Biomedical subjects

W M Abbott

Publications and source records attributed to W M Abbott.

At least 145 records · Page 8Linked to original sources

PubMed1985

Increased compliance near vascular anastomoses.

Mismatch in mechanical properties (compliance mismatch) between host artery and prosthetic graft has been suggested as a cause of graft failure, but no mechanism linking the two has been identified. With the use of a simplified model based on isocompliant arterial grafts, pulsed ultrasound was used to generate detailed longitudinal profiles of diameter and compliance near the anastomoses. These longitudinal profiles revealed that although arterial diameter decreases monotonically to a minimal level at an anastomosis, arterial compliance first increases by approximately 50% before decreasing to 60% of the control value. This para-anastomotic hypercompliant zone (PHZ) is centered 3.6 mm from the anastomosis. PHZ also occurs in the artery adjacent to compliant or stiff grafts and is probably caused by transmitted effects of the suture line on the arterial wall. PHZ adds to any mismatch in compliance that already exists between artery and graft and can produce a compliance mismatch even between an artery and a nominally isocompliant prosthetic graft. It is hypothesized that PHZ, a region of increased cyclic stretch, promotes subintimal hyperplasia near anastomoses and may thus be a link between the mechanical properties of arteries and the failure of bypass grafts.

Animals↗

PubMed1984

Isolated popliteal segment v tibial bypass. Comparison of hemodynamic and clinical results.

Clinical and hemodynamic results of isolated popliteal segment, tibial, and sequential bypass grafts were compared in a retrospective review. Results were good with vein grafts to either an isolated segment or infrapopliteal vessel, with five-year patency rates of 71% and 72%, respectively. Prosthetic grafts performed poorly in both groups, and sequential grafts appeared advantageous in such circumstances. Average ankle pressure increased 49 mm Hg following successful isolated segment grafts. Although less than with patent tibial or sequential grafts, improvement was sufficient to relieve rest pain in all instances and heal ischemic lesions or local amputations in all but four patients. If an adequate vein is available and a good tibial vessel exists, distal grafting may be elected, particularly if advanced ischemic lesions demand restoration of pulsatile flow to the foot. If such conditions are not present, isolated segment grafting will give highly satisfactory results.

Aged↗

PubMed1984

Acute arterial thrombosis of the lower extremity. Its natural history contrasted with arterial embolism.

We compared a group of 52 patients with acute lower extremity ischemia secondary to arterial thrombosis with a series of 220 patients with peripheral embolism who were seen at the Massachusetts General Hospital, Boston, from 1967 through 1980. The conditions of patients with arterial thrombosis were misdiagnosed as acute embolism at a rate of 20%. Mortality in the patients with embolism was significantly higher. While patients with acute embolism were routinely treated with embolectomy, two thirds of the patients with thrombotic occlusion required surgery during their initial hospitalization for ongoing severe ischemia. More than half of these operations were carried out as emergency procedures. Limb salvage in surgically treated patients with arterial thrombosis was inferior to that seen with embolism. Early revascularization for acute thrombosis was carried out with a 30-day patency rate of 82%. While the mortality associated with acute thrombosis was significantly lower than that seen with peripheral embolism, the risk of major amputation was 35%. There should be no reluctance to proceed with indicated vascular reconstruction in the setting of acute limb ischemia secondary to arterial thrombosis.

Acute Disease↗

PubMed1984

Postsurgical changes in arterial compliance.

Mismatch in elasticity between artery and graft, a possible contributing factor to graft failure, has traditionally been believed to be caused by the graft. Compliance of the artery and/or graft may change after surgery, resulting in a different compliance mismatch. To study the arterial contribution to compliance mismatch, we measured compliance-pressure (CP) curves noninvasively in the femoral arteries of five dogs. One femoral artery was then simply exposed, and the incision was closed. Repeated CP curves were obtained after 24 hours, and after 1, 2, 3, and 4 weeks. Compliance remained normal after 24 hours, but by one week compliance of the dissected arteries had dropped significantly at all pressures between 70 and 120 mm Hg. Compliance reached a minimum after two weeks and remained low until after four weeks. Postsurgical arterial stiffening causes a significant decrease of arterial-graft compliance mismatch and may suggest an upper limit for synthetic graft compliance.

Animals↗

PubMed1984

Transcutaneous oxygen tension in selection of amputation level.

