David G. Cable

The Allen test

There has been renewed interest in radial artery bypass conduits for coronary artery revascularization, and surgeons should be familiar with methods of assessing circulation of the hand to determine which patients are candidates for this procedure. The Allen test originally was described in 1929, and this report reviews its initial description and contribution to our surgical heritage.

Endoscopic Saphenous Vein Harvesting: Minimally Invasive Video-Assisted Saphenectomy

A technique of greater saphenous vein harvesting for coronary artery revascularization using an endoscopic approach is herein detailed. The saphenous vein is directly identified at the knee through a single incision. An endoscopic dissector is advanced proximally and distally along the course of the vein, ligating side-branches with clips. The vein is divided at the ends of dissection, dependent on patient anatomy, by either a counterincision, endoscopic clips, or ligation with an Endo-loop.

Minimally invasive saphenous vein harvesting: endothelial integrity and early clinical results

BACKGROUND Endoscopic harvesting of vein grafts may reduce wound complications but the effect on the venous endothelium is unknown. Endothelium-derived vasoactive substances may be important in vein graft disease prevention. We investigated the impact of endoscopic harvesting on the release of these factors and proceeded to evaluate the clinical applicability. METHODS AND RESULTS Porcine veins were harvested in either an endoscopic or open fashion. Superfusion bioassay from endoscopic veins had a similar basal secretion as control veins (6.5% +/- 1.5% versus 3.2% +/- 2.2%, respectively; n = 5, p = 0.39). Calcium ionophore A23187 stimulation was similar in both groups (24.6% +/- 5.1% versus 27.3% +/- 9.6%; n = 5, p = 0.68). Light and electron microscopy documented a normal endothelial monolayer in both groups with no endothelial cell or connective tissue loss. Encouraged by these results, 38 patients have subsequently undergone this procedure at our institution. Total operative time for harvesting 35 to 45 cm of saphenous vein was 62.3 +/- 5.3 minutes (range, 35 to 120 minutes). The procurement time in the most recent five patients was 41.6 +/- 3.3 minutes. Patients had little incisional pain, but did have mild ecchymosis. CONCLUSIONS Endothelial release of vasoactive substances after endoscopic harvesting is similar to that after the traditional, extended incision technique, and microscopy confirmed similar histology. These laboratory findings support the satisfactory early clinical experience with endoscopic harvesting of saphenous veins.

Expression and function of a recombinant endothelial nitric oxide synthase gene in porcine coronary arteries

OBJECTIVES Direct gene transfer of exogenous nitric oxide synthase, with the subsequent increase in nitric oxide production, could represent a potential therapeutic strategy in the treatment of vascular proliferative disorders. The goal of the present study was to determine if porcine coronary arteries could be transduced with an adenoviral vector encoding endothelial nitric oxide synthase (Ad.CMVeNOS) resulting in functional expression. METHODS AND RESULTS Segments of porcine right coronary artery were exposed for 1 h at 37 degrees C to either replication-deficient adenovirus encoding bovine endothelial nitric oxide synthase (Ad.CMVeNOS, 5 x 10(9) pfu/ml) or control adenovirus encoding Escherichia coli beta-galactosidase (Ad.CMVLacZ, 5 x 10(9) pfu/ml). Immunohistochemistry with a monoclonal antibody specific for nitric oxide synthase (NOS) demonstrated recombinant gene expression in both the endothelial and adventitial layers of Ad.CMVeNOS transduced coronaries with only endogenous NOS confirmed in the endothelium of Ad.CMVLacZ arteries. Coronary arteries transduced with Ad.CMVeNOS yielded 517 +/- 110 (mean +/- S.E.M.) nM/ng nitrite while vessels transduced with Ad.CMVLacZ yielded 126 +/- 84 nM/ng (P < 0.05, n = 6). Isometric tension recording, following prostaglandin F2 alpha constriction, documented a reduced tension in Ad.CMVeNOS transduced coronaries, compared to matched Ad.CMVLacZ coronaries (6.10 +/- 1.08 g vs. 8.45 +/- 1.19 g, respectively, P = 0.05, n = 8). This tension differential was eliminated with prior incubation in NG-monomethyl-L-arginine (L-NMMA, 10(-4) M). The EC50 for calcium ionophore relaxation of Ad.CMVeNOS coronary arteries was reduced compared to Ad.CMVLacZ (-7.90 +/- 0.03 logM vs. -7.26 +/- 0.11 logM, respectively, P < 0.05, n = 8). CONCLUSIONS These studies demonstrate successful transfer of endothelial nitric oxide synthase into porcine coronary arteries as verified by histochemical localization of recombinant protein with an increase of nitric oxide release as demonstrated by enhanced nitrite production and an alteration in vasomotor function.

