Christos A. Athanasoulis

Complications and validity of pulmonary angiography in acute pulmonary embolism.

BackgroundThe Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) addressed the value of ventilation/perfusion scans in acute pulmonary embolism (PE). The present study evaluates the risks and diagnostic validity of pulmonary angiography in 1,111 patients who underwent angiography in PIOPED. Methods and ResultsComplications were death in five (0.5%), major nonfatal complications in nine (1%), and less significant or minor in 60 (5%). More fatal or major nonfatal complications occurred in patients from the medical intensive care unit than elsewhere: five of 122 (4%) versus nine of 989 (1%) (p<0.02). Pulmonary artery pressure, volume of contrast material, and presence of PE did not significantly affect the frequency of complications. Renal dysfunction, either major (requiring dialysis) or less severe, occurred in 13 of 1,111 (1%). Patients who developed renal dysfunction after angiography were older than those who did not have renal dysfunction: 74±13 years versus 57±17 years (p<0.001). Angiograms were nondiagnostic in 35 of 1,111 (3%), and studies were incomplete in 12 of 1,111 (1%), usually because of a complication. Surveillance after negative angiograms showed PE in four of 675 (0.6%). Angiograms, interpreted on the basis of consensus readings, resulted in an unchallenged diagnosis in 96%. ConclusionsThe risks of pulmonary angiography were sufficiently low to justify it as a diagnostic tool in the appropriate clinical setting. Clinical judgment is probably the most important consideration in the assessment of risk.

PERCUTANEOUS RADIOFREQUENCY TISSUE ABLATION : DOES PERFUSION-MEDIATED TISSUE COOLING LIMIT COAGULATION NECROSIS ?

PURPOSE To determine, by decreasing hepatic perfusion during radiofrequency (RF) ablation, whether perfusion-mediated tissue cooling can explain the reduced coagulation observed in in vivo studies compared to that seen with RF application in ex vivo tissue. MATERIALS AND METHODS RF was applied in vivo with use of cooled-tip electrodes to normal porcine liver without (n = 8) and with balloon occlusion of the portal vein (n = 8), celiac artery (n = 3), or hepatic artery (n = 2), and to ex vivo calf liver (n = 10). In vivo trials of vasopressin (0.3-0.6 U/min) infusion during RF application with (n = 10) and without (n = 2) arterial balloon occlusion were also performed. Intraoperative RF was subsequently performed in seven patients with hepatic colorectal metastases with and without portal inflow occlusion. Remote thermometry was performed in four patients. RESULTS RF application (12 minutes) during portal venous occlusion produced larger areas of coagulation necrosis than RF with unaltered blood flow (2.9 cm +/- 0.1 vs 2.4 cm +/- 0.2 diameter; P < .01). With celiac and hepatic artery occlusion, coagulation diameter measured 2.7 cm +/- 0.2 and 2.5 cm +/- 0.1, respectively. Infusion of vasopressin without vascular occlusion reduced coagulation diameter to 1.1 cm. However, different methods of hepatic or celiac arterial balloon occlusion with simultaneous vasopressin infusion produced a mean 3.4 cm +/- 0.2 of necrosis. Coagulation in ex vivo liver was 2.9 cm +/- 0.1 in diameter. Clinical studies demonstrated greater coagulation diameter for metastases treated during portal inflow occlusion (4.0 cm +/- 1.3) than for tumors treated with normal blood flow (2.5 cm +/- 0.8; P < .05). Thermometry documented a 10 degrees C increase compared to baseline at 10 mm and 20 mm from the electrode after 5 minutes of portal inflow occlusion during constant RF application. CONCLUSIONS Perfusion-mediated tissue cooling reduces coagulation necrosis achievable with RF ablation. Reduction of blood flow during RF application increases coagulation in both an animal model and human liver metastases.

Aspirin prophylaxis of venous thromboembolism after total hip replacement.

