Biomedical subjects

D F Bandyk

Publications and source records attributed to D F Bandyk.

At least 91 records · Page 5Linked to original sources

PubMed1988

Hemodynamics of vein graft stenosis.

The hemodynamics of 56 femorodistal saphenous vein bypasses (in situ [n = 53] or reversed [n = 3]) identified to have residual or recurrent graft stenoses were characterized with Doppler-derived blood flow velocity and resting limb systolic pressure measurements. The magnitude and configuration of the graft blood flow velocity waveform were the best predictors of graft stenosis. Transformation of the graft blood flow velocity waveform from a triphasic to a monophasic or biphasic configuration coupled with a low (less than 45 cm/sec) or decrease (greater than 30 cm/sec) in peak systolic blood flow velocity relative to initial postoperative levels reliably predicted the presence of a remote occlusive lesion. In 20 (36%) of the 56 limbs, the ankle-brachial systolic pressure index (ABI) did not identify graft stenosis. The low sensitivity of ABI in the identification of graft stenosis was due to insignificant decrease (less than 0.15) of ABI (n = 11), incompressibility of the tibial arteries (n = 6), or residual occlusive lesions after surgery (n = 3). Duplex scanning of grafts with low blood flow velocity localized the site of stenosis in 31 (86%) of 36 patients examined. Graft revision increased systolic blood flow velocity from 33 +/- 9 to 77 +/- 18 cm/sec (mean +/- one standard deviation) a velocity similar to immediate postoperative levels (74 +/- 17 cm/sec). Resting ABI increased from 0.61 +/- 0.2 to 0.92 +/- 0.1 after graft revision. Four grafts with low systolic blood flow velocity (range 18 to 40 cm/sec) not revised occluded 5 to 45 days later.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Accuracy of duplex scanning in the detection of stenosis after carotid endarterectomy.

The results of duplex ultrasonography in grading stenosis after carotid endarterectomy (78 sites) were compared with those of contrast angiography in 71 patients studied for recurrent or contralateral occlusive disease of the carotid bifurcation. Duplex and angiographic studies were performed within one month of each other at a mean postoperative interval of 44 months (range 3 to 122 months). Stenosis of the common carotid (CCA) and internal carotid artery (ICA) was classified into five disease categories (normal or less than 15% diameter reduction [DR], 16% to 49% DR, 50% to 75% DR, greater than 75% DR, and occlusion). The overall accuracy of duplex scanning compared with angiography in predicting recurrent carotid bifurcation disease was 83%, a level of agreement similar to classification of disease involving the nonoperated, contralateral bifurcation (overall accuracy 87%). Recurrent stenosis (greater than 50% DR) or occlusion of the CCA or ICA after endarterectomy was identified with an accuracy of 97%. Overestimation of severity of recurrent stenosis accounted for 11 of 13 duplex classification errors (85%). Presence of moderate (30% to 50% DR) recurrent stenosis of the CCA, tortuosity of the ICA, and severe contralateral carotid bifurcation disease were associated with velocity spectra that predicted a more severe recurrent stenosis at the endarterectomy site compared with angiographic grading. The level of agreement between duplex scanning and angiography was comparable to the interobserver variability in angiographic interpretation. The accuracy reported justifies the use of duplex scanning to grade the severity of carotid bifurcation recurrent stenosis and to follow these lesions for disease progression.

Carotid Artery Diseases↗

PubMed1988

Monocular ischemia--the influence of carotid atherosclerosis versus primary ocular disease on prognosis.

The etiology of monocular ischemia influences the clinical manifestation and long-term neurologic and visual prognosis. During a 10-year period, 140 patients with monocular visual symptoms were evaluated and assigned to a carotid bifurcation occlusive disease group (group I) or a primary ocular disease group (group II) on the basis of angiographic findings and ophthalmologic evaluation. Patients with symptoms secondary to emboli from the carotid bifurcation tended to have a shorter duration of blindness and a lower incidence of permanent blindness initially and during follow-up. The presence of Hollenhorst plaques or retinal artery occlusion did not have any discriminatory diagnostic value since the incidence was similar in both patient groups. Since both primary eye disease and carotid bifurcation occlusive disease can be initially seen as monocular ischemia, carotid angiography and ophthalmologic consultation are necessary to select those patients who will benefit from carotid endarterectomy.

Arteriosclerosis↗

PubMed1987

Surface biofilm disruption. Enhanced recovery of microorganisms from vascular prostheses.

