Minimally invasive cardiac surgery defined.

There is no operation as complex, yet as fundamentally unchanged over time, as conventional coronary artery bypass grafting (CABG). This remarkable achievement is attributed to the operation's adaptability to a wide variety of clinical settings; its reproducibility, although performed by surgeons all across the world; and its proved track record for safety and effectiveness. A monumental effort, however, is currently under way to redefine CABG. This paradigm shift has received a groundswell of support as advances in minimally invasive surgery in other areas, such as arthroscopy, laparoscopic cholecystectomy, and thoracoscopy, combined with an increasing focus on cost containment, have forever changed the milieu of the cardiac surgeon. This review examines the clinical and research issues surrounding minimally invasive CABG from the vantage point of a surgeon-scientist working in the field.

Endoscopic versus open saphenous vein harvest: the effect on postoperative outcomes.

BACKGROUND: Endoscopic vein harvest (EVH) has been promoted as a possible solution to the wound complications, incisional pain, and prolonged convalesce associated with open vein harvesting (OVH). The purpose of this study was to objectively compare the two techniques. METHODS: One hundred patients were prospectively randomized to EVH or OVH. Primary outcomes were wound complications, pain (Medical Outcomes Study Pain Survey), and general health (SF-12). Secondary outcomes were operative times and patient preferences. Patients were assessed at hospital discharge, 3, and 6 weeks postdischarge. RESULTS: No significant differences were detected in the primary outcomes: leg infection (p = 0.75), incisional pain (p = 0.74), physical health (p = 0.84), mental health (p = 0.47), and postoperative length of stay (p = 0.74). However, patient preference for EVH was highly significant (p < 0.01). CONCLUSIONS: EVH does not demonstrate significant differences compared with OVH. This, coupled with higher operating room costs, should limit its use until clinical benefit is shown. However, strong patient preference and demand for EVH overshadow equivocal clinical outcomes.

High-flow gas insufflation to facilitate MIDCABG: effects on coronary endothelium.

BACKGROUND: During less invasive coronary bypass operations on the beating heart, as well as conventional operations using continuous warm cardioplegia, a precise anastomosis is facilitated by a bloodless field. To maintain a clear field, many surgeons use high-flow gas insufflation. However, the potentially damaging effects of gas insufflation on coronary endothelium have not been elucidated. METHODS: Seven pigs underwent median sternotomy. Between two coronary occluders, an arteriotomy in the mid left anterior descending coronary artery (LAD) was performed. In the experimental group (n = 5), the operative field was kept clear by exposing the arteriotomy to a catheter-directed stream of carbon dioxide at 15 L/min. In the control group (n = 2), the arteriotomy was left open to room air. After 20 minutes, the segments of LAD exposed to carbon dioxide or room air, and the unexposed proximal LAD and right coronary artery, were processed, sectioned, and stained together. A murine anti-human tie-2 monoclonal antibody was used to identify endothelium. RESULTS: All unexposed LAD and right coronary artery segments and all LAD segments exposed only to room air demonstrated normal, contiguous staining of endothelium with the murine anti-human tie-2 monoclonal antibody. In contrast, all LAD segments exposed to high-flow carbon dioxide gas insufflation demonstrated near-complete loss of endothelium. CONCLUSIONS: These data demonstrate that high-flow carbon dioxide gas insufflation denudes the coronary artery of its endothelium. This exposes blood elements to the subendothelium and promotes clotting, and endothelial loss may promote smooth muscle cell migration and proliferation. These events set the stage for early and late graft failure.

The effects of mechanical cardiac stabilization on left ventricular performance.

