David H. Porter

Magnetic resonance imaging: A reliable test for the evaluation of proximal atherosclerotic renal arterial stenosis

Abstract Symptomatic renal artery stenosis is a significant and treatable clinical problem. A reliable and accurate noninvasive method of screening for renal artery stenosis has not yet been found. We used magnetic resonance imaging to study 37 patients who had undergone recent renal angiography. Fourteen patients had normal renal arteries by angiography. In 23 patients either unilateral or bilateral stenosis or occlusion was present. The disease process in all patients appeared to be atherosclerosis. The average age of the 37 patients was 68 years. The magnetic resonance scans and angiograms were read independently by two different radiologists, each of whom was blinded to the clinical history and the results of the other study. Renal arterial stenoses found on angiogram and magnetic resonance scans were graded as absent (0% to 24%), mild (25% to 49%), moderate (50% to 74%), or severe (75% to 99%). The magnetic resonance imaging results concurred with the angiographic findings in 70 of 77 arteries (91%). Magnetic resonance imaging predicted the presence of a greater than 50% stenosis of the renal artery with a sensitivity of 100% and a specificity of 94%. Magnetic resonance imaging may prove to be the best noninvasive screening test for proximal atherosclerotic renal arterial stenosis. (J VASC SURG 1991;13:311-8.)

Simultaneous occurrence of superficial and deep thrombophlebitis in the lower extremity

Forty-two consecutive patients diagnosed with superficial phlebitis were seen during a 5-year period. Thirty-five of the 42 patients were outpatients. The diagnosis of superficial phlebitis was made by the presence of palpable subcutaneous cords in the course of the greater saphenous vein or its tributaries in association with tenderness, erythema, and edema. The presence of concurrent deep venous thrombosis (DVT) was assessed by impedance plethysmography in 37 patients, compression venous ultrasonography in 3 patients, and venography in 8 patients. Five of the 42 patients (12%) had DVT. Four of these five patients had a positive impedance plethysmographic or ultrasonographic test result followed by a confirmatory venogram. The fifth patient had a positive ultrasonographic test result, but no venogram was performed. Two of the five patients had clots that involved the popliteal or femoral veins. Four of 23 patients (17%) with superficial phlebitis at or above the knee had DVT. Only 1 of the 19 patients (5%) with superficial phlebitis below the knee had DVT. Three of the five patients with both superficial phlebitis and DVT had undergone surgery recently. All but 3 of the 42 patients (93%) had varicose veins. No patients had clinically apparent pulmonary emboli. DVT occurred in 17% of the patients with above-knee extension of the superficial phlebitis. In the clinical management of superficial lower-limb thrombophlebitis, noninvasive tests should be performed to guide therapy. When superficial phlebitis develops after recent surgery or the superficial phlebitis extends above the knee, diagnostic surveillance should be especially strict. When the noninvasive test results are equivocal, phlebography is indicated to rule out DVT.

The Simon Nitinol Filter: Evaluation by MR and Ultrasound

In this prospective blinded study of inferior vena caval (IVC) patency, 18 patients underwent 25 duplex ultrasound (US) and magnetic resonance (MR) angiography examinations over an eight-month period following Simon nitinol filter placement. Clinical examination for lower extremity venous stasis and plain abdominal radiography were also performed. Twenty-three of 24 MR ex aminations and 11 of 24 US examinations were judged technically adequate by the blinded observers. One technically adequate US exam was false positive for intraluminal caval thrombus. Thirteen technically inadequate US examinations missed 3 complete caval occlusions and 2 partial occlusions. MR identified all patients with complete or partial caval occlusion. The authors conclude that duplex US reliably confirms IVC patency only when strict criteria for technical adequacy and interpretation are met (good visualization of filter and IVC above and below filter). MR, although expensive, more reliably identifies nonoccluding intraluminal thrombus and caval occlu sion. It should be the noninvasive study of choice in symptomatic patients with venous stasis and patients with recurrent pulmonary emboli.