Ultrasonic oscillation (sonication) of explanted vascular prosthetic graft material can disrupt surface biofilms and increase the recovery of adherent microorganisms. Recovery of microorganisms from vascular grafts was studied in a canine model of Staphylococcus epidermidis graft contamination (N = 26) and on graft material excised from patients undergoing femoral anastomotic pseudoaneurysm repair (N = 7). Surface biofilm disruption by sonication significantly increased the incidence of positive cultures of excised graft material compared with broth (P less than .010) and blood agar plate (P less than .005) culture techniques. The S epidermidis was recovered from 31% of the canine vascular grafts and 100% of the clinical specimens. The in vitro production of a glycocalyx "slime" was demonstrated in 73% of the recovered staphylococcal strains. The formation of an adherent bacteria biofilm on implanted vascular prostheses is not an uncommon occurrence and is an important factor in the pathogenesis of anastomotic pseudoaneurysm formation and late graft infection.

Animals↗

PubMed1987

Influence of vein-patch angioplasty on carotid endarterectomy healing.

We studied the influence of venous patching on the patency, endothelial regeneration, and wall healing of endarterectomized carotid arteries in a canine model. Thirteen dogs underwent bilateral common carotid endarterectomies (intimectomy and partial media excision). In each dog, one artery was closed by continuous suture and the contralateral artery was closed by external jugular vein-patch angioplasty; arteries were excised at two postoperative intervals (two to three and four to five weeks) for light, scanning, and transmission electron microscopy. The patency of arteries closed primarily (9/13 [69%]) was not significantly different compared with arteries closed with venous patches (12/13 [92%]). By scanning electron microscopy, regeneration of the endothelial monolayer occurred by migration from the endarterectomy end points and suture lines. Despite survival of the vein-patch endothelium, the rate and pattern of reendothelialization was not altered by venous patching. In both patched and unpatched vessels, endothelial regeneration was incomplete at two to three weeks and completed by four to five weeks. The histologic characteristics of the endarterectomized arterial wall after operation were also not influenced by the closure technique. In contrast with the healing artery wall, vein-patch walls did not develop a thickened intima. Although venous patching does not influence early patency, endothelial regeneration, or wall healing after endarterectomy, vein-patch angioplasty does increase vessel diameter and prevents the development of circumferential intimal thickening, attributes that are beneficial in minimizing restenosis.

Animals↗

PubMed1987

Application of thrombolytic therapy in vascular occlusive disease. A surgical view.

The use of fibrinolytic agents to control the fibrinolytic enzyme system and lyse pathologic fibrin deposits or thrombus has now assumed a position with anticoagulants and vascular surgery in the physician's therapeutic armamentarium. The principal exogenous activators that are used clinically are streptokinase, urokinase, and tissue plasminogen activator. Acute arterial occlusions are more likely than chronic occlusions to respond to thrombolytic therapy, especially if treatment is instituted within a few hours of onset of symptoms and if the disease is due to embolic material rather than in situ thrombosis. Since the duration of drug infusion necessary to lyse arterial thrombus cannot be predicted, patients in whom tissue viability cannot be determined or in whom ischemia cannot be tolerated during the drug infusion interval are not candidates for intraarterial fibrinolytic drug infusion. In treating patients with venous occlusion, thrombolytic therapy is more effective against proximal clots than in calf thrombosis. No protective effect from pulmonary embolism has been noted in trials comparing heparin with streptokinase. Fifty percent of patients with an initial episode of deep venous thrombosis treated within 72 hours of onset will have complete resolution of thrombus with preservation of valve function.

Arterial Occlusive Diseases↗

PubMed1987

Durability of the in situ saphenous vein arterial bypass: a comparison of primary and secondary patency.

The use of the saphenous vein in situ is associated with unique problems that decrease primary graft patency (patency uninterrupted by revision). During the past 5 years, we have performed 192 in situ saphenous vein bypasses in 182 patients, including 61 to the popliteal artery, 128 to infrapopliteal arteries, and three to isolated popliteal artery segments. The operative indications were critical limb ischemia in 178 cases (93%), popliteal aneurysm in eight cases (4%), and disabling claudication in six cases (3%). A progressive decline in primary patency occurred after operation. The primary patency rate at 36 months was only 48% for femoropopliteal bypasses and was 58% for femorotibial bypasses. In contrast, the secondary patency rate (patency maintained by thrombectomy, thrombolysis, or revision) at 36 months was 89% and 80% for femoropopliteal and femorotibial bypasses, respectively. The improved secondary patency was due to postoperative surveillance of graft hemodynamics and the success of graft revision. Problems unique to the in situ technique (incomplete valve incision, residual arteriovenous fistula, graft torsion and entrapment) accounted for 58% of early (less than 30 days) graft revisions and 52% of late revisions. The use of Doppler spectral analysis at operation and duplex scanning after operation can locate unsuspected technical errors and identify grafts with low flow at increased risk for failure. The primary patency of the in situ bypass mandates objective assessment of valve incision sites at operation and a protocol of postoperative surveillance to identify grafts that require revision. Early surgical intervention of hemodynamically abnormal but patent in situ bypasses is rewarded by excellent secondary patency.

