[Functional control of vena cava filters using duplex sonography].
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Biomedical subjects
Publications and source records attributed to P Stulz.
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In the period from January 1976 to December 1986, 31 (56.3%) out of 55 patients with pleural empyema were treated, after failure of conservative treatment with antibiotic drugs, pleural puncture and tube drainage. Twenty-two patients were submitted to a posterolateral thoracotomy with debridement in the early stage or decortication in the later stage of empyema thoracis. There was no relapse of empyema in this group, but 7 patients suffered from air leakage for 7 to 19 days (mean 12 days). One patient needed rethoracotomy after debridement for continuous bleeding. Nine patients were treated in a first step with limited thoracotomy in local anaesthesia with or without costotomy. There were 5 relapses of empyema in this group. The average time of hospitalization was for the debrided cases 13.6 days and for the decortication group 19.6 days. The conservatively treated group remained during 39.5 days in the hospital.
Endothelial cells release a potent vasodilator which activates guanylate cyclase and thereby induces relaxation of vascular smooth muscle cells. The so-called endothelium-derived relaxing factor (EDRF) is released by acetylcholine, local and circulating hormones, and substances released from aggregating platelets or formed during activation of the coagulation cascade. Nitric oxide (NO) probably accounts for the factor's activity. Thus, endothelial cells produce endogenous nitrates causing vasodilatation and inhibition of platelet adhesion and aggregation. Under physiological conditions, EDRF may play a role in the prevention of vasospasm and thrombosis. On the other hand, the impairment of endothelial regulatory mechanisms in atherosclerosis and hypertension may be involved in the pathogenesis of vascular occlusion and thereby of myocardial infarction, stroke and peripheral vascular disease.
Both the internal mammary artery and the saphenous vein are used to construct coronary-artery bypass grafts. We hypothesized that the release or production of endothelium-derived relaxing factor, which regulates blood flow and inhibits platelet function, may differ in venous and arterial grafts. We therefore studied endothelium-dependent relaxation in internal mammary arteries, internal mammary veins, and saphenous veins obtained from 58 patients undergoing coronary bypass surgery. Vascular rings with and without endothelium were suspended in organ chambers, and isometric tension was recorded. Acetylcholine (10(-8) to 10(-4) M), thrombin (1 U per milliliter), and adenosine diphosphate (10(-7) to 10(-4) M) evoked potent endothelium-dependent relaxation in the mammary artery but weak response in the saphenous vein (P less than 0.005; n = 6 to 27). In the mammary artery, relaxation was greatest in response to acetylcholine (86 +/- 4 percent reduction in norepinephrine-induced tension), followed by thrombin (44 +/- 7 percent) and adenosine diphosphate (39 +/- 8 percent). In the saphenous and mammary veins, relaxation was less than 25 percent. Relaxation was unaffected by indomethacin but was inhibited by methylene blue and hemoglobin (P less than 0.005 and 0.01, respectively), which suggests that endothelium-derived relaxing factor was the mediator. Endothelium-independent relaxation in response to sodium nitroprusside was similar in arteries and veins. We conclude that endothelium-dependent relaxation is greater in the mammary artery than in the saphenous vein. The possibility that this contributes to the higher patency rate among arterial grafts than among venous grafts will require further study.
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The effects of antiplatelet therapy (AP; dipyridamole 400 mg [beginning 2 days preoperatively] + aspirin 50 mg/day) and anticoagulation (AC) were compared prospectively in 251 patients with coronary artery bypass grafting (CABG). Two weeks postoperatively, 85.2% of AP and 81% of AC patients had all grafts patent with graft patency rates of 93.6% and 91.3% respectively (p = n.s.) Significant differences in favour of AP therapy were found in subgroups with multiple grafts and with low intraoperative graft flow. Up to 3 months postoperatively, severe complications occurred in 22 AC patients (11 bleedings) but only in 9 patients on AP therapy (p less than 0.01). Overall, AP therapy should therefore be preferred to AC in patients with CABG surgery.
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Doppler ultrasound without concomitant echocardiographic imaging was used to grade isolated aortic regurgitation in 21 patients. The severity of aortic regurgitation was subsequently graded (from 0 to IV) angiographically. A 2 MHz continuous wave Doppler transducer was placed over the apex of the heart and the beam was aimed parallel to the mitral flow by means of acoustic guidance. Mitral pressure half time was calculated from the analogue maximum velocity tracing and it was less than or equal to 60 ms in 10 controls; 50-120 ms in five patients with grade II, 120-160 ms in nine patients with grade III, and greater than or equal to 160 ms in seven patients with grade IV aortic regurgitation. These results indicate that a semi-quantitative grading of aortic regurgitation may be obtained non-invasively with non-imaging Doppler ultrasonography in patients without concomitant mitral valve disease.
A report is made on a woman patient with a Björk-Shiley prosthesis in the mitral position, whose pregnancy was complicated by bacteraemia and a thrombotic obstruction of the artificial heart valve. With reference to research, the authors discuss the question of anticoagulation in pregnant women with artificial heart valves as well as the question of the choice of prosthesis in women wishing to have children.
During aorto-coronary bypass surgery, electromagnetic flow measurements of venous grafts were performed in 50 consecutive patients at rest and after stimulation with papaverine (2 mg) to assess whether early postoperative patency was predictable. The overall patency rate at day 9-11 was 95.4% (145/152 distal grafts; 118 proximal grafts). Flow in all bypass grafts averaged 52.5 +/- 31.4 ml/min and increased after papaverine stimulation by 46.9 +/- 32.2 ml/min (p less than 0.01). 5 of 6 grafts with a flow of less than 30 ml/min and without adequate flow increase after papaverine (less than 80%) were occluded. Grafts with a flow of greater than or equal to 30 ml/min or an increase of greater than or equal to 80% after papaverine, had a high short-time patency rate (98%). Thus, perioperative flow measurements combined with papaverine stimulation predicted early patency of single grafts with an accuracy of 95%.
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The authors summarize their experience of the management of 26 patients with prosthetic valve endocarditis. Out of 11 patients who did not undergo surgery, 8 were treated medically, with 9 early deaths (mortality 75%). 15 patients were treated surgically with 3 deaths caused by resistant infection (mortality 20%). Prosthetic valve endocarditis remains a dangerous complication of valve replacement, and the authors recommend immediate valve replacement in all patients with infected mechanical valves.
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