John J. Cranley

Real-time B-mode venous ultrasound*

The ability of real-time B-mode ultrasound to directly visualize arteries and veins and thereby give anatomic rather than physiologic information is unique among the currently available noninvasive methods of vascular evaluation. The usefulness of this technique for examination of the carotid arteries has been well proven. Little attention, however, has been given to its applicability for deep venous evaluation. Over the past 12 months the veins of 108 upper and 215 lower extremities have been studied with high-resolution real-time ultrasound. The technique and interpretive criteria are presented. Thirty extremities underwent confirmatory venography, and in this group the specificity and sensitivity of the ultrasound were 94% and 100%, respectively. In addition, the age of the thrombi detected was accurately predicted in 93% of this group. These preliminary results suggest that real-time B-mode venous ultrasound is an accurate, clinically useful noninvasive technique for the detection of deep venous thrombosis that complements the more widely used physiologic screening tests.

Lower extremity calf thrombosis: To treat or not to treat?☆

Seventy-five patients with isolated calf vein thrombi were prospectively monitored with sequential duplex scans at 3- to 4-day intervals. Twenty-four patients (32%) propagated and 11 of these 24 (46%) into the popliteal or larger veins of the thigh. Sex, age, obesity, trauma, estrogen use, malignancy, varicose veins, smoking, surgery, and activity level were not predictive for proximal propagation. Proximal soleal vein thrombi had the highest incidence in both propagating and non-propagating groups. Thrombus extent and bilateral involvement were not predictive of propagation. Five percent (4 of 75 patients) had highly probable ventilation perfusion scans as their initial indication for duplex scanning. Deep vein thrombosis isolated to the calf is not a benign problem. If anticoagulant therapy is contraindicated, the progress of the thrombus can be followed by duplex scanning.

Upper extremity venous thrombosis diagnosed by duplex scanning

The incidence of axillary-subclavian venous thrombosis continues to rise, while reports of noninvasive methods to diagnose this condition have been sparse. A review of the records of 693 consecutive upper extremity duplex scans was performed, and a diagnosis of acute venous thrombosis was made in 123 of these patients. Of these, 85 involved the axillary or subclavian vein. Use of a central venous catheter was the most common risk factor for axillary-subclavian venous thrombosis. Within this group, 8% had a pulmonary embolism, of which 25% were fatal. Follow-up of patients with axillary-subclavian venous thrombosis at a mean of 2 years revealed that 49% of these patients had died. Of the remaining patients, more than one third had evidence of the post-thrombotic syndrome. Duplex scanning of the venous system provides a safe, reliable, and repeatable method of evaluating and following patients with suspected venous thrombosis of the upper extremity.

Real-time B-mode carotid imaging: A three-year multicenter experience

This report attempts to establish the place of real-time B-mode carotid imaging in the diagnosis of carotid artery disease through an analysis of the results of 3 years of experience in three major noninvasive vascular laboratories. Over 7000 patients were studied noninvasively with real-time B-mode carotid imaging and oculoplethysmography (OPG). Angiographic comparisons of 1723 vessels form the basis of this study. All tests were interpreted by physicians who had no knowledge of the angiograms. Images and x-ray films were classified by diameter of stenosis: grade I (0% to 39%), grade II (40% to 69%), grade III (70% to 99%), and grade IV (total occlusion). The effect of the imaging experience was determined by dividing the study into two periods. The results of image quality vs. accuracy and of combining the anatomic study (scan) and physiologic study (OPG) were also evaluated. The overall data show a specificity of 87% (985 of 1139), a sensitivity for grade II disease of 72% (193 of 267), a sensitivity for grade III of 66% (133 of 201), and a sensitivity for grade IV of 64% (74 of 116). With experience each center showed improvement of the imaging technique in diagnosing grade III (p greater than 0.1: not significant) and grade IV disease (p less than 0.0002: highly significant), although there was no improvement in the specificity and sensitivity of grade II disease. All scan errors were analyzed. Most errors were interpretation errors (27%: 90 of 338), scan/arteriogram mismatches (23%: 79 of 338), or poor-quality scans secondary to existing disease (22%: 75 of 338). There was a direct correlation of scan quality and accuracy, with a 97% specificity for grade I scans of good to excellent quality. When the scan and OPG agreed, there were uniform predictive values for all grades (88% to 93%). Sixteen of 79 scan/arteriogram mismatch vessels were operated on, and the scan proved more reliable in 86%. Real-time B-mode carotid imaging is a reliable technique for defining the normal carotid artery and is becoming increasingly sensitive in identifying existing disease. Despite its limitations, its strong points make it a valuable clinical tool.

Venous thrombotic complications of pregnancy

A total 30,040 pregnancies were reviewed at one institution over 5 years to determine the incidence of venous thrombotic complications. Thirty-one patients experienced such complications related to pregnancy (incidence 0.1%); 13 had deep venous thrombosis and 14 had superficial venous thrombophlebitis diagnosed by duplex ultrasound. Four had pelvic vein thrombophlebitis diagnosed by computed tomography scan; three patients (one from each group) sustained a non-fatal pulmonary embolus. Of those with deep venous thrombosis, 10 (77%) were left-sided, and three (23%) were right-sided. Three had a prior history of deep venous thrombosis and one of pulmonary embolism. Of those with superficial venous thrombophlebitis, seven (50%) were left-sided, six (43%) were right-sided, and one (7%) was bilateral. Most with deep venous thrombosis presented later in pregnancy; three in the first trimester, two in the second, three in the third, and five early postpartum. Most (10/14) with superficial venous thrombophlebitis presented within 48 hours of delivery. Distribution of thrombi in those with deep venous thrombosis was compared with 643 non-pregnant women with a similar condition. A pattern of proximal involvement on the left was found, with left common femoral vein (54% versus 28%, P = 0.03) and superficial femoral vein (62% versus 26%, P = 0.006) more often involved in pregnant patients. The average number of vein segments involved was greater on the left than the right (5.3 versus 3.7). Symptoms of chronic venous insufficiency developed in three with deep venous thrombosis (25%) and in three with superficial venous thrombophlebitis (27%). None had recurrence of deep venous thrombosis. It is concluded that venous thrombotic complications associated with pregnancy are not necessarily benign, with the risk of pulmonary embolism and chronic venous insufficiency not limited to patients with deep venous thrombosis only.