OBJECTIVE: Mechanical cardiac stabilization is beneficial for precise coronary anastomoses on the beating heart. However, the effect of mechanical cardiac stabilization on hemodynamics, left ventricular performance, and the degree of injury to underlying tissue are uncertain. METHODS: Twelve swine (20-30 kg) underwent median sternotomy and a mechanical stabilizing device (United States Surgical, Norwalk, CT) was positioned astride a segment of left anterior descending coronary artery (LAD). Coronary blood flow was measured by Doppler. Sonomicrometry crystals were placed distal to the stabilizer in a region of myocardium subtended by the LAD, and a left ventricular micromanometer was inserted. Regional myocardial function was determined using the preload recruitable stroke work (PRSW) relationship. Data were acquired at three time points: 20 min before (PRE) and after placing the stabilizer (EXPT); and 20 min after removing the stabilizer (POST). Tissue subjacent to the stabilizer was then biopsied. Means +/- standard deviation are reported. RESULTS: The mechanical stabilizer caused a decrease in cardiac output from 4.2+/-1.5 to 3.6+/-1.3 l/min (P < 0.05), which returned to baseline values after its removal. Regional myocardial function (percent systolic shortening and MW and x-intercept of the PRSW relationship) was unchanged. Blood pressure, heart rate, and LAD blood flow remained constant. Histologic findings included a layer of myocyte necrosis less than 1 mm in depth immediately beneath the stabilizer. CONCLUSIONS: These data demonstrate that mechanical stabilization of the LAD may temporarily decrease cardiac output. This is not attributed to impaired contractility or ischemia, but is secondary to direct ventricular compression with reduced stroke volume. Injury to underlying tissue is negligible.

Thoracoscopic harvest of the internal thoracic artery: a multicenter experience in 218 cases.

BACKGROUND: Off-pump bypass grafting most commonly involves harvest of the left internal thoracic artery (ITA) through a minithoracotomy under direct vision. Disadvantages to this approach, however, include poor exposure, incomplete dissection resulting in inadequate ITA length, and significant postoperative pain because of rigorous chest retraction. This study determined the safety and efficacy of an alternative to direct ITA harvest using a thoracoscopic approach. METHODS: Two hundred eighteen patients at three institutions underwent thoracoscopic ITA harvest; 118 (54%) for off-pump coronary bypass grafting. RESULTS: The left ITA was harvested in 211 patients (96%); the mean harvest time ranged from 42 to 55 minutes. The ITA was injured in 4 patients (1.8%), and conversion to open ITA harvest occurred in 18 (8%). Complications included intercostal neuropathy (4), reoperation for ITA bleeding (2), phrenic nerve injury (1), and wound infection (1). CONCLUSIONS: This large, multicenter experience demonstrates that thoracoscopic harvest of the ITA can be accomplished safely and within a reasonable time frame in most patients undergoing coronary bypass grafting.

Feasibility study of a mechanical suturing device for less invasive mitral operations.

BACKGROUND: Because of smaller incisions and limited exposure, less invasive operations on the mitral valve can be arduous and time-consuming. This study examined the feasibility of a mechanical suturing device to facilitate less invasive mitral replacement. METHODS: Five mongrel dogs underwent limited left thoracotomy. After conventional cardiopulmonary bypass and cardioplegia, the mitral valve was exposed through a left atriotomy. After excision of the anterior leaflet, subannular sutures were placed using a mechanical suturing device. This device simultaneously passes two ends of a pledgeted 2-0 braided suture through the valvular annulus, then mechanically grasps both needles on the atrial aspect. Hence, a mattress suture is accomplished one-handed in a single continuous motion. This procedure was repeated around the entire annulus. A mechanical valve was seated and the sutures were tied and cut. RESULTS: All mechanical valves were implanted successfully. In the 4 animals in which it was attempted, cardiopulmonary bypass was successfully weaned. No evidence of perivalvular leak was observed by echocardiography. CONCLUSIONS: These data establish the feasibility of a mechanical suturing device for operations on the mitral valve. The device is easily mastered, maintains precise spacing between sutures, and permits rapid placement of mattress sutures. We predict widespread application for both less invasive and conventional valve operations.

Pulmonary abnormalities and PET data analysis: a retrospective study.