The utility of transcutaneous oxygen tension measurements in selection of a reliable amputation level was evaluated. Measurements were made at the proposed level of amputation in 37 patients, 22 of whom underwent major limb amputation and in 15 amputation was confined to the forefoot or toes. In patients with successful amputation healing, mean transcutaneous oxygen tension on the anterior skin surface was 50 +/- 8 mm Hg (index 0.79 +/- 0.1 mm Hg). In contrast, patients with failure of healing had a mean transcutaneous oxygen tension of 22 +/- 16 mm Hg (index 0.32 +/- 0.19 mm Hg) (p less than 0.001). Measurements on the posterior or plantar skin surface and posteroanterior differences provided even greater separation between success and failure groups, with no overlap of transcutaneous oxygen tension values or index. Transcutaneous oxygen tension measurement is easily obtained and noninvasive, and can be applied to all patients irrespective of Doppler signals, noncompressible vessels, or painful lesions. Transcutaneous oxygen tension appears to predict successful healing with accuracy, and should be a useful addition to clinical judgment in selection of optimal amputation level.

Adult↗

PubMed1984

Utility of transcutaneous oxygen tension measurements in peripheral arterial occlusive disease.

The use of transcutaneous oxygen tension (TCpO2) measurements to objectively and noninvasively diagnose peripheral arterial occlusive disease (PAOD) and to aid in the planning of vascular surgery was investigated. Thirty-two normal subjects and 100 patients with PAOD were studied. TCpO2 values decreased with age; when normalized by measurements on the chest, they did not. Absolute and normalized values of TCpO2 were equally effective in identifying the presence of PAOD and accurately characterized different degrees of severity (claudication vs. rest pain vs. impending gangrene; p less than 0.001). This was true even in diabetic patients, in whom tests based on hemodynamic function were less reliable. Healing of amputations was observed when TCpO2 greater than or equal to 38 mm Hg either preoperatively or after reconstruction; failure to heal in the absence of infection was associated with TCpO2 less than or equal to 38 mm Hg. The need for revascularization was associated with TCpO2 less than 30 mm Hg. A similar distribution of TCpO2 values was associated with success vs. failure of ulcer healing. TCpO2 is a useful complement to standard hemodynamic tests in the diagnosis and management of PAOD and, in addition, provides some distinct advantages.

Adult↗

PubMed1984

Aortofemoral bypass grafts: safety of percutaneous puncture.

To assess the safety of percutaneous puncture for the angiographic study of aortofemoral bypass grafts, we reviewed the medical records of 58 patients who underwent a total of 86 graft punctures. Short- and long-term follow-up revealed that in 83 punctures there were no complications. In three instances (3.5%) there was acute thrombosis of the punctured limb of the graft. This complication may have expedited but did not substantially alter the surgical plans of managing the underlying clinical problem. Although the incidence of complications of direct graft puncture is higher than that associated with puncture of native vessels, alternative approaches are also associated with complications, many of which may be more serious. Therefore, for angiographic studies of patients with aortofemoral bypass grafts, we favor the direct percutaneous puncture provided that enough time has elapsed from surgery.

Adult↗

PubMed1984

Local thrombolysis in the treatment of arterial graft occlusions.

Nineteen patients with 20 occluded arterial bypass grafts were treated with local infusion of streptokinase. Grafts treated included four aortofemoral graft limbs, 14 femoropopliteal or femorotibial grafts, one axillofemoral graft, and one transpubic femorofemoral graft. Complete lysis of thrombus was possible in 12 patients, partial lysis in five patients, and no lysis in two patients. Thrombolytic therapy was thought to be beneficial in the management of 14 patients. In two of these 14 only thrombolysis was required to restore and maintain graft patency, and in an additional two patients angioplasty was performed after thrombolytic therapy with no subsequent therapy necessary. In three patients who were initially poor operative risks, surgery could be postponed. Thrombolysis revealed the probable cause of thrombosis in 12 patients. Complications included four bleeding episodes, two of which were significant. There were no significant embolic complications. Unsuccessful thrombolytic therapy did not result in worsening of ischemia in any patient. Local infusion of thrombolytic agents is a useful adjunct in the management of occluded bypass grafts.

Adult↗

PubMed1984

Embolism of the popliteal artery.

The experience with popliteal arterial embolism at the Massachusetts General Hospital was surveyed, and the results of therapy prior and after the introduction of the balloon-tipped embolectomy catheter were compared. During the 17 year period from January of 1964 to January 1981, 67 popliteal emboli were diagnosed. Nonsurgical management was successful in salvaging 11 of 13 extremities in ten patients with one death. Surgical embolectomy was performed upon 54 extremities in 48 patients with 40 limbs salvaged and 11 deaths. Although the percentage of patients undergoing surgical therapy for popliteal emboli has dramatically increased since the introduction of embolectomy catheters, no improvement in limb salvage or in patient survival has resulted. In fact, the limb salvage rate has declined. Nonsurgical management in appropriately chosen patients is clearly successful. The results of this survey emphasize the necessity of early diagnosis and treatment as well as selective patient management. Recommendations for a therapeutic approach to popliteal emboli are presented which hopefully will improve the results.

