Thrombin is an important mediator of platelet aggregation in stenosed canine coronary arteries with endothelial injury.

Cyclic variations in coronary blood flow (CFVs) in dogs with experimental coronary artery stenosis and endothelial injury appear to result primarily from the aggregation of platelets at the site of stenosis followed by dislodgement and distal embolization. Using this canine model, we tested the hypotheses: (a) that thrombin is an important mediator of CFVs in dogs with coronary stenoses and endothelial injury; (b) that inhibition of thrombin with heparin, or MCI-9038, a selective thrombin inhibitor, abolishes CFVs in this model; and (c) that abolition of CFVs by thrombin inhibition is time dependent. CFVs, produced in open-chest dogs by placing a flow-reducing plastic constrictor around the left anterior coronary artery, were monitored for either 30 min (group I) or 3 h (group II) before treatment with either heparin or 4-methyl-1-(N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl (MCI-9038). In group I, cyclic flow variations were abolished by heparin in 12 of 18 dogs and by MCI-9038 in 5 of 7 dogs. In group II, cyclic flow variations were not abolished by heparin in any of seven dogs and were abolished by MCI-9038 in only one of seven dogs. Thus, (a) thrombin appears to be an important mediator of cyclic flow variations in dogs with coronary artery stenosis and endothelial injury and (b) inhibition of thrombin abolishes CFVs after short but not prolonged periods of CFVs.

Treadmill exercise promotes cyclic alterations in coronary blood flow in dogs with coronary artery stenoses and endothelial injury.

We have previously shown in anesthetized, open-chest dogs with coronary stenosis and endothelial injury that serotonin and/or thromboxane A2 (TXA2) receptor activation play a major role in the mediation of platelet-dependent, intermittent coronary occlusion. Using a similar model in awake, closed-chest dogs, we tested the following hypotheses: (a) treadmill exercise promotes the development of cyclic flow variations in dogs with coronary stenoses and endothelial injury; (b) ventricular pacing does not induce cyclic flow variations in the same dogs; and (c) TXA2 and/or serotonin are important mediators of exercise-induced cyclic flow variations in this model. The surgical preparation consisted of the application of a hard, flow-limiting constrictor and a Doppler ultrasonic flow probe around the left coronary artery of 11 dogs. Treadmill exercise resulted in the prompt development of cyclic flow variations in all 11 dogs. Ventricular pacing at rates as high as 170 beats/min induced cyclic flow variations in only one of five dogs. Exercise-induced cyclic flow variations were abolished by TXA2 and/or serotonin receptor antagonists in all but one dog. Thus, (a) treadmill exercise promotes the development of cyclic flow variations in dogs with coronary stenoses and endothelial injury; (b) ventricular pacing does not induce cyclic flow variations in most dogs in the same model; and (c) TXA2 and/or serotonin are important mediators of cyclic flow variations in this model.

Role of thromboxane and serotonin as mediators in the development of spontaneous alterations in coronary blood flow and neointimal proliferation in canine models with chronic coronary artery stenoses and endothelial injury.

Platelet-mediated obstruction of stenotic and endothelium-injured coronary arteries may be important in the abrupt progression from chronic stable to unstable coronary heart disease syndromes in patients. Transcardiac accumulation of thromboxane A2 and serotonin has been demonstrated in patients as chronic stable angina is converted to unstable angina. In this study in anesthetized open chest dogs with coronary artery stenosis and endothelial injury, thromboxane A2 and serotonin were shown to be important mediators of intermittent coronary obstruction caused by platelet aggregation and dynamic vasoconstriction. Furthermore, thromboxane A2 synthesis inhibitors and receptor antagonists and serotonin receptor antagonists, singly and together, provided substantial protection against repetitive platelet aggregation and dislodgment in canine models with coronary artery stenosis and endothelial injury even when systemic catecholamine concentrations were markedly elevated. These same observations apply in chronically instrumented, awake, unsedated dogs with coronary artery stenosis and endothelial injury in which recurrent platelet attachment and dislodgment cause cyclic flow alterations that may be prevented by thromboxane A2 synthesis inhibitors and receptor antagonists and serotonin receptor antagonists. Chronically instrumented dogs with coronary stenosis and endothelial injury in which recurrent platelet attachment and dislodgment occurred also developed neointimal proliferation of varying severity within 10 days to 3 weeks; the morphologic appearance of the neointimal proliferation was identical to that found in patients who develop restenosis after coronary angioplasty.

