Secondary recurrent carotid stenosis.

PURPOSE: Recurrent carotid stenosis after carotid endarterectomy has been extensively reported. The occurrence, however, of another ipsilateral restenosis that requires a third carotid operation is rare. The purpose of this study was to evaluate possible risk factors and the most efficacious management of the patient with "secondary" recurrent carotid stenosis. METHODS: A survey of the Southern Association for Vascular Surgery was performed, and 31 patients who had had surgery for secondary recurrent carotid stenosis were identified. RESULTS: The mean interval between the recurrent stenosis operation and secondary recurrent carotid stenosis was 39.8 months (range, 9 to 83 months). At the third operation, 21 patients underwent carotid patch angioplasty and 10 underwent carotid resection with an interposition saphenous vein graft. No postoperative strokes or deaths occurred; three patients (10%) had a peripheral nerve injury. Nine early (< 24 mo) secondary recurrent carotid stenoses occurred, and these patients underwent patch angioplasty. Twenty-three female, cigarette-smoking patients and 20 patients with elevated lipid levels had early restenosis and were identified as being at high risk for the development of another stenosis. A fourth significant stenosis developed in five of these high-risk patients who had saphenous vein patch angioplasty at their third carotid operation; eight other high-risk patients had carotid resection with an interposition saphenous vein graft, and no other stenosis developed. CONCLUSION: Patients who have secondary recurrent carotid stenoses can safely undergo a third carotid operation. Female habitual smokers with elevated lipid levels and an early restenosis appear to be at high risk of secondary recurrent carotid stenoses. When surgery is necessary, carotid resection with an interposition saphenous vein graft appears more durable than patch angioplasty.

The natural history of asymptomatic carotid disease in patients undergoing cardiovascular surgery.

Prospective screening of 449 patients undergoing coronary or peripheral arterial revascularization detected asymptomatic cervical bruits in 44 patients (9.8%) and carotid obstruction by Doppler ultrasound in 63 individuals (14.0%). There was poor correlation between cervical bruit and carotid obstsruction. No patient underwent prophylactic casrotid endarterectomy. Three patients had transient ischemic attacks (TIAs), and five had nonfatal strokes perioperatively, only one of which was in the territory appropriate to carotid obstruction. Of 72 surviving patients with asymptomatic carotid disease, 10 (13.9%) had TIAs and one (1.4%) died of stroke during a 2-year follow-up, during which time only two (0.8%) of 254 patients without carotid disease reported symptoms of TIAs. Patients with asymptomatic carotid disease had a significantly higher incidence of perioperative and late deaths (10.6% and 9.2%, respectively), usually of myocardial infarction, as compared to patients without carotid disease (0.3% and 0.8%, respectively, P less than 0.001). Asymp-tomatic carotid disease, although correlating poorly with perioperative stroke in patients undergoing cardiovascular operations, identifies patients at risk of late neurologic events and peroperative or late deaths from myocardial infarction. We do not recommend prophylactic carotid endarterectomy but favor operative intervention if patients develop TIAs during a period of careful follow-up .

Intraoperative arteriography in femoropopliteal and femorotibial bypass grafts.

We reviewed our experience with intraoperative arteriography following femoropopliteal and femorotibial reconstruction during a five-year period beginning in January 1975. During 171 of 250 procedures an intraoperative arteriogram was performed. In nine (5.2%) instances, a correctable abnormality was detected. These consisted of three cases of distal anastomotic stenoses, two cases of intimal flaps, three cases of poor inflow, and one case of clot. Intraoperative arteriography may reveal a correctable abnormality in 5% of femoropopliteal and femorotibial bypass grafts and thus prevent early graft failure. The false-positive rate was 0.06%. In our experience, routine intraoperative arteriography has been a safe, easy to perform, and effective method of assessing technical problems in femoropopliteal and femorotibial reconstruction.

Humorally mediated alterations in cardiac performance as a consequence of positive end-expiratory pressure.

Two experimental designs were used to study the mechanism of the decreased cardiac output associated with the use of positive end-expiratory pressure (PEEP). In the first study of nine dogs the application of 15 cm H2O PEEP led to a decrease in cardiac output (CO) from 2.68 +/- 1.05 to 2.01 +/- 1.26 liters/min (+/- SD) (p less than 0.05) concomitant with an increase in transmural central venous pressure of 5.2 +/- 0.9 to 8.4 +/- 2.7 mm Hg (p less than 0.05) and a slight increase in transmural left atrial pressure of 6.8 +/- 3.3 to 7.3 +/- 3.6 mm Hg (p less than 0.1). These data are consistent with altered ventricular performance. In a second study nine pairs of dogs were cross-circulated. Application of 15 cm H2O PEEP to one member of the experimental pair led to a decrease in the CO of the other member from 2.71 +/- 0.98 to 2.21 +/- 0.81 liters/min (p less than 0.001). This decrease returned toward baseline with the removal of PEEP (p less than 0.02). Results indicate that one mechanism whereby PEEP reduces the cardiac output is through the action of a humoral agent.

Limitations of portable roentgenography of the chest in patients with acute respiratory failure.