Ex vivo gene transfer of endothelial nitric oxide synthase to atherosclerotic rabbit aortic rings improves relaxations to acetylcholine

Cholesterol feeding results in impaired endothelium dependent vasorelaxation. The role of nitric oxide in this process is unclear. The aim of this study was to evaluate the role of nitric oxide in cholesterol-induced vasomotor dysfunction by examining the effect of overexpression of eNOS in the hypercholesterolemic rabbit aorta on vascular reactivity. Vascular rings from the thoracic aorta of hypercholesterolemic rabbits were exposed ex vivo either to an adenoviral vector encoding endothelial nitric oxide synthase (AdeNOS) or Escherichia coli beta Galactosidase (AdbetaGal). Transgene expression was examined by histochemistry for beta galactosidase, immunohistochemistry for eNOS and cyclic GMP measurements and vasomotor studies were performed. Transgene expression was found to localize to the endothelium and adventitia. cGMP levels were significantly greater in AdeNOS compared to AdbetaGal transduced rings. Acetylcholine mediated relaxation was significantly impaired in cholesterol fed rabbits and was markedly improved by overexpression of eNOS. These results suggest that reduced NO bioavailability observed in cholesterol-induced vascular dysfunction can be partially overcome by eNOS gene transfer.

Selective convective brain cooling during normothermic cardiopulmonary bypass in dogs

BACKGROUND Neurologic complications, primarily resulting from ischemic insults, represent the leading cause of morbidity and disability, and the second most common source of death, after cardiac operations. Previous studies have reported that increases (as occur during the rewarming phase of cardiopulmonary bypass [CPB]) or decreases in brain temperature of a mere 0.5 degrees to 2 degrees C can significantly worsen or improve, respectively, postischemic neurologic outcome. The purpose of the present study was to evaluate a novel approach of selectively cooling the brain during hypothermic CPB and subsequent rewarming. METHODS Sixteen dogs were anesthetized with either intravenous pentobarbital or inhaled halothane (n = 8 per group). Normocapnia (alpha stat technique) and a blood pressure near 75 mm Hg were maintained. Temperatures were monitored by placing thermistors in the esophagus (i.e., core), parietal epidural space, and brain parenchyma at depths of 1 and 2 cm beneath the dura. During CPB, core temperature was actively cycled from 38 degrees C to 28 degrees C, and then returned to 38 degrees C. Forced air pericranial cooling (air temperature of approximately 13 degrees C) was initiated simultaneous with the onset of CPB, and maintained throughout the bypass period. Brain-to-core temperature gradients were calculated by subtracting the core temperature from regional brain temperatures. RESULTS In halothane-anesthetized dogs, brain temperatures at all monitoring sites were significantly less than core during all phases of CPB, with one exception (2 cm during systemic cooling). Brain cooling was most prominent during and after systemic rewarming. For example, during systemic rewarming, average temperatures in the parietal epidural space, and 1 and 2 cm beneath the dura, were 3.3 degrees +/- 1.3 degrees C (mean +/- standard deviation), 3.2+/-1.4 degrees C, and 1.6 degrees +/-1.0 degrees C, cooler than the core, respectively. Similar trends, but of a greater magnitude, were noted in pentobarbital-anesthetized dogs. For example, during systemic rewarming, corresponding brain temperatures were 6.5 degrees +/-1.7 degrees C, 6.3 degrees +/-1.6 degrees C, and 4.2+/-1.3 degrees C cooler than the core, respectively. CONCLUSIONS The magnitude of selective brain cooling observed in both study groups typically exceeded the 0.5 degrees to 2.0 degrees C change previously reported to modulate ischemic injury, and was most prominent during the latter phases of CPB. When compared with previous research from our laboratory, application of cold forced air to the cranial surface resulted in brain temperatures that were cooler than those observed during hypothermic CPB without pericranial cooling. On the basis of the assumption that similar beneficial brain temperature changes can be induced in humans, we speculate that selective convective brain cooling may enable clinicians to improve neurologic outcome after hypothermic CPB.