Thrombomodulin activity and localization.

An overview on the properties, actions and localization of thrombomodulin (TM) in situations of tissue injury and in selected tumors is presented. The localization and activity of TM after injury to vascular endothelium shows that following balloon catheter denudation of the endothelium of the rabbit aorta, the activity and immunohistochemical staining is markedly reduced. The functional and antigenic levels approach the control levels approximately one week after the initial injury. The results suggest that the neointimal smooth muscle cells express TM. This phenotypic plasticity of the neointimal smooth muscle cells may be important in conferring thrombo-resistance to the lumenal lining cells of vessels after injury. Studies are also reviewed on the use of soluble recombinant TM to prevent thrombosis after ligature of vessels in an experimental model. Further characterization on the immunohistochemical distribution of TM in normal tissues and tumors shows that staining with a monoclonal anti TM antibody can be very useful in separating mesotheliomas from pulmonary adenocarcinomas. These studies may lead to insights concerning the role of TM in tissue-injury-repair and tissue differentiation.

Pulmonary artery sleeve resection for abutting left upper lobe lesions.

Because the left upper lobe bronchus overlies the left pulmonary artery (PA), T2-3 lesions, N0-1 disease, or rarely inflammation may involve this vessel, necessitating lobectomy with partial PA resection or pneumonectomy with sacrifice of the lower lobe. In 486 operations performed for left upper lobe lesions between 1966 and 1992 (wedge, 111; segmentectomy, 131; lobectomy, 155; pneumonectomy, 89), isolated PA encroachment was caused by bronchogenic carcinoma (32), invasive aspergillosis (2), or organized pneumonitis (1) and occurred in 9% (32/360) of malignant left upper lobe tumors and 2% (3/126) of benign lesions. Initially (1966 through 1979), PA involvement was the indication for 30% (18/60) of left pneumonectomies. Later (1980 through 1990), tangential resection of the PA was attempted in 11, 5 ending up with pneumonectomy. Overall, 35 of 244 patients undergoing major left upper lobe resection (lobectomy or pneumonectomy) had PA encroachment. Recently, we have performed, selectively in patients with restricted lung function, six left upper lobectomies with sleeve resection of the PA. Paneled saphenous vein interposition was used (3) or 18-mm polytetrafluorethylene tube prostheses (3). All patients survived, 1 later requiring completion pneumonectomy for bronchostenosis after wedge bronchoplasty. Two have since died of metastases or pulmonary insufficiency; the remainder (average follow-up, 17 months) are asymptomatic with lower lobe function in 3 confirmed by differential ventilation-perfusion scans and pulmonary angiography.

Delayed diagnosis of duodenal rupture.

BACKGROUND: Although duodenal rupture is usually diagnosed during the course of surgery for other injuries, a small portion of such injuries occur in isolation. In such cases, the significance of the clinical and diagnostic findings may not be appreciated for an extended period. The primary determinant of mortality in duodenal rupture is the presence of associated injuries, but delay in diagnosis is often a secondary factor. METHODS: A retrospective case review of 8 patients with isolated duodenal rupture that was diagnosed more than 24 hours following the injury. RESULTS: In 5 cases, physicians did not look for the occult injury. In 3, patients did not seek medical attention. Two patients were initially treated with primary duodenal repair and drainage with poor results. All patients were eventually treated with pyloric exclusion that resulted in no deaths and no duodenal fistulas. Three patients developed abscesses after pyloric exclusion. They were drained without difficulty. CONCLUSION: Pyloric exclusion appears to offer a satisfactory option for dealing with the inflammation and contamination that result from prolonged soilage by duodenal contents.

Abnormal gallbladder nuclear ejection fraction predicts success of cholecystectomy in patients with biliary dyskinesia.

The management of patients with symptoms consistent with biliary tract disease who do not have gallstones is difficult. We retrospectively reviewed the charts of 18 patients who underwent cholecystokinin cholescintigraphy at our institution to determine if this procedure was reliable in identifying patients who would benefit from cholecystectomy. All patients underwent biliary screening, and a gallbladder ejection fraction of less than or equal to 35% was considered abnormal. None of the patients had evidence of gallstones by ultrasound. There were 11 patients with abnormal ejection fractions. All 11 patients (100%) had "classic" biliary colic and underwent cholecystectomy. The pathologic diagnosis was chronic cholecystitis in every patient. All patients had complete relief of their symptoms postoperatively with a mean follow-up of 10 months. There were six patients with normal ejection fractions. Only one patient in this group had "classic" biliary colic. This patient had a gallbladder ejection fraction of 38% and endoscopic evidence of gastritis. This patient remains symptomatic despite H2 blockade. The remaining five patients had nonspecific right upper quadrant or epigastric pain. These patients had endoscopic evidence of gastritis, and symptoms were relieved with H2 blockade. The remaining patient had an indeterminate scan due to radioactivity in the duodenum overlying the gallbladder and was excluded from this analysis. Cholecystokinin cholescintigraphy is a useful test in identifying those patients with biliary dyskinesia or acalculous cholecystitis who will benefit from cholecystectomy.