Adult↗

PubMed1987

The microbiology of explanted vascular prostheses.

The incidence of bacterial colonization and the microflora of prosthetic vascular graft material explanted from 44 patients undergoing graft revision was determined. Graft material for culture was obtained from aortofemoral or femoropopliteal vascular prostheses without signs of infection but requiring revision for femoral anastomotic aneurysm (n = 21) or thrombosis (n = 26). Explanted graft material was placed in tryptic soy broth and ultrasonically oscillated to disrupt the adherent graft surface biofilm, which is a technique that increases the recovery of microorganisms compared with standard microbiologic culture methods. Microorganisms were isolated from 90% (19/21) of grafts associated with anastomotic aneurysms and 69% (18/26) of thrombosed grafts. Staphylococcus epidermidis was the prevalent organism recovered and accounted for 69% of the isolates. Slime production, a growth characteristic of S. epidermidis associated with prosthetic device infection in humans, was demonstrated by 87% (13/15) of strains isolated from grafts with pseudoaneurysms compared with 33% (4/12) of strains isolated from occluded grafts (p less than 0.01). Despite the high incidence (79%) of colonization of vascular prostheses, no patient developed wound or graft infection after graft replacement and perioperative antibiotic administration. Low-virulent microorganisms, such as S. epidermidis, can colonize vascular prostheses and not provoke signs of graft infection. The high recovery rate of slime-producing S. epidermidis strains from grafts with anastomotic aneurysms and the adherence-mediated growth of these bacteria on biomaterials suggest this late graft complication is the sequelae of a bacteria-laden biofilm infection.

Aneurysm↗

PubMed1987

The influence of sepsis and ischemia on the natural history of the diabetic foot.

One hundred seventeen diabetic patients with lesions involving 174 extremities were reviewed to evaluate the natural history of the problem and specifically those factors that influence its course both acutely and chronically. The extremities of diabetic patients with foot lesions can be categorized based on severity of infection and presence of ischemia. Half of these patients developed lesions in the contralateral extremity either concurrently (synchronous) (7%) or later (metachronous) (43%). Major amputation was required in 59 of the 174 extremities evaluated (34%). In patients with metachronous lesions, unilateral amputations were required in 28 per cent of patients and bilateral amputations in 26 per cent. Limb salvage by revascularization required 1.4 operations per extremity, carried 2 per cent operative mortality and was successful in 66 per cent. Although 24 per cent of these patients died within 5 years of the initial presentation of their foot lesions, these data suggest that limb salvage attempts are reasonably successful and relatively safe. The combination of extremity sepsis and ischemia in the diabetic adversely effects the survival of both the extremity and the patient.

Amputation, Surgical↗

PubMed1986

Mucin production by Staphylococcus epidermidis. A virulence factor promoting adherence to vascular grafts.

The production of an exopolysaccharide (mucin) by some Staphylococcus epidermidis strains facilitates bacterial adhesion to prosthetic vascular grafts and may play an important role in adherence-mediated growth. An in vitro model was developed to measure the differential adherence of mucin-producing (RP-12) and nonmucin-producing (SP-2) S epidermidis strains onto expanded polytef and velour knitted Dacron graft material. After incubation in a 10(7)/mL suspension of organisms, graft specimens were repeatedly washed to remove nonadherent organisms and then sonicated to dislodge adherent organisms. Bacterial adherence was calculated from a quantitative culture of the sonication effluent. Both S epidermidis strains adhered in ten to 100 times greater numbers to the knitted Dacron graft material than to expanded polytef. The production of an exopolysaccharide by the RP-12 strain significantly increased adherence to both graft types compared with the SP-2 strain. The increased adherence of the RP-12 strain was inhibited by adding D-mannosamine to the inoculum. The in vitro model developed is well suited for further study of the mechanisms by which bacteria adhere to and colonize vascular grafts.