PURPOSE: To assess methods of standard uptake ratio (SUR) calculation with 2-deoxy-2-[fluorine-18]fluoro-D-glucose (FDG) positron emission tomography (PET) in indeterminate focal pulmonary abnormalities. MATERIALS AND METHODS: One hundred ninety-seven adult patients with indeterminate pulmonary abnormalities had complete FDG PET data, consistent methods of data acquisition, and definitive diagnosis with tissue biopsy or negative 2-year follow-up findings. PET studies were evaluated by using SURs calculated with the average or maximum region-of-interest pixel value in the numerator and with weight, lean body mass, or body surface area in the denominator. RESULTS: One hundred twenty malignant lesions and 77 benign processes were identified. Receiver operating characteristic (ROC) curve areas were statistically significantly larger with the average rather than the maximum pixel value in the calculation of the SUR for any of the three denominators (P < or = .05). SURs calculated with weight versus lean body mass versus body surface area in the denominator showed no statistically significant difference in ROC curve areas. CONCLUSION: SURs determined by using average pixel values provide statistically significant improvement in ROC curve areas over those determined by using maximum pixel values. Weight, lean body mass, and body surface area in the denominator of the SUR calculation provide equivalent ROC curve areas and are therefore equivalent in accuracy in this population.

Lung tumor growth correlates with glucose metabolism measured by fluoride-18 fluorodeoxyglucose positron emission tomography.

BACKGROUND: The growth rate, or doubling time, of radiographically indeterminate pulmonary abnormalities is an important determinant of malignancy. Prospective calculation of doubling time, however, delays diagnosis and treatment. Positron emission tomography (PET) using the glucose analogue fluoride-18 fluorodeoxyglucose (FDG) measures the enhanced glucose uptake characteristic of neoplastic cells. We postulated that if FDG activity correlates with doubling time, then PET may allow prompt diagnosis of lung cancer. METHODS: From March 1992 to July 1993, all patients with indeterminate focal pulmonary abnormalities were eligible for FDG PET imaging. In 53 patients, serial chest radiographs or computed tomograms were available and doubling time was computed. The FDG activity within the lesion was expressed as a standardized uptake ratio. RESULTS: The mean standardized uptake ratio (+/- SD) was 5.9 +/- 2.7 in 34 patients with cancer, versus 2.0 +/- 1.7 in 19 with benign disease (p < 0.001). Using a criterion of standardized uptake ratio 2.5 or greater for malignancy, the accuracy of PET was 92% (49 of 53). The standardized uptake ratio was significantly correlated with doubling time (r = -0.89; p = 0.002). CONCLUSION: These data suggest a direct relation between tumor growth and FDG uptake in lung cancer. The technique of FDG PET demonstrates exceptional accuracy and may permit prompt diagnosis of lung cancer.

Detection of primary and recurrent lung cancer by means of F-18 fluorodeoxyglucose positron emission tomography (FDG PET).

Positron emission tomography (PET), with the glucose analog F-18 fluoro-deoxyglucose (FDG), takes advantage of the enhanced glucose uptake observed in neoplastic cells. We examined whether the detection of preferential FDG uptake with PET permits differentiation between benign and malignant focal pulmonary lesions in patients with suspected primary or recurrent lung cancer. Between November 1991 and September 1993, 100 patients with indeterminate focal pulmonary abnormalities including 16 patients who had previous lung resections for cancer were prospectively studied. Tissue diagnosis was obtained by transbronchial or percutaneous biopsy (n = 49) and open biopsy or resection (n = 35). Three patients underwent extended observation (> 2 years) alone. Excluded were 13 patients lacking firm pathologic diagnoses and less than 2-year follow-up. FDG activity in the lesion was expressed as a calculated standardized uptake ratio. Mean standardized uptake ratio (+/- standard deviation) was 6.6 (+/- 3.1) in 59 patients with cancer versus 2.0 (+/- 1.6) in 28 with benign disease (p = 0.0001; unpaired t test, two-sided). With a standardized uptake ratio > or = 2.5 used for detecting malignancy, sensitivity, specificity, and accuracy were 97% (57/59), 82% (23/28), and 92% (80/87), respectively. Notably, in patients evaluated for pulmonary abnormalities after lung resection for cancer, all chest recurrences were correctly identified. The exceptional sensitivity of FDG PET demonstrates that malignant pulmonary lesions preferentially accumulate FDG, which results in a standardized uptake ratio > or = 2.5. PET may be useful for distinguishing recurrent tumor from postoperative, or postradiation, changes. If performed in all patients before open biopsy, PET increases the diagnostic yield by reducing the number of patients who have benign lesions at operation. Moreover, by lowering expenditures for hospitalization and other diagnostic procedures, FDG PET may significantly reduce health care costs.