Current status of duplex Doppler ultrasound in the examination of the abdominal vasculature.

Duplex Doppler ultrasound has come to play a central role in the diagnosis of a broad spectrum of vascular diseases such as carotid artery occlusive disease and deep vein thrombosis. The role of duplex Doppler in the evaluation of intra-abdominal vascular disease remains unclear. This article summarizes the current status of duplex scanning in the investigation of the mesenteric arteries, the renal arteries, and the portal venous system. The examination is technically demanding, operator-dependent, time-consuming, and frequently unsatisfactory due to bowel gas, obesity, complex anatomy, or postoperative alterations in the normal anatomic patterns. Its advantages reside primarily in the absence of toxicity and in the generation of physiologic as well as anatomic information. In centers with the proper instrumentation and a skilled technician, duplex examination can be useful in the diagnosis and management of abdominal vascular disease and avoids the inherent dangers of contrast angiography.

Infectious complications resulting from use of hemostatic puncture closure devices.

BACKGROUND: Femoral access site complications have increased as the fields of invasive cardiology, radiology, and endovascular surgery have emerged. In order to address one of these complications, hemorrhage, the hemostatic puncture closure devices were developed. METHODS: Retrospective review of cardiac catheterizations performed at a single institution to investigate infectious groin complications related to use of the Perclose Prostar and Techstar devices. RESULTS: Infectious groin complications were significantly higher in the Perclose group as compared with manual compression. Three patients had clinical and laboratory evidence of arterial infection whereas 2 had soft tissue infections. All 5 required operative intervention ranging from incision and drainage to arterial reconstruction. Hemorrhagic complications were not significantly different between the two groups. CONCLUSIONS: The Perclose devices provide hemostasis after femoral artery catheterization similar to manual compression. However, infectious groin complications appear to be more common with these devices.

Emergency operation in patients with symptomatic abdominal aortic aneurysms.

To assess the need for routine preoperative computerized tomography scanning to discern patients with rupture among those presenting with acutely symptomatic abdominal aortic aneurysms, a retrospective review was performed. During a 5-year period, all patients presenting with symptomatic aneurysm underwent emergency operation without preoperative computerized tomography. The mortality rate was not significantly different among patients with symptomatic, intact aneurysms undergoing emergency operation (3 percent) and those without symptoms having elective operation (5 percent). The mortality rate of patients with ruptured aneurysms was 68 percent. We concluded that the addition of preoperative computerized tomography to the clinical evaluation would not have improved these results. Furthermore, since it is expensive and delays emergency operation in patients with ruptured aneurysms, computerized tomography seems rarely indicated in symptomatic patients with obvious aneurysms.

Surgical complications from hemostatic puncture closure devices.

BACKGROUND: For securing immediate hemostasis following percutaneous arterial catheterization, the Food and Drug Administration has approved three hemostatic puncture closure devices. We reviewed our institutional experience with one device (Angio-Seal). METHODS: A retrospective, single-center, nonrandomized observational study was made of all vascular complications following femoral cardiac catheterization. RESULTS: An immediate mechanical failure of the device was experienced in 34 (8%) patients. Surgical repair was required in 1.6% (7 of 425) of patients following Angio-Seal versus 0.3% (5 of 1662) following routine manual compression (P = 0.004). In 5 patients, the device caused either complete occlusion or stenosis of the femoral artery. The polymer anchor embolized in 1 patient and was retrieved with a balloon catheter at surgery. CONCLUSION: During the first year of utilization of a percutaneous hemostatic closure device following cardiac catheterization, we observed a marked increase in arterial occlusive complications requiring surgical repair. Surgeons must be familiar with the design of these devices to achieve precise repair of surgical complications.

Isolated symptomatic midcervical stenosis of the internal carotid artery.