Heparin-induced thrombocytopenia: A prospective study of 142 patients

In a prospective study of 142 patients receiving intravenous heparin of bovine lung origin, thrombocytopenia developed in nine (6%) patients. In the group of 70 patients with a history of prior heparin therapy, seven (10%) had thrombocytopenia. By contrast, only 2 (3%) of 72 patients with no history of previous heparin treatment had thrombocytopenia, a statistically insignificant difference (p less than 0.5). In this group 58 patients received heparin for less than 10 days, and none of them had thrombocytopenia. Of the remaining 14 patients who were given heparin longer than 10 days, two patients (14%) had thrombocytopenia. This difference was statistically significant (p less than 0.01). Monitoring the platelet count detects the disorder early and prompt cessation of heparin prevents serious complications. All patients undergoing heparin therapy should have determination of pretreatment platelet count. In patients with a history of previous heparin therapy, thrombocytopenia may develop even with short duration of heparin treatment, and hence platelet counts should be monitored throughout the duration of treatment. The platelet count of patients who have no history of previous treatment with heparin should be monitored if heparin is continued for more than 7 days.

Extended study of aneurysm formation in umbilical vein grafts

The rate of aneurysm formation in umbilical vein grafts has been reported to lie between 1% and 8%. However, in these reported series the number of grafts with aneurysms was related to the number of grafts inserted. When the denominator is changed to patent grafts at a given time period, the incidence changes drastically. In this study, duplex scanning was used to detect aneurysms in patent grafts. Four types of aneurysms--localized fusiform, localized eccentric, diffuse, and anastomotic--were recognized. Excluding anastomotic aneurysms, 33% of the grafts patent at 3 years were aneurysmal; in those patent at 4 years, 45% were aneurysmal; and in those patent at 5 or more years, 65% were aneurysmal. On grounds of theoretical considerations, it is believed that duplex scanning is more reliable than either clinical examination or arteriographic study for detecting these aneurysms. There is now evidence that the supporting Dacron mesh is too weak and must be strengthened. Despite aneurysm formation, the patency rate in our series has remained second only to saphenous vein grafts, as previously reported.

Does the asymptomatic limb harbor deep venous thrombosis

Deep venous thrombosis (DVT) is a great masquerader that cannot be reliably predicted by a patients symptoms, history, or risk factors. Bilateral lower extremity duplex ultrasonography scans were made of 2,511 patients and analyzed to identify, if possible, a population in which a unilateral study would be appropriate. A total of 1,086 (43%) patients were found to have deep venous thrombosis--742 (30%) unilateral and 344 (14%) bilateral. Of the patients with DVT for whom side-of-symptom information was recorded, 64% had symptoms referable to the involved extremity and 36% had symptoms referable to the contralateral extremity. Of the 362 patients who had asymptomatic lower extremities, 128 (35%) had DVT. Moreover, clots were found in asymptomatic limbs in an additional 263 patients whose contralateral limb was symptomatic. Logistic regression analysis did not reveal combinations of symptoms and risk factors that could predict DVT. If DVT is suspected, the patient should undergo bilateral lower extremity duplex scanning.

Measurement of blood flow rates in the lower extremities with use of a nuclear magnetic resonance based instrument

Direct, noninvasive measurement of pulsatile blood flow to the human extremity is now possible by means of a flow measurement instrument that is based on the principles of nuclear magnetic resonance. The instrument uses a physically independent calibration module as a primary calibration standard. Volumetric calibration of this module indicates that it is precise and accurate over the range of 0 to 100 ml/min. The calibration module is used, in turn, to calibrate an electromagnetic flow sensor that is incorporated into the instrumentation. The calibration module and the electromagnetic sensor were found to be linearly related over the range of 5 to 100 ml/min, with a regression correlation coefficient of 0.996. The calibrated electromagnetic flow sensor is used as a secondary standard for calibration of the nuclear magnetic resonance sensor. Blood flow measurements, obtained by use of this method, agree closely with those obtained by plethysmographic methods. They differ from the plethysmographic results in that magnetic resonance flows will distinguish between the at-rest blood flow in the normal extremity and the flows seen in the extremity (also at rest) with claudication. Based on the results obtained from studying a limited number of limbs with a high degree of ischemia, the method will not distinguish the limb with ischemia from the limb with claudication. Limitations of the method and refinements required to make the method clinically useful are discussed.

Near Parity in the Final Diagnosis of Deep Venous Thrombosis by Duplex Scan and Phlebography

A collective experience in six vascular laboratories, using the same equipment and instrumentation, provided 351 extremities in which both duplex scan and phlebography were performed, most within 24 h of each other. When the phlebogram was positive, it was a true standard and in these instances the sensitivity of duplex scanning was 95.65%. When the phlebogram was negative, it was incorrect six times, making the sensitivity of phlebography 96.9%. The specificity of phlebography was 100%. When the duplex scan was positive and the phlebogram truly negative, the duplex scan was falsely positive five times (97.3%).