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Biomedical subjects

J B Towne

Publications and source records attributed to J B Towne.

17 recordsLinked to original sources
PubMed1979

Periorbital ultrasound findings. Hemodynamics in patients with cerebral vascular disease.

The direction of supraorbital and frontal artery flow and its response to compression of the superficial temporal, facial, and angular arteries were measured in 250 carotid arteries in 114 patients. All patients had arch and/or selective carotid arteriography. The carotid arteries were placed into the following three groups: hemodynamically normal, greater than 60% occlusion of the internal carotid artery, and total occlusion of the internal carotid artery. The test's accuracy was 94.5% in the hemodynamically normal group, 68.8% in the totally occluded group, and only 51.4% in the group with hemodynamically significant stenosis. Although the carotid Doppler examination is not reliable in detecting hemodynamically significant lesions of the internal carotid artery, it is valuable in assessing the adequacy of collateral cerebral circulation.

Carotid Artery Diseases↗
PubMed1979

White clot syndrome. Peripheral vascular complications of heparin therapy.

Heparin sodium-induced thrombosis is insidious and difficult to diagnose. If untreated, it results in death or major amputation. We have treated seven patients with thromboses resulting from platelet aggregation induced by heparin. Four patients had acute arterial ischemia of the lower extremity, venous gangrene developed in two, and one patient had an occluded autogenous vein femoral popliteal bypass in the immediate postoperative period. The platelet count was noticeably reduced in affected patients. White platelet thrombi were noted in four patients, three of whom had acute arterial occlusion. A white thrombus was the cause of immediate failure of a femoral popliteal graft. Electron microscopic examination of these thrombi demonstrated predominantly fibrin platelet aggregates with an occasional entrapped WBC and a rare RBC. All patients receiving heparin therapy must have platelet counts performed regularly. If thrombocytopenia is detected, platelet aggregation studies are indicated. When abnormal platelet aggregation is noted, heparin therapy should be reversed with protamine sulfate and the patient treated with low-molecular-weight dextran and warfarin sodium.

Aged↗
PubMed1979

Heparin-induced thromboembolism: angiographic features.

Angiographic evaluation of heparin-induced thromboembolism in 3 patients who suffered disastrous consequences revealed a distinctive radiographic appearance consisting of mural filling defects quite unlike atheromatous plaques. These lesions were broad-based, isolated, gently lobulated excrescences which produced 30-95% narrowing of the arterial lumen. In eache case, the lesions were located proximal to sites of arterial occlusion.

Aged↗
PubMed1978

Revascularization of the ischemic kidney.

Although acute renal artery obstruction causes cessation of kidney function, the viability of the nephron is often maintained by collateral circulation. When renal artery blood flow is restored, filtration is resumed and the resulting acute tubular necrosis is gradually resolved as renal tubular cells regenerate. We have observed several different mechanisms of acute renal artery obstruction resulting in anuric renal failure: temporary suprarenal placement of an aortic clamp during absominal aneurysmectomy, resulting in bilateral renal artery occlusion; embolus, presumably of cardiac origin, to a solitary kidney; and thrombosis of the distal aorta extending to a level proximal to the renal arteries. There is no correlation between the duration of renal artery occlusion and the viability of kidney parenchyma. Viability of the kidney can only be determined by visual inspection at operation and response to revascularization. When vascular obstruction is a possible cause of acute anuric renal failure, immediate angiography is indicated. If a correctable vascular lesion is identified, operative intervention is mandatory.

Acute Kidney Injury↗
PubMed1978

Comparison of caval filters in the management of venous thromboembolism.

Over a seven-year period, 38 Mobin-Uddin MU and 33 Kim-Ray Greenfield KG vena cava filters were inserted in 71 patients with no substantial complications or deaths directly related to the surgical procedure. Thirteen of the 16 early deaths were due to progression of associated diseases. The remaining three deaths were caused by pulmonary emboli and occurred in each instance after insertion of a MU filter. None of the 14 late deaths were related to the caval filter or sequellae of venous thrombosis. Inferior vena cava patency was objectively assessed in 36 patients by cavagram (22) or autopsy (14). Caval patency of 95% (18 of 19) in those with KG filters was significantly greater than the 47% patency (eight of 17) seen with MU devices (P less than .01). Gray scale ultrasound, when successful in visualizing the vena cava, was found to be a reliable indicator of patency. Venous stasis phenomena were noted in 50% of those with a patent cava and in 70% of those with an occlusion. Thus, it is not surprising that edema was found in only 38% of the patients as compared with 75% of the patients with the MU filter. Both of these devices are safe to insert. However, on the basis of superior patency rate, lower incidence of stasis phenomena, and the absence of recurrent pulmonary emboli in our series, we prefer insertion of a KG filter when caval interruption is required.

Adult↗
PubMed1977

The reoperation of choice for aortofemoral graft occlusion.