Adhesiveness↗

PubMed1986

Intraoperative assessment of in situ saphenous vein arterial grafts using pulsed Doppler spectral analysis.

Errors in anastomotic construction, retained competent valves, and arteriovenous fistulas can cause both early and delayed failure of in situ saphenous vein arterial grafts. Pulsed Doppler spectral analysis of midstream flow was compared with arteriography in 50 consecutive in situ saphenous vein bypasses for the detection of unsuspected technical error. Based on spectral changes in the velocity waveform indicating flow disturbance, intact valve cusps could be distinguished from arteriovenous fistulas, and technically unsatisfactory anastomoses were identified. Competent valve cusps were identified in nine (5%) of 180 valve-incision sites, and six anastomoses (6%) were judged unsatisfactory. The presence of severe flow disturbance was always associated with an anatomic defect on arteriography. Incision of missed valve cusps and anastomotic revisions corrected associated flow disturbances. Doppler flow analysis readily located high-flow arteriovenous fistulas, thereby reducing operative time and the need for multiple arteriograms. The high sensitivity of this method (no false-negative assessments) makes it an ideal screening test, resulting in the selective use of operative arteriography.

Angiography↗

PubMed1986

Bacterial adherence to vascular prostheses. A determinant of graft infectivity.

An in vitro model was developed to quantitatively measure bacterial adherence to the surface of prosthetic vascular graft material. Four strains of bacteria (Staphylococcus aureus, nonmucin-producing S. epidermidis [SP-2], mucin-producing S. epidermidis [RP-12], and Escherichia coli) were used to inoculate expanded polytetrafluoroethylene (ePTFE), woven Dacron, and velour knitted Dacron graft material. After graft specimens were incubated in a 10(7) suspension of bacteria, they were washed to remove nonadherent organisms and ultrasonically oscillated to dislodge adherent organisms. Quantitative culture of the sonication effluent was used to calculate bacterial adherence, expressed as the number of colony-forming units found in each square centimeter of graft material per 10(7) inoculum. All bacterial strains had a greater affinity to velour knitted Dacron graft than to ePTFE (p less than 0.025). E. coli and S. aureus adhered to velour knitted Dacron in greater numbers than to woven Dacron (p less than 0.04). The production of extracellular polysaccharide (mucin) by the RP-12 strain significantly increased adherence to both EPTFE and Dacron grafts compared with the other three bacterial strains tested (p less than 0.04). Although E. coli was less adherent to ePTFE than nonmucin-producing staphylococcal strains (S. aureus and SP-2), no difference in adherence to knitted or woven Dacron graft material was demonstrated. The differential adherence of bacteria to prosthetic vascular grafts pays an important role in the pathogenesis of graft sepsis and determines relative graft infectivity. The in vitro model developed is well suited for further study of the mechanisms by which bacteria adhere to and colonize vascular grafts.

Adhesiveness↗

PubMed1986

Multiple paradoxical emboli.

We report a case of multiple paradoxical emboli involving the common carotid, right subclavian, right renal, celiac, and superior mesenteric arteries. Paradoxical embolus is an uncommon but important cause of acute arterial occlusion. Successful management requires prompt recognition, prevention of further embolization, and treatment directed toward relief of the acute arterial occlusion.

Adult↗

PubMed1985

Classification of carotid bifurcation disease using quantitative Doppler spectrum analysis.

Spectrum analysis of continuous-wave Doppler recordings from the region of the carotid bifurcation was used to classify the degree of stenosis in the internal (ICA) and external (ECA) carotid arteries. Measurements of systolic peak frequency, end-diastolic frequency, and the degree of spectral broadening were used to define five ICA disease categories: 0% to 15% diameter reduction (DR), 16% to 49% DR, 50% to 80% DR, greater than 80% DR, and occlusion. The results were compared to contrast arteriography in 122 patients (243 arteries). The agreement with angiography in classifying ICA stenosis was 82%. Doppler spectrum analysis identified 96% of hemodynamically significant disease (greater than 50% DR) in the ICA and ECA and 97% of ICA occlusions. Attention to the common carotid artery waveform and the ICA diastolic frequency improved the accuracy of predicting greater than 80% DR and occlusion of the ICA. Noninvasive classification of carotid bifurcation disease is useful in clinical decision making to select the angiographic technique most likely to accurately define disease morphology and to follow up patients for disease progression.