Aged↗

PubMed1983

Vascular complications of intra-aortic balloon counterpulsation.

Although the intra-aortic balloon pump (IABP) saves many lives, complication rates as high as 36% have been reported. Many of the complications require surgical attention. In 794 patients of the Massachusetts General Hospital in Boston, an IABP was inserted into either the femoral or iliac artery between Nov 1, 1968, and June 30, 1981. Eighty-seven major vascular complications occurred in 70 (8.8%) of them. Of those 70 patients, 95% denied previous symptoms of vascular disease, and 78% had had normal pulses before insertion. The two most common complications were limb ischemia (n = 36) and arterial trauma (n = 20). Other complications included sepsis (n = 14), wound problems (n = 10), and hemorrhage (n = 7). No limbs were lost. Analysis of each group of complications allowed specific conclusions to be drawn concerning prevention, early diagnosis, and the most appropriate treatment.

Adult↗

PubMed1983

Femoropopliteal and tibioperoneal artery reconstruction using human umbilical vein.

We used 99 human umbilical vein (HUV) grafts for femoropopliteal or tibioperoneal artery reconstruction in 94 patients. Results were calculated according to the life-table method for several categories possibly influencing graft patency. For above-knee v below-knee distal anastomosis, there was no difference in patency or limb-salvage rates at 30 months. Comparison of good and poor runoff situations disclosed similar 30-month graft patency rates, but significantly better limb-salvage rates among patients with good runoff. Primary revascularization fared significantly better than secondary procedures in terms of patency and limb salvage. We found no significant differences between HUV and polytef (polytetrafluoroethylene) for above-knee anastomoses or good runoff situations. However, patency and limb salvage were better for HUV use in below-knee anastomosis and poor runoff situations. The HUV may offer advantages in long-term patency and limb salvage in selected patients.

Aged↗

PubMed1983

Noninvasive intraoperative assessment of arterial reconstruction. Experimental validation of the role of central and regional hemodynamics.

We developed an experimental model of graded arterial stenosis to emulate conditions that might be encountered immediately following arterial grafting. Noninvasive measurements of systolic BP and limb blood flow were recorded with a Doppler probe and segmental air plethysmography, respectively, under conditions of different cardiac output and local arterial resistance. These measurements were correlated with direct intra-arterial pressure recordings and flow measurements taken with an electromagnetic flowmeter. There was an excellent correlation between noninvasive and intra-arterial measurements of systolic pressure over a range of cardiac outputs and degree of arterial stenosis. Pulse volume recordings correlated with direct measurements of blood flow at high and baseline cardiac outputs, but the calibration of pulse volume amplitude varied between cuff applications in this canine model. Noninvasive intraoperative monitoring techniques can faithfully represent known physiologic responses to graded arterial stenoses, irrespective of a high cardiac output or peripheral vasodilation.

Animals↗

PubMed1983

Aggressive surgical management of popliteal artery aneurysms.

One hundred fifty-nine patients with 244 popliteal aneurysms underwent 167 reconstructive procedures. Patients were divided into those with asymptomatic aneurysms, those with acute ischemia secondary to thrombosis or embolism, those with claudication secondary to chronic thrombosis or embolism, and those with local symptoms referable to the aneurysm itself. Patients who underwent successful revascularization were considered to have good early results. Patients with asymptomatic aneurysms had uniformly good results (97.2 percent) as opposed to those presenting with acute (70.7 percent) or chronic symptoms (83.8 percent). Similar statistically significant differences were seen when patients with thrombosis (71.7 percent) or embolism (81.3 percent) were compared with asymptomatic patients. Analysis of late results indicates that if an initial good result was obtained, the late patency rate was independent of type of presentation. Late results were affected by type of conduit employed where life table analysis showed the superiority of saphenous vein over Dacron prosthesis. At 5 year follow-up, 77.2 percent of all saphenous veins were patent whereas only 29.5 percent of Dacron prostheses remained patent.

Acute Disease↗

PubMed1983

Imaging vascular grafts in vivo with Indium-111-labeled platelets. Influence of timing on image interpretation.