Restoration of circulation following occlusion of an aortofemoral graft was attempted in 50 limbs in 38 patients. Progressive arteriosclerosis in the femoral vessels was the cause of graft limb thrombosis in most instances. Profundaplasty was employed in 47 limbs and femoral-popliteal bypass in two to provide effective runoff. Inflow was established by thrombectomy in 30 of the 37 limbs in which it was attempted, and it was readily accomplished with a Fogarty catheter if carried out within a few weeks after graft occlusion. In the 20 limbs in which thrombectomy was either abandoned (seven or not feasible because of prolonged delay (13), new grafts were inserted (13) or extra-anatomic bypass was carried out by femoral-femoral (four) or axillary-femoral (three) techniques. Operative death occurred in one patient (2.6%) after transabdominal graft replacement, and only two other patients had significant complications with full recovery. Initial graft patency was achieved in 96.6% following thrombectomy and in 85% following new graft or extra-anatomic bypass. Cumulative patency was 75% after 3 years. Amputation was required in five of the limbs in which graft patency could not be maintained. Reoperation should be performed promptly after graft limb thrombosis. The procedure of choice is thrombectomy and profundaplasty through a simple groin incision.

Amputation, Surgical↗
PubMed1977

Vascular endoscopy: useful tool or interesting toy.

A prospective protocol was designed to evaluate the efficacy and practically of intraluminal endoscopy in vascular reconstructive procedures. The choledochoscope and the arthroscope which utilize the Hopkins Optical System, as well as other available fiberoptic endoscopy units, were evaluated in 91 vascular reconstructions, including 42 carotid endarterectomies, 24 femoral artery reconstructions, 13 popliteal artery anastomoses, seven aortic and iliac procedures, one renal reconstruction, and one tibial reconstruction. In three cases the internal surface of an occluded limb of an aortic graft was examined endoscopically following thrombectomy. The optical resolution of the Hopkins Optical System was superior to the fiberoptic units. Vascular endoscopy required 5 minutes or less in 53 cases, between 5 to 10 minutes in 29 cases, and more than 10 minutes in nine. There were no infections. The single complication was a 1 cm linear tear in the intima of an internal artery. Positive findings were noted in 60 endoscopic studies, for an incidence of 66%. These consisted of intimal shreds in 47, elevated or irregular intimal flaps in 25, clot in five, and stenosis in three. In 26 cases the endoscopic findings were considered to be significant enough to possibly affect the ultimate outcome of the reconstruction.

Carotid Arteries↗
PubMed1976

Progression of popliteal aneurysmal disease following popliteal aneurysm resection with graft: a twenty year experience.

Multifocal occurrence of peripheral atherosclerotic aneurysm is well known. However, little attention has been directed to subsequent progressive aneurysmal development adjacent to sites of previously resected and grafted popliteal aneurysms. During a 20 year follow-up study of 79 patients with 115 popliteal aneurysms, we have observed the development of six atherosclerotic femoropopliteal aneurysms adjacent to the original aneurysm site in four patients, occurring 5 months to 10 years (average, 5 1/2 years) after the initial operation. Operative repaire was accomplished successfully of five of the six aneurysms; one popliteal aneurysm has not been operlateral popliteal aneurysm (46 percent). Fifty-seven patients (72 percent) presented with complications of the aneurysm, including 35 with thrombosis. As initial therapy, 69 grafting procedures were performed on 58 patients; nine extremities had sympathectomy only; four aneurysms were ligated or resected without grafting; and four extremities required amputation as the only procedure. Among patients with grafts, nine subsequent amputations were necessary in the early postoperative period, all occurring in patients presenting with thrombosed aneurysms. No patient who developed pedal pulses in the period immediately after operation required amputation. In addition, two patients developed aneurysmal degeneration in popliteal homografts. These data demonstrate the progressive nature of popliteal aneurysmal disease and emphasize the need for regular and life-long follow-up.

Adult↗
PubMedDate not supplied

Vascular endoscopy --- an adjunct to carotid surgery.

Technical advances in optical instrumentation have made vascular endoscopy a potential method for intraoperative evaluation of carotid endarterectomy. A prospective protocol was designed to evaluate the efficacy and practicality of this technique using the Hopkins Optical System in 35 carotid endarterectomies. The external carotid artery was examined after completion of the endarterectomy. The distal internal carotid artery was examined after removal of the shunt with all but 1 cm of the arteriotomy closed. Total time required for the procedure was less than 5 minutes in 21 cases and between 5 and 10 minutes in 14. Positive findings were noted in 71% of the external carotid endarterectomies which consisted of intimal flaps in 13 cases and intimal shreds in 25. In 2 patients (6%), internal carotid endoscopy revealed intimal shreds capable of embolizing and probably capable of causing a postoperative neurologic deficit. This technique permits a precise and complete evaluation of the vascular reconstruction.

Carotid Arteries↗
PubMedDate not supplied

Supraorbital Doppler evaluation in vascular surgery.

Directional Doppler examination of the supraorbital vessels is an effective, noninvasive method of evaluating patency of the internal carotid artery. In the presence of occlusive disease in the internal carotid artery, flow in the superficial temporal and frontal artery is reversed so that blood flows in a retrograde fashion into the orbit, providing valuable collateral circulation to the brain. Using these basic anatomical and physiological facts, the direction of arterial flow in the supraorbital vessels and the response to compression of the superficial temporal and facial arteries were measured with the directional Doppler. Evaluation of 125 carotid arteries in 63 patients by both arteriography and Doppler examination established an overall accuracy of 87 percent by the Doppler supraorbital test. This study demonstrated the value of carotid Doppler examination in the evaluation of extracranial cerebral circulation.

Arterial Occlusive Diseases↗