The ability of the portable roentgenography of the chest to define the amount of physiologic shunting and the severity of noncardiogenic pulmonary edema was evaluated in 37 observations of 11 patients. Ten of the 11 patients had acute respiratory failure. The roentgenologic assessment of the amount of pulmonary edema and the severity of left ventricular failure was compared with the physiologic shunt fraction, tracer measured lung water and the pulmonary arterial wedge pressure. The roentgenologic scores for edema did not predict the shunt fraction or tracer measured lung water. The roentgenologic score for congestive heart failure correlated with the wedge pressure but not well enough to be clinically useful. Five per cent of the roentgenograms were false-positive and 11 per cent were false-negative. Roentgenologic findings lagged behind physiologic derangements. Thus, the roentgenogram could predict the shunt value of the preceding day. Results indicate that it is hazardous to accept a portable roentgenographic diagnosis of congestive heart failure as a cause of pulmonary edema.

Diagnostic value of the portable chest x-ray technic in pulmonary edema.

The ability of the portable chest x-ray film to define the amount of physiologic shunting and the severity of noncardiogenic pulmonary edema was evaluated in thirty-seven observations of eleven patients. Ten of the eleven patients were suffering from acute respiratory failure. The radiologic assessment of the amount of pulmonary edema and the severity of left ventricular failure were compared with the physiologic shunt fraction, tracer-measured lung water, and pulmonary arterial wedge pressure. The radiologic scores for edema did not predict the shunt fraction or tracer measurements of lung water. The radiologic score for congestive failure correlated with the wedge pressure but not well enough to be clinically useful. Five per cent of the x-ray results were false-positive and 11 per cent false-negative. Results indicate that the portable chest x-ray technic does not provide quantitative information regarding cardiopulmonary function. It is especially hazardous to accept an x-ray diagnosis of congestive failure as the cause of pulmonary edema.

Hepatic--portal venous gas in adults: etiology, pathophysiology and clinical significance.

The roentgenographic finding hepatic--portal venous gas (HPVG) has been reported extensively in the pediatric and radiology literature. The surgical implications and clinical significance have yet to be fully defined. This study reviews the 60 reported cases in the literature and adds four new cases. HPVG appears as a branching radiolucency extending to within 2 cm of the liver capsule. HPVG is associated with necrotic bowel (72%), ulcerative colitis (8%), intra abdominal abscess (6%), small bowel obstruction (3%), and gastric ulcer (3%). Mucosal damage, bowel distention and sepsis predispose to HPVG. The current mortality rate of 75% represents an improvement from previous experience. Analysis of survivors indicates that the finding of HPVG requires urgent surgical exploration except when it is observed in patients with stable ulcerative colitis.

The association of lung distention, PEEP and biventricular failure.

Although positive and expiratory pressure (PEEP) is known to depress the cardiac output, the mechanism remains debated. Two series of experiments were designed to explore this mechanism. In the first study, the application of 15 cm H(2)O of PEEP to nine anesthetized, ventilated dogs led to a reduction of cardiac index from (mean +/- one standard error of the mean) 2.71 L/min .m (2) +/- 0.35 to 2.19 L/min m(2) +/- 0.22 (p < .05) and a drop in mean arterial pressure (MAP) from 117 mm Hg +/- 8 to 91 mm Hg +/- 11 (p < .01). The mean net (vascular minus pleural pressure) pulmonary artery pressure (MPAP) rose from 15.3 mm Hg +/- 1.2 to 20.6 mm Hg +/- 1.8 (p < .02). The mean net central venous pressure (CVP) rose from 5.2 mm Hg +/- 0.9 to 8.4 mm Hg +/- 0.9 (p < .05) and the net pulmonary arterial wedge pressure (PAWP) rose from 6.7 mm Hg +/- 0.7 to 9.5 mm Hg +/- 0.9 (p < .01). There was a nonsignificant rise in the mean net left atrial pressure (LAP). As PEEP was raised in increments from 0 to 20 cm H(2)O, both LAP and PAWP increased. The rise in PAWP was always greater than the increase in LAP. The difference between PAWP and LAP was strongly correlated with the increase in MPAP (r = 0.98). This relationship was useful in correcting the PAWP during PEEP. The problem of cardiac depression was evaluated in a second series of eight dogs. These animals underwent complete chest wall excision to eliminate any possible direct effects of increased pleural pressure on the heart and great vessels. The absence of the chest wall permitted hyperexpansion of the lungs, particularly with positive end expiratory pressure. At 15 cm H(2)O of PEEP, the mean cardiac index fell in these animals from 2.36 L/min. m(2) +/- 0.26 to 1.47 L/min.m(2) +/- 0.18 (p < .01) and the MAP fell from 105 mm Hg +/- 16.2 to 68 mm Hg +/- 4.8 (p < .001). The CVP rose from a mean of 5.5 mm Hg +/- 0.4 to 8.3 mm Hg +/- 0.6 (p < .01) and the LAP rose from 6.3 mm Hg +/- 0.8 to 8.0 mm Hg +/- 1.1 (p < .05). The MPAP rose from 18.0 mm Hg +/- 0.6 to 23.3 mm Hg +/- 1.6 (p < .01). Comparison of Group I and II showed a significantly greater depression of the cardiac output and MAP in the open-chested animals. At the same time LAP was significantly higher. These data strongly suggest that PEEP and particularly pulmonary hyperinflation induce biventricular failure.

A method for direct coronary sinus flow measurement and blood sampling in the dog.

Various methods for sampling and measurement of coronary sinus flow in animals have been reported. All have disadvantages because of the need for fluoroscopy or for special tubing or equipment. A technique using readily available materials is described that provides direct measurement of coronary sinus blood flow and allows coronary sampling.