The significance of c-erb B-2 and p53 immunoreactivity in patients with adenocarcinoma of the esophagus.

OBJECTIVE: Studies in breast cancer suggest that p53 and c-erb B2 protein overexpression are predictive of outcome. The authors determined whether these molecular markers correlated with treatment response and survival in patients with adenocarcinoma of the esophagus and esophagogastric junction. METHOD: Immunostaining for p53 and c-erb B2 was performed on paraffin-embedded specimens from 42 patients with esophageal adenocarcinoma. All patients received neoadjuvant chemotherapy (cisplatin and fluorouracil [5-FU] x 3 cycles) and irradiation (4500 rads) followed by resection. RESULTS: In this cohort of patients, 79% (33/42) were positive for p53, and 43% (18/42) were positive for c-erb B2. p53 positivity correlated with residual disease in the resection specimen but not with disease-free survival. Although c-erb B2 negatively correlated with residual disease after resection and a 5-year survival of 10%, c-erb B2 positivity was associated with a 5-year actuarial survival of 60%. CONCLUSIONS: Although p53 protein overexpression is commonly observed in adenocarcinoma of the esophagus, its prognostic value appears limited. In contrast, c-erb B2 protein expression predicts a favorable response to therapy and improved survival.

Artificial surfactant attenuates hyperoxic lung injury in primates. II. Morphometric analysis.

Diffuse lung injury from hyperoxia is accompanied by low compliance and hypoxemia with disruption of endothelial and alveolar epithelial cell layers. Because both function and content of surfactant in diffuse lung injury decrease in animals and in humans, changes in the extent of injury during continuous hyperoxia were evaluated after treatments with a protein-free surfactant in primates. Ten baboons were ventilated with 100% O2 for 96 h and five were intermittently given an aerosol of an artificial surfactant (Exosurf). Physiological and biochemical measurements of the effects of the surfactant treatment are presented in a companion paper (Y.-C. T. Huang, A. C. Sane, S. G. Simonson, T. A. Fawcett, R. E. Moon, P. J. Fracica, M. G. Menache, C. A. Piantadosi, and S. L. Young. J. Appl. Physiol. 78: 1823-1829, 1995.) After O2 exposures, lungs were fixed and processed for electron microscopy. The cellular responses to O2 included epithelial and endothelial cell injuries, interstitial edema, and inflammation. Morphometry was used to quantitate changes in lungs of animals treated with the artificial surfactant during O2 exposure and to compare them with the untreated animals. The surfactant decreased neutrophil accumulation, increased fibroblast proliferation, and decreased changes in the volume of type I epithelial cells. Surfactant-treated animals also demonstrated better preservation of endothelial cell integrity. These responses indicate ameliorating effects of the surfactant on the pulmonary response to hyperoxia, including protection against epithelial and endothelial cell destruction. Significant interstitial inflammation and fibroblast proliferation remained, however, in surfactant-treated lungs exposed to continuous hyperoxia.

Natural surfactant and hyperoxic lung injury in primates. II. Morphometric analyses.