Clustering of Recurrent Pericarditis With Effusion and Constriction in a Family

OBJECTIVE To describe a cluster of cases of pericarditis in a midwestern family of German and Danish ancestry. PATIENTS AND METHODS Retrospective review of available medical records identified 5 family members in 2 generations with confirmed diagnosis of pericarditis. RESULTS Five family members, 3 males and 2 females, presented for medical evaluation of recurrent chest pain between 1969 and 1991. Physical examination resulted in the diagnosis of pericarditis with effusive and constrictive features. The age at presentation ranged from 8 to 46 years. Despite extensive investigations, an idiopathic etiology was assigned to each case. In follow-up, all 5 family members had recurrent episodes of chest pain, self-limiting or responsive to medical therapy, but the effusive component remained a notable feature of the syndrome. CONCLUSIONS Diagnosis of pericarditis in 5 family members may represent the first description of familial clustering of isolated pericarditis. In addition, 3 other family members had symptoms of chest pain, but pericarditis remained undiagnosed. The aggregate history suggests autosomal dominant inheritance with incomplete penetrance.

Anesthetic Technique Influences Brain Temperature During Cardiopulmonary Bypass in Dogs

BACKGROUND Because different anesthetics have different effects on cerebral blood flow and cerebral metabolism, we hypothesized that they also may have different effects on brain temperature during hypothermic cardiopulmonary bypass (CPB) and subsequent rewarming. METHODS Sixteen dogs were anesthetized either with inhaled halothane, 1.0 minimum alveolar concentration (ie, an anesthetic that should increase cerebral blood flow and minimally affect cerebral metabolism; n = 8), or with intravenous high-dose pentobarbital (ie, an anesthetic that should reduce cerebral blood flow and cerebral metabolism by approximately one half; n = 8). Normocapnia (alpha-stat technique) and a blood pressure near 90 mm Hg were maintained. Thermistors were placed in the esophagus (ie, the body core), in the parietal epidural space, and in the parietal brain parenchyma at depths of 1 and 2 cm. Initially, all temperatures were controlled at 38.0 degrees +/- 0.2 degrees C (mean +/- standard deviation). Thereafter, atrial-femoral artery CPB was initiated, and after 15 minutes at 38 degrees C, the core temperature was decreased to 28 degrees C over approximately 21 minutes. After 30 minutes at 28 degrees C, the core temperature was returned to 38 degrees C over approximately 21 minutes and was maintained at 38 degrees C for the next 30 minutes. RESULTS In halothane-anesthetized dogs, the mean brain-to-core temperature gradient always was 1.0 degrees C or less for all brain sites during all phases of CPB. In contrast, in pentobarbital-anesthetized dogs, the mean brain temperature during active cooling typically exceeded the core temperature by 1.7 degrees to 2.2 degrees C. This brain-to-core temperature gradient persisted into the period of stable hypothermia. During the rewarming phase of CPB, the mean brain temperature was 2.9 degrees to 3.4 degrees C cooler than the core temperature. This trend of relative cerebral hypothermia persisted well into the period in which the core temperature was 38 degrees C. CONCLUSIONS Deep barbiturate anesthesia resulted in a brain-to-core temperature gradient during CPB that was of a magnitude greater than the 1 degrees C previously reported to modulate ischemic neurologic injury. We speculate that the timely administration of barbiturates (eg, during the latter stages of CPB) may be useful as part of a cerebroprotective regimen in humans undergoing CPB, in part because the barbiturates influence brain temperature.