Platelets labeled with Indium-111 were used to visualize polytetrafluoroethylene (PTFE) bypass grafts in vivo and to quantitate platelet deposition vs. time. The grafts were inserted into the femoral and carotid arteries of dogs and were first exposed to unlabeled blood for 0 to 3 hours. They were then imaged for up to 5 days. An index of activity, designed to correct for isotope decay and changing levels of background, was used to quantitate platelet deposition. Grafts exposed to unlabeled blood for, at most, 1 hour were visible immediately. When labeled platelets were administered to the circulation after at least 2 hours, grafts became visible only after 3 days. Continuous imaging of fresh implants, showing that platelet deposition does not increase monotonically with time, was used to explain this phenomenon. The interpretation of nuclear images of synthetic grafts depends on the delay between establishing flow in the grafts and the administration of labeled platelets.

Animals↗

PubMed1983

The effect of halothane anesthesia on platelet aggregation in vivo: decreased deposition on polytetrafluoroethylene arterial grafts in dogs.

The technique of gamma-imaging can be used to study the deposition of 111In-labeled platelets onto synthetic arterial grafts in vivo. Recent results suggested that platelet uptake on polytetrafluoroethylene (PTFE) grafts might depend on the choice of anesthetic. To evaluate the effect of anesthesia a series of experiments was performed in seven dogs wherein each animal served as its own control. The first of paired femoral or carotid PTFE grafts was inserted with the animal under pentobarbital anesthesia, and the graft was imaged for 90 minutes. A second graft was then inserted after at least 1 hour of halothane anesthesia. The mean activity ratio (describing platelet deposition) in the grafts inserted when only pentobarbital anesthesia was used was 7.04 +/- 0.55, compared to 1.20 +/- 0.07 in the grafts inserted with halothane anesthesia (P less than 0.01). Halothane anesthesia led to significantly decreased platelet uptake on canine PTFE arterial grafts. This effect was reversible, though not immediately, with no significant difference in graft activity noted by the day following surgery.

Anesthesia, Inhalation↗

PubMed1982

Deep venous thrombophlebitis following aortoiliac reconstructive surgery.

One hundred patients undergoing elective aortic surgery were scanned prospectively for development of deep venous thrombosis (DVT). The incidence of DVT in this population was 13%. Eleven patients showed only calf vein thrombosis on venography, whereas two had occlusive iliofemoral thrombus. The correlation between venous Doppler ultrasound and venography was 80%. More importantly, Doppler examination correctly identified both patients with occlusive thrombus. Fibrinogen scanning was associated with a false-positive rate of 31%. Only one patient suffered a nonfatal pulmonary embolus. Fibrinogen scanning has an unacceptably high false-positive rate; however, Doppler ultrasound will identify significant occlusive thrombus without a high false-positive rate. The low incidence of pulmonary emboli does not warrant such definitive measures as prophylactic vena caval interruption.

Adult↗

PubMed1982

Transluminal angioplasty of the iliac and femoropopliteal arteries. Current status.

Transluminal angioplasty for the management of atherosclerosis obliterans has been performed in 160 patients for 100 iliac and 98 femoropopliteal lesions. The procedure was performed percutaneously except in eight patients in whom operative exposure was required. Angioplasty was technically successful in all 100 iliac artery lesions. There was hemodynamic and clinical improvement in 92 lesions. The procedure was technically successful in 84 of the 98 femoropopliteal artery lesions with hemodynamic improvement in 74 and clinical improvement in 78. There were ten complications directly related to the angioplasty and six related to the arteriographic procedure. Cumulative patency rates for the angioplasties were 92% and 75% at three years for iliac and femoropopliteal lesions, respectively. These promising results suggest that transluminal angioplasty has a definite role in the management of atherosclerosis obliterans of iliac and femoropopliteal arteries.

Adult↗

PubMed1982

Modification of the Haemonetics Cell Saver for optional high flow rate autotransfusion.

Intraoperative autotransfusion is a technique well-suited to major vascular surgery. It is most effective when salvage and reinfusion of shed blood can be accomplished at flow rates compatible with the degree of hemorrhage encountered in both elective and emergency procedures. Appropriate equipment modifications can render commercially available autotransfusion devices safer and more effective in the management of intraoperative blood loss. The Cell Saver, a device which concentrates and washes salvaged red blood cells, is limited in its potential as an autotransfusion device because of its slow reinfusion rate. A modification was devised which expands the flow capabilities of the Cell Saver and allows rapid reinfusion of autologous whole blood. The modified blood circuit has been employed in 10 major vascular cases with favorable results, thus demonstrating its efficacy in the management of massive hemorrhage during vascular repair. Guidelines for the safe and effective use of the modified unit are stressed.

Adult↗