Diffuse lung injury is accompanied by low compliance and hypoxemia with histological evidence of endothelial and alveolar epithelial cell disruption. The histological effects of treatment of an acute diffuse lung injury with a natural surfactant product were evaluated in a primate model because surfactant function and content have been shown to be abnormal in diffuse lung injury in both animals and humans. Ten baboons were ventilated with 100% O2 for 96 h, and 5 were given an aerosol of natural porcine surfactant. Physiological and biochemical measurements of the effects of hyperoxia and surfactant treatment are presented in a companion paper. After O2 exposure, lungs were fixed and processed for quantitative electron microscopy. The responses to O2 included epithelial and endothelial cell injuries, interstitial edema, and inflammation. The hyperoxic animals treated with surfactant were compared with the untreated animals; the treatments altered neutrophil distribution, fibroblast proliferation, and changes in the volumes of type I epithelial cells and endothelial cells. Surfactant-treated animals also had decreased lamellar body volume density in type II epithelial cells and preservation of endothelial cell integrity. These changes suggest complex effects of natural surfactant on the pulmonary response to hyperoxia, including protection against epithelial and endothelial cell destruction as well as significant interstitial inflammation and fibroblast proliferation. We conclude that natural surfactant treatment of hyperoxic lung injury in primates resulted in partial protection of epithelial and endothelial cells but also increased the accumulation of fibroblasts in the lung.

Myocardial oxygenation in dogs during partial and complete coronary artery occlusion.

Regional myocardial oxygenation was assessed during partial and complete coronary artery occlusion using near infrared spectroscopy. In eight open-chest dogs, partial occlusions resulting in an approximately 42% decrease in left anterior descending coronary artery (LAD) blood flow produced an approximately 21% decrease in tissue O2 stores (tissue oxyhemoglobin plus oxymyoglobin) and no change in the oxidation level of mitochondrial cytochrome aa3. An approximately 81% reduction in LAD blood flow produced nadir levels of tissue oxyhemoglobin plus oxymyoglobin, maximal levels of deoxyhemoglobin plus deoxymyoglobin, a decline in tissue blood volume, and an approximately 39% decrease in cytochrome aa3 oxidation level. These changes were associated with an approximately 52% decrease from the preischemic baseline in mean transmural myocardial blood flow, measured by radiolabeled microspheres, and an approximately 41% decrease in myocardial O2 consumption. Complete occlusion resulted in further decreases in myocardial blood flow, O2 consumption, tissue blood volume, and cytochrome aa3 oxidation state but also produced increases in tissue O2 stores to above the nadir levels noted during partial occlusion. These results indicate that decreases in O2 delivery during partial coronary occlusion increase O2 extraction to sustain mitochondrial O2 availability, but as little as a 52% reduction in myocardial blood flow produces maximal O2 extraction and depletion of tissue O2 stores. Mitochondrial O2 availability is restricted further during complete occlusion because of limited O2 delivery and, possibly, decreases in tissue blood volume and O2 extraction.

Effects of muscle contraction on cytochrome a,a3 redox state.

The relationships among mitochondrial O2 availability, O2 delivery, and lactate formation in exercising skeletal muscle remain unclear. Some data suggest that muscle O2 provision is sufficient at maximal O2 consumption (VO2max) to challenge the concept of a mitochondrial O2 limitation at VO2max. The relationships among VO2, mitochondrial O2 availability, and net lactate production were studied over a wide range of exercise intensities. Using near-infrared spectroscopy, the oxidation-reduction state of cytochrome a,a3 was monitored in the canine gracilis in vivo. Twenty adult dogs were anesthetized with alpha-chloralose, intubated, and mechanically ventilated on room air. Five-minute stimulation periods at rates of 2, 3, 4, 5, 7, 8, 10, or 12 stimuli/s were performed. VO2max generally was achieved at a stimulation rate of 8 stimuli/s; mean VO2max was 0.12 +/- 0.09 (SE) ml.min-1 x g-1. The concentration of oxidized mitochondrial cytochrome a,a3 decreased at all work loads relative to resting state and demonstrated a near-linear relationship with muscle VO2 (r2 = 0.99). Muscle lactate efflux and the lactate-pyruvate ratio also were correlated positively with cytochrome a,a3 reduction, suggesting a common regulatory mechanism coupling the processes of aerobic glycolysis and oxidative phosphorylation. At VO2max, the corresponding cytochrome oxidation was not significantly different from that observed at death. Thus, in the gracilis maximal exercise leads to near-complete reduction of cytochrome a,a3 secondary to deficient O2 provision. We conclude that VO2max is limited primarily by O2 delivery to this muscle and not by other factors limiting mitochondrial ATP production or substrate oxidation.