Systemic thrombolytic therapy after recent abdominal aortic aneurysm repair: an absolute contraindication?

Systemic thrombolysis in the early postoperative period can cause fatal hemorrhage. Systemic thrombolysis is often considered contraindicated after major vascular procedures; thus, experience with this scenario is limited. A 67-year-old man experienced massive pulmonary embolization after his abdominal aortic aneurysm was repaired with a bifurcated, woven Dacron graft. Because systemic thrombolysis was the only option for our patients survival, he underwent this procedure with recombinant tis-sue-type plasminogen activator just 2 weeks after the Dacron graft repair of his abdominal aortic aneurysm. After clinical stabilization, abdominal and pelvic computed tomography showed no periprosthetic graft hemorrhage. The successful systemic thrombolysis suggests that this therapy may prove useful in extreme situations.

Selective convective brain cooling during hypothermic cardiopulmonary bypass in dogs

Abstract Background . Neurologic complications, primarily resulting from ischemic insults, represent the leading cause of morbidity and disability, and the second most common source of death, after cardiac operations. Previous studies have reported that increases (as occur during the rewarming phase of cardiopulmonary bypass [CPB]) or decreases in brain temperature of a mere 0.5° to 2°C can significantly worsen or improve, respectively, postischemic neurologic outcome. The purpose of the present study was to evaluate a novel approach of selectively cooling the brain during hypothermic CPB and subsequent rewarming. Methods . Sixteen dogs were anesthetized with either intravenous pentobarbital or inhaled halothane (n = 8 per group). Normocapnia (alpha stat technique) and a blood pressure near 75 mm Hg were maintained. Temperatures were monitored by placing thermistors in the esophagus (ie, core), parietal epidural space, and brain parenchyma at depths of 1 and 2 cm beneath the dura. During CPB, core temperature was actively cycled from 38°C to 28°C, and then returned to 38°C. Forced air pericranial cooling (air temperature of approximately 13°C) was initiated simultaneous with the onset of CPB, and maintained throughout the bypass period. Brainto-core temperature gradients were calculated by subtracting the core temperature from regional brain temperatures. Results . In halothane-anesthetized dogs, brain temperatures at all monitoring sites were significantly less than core during all phases of CPB, with one exception (2 cm during systemic cooling). Brain cooling was most prominent during and after systemic rewarming. For example, during systemic rewarming, average temperatures in the parietal epidural space, and 1 and 2 cm beneath the dura, were 3.3° ± 1.3°C (mean ± standard deviation), 3.2° ± 1.4°C, and 1.6° ± 1.0°C, cooler than the core, respectively. Similar trends, but of a greater magnitude, were noted in pentobarbital-anesthetized dogs. For example, during systemic rewarming, corresponding brain temperatures were 6.5° ± 1.7°C, 6.3° ± 1.6°C, and 4.2° ± 1.3°C cooler than the core, respectively. Conclusions . The magnitude of selective brain cooling observed in both study groups typically exceeded the 0.5° to 2.0°C change previously reported to modulate ischemic injury, and was most prominent during the latter phases of CPB. When compared with previous research from our laboratory, application of cold forced air to the cranial surface resulted in brain temperatures that were cooler than those observed during hypothermic CPB without pericranial cooling. On the basis of the assumption that similar beneficial brain temperature changes can be induced in humans, we speculate that selective convective brain cooling may enable clinicians to improve neurologic outcome after hypothermic CPB.