Aged↗

PubMed1985

The significance of hydronephrosis after aortofemoral reconstruction.

Hydronephrosis due to ureteral obstruction is a rarely reported complication of aortic bypass grafting. Patients who had undergone aortic reconstruction were screened using serial real-time ultrasound examination to detect ureteral obstruction. The clinical course and incidence of graft complications, renal impairment, amputation, and death were determined for hydronephrotic patients and compared with the incidence of similar complications in a control group. Hydronephrotic patients had an extremely high incidence of graft infection, anastomotic aneurysm, graft thrombosis, and amputation. Obstructed ureters were at high risk for intraoperative injury during removal of infected aortic grafts. A subgroup of hydronephrotic patients who developed multiple anastomotic aneurysms without graft infection was identified. Hydronephrosis was frequently silent, and detection required active investigation. After aortic reconstruction, routine screening with real-time ultrasound examination appears warranted to identify a high-risk subset of patients.

Aged↗

PubMed1985

Lessons learned in adopting the in situ saphenous vein bypass.

A 3-year experience with in situ saphenous vein bypasses was analyzed to evaluate the suitability of the conduit, the effect on vein utilization rate, the ease of valve ablation, the incidence of persistent arteriovenous (AV) fistula, the duration of the operation, and the nature of the learning curve to become adept at this technique. From 1981 through 1983, 74 patients underwent 55 femoral-tibial and 23 femoral-popliteal in situ saphenous vein bypasses. The operative indications were threatened limb loss in 76 (97%) and disabling claudication in 2 (3%); 35 of 74 patients (48%) were diabetic. In the last year pulsed Doppler spectrum analysis was added to arteriography for intraoperative graft assessment. For 55 femoral-tibial grafts measured by life-table patency rates at 30 days, only one femoral-popliteal graft failed (1 1/2 years). Complete vein utilization was accomplished in 91% of the bypasses attempted. In 41 of the 78 (51%) grafts, vein diameter was 3.5 mm or less. Operative time decreased with experience. Pulsed Doppler spectral analysis has proved useful for intraoperative graft evaluation. The in situ saphenous vein has become the conduit of choice for infrageniculate bypass.

Adult↗

PubMed1985

A low flow velocity predicts failure of femoropopliteal and femorotibial bypass grafts.

The prognostic value of Doppler-derived blood flow velocity measurements for predicting the patency of femoropopliteal and femorotibial bypass grafts was analyzed. Peak systolic and end-diastolic blood flow velocities were measured in 42 femorotibial, 24 femoropopliteal, and three femoropopliteal (isolated segment) in situ saphenous vein bypasses at operation and serially in the postoperative period. At operation peak systolic flow velocity was greater (p less than 0.01) in femoropopliteal grafts (90 +/- 22 cm/sec) compared with femorotibial grafts (68 +/- 19 cm/sec) and isolated segment femoropopliteal (58 +/- 16 cm/sec) grafts. Diastolic forward flow, indicative of low outflow resistance, was present in all successful grafts at operation and in the immediate postoperative period, but decreased thereafter. Early graft occlusion was associated with a low peak systolic flow velocity (less than 40 cm/sec) and absent diastolic forward flow. Postoperative decrease in peak systolic velocity to less than 45 cm/sec identified grafts with impending failure due to intrinsic graft lesions or progression of atherosclerosis. A low blood flow velocity threatens graft patency and should prompt an angiographic evaluation to identify correctable graft lesions or an outflow tract suitable for sequential grafting for the purpose of augmenting flow velocity.

Adult↗

PubMed1984

Aortofemoral graft infection due to Staphylococcus epidermidis.

A ten-year review of aortofemoral graft infection documented Staphylococcus epidermidis as the infecting organism in 18 (60%) of 30 cases. Diagnosis of such infection required a high index of suspicion because of its late postoperative appearance (mean interval of 41 months) and the inability to identify a microorganism at operation by routine wound culture or Gram's stain. Clinical findings suggesting graft infection included multiple anastomotic aneurysms (18 patients), perigraft exudate (16 patients), a draining groin mass (five patients), and aortoduodenal fistulas (two patients). Due to the low concentration and virulence of the organism, aerobic culture of the prosthetic fabric in broth media provided the optimum method of confirming the S epidermidis infection. Total graft excision with immediate vascular reconstruction was the preferred treatment method and resulted in a mortality and major amputation rate of 11%.

Aneurysm↗