Survival of patients with carcinoma of the esophagus treated with combined-modality therapy.

Since 1985, 229 cases of carcinoma of the esophagus have been considered for entry into a protocol with the use of preoperative chemotherapy and radiation therapy followed by surgical intervention as the primary element of treatment. One hundred sixty-five patients (93 with adenocarcinoma and 72 with squamous cell carcinoma) had esophagogastrectomy. The 5-year survival of the protocol patients who underwent resection was 25% for both groups--squamous cell carcinoma and adenocarcinoma. Of the protocol patients with squamous cell carcinoma who underwent resection, 40% had a sterilized specimen, whereas of those with adenocarcinoma, 20% had a sterilized specimen. If the patient had a sterilized specimen, the 5-year survival was approximately 60% for adenocarcinoma and 40% for squamous cell carcinoma. Those patients with adenocarcinoma and Barrett's esophagus had a 5-year survival of 55%. Of the patients who underwent only esophagectomy and esophagogastrectomy and had not been entered into the protocol, none lived beyond 3 years. The operative mortality rate for those who had esophagogastrectomy was 5%. Sixty-four patients completed the radiation therapy and chemotherapy but did not undergo surgical procedures because of progressive disease or refusal. Of those patients who completed chemotherapy and radiation therapy without surgical intervention, 5-year survival was 18% in patients with squamous cell carcinoma, whereas no patients with adenocarcinoma survived beyond 3 years. The finding of a sterilized specimen after esophagectomy is a favorable prognostic factor in patients with adenocarcinoma or squamous cell carcinoma. The finding that patients with Barrett's esophagus and adenocarcinoma have an improved chance for survival is perhaps related to an earlier diagnosis. It is clear that some patients with squamous cell carcinoma who did not undergo surgical procedures did have a sterilized specimen, because the survival in this group approached 20% at 5 years.

Acute traumatic aortic aneurysm: the Duke experience from 1970 to 1990.

Improvements in the operative management of acute traumatic thoracic aortic aneurysm have resulted in safe and expeditious repair. Nonetheless, multisystem injuries continue to inflict significant numbers of deaths. From 1970 to 1990, 108 patients with acute traumatic thoracic aortic aneurysm were evaluated. Mean injury severity score, excluding aortic injury, was 17.5. Ninety-three patients (86%) survived beyond initial resuscitation and came to operation. Median interval from injury to aortic repair was 8 hours (range, 2 hours to 19 days); there were five operative deaths. Lethal nonaortic injuries included 18 closed head injuries, four myocardial contusions, two intraabdominal vascular injuries, and one pulmonary contusion. The overall mortality rate was 39% of total admissions (42 of 108), and 29% of survivors of resuscitation (27 of 93). It is significant that only 11 of the 42 deaths (26%) were directly attributable to thoracic aortic aneurysm. Adjuncts to prevent spinal cord ischemia (shunt/bypass) were used in 76 patients, whereas 12 underwent clamp/repair. Postoperative paraplegia developed in 5 of 79 patients (6.8%, including 4 of 68 (5.9%) repaired with shunt/bypass and 1 of 11 (9.1%) repaired with clamp/repair (p = NS). Among those who developed paraplegia, the injury severity score was 27.0, and the median interval from injury to repair was 4.9 hours (range, 2 to 6.5). Intraoperative hypotension occurred in three of five patients with paraplegia. Death in patients with thoracic aortic aneurysm is due primarily to associated injuries and has remained relatively constant over the 20-year period of review. Overall injury severity, intraoperative hypotension, and extensive aortic tissue destruction may correlate with the development of postoperative paraplegia; however, a larger population sample is required to confirm this conclusion. A plea is made for standardized reporting of all patients with thoracic aortic aneurysm.