Reassessment of Vena Caval Filter Use in Patients with Cancer

PURPOSE Noting a doubling in mortality soon after placement of filters in the inferior vena cava (IVC) from 1985 (7.8%) to 1992 (15.2%), the authors performed a study to define risk factors associated with death soon after IVC filter placement and to develop revised guidelines for filter placement. PATIENTS AND METHODS During a 4-year period, 141 IVC filters were placed in 137 patients. Patients were divided into two clinical risk groups: those with possible malignancy and those with possible suprainguinal venous thrombus. Survival was monitored for up to 3 weeks after hospital discharge. RESULTS Death occurred in 16 (26%) of 61 patients with malignancy (P = .0086, compared with patients without malignancy), seven (35%) of 20 patients with suprainguinal venous thrombus (P = .0422, compared with patients without suprainguinal venous thrombus), and six (46.2%) of 13 patients with malignancy and suprainguinal venous thrombus (P = .0091, compared with patients without malignancy or suprainguinal venous thrombus). CONCLUSION The data indicate that for some patients with malignancy or suprainguinal venous thrombus, insertion of an IVC filter gives little or no survival benefit. A reassessment of IVC filter use in these patients is warranted.

Isolated external iliac artery aneurysm secondary to cystic medial necrosis.

The computed tomographic and angiographic findings of an isolated external iliac artery aneurysm secondary to cystic medial necrosis in a patient without Marfans disease are demonstrated. A review of the differential diagnosis and surgical treatment of iliac artery aneurysms is presented. The dramatic surgical sequelae in this patient underscore the importance of preoperative consideration of this rare diagnosis.

False-positive aortography following blunt chest trauma: Case report

We describe a patient in whom thoracic aortography performed following blunt chest trauma revealed what appeared to be a traumatic tear of the proximal descending aorta. As the patient initially refused surgery, aortography was repeated 18 days later, confirming these findings. At thoracic aortotomy the aorta appeared normal; there was no hematoma or tear. We believe this to be the first reported case of false-positive aortography following blunt chest trauma (see Note added in proof).

Use of a reperfusion catheter after angioplasty dissection for salvage of ischemic renal allograft : case report

Percutaneous transluminal angioplasty was performed on a right common iliac artery stenosis presumed to be causing renovascular hypertension in a patient with a renal allograft anastomosis to the right external iliac artery. This was complicated by an obstructive dissection resulting in acute threatening renal allograft ischemia. Renal blood flow was restored by means of a transluminal reperfusion catheter until corrective surgery could be performed. This case is reported because such catheters can be acutely helpful to the interventionalist, and they have not been described in the radiology literature.

Valvectomy with Use of a Percutaneous Directional Atherectomy Catheter in Failing In Situ Saphenous Vein Grafts

O SCVIR, 1997 IN situ saphenous vein grafts are commonly employed for arterial bypass grafting for lower extremity ischemia, with reported initial patency rates of up to 96% (1). The relatively higher patency rate of in situ saphenous vein grafts is believed to be secondary to decreased vein graft trauma, preservation of the vasa vasorum, and hemodynamic factors (2). Complications occurring in in situ grafts include thrombosis, stenosis, creation of an arteriovenous fistula, and retained valves (3). Even when surgery is performed by an experienced surgeon, residual intact valve leaflets are occasionally missed a t surgery (3-6). Residual intact valve leaflets are believed to cause turbulent flow with secondary endothelial damage and stenosis, which may ultimately result in graft thrombosis and failure (5). Valvectomy has been traditionally accomplished with use of surgical techniques. However, surgical removal of retained valve leaflets may cause further subendothelial damage. A minimally invasive percutaneous valvectomy has been described by Becker et al, which uses a cardiac biopsy forceps to avulse the retained valve leaflet from the vessel wall (7). We describe three cases in which valvectomy was successfully performed with use of a percutaneous directional atherectomy catheter (DAC), a technique that has the potential to result in less venous endothelial trauma than either the surgical or previously described percutaneous approaches.