All carotid arteriograms performed between January 1, 1986 and December 31, 1991 were reviewed for instances of midcervical carotid stenosis. Sixteen cases were identified. A stenosis related to the hypoglossal nerve was specifically identified in three operative reports in the retrospective review. Pathologic examinations of the specimens confirmed the presence of atherosclerotic plaque or fibrous dysplasia. In another case, relief of intermittent neurologic symptoms (TIAs) was obtained by division of the stylohyoid ligament. Prospective observation of five cases confirmed a stenosis immediately distal to a transverse neurofascial band formed by the hypoglossal nerve, which arose with the vagus nerve in three patients, and a large cervical contribution to the ansa hypoglossi in two. Presumably the lesion was caused by the turbulent flow in the internal carotid artery distal to the band. Isolated stenosis of the midcervical internal carotid artery unrelated to bifurcation disease may be the result of turbulence induced by tethering neural or myofascial bands.

The anterior extrapleural approach to the thoracolumbar junction revisited.

General surgeons often provide the exposure for the anterior repair of vertebral body lesions. The standard anterior approach to the thoracolumbar junction (T11-L1) is a transpleural 9th or 10th rib thoracoabdominal incision. From October 1995 through March 1997, 22 patients underwent anterior repair of thoracolumbar junction vertebral lesions through an alternative 11th rib resection while maintaining an extrapleural approach. Exposure was excellent, as judged by the neurosurgical team completing the repairs. Chest tubes were not used routinely, and all patients healed without complications. A major limitation of the 11th rib extrapleural approach to the thoracolumbar junction has been poor exposure. This problem is eliminated with the use of an abdominal self-retaining retractor system. With many potential advantages to this 11th rib exposure (less pain, fewer pulmonary problems, and better wound healing), we consider the 11th rib incision to be the approach of choice to the thoracolumbar junction and recommend renewed interest in this incision.

"General surgical pearls" for the anterior exposure of vertebral fractures.

Recently interest has been increasing in the anterior surgical approach for spinal cord decompression and bony stabilization of vertebral compression fractures. Our neurosurgical spine service routinely consults us to provide anterior operative exposure and wound closure for all levels of the thoracic and lumbar vertebral spine. Averaging about 30 exposures per year we have developed an excellent operative experience with these vertebral exposures. With no complete general surgery reference on anterior vertebral identified this summary of our "general surgical pearls" that we have learned and/or have developed should significantly aid other general and trauma surgeons who may be asked by their neurosurgical and/or orthopedic surgical colleagues for assistance with these operations.

Candida arteritis: are GI endoscopic procedures a source of vascular infections?

A 53-year-old woman, 11 years after a renal transplant on chronic immunosuppression, presented with a sudden onset of a painless left groin mass. Ultrasound revealed a 3 cm common femoral artery pseudoaneurysm and a 3 cm saccular aneurysm of the infrarenal aorta. Operative repair was excision and patch angioplasty of the aortic aneurysm with internal iliac artery and interposition grafting of the femoral artery aneurysm with saphenous vein. Postoperatively, Candida albicans was identified in the aortic and common femoral arterial cultures. Candida infections often occur in patients with impaired cellular immunity due to seeding from urinary tract infections, vascular catheters, or manipulation of the gastrointestinal tract. Our patient, without any prior history of a fungal infection, had undergone a colonoscopy 3 weeks earlier. Without any other possible source being identified, the proposed mechanism for fungal entry into the vascular system was via the gastrointestinal tract, with seeding from the portal venous system. The exact medical and surgical management of these patients remains undefined, and a transplant vascular registry is really needed. However, immunocompromised solid organ transplant recipients undergoing gastrointestinal endoscopic procedures may be at a greater risk for the development of subsequent septicemia. Further reports are really needed to confirm the possible need in these patients for both periprocedural antibiotic and antifungal prophylactic coverage.

Interventions in pulmonary embolism.

Various interventions are available to assist in the management of patients with pulmonary embolism. Most are reserved for patients who either fail standard systemic anticoagulation therapy or are not candidates for anticoagulant therapy. The most common intervention is placement of a vena caval filter. Several different filter devices are available, most of which may be placed percutaneously. Pulmonary thrombolysis with urokinase or streptokinase may be appropriate in some patients with severe, symptomatic pulmonary embolism. Finally, pulmonary embolectomy by means of either a transvenous catheter or surgical technique may be necessary in cases of refractory cardiovascular collapse.