original repair procedure). Most patients (n = 12) required a new annuloplasty ring and additional repair procedures. Two patients died within the immediate post-operative period, and five died subsequently from non-cardiac causes during a mean follow up period of 24 months. Among the remaining 16 patients, 13 were free from mitral regurgitation at follow up and two required subsequent mitral valve replacement. CONCLUSION: Re-repair of the mitral valve is a technically feasible operation that can be safely performed with good functional results. It is, however, associated with some increase in postoperative morbidity and mortality due to the reoperative setting.
BACKGROUND: Understanding the spatial and temporal drainage patterns of the pleural space could have profound impact on the treatment of lung cancer and mesothelioma. The purpose of this study was to identify the in vivo pattern of drainage from the pleural space to prognostic lymph node stations. METHODS: Fifty-six rats underwent pleural space injection of a novel lymph tracer composed of recombinant human serum albumin (HSA) covalently conjugated to the near-infrared (NIR) fluorophore IRDye78 via an amide bond (HSA-78). Nodal uptake was imaged at 10, 20, 30, and 60 minutes and 4, 12, and 24 hours after injection with a custom system that simultaneously acquires color video, NIR fluorescence of HSA-78, and a merged picture of the two. Six pigs underwent the same procedure with imaging at 30 minutes, 1 hour, and 24 hours. RESULTS: In both the rat model and the pig model, HSA-78 drained from the pleural space to superior mediastinal lymph nodes first, followed by other intrathoracic and then extrathoracic lymph nodes over the course of 24 hours. CONCLUSION: NIR fluorescence imaging in two species shows that the superior mediastinal lymph nodes are the first to drain the pleural space. Over the course of 24 hours, the pleural space also communicates with other intrathoracic and then extrathoracic lymph nodes. This study also demonstrates an intraoperative method for identifying nodes communicating with the pleural space, with potential utility in the staging and/or resection of lung cancer and mesothelioma.
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