Abstract We assessed aspirin prophylaxis against venous thromboembolism in a prospective, controlled, double-blind study of patients over 40 years of age, who had undergone total hip replacement. Radiographic phlebography was the diagnostic end point. Thromboembolism developed in 11 of 44 patients receiving aspirin, as compared to 23 of 51 receiving the placebo (P<0.03). Unexpectedly, this protection was limited to men. In four of 23 men on aspirin thrombi developed, as compared to 14 of 25 receiving placebo (P<0.01). Corresponding figures for women were seven of 21 versus nine of 26. Review of a similar group of patients receiving aspirin revealed significantly greater protection (P<0.03) in men (three of 15) than in women (15 of 27). These data establish statistically significant prophylaxis in men over the age of 40 by 600 mg of aspirin given twice daily. The absence of a protective effect in women remains unexplained. (N Engl J Med 297:1246–1249, 1977)

Comparison of Warfarin, Low-Molecular-Weight Dextran, Aspirin, and Subcutaneous Heparin in Prevention of Venous Thromboembolism following Total Hip Replacement

In a prospective study of 187 patients without known prior phlebitis who underwent total hip replacement, we compared the efficacy of warfarin, low-molecular-weight dextran, aspirin, and subcutaneous heparin for prevention of postoperative venous thrombi. Detection of thrombi was by phlebography. Warfarin dextran, and aspirin were superior to heparin. There was no significant difference between the effects of warfarin, dextran, and aspirin on the number of patients with fresh thrombi. In reducing the number of thrombi formed, warfarin and dextran were superior to aspirin. For reduction of the prevalence of thrombi in the thigh, the three drugs were equally effective. Significantly fewer bleeding complications occurred with aspirin than with warfarin. Even in patients who received warfarin, dextran, or aspirin, the prevalence of fresh thrombi was high. Thrombi often formed in the thigh without an associated calf thrombus. Fifty-one of fifty-six episodes of thromboembolic disease were clinically silent at the time of detection. The prophylactic use of warfarin or aspirin, followed by warfarin treatment if a thrombus was detected on phlebograms, provided effective protection against pulmonary embolism.

Arteriographic Management of Hemorrhage Following Pelvic Fracture

Nine patients with massive pelvic hemorrhage were evaluated angiographically. In each case the site of bleeding was identified by pelvic aortography and hemostasis was produced by intra-arterial techniques. Embolization with autologous clotted blood was employed in 8 cases and in one patient bleeding was controlled by proximally occluding the hypogastric artery with an inflated Fogarty catheter balloon.

Mesenteric arterial infusions of vasopressin for hemorrhage from colonic diverticulosis

Twenty-four patients with massive rectal hemorrhage and known or subsequently proved colonic diverticular disease had the bleeding site localized by mesenteric angiography and received intra-arterial infusion of vasopressin to arrest the bleeding. In twenty-two patients the bleeding was controlled with the vasopressin infusion whereas in the remaining two, hemorrhage did not stop and surgery was performed. Of the twenty-two patients in whom bleeding was arrested by vasopressin infusion, twelve received no further surgical therapy, five had elective prophylactic surgical resection after a period of hemostasis, and the remaining five underwent segmental resection for bleeding that recurred after cessation of the infusion. Of the twelve patients who were not operated on, three had rebleeding two, four, and twelve months after vasopressin infusion and two of these three patients required surgery. The remaining nine have had no recurrent bleeding for periods ranging from seven to thirty-four months. Of ten patients who had segmental resection after precise localization of the bleeding site and initial control with vasopressin, no one has had recurrent hemorrhage for periods ranging from two to eighteen months.

Comparison of 125I Fibrinogen Count Scanning with Phlebography for Detection of Venous Thrombi after Elective Hip Surgery

A comparison was made of 125I fibrinogen count scanning and phlebography in 142 limbs of 83 patients without known prior deep venous thrombosis who underwent total hip replacement. A localized accumulation of fibrinogen located away from the hip wound represented a fresh thrombus in 25 of 29 cases (86 per cent). However, of all the fresh thrombi demonstrated by phlebography, the fibrinogen scan detected only approximately 50 per cent. Major reasons for failure to detect thrombi were the presence of the wound and the small size of some thrombi. In defining whether or not fresh venous thrombosis was present in a given patient, the scan was accurate in three quarters of the cases. We conclude that fibrinogen scanning is a useful examination in patients after elective hip surgery, but less accurate than previously reported.