Barrett's esophagus and adenocarcinoma of the esophagus and gastroesophageal junction.

Since 1985, 57 patients with adenocarcinoma of the esophagus and gastroesophageal (GE) junction have undergone surgical resection. In this group, 16 of the tumors arose in a Barrett's esophagus. There was a significant predilection toward white men above the age of 55 (15/16; 94%) in this subgroup. The mean proximal extent of abnormal columnar involvement was 5.4 cm above the gastroesophageal junction (range 2.5 to 11 cm). The mean location of the neoplasm centered in the distal esophagus 1.8 +/- 0.5 cm above the gastroesophageal junction. During the same time period, 30 patients with Barrett's esophagus were seen without associated adenocarcinoma. There were no statistical differences in the proximal extent of columnar involvement or the presence of reflux symptoms between the two groups. There were no significant differences in age, smoking history, and alcohol consumption between patients with benign or malignant Barrett's esophagus as compared to those with adenocarcinoma of the gastroesophageal junction not associated with Barrett's mucosa. The marked male predominance seen in the group with malignant Barrett's esophagus was in contrast to the benign cases (16/30; 53%) but was similar to the adenocarcinoma group, without recognized Barrett's esophagus (38/41; 93%). The mean location of the tumor in the latter was 0.9 +/- 1.2 cm above the gastroesophageal junction and was comparable to the location in the group with Barrett's adenocarcinoma. The 4-year survival rate of patients in the non-Barrett's adenocarcinoma group is approximately 30%. Of those with Barrett's adenocarcinoma, the present 4-year survival rate is 60%. The demographic and morphometric similarities between the Barrett's and non-Barrett's adenocarcinoma groups may be of primary importance in determining the true clinical prevalence of Barrett's adenocarcinoma. Our findings suggest that the sensitivity of endoscopic surveillance may be improved if biopsy specimens are concentrated within the distal 3 cm of the esophagus and the esophagogastric junction. Finally, the reason for the current difference in survival between the Barrett's and non-Barrett's adenocarcinoma groups is uncertain but may be related to endoscopic surveillance permitting earlier diagnosis and treatment.

Porcine heparin increases postoperative bleeding in cardiopulmonary bypass patients.

One hundred thirteen patients undergoing cardiopulmonary bypass were randomly assigned to receive either bovine or porcine heparin. Heparin was infused at 4.5 mg/kg during bypass and administered at the lesser of 70 units/kg or 5000 units/dose at 12-hour intervals postoperatively. Platelet counts decreased to 45% of preoperative levels during the first 3 days postoperatively (porcine, 44 +/- 13%, n = 50; bovine, 46 +/- 15%), but returned to preoperative levels by the seventh postoperative day. The average blood loss in the porcine heparin group significantly exceeded that of the bovine heparin group (porcine, 1350.7 +/- 727.8 ml; bovine, 1059.6 +/- 381.0 ml; p less than .01). Consequently, the platelet transfusion requirement was greater in the porcine heparin group (porcine, 1.7 +/- 3.9 units; bovine, 0.5 +/- 1.7 units; p less than .05); however, blood and blood component (with the exception of platelets) administration was not significantly different between the two groups. The four patients taking anticoagulants or antiinflammatory agents in the porcine group required a mean of 8.5 units of red blood cells (RBC) plus supplemental platelets. The seven such patients in the bovine group received a mean of 3.0 units of RBC and no platelets. Thus, the use of porcine heparin resulted in a generalized increase in postoperative bleeding with increased management problems in patients undergoing cardiopulmonary bypass.