Angiodysplasia clinical presentation and colonoscopic diagnosis

: Angiodysplasia is a recently recognized important cause of lower intestinal bleeding in older patients. Although angiography is an established procedure for the diagnosis of angiodysplasia, colonoscopy is being used increasingly for evaluation of lower intestinal bleeding. In order to define the nature of bleeding due to angiodysplasia and the appropriate role of colonoscopy, 80 patients diagnosed by angiography, pathology, or colonoscopy were reviewed. Bleeding attributable to angiodysplasia varied from acute life-threatening hemorrhage to occult blood in stools. Thirteen patients with angiodysplasia had no bleeding and were identified incidentally by colonoscopy performed for other indications. Eighty-nine percent of the lesions were located in the right colon and there was a mean of 1.5 angiodysplastic lesions per patient. The sensitivity of colonoscopy compared to angiography and pathology was 68% overall and 81% when the colon was completely examined and lesions were located in the colon. The predictive value of a positive colonoscopic diagnosis was 90% in this population. Colonoscopy should be employed as an initial study in patients with chronic or mild acute rectal bleeding.Angiodysplasia is a recently recognized important cause of lower intestinal bleeding in older patients. Although angiography is an established procedure for the diagnosis of angiodysplasia, colonoscopy is being used increasingly for evaluation of lower intestinal bleeding. In order to define the nature of bleeding due to angiodysplasia and the appropriate role of colonoscopy, 80 patients diagnosed by angiography, pathology, or colonoscopy were reviewed. Bleeding attributable to angiodysplasia varied from acute life-threatening hemorrhage to occult blood in stools. Thirteen patients with angiodysplasia had no bleeding and were identified incidentally by colonoscopy performed for other indications. Eighty-nine percent of the lesions were located in the right colon and there was a mean of 1.5 angiodysplastic lesions per patient. The sensitivity of colonoscopy compared to angiography and pathology was 68% overall and 81% when the colon was completely examined and lesions were located in the colon. The predictive value of a positive colonoscopic diagnosis was 90% in this population. Colonoscopy should be employed as an initial study in patients with chronic or mild acute rectal bleeding.

Long-term results of combined iliac balloon angioplasty and distal surgical revascularization.

Long-term results of combined use of iliac artery percutaneous transluminal angioplasty (PTA) and distal surgical revascularization for the management of multilevel occlusive disease were evaluated over a 12-year period. A total of 79 combined procedures were performed in 75 patients. All patients had tandem occlusive disease, with the inflow lesion felt to preclude a distal revascularization procedure alone. Revascularization was performed for incapacitating claudication in 17 (22%) and limb salvage indications in 62 (78%) cases. A mean resting iliac artery pressure gradient of 29 +/- 11 mmHg pre-PTA was reduced to 0.9 +/- 0.4 post-PTA. Major complications of PTA occurred in five (6%) cases, but four were successfully corrected at the time of the distal surgical procedure without alteration of the operative plan. Infrainguinal operations included 55 femoropopliteal or tibial bypass grafts, 18 femorofemoral grafts, and 6 profundaplasties. Mean follow-up was 43 months. By life table analysis, the 5-year primary patency rate of the distal surgical procedures was 76%; a secondary patency of 88% at 5 years was achieved by various means of reintervention. Mean pretreatment ankle/brachial index of 0.31 +/- 0.14 increased to 0.80 +/- 0.16 after operation (p less than 0.0001). The 5-year limb salvage rate was 90%. There were no operative deaths. We conclude that in carefully selected patients, combined use of iliac PTA and distal surgical reconstruction is effective and durable, safely reducing the extent of surgical intervention while reliably increasing the comprehensiveness of revascularization.

Inhibition of Angiotensin-Converting Enzyme for Diagnosis of Renal-Artery Stenosis

To determine its utility as an aid in diagnosis of renovascular hypertension, we administered nonapeptide converting-enzyme inhibitor (CEI) (which inhibits conversion of angiotensin I to angiotensin II) (0.25 mg per kilogram) to 14 unselected hypertensive patients undergoing bilateral renal-vein catheterization. In seven (Group I) predominantly unilateral disease was discovered by angiography (renal-artery stenosis in six and hydronephrosis in one); in the remaining seven (Group II) no rennal-artery abnormality was found. In Group I, mean (+/- S.E.) ratio of involved to uninvolved renal-vein plasma renin activity (PRA) increased from 2.94 +/- 0.91 before to 8.36 +/- 2.94 after CEI (P less than 0.01). In Group II, the ratio (of the initially higher to the lower side) was 1.99 +/- 0.49 before and 1.17 +/- 0.07 after CEI (P greater 0.02). Post-CEI PRA was predicted by pretreatment PRA. Mean blood pressure fell in both groups after CEI, and the decrement was predicted by pre-CEI PRA. These data suggest that CEI can be of use at the time of renal-vein catheterization, serving to increase diagnostic accuracy by increasing the difference in PRA between the two sides when there is unilateral disease.