Biomedical subjects

M C Dalsing

Publications and source records attributed to M C Dalsing.

At least 55 records · Page 3Linked to original sources

PubMed1991

Clinical implications of combined hypogastric and profunda femoral artery occlusion.

From 1983 to 1990, nine patients with combined hypogastric (HA) and profunda femoral arterial (PFA) occlusive disease presented with five nonhealing hip disarticulations, three nonhealing above-the-knee amputations, perineal necrosis in six patients, buttock necrosis in four patients, visceral ischemia in two patients, and lumbosacral spinal ischemia in one patient. Obviously some patients had more than one regional complication. Five patients died from complications of HA/PFA ischemia. Survivors included two patients who required a hemipelvectomy, one patient who required an axillary-to-hypogastric artery bypass graft for stump salvage, and one patient who survived despite lumbosacral paralysis and complete cystectomy. The 56% mortality and 100% morbidity emphasize the critical significance of combined hypogastric/profunda femoral artery circulatory compromise. Efforts should be made to preserve or re-establish the HA and/or PFA circulation whenever possible. A hemipelvectomy may be required to allow the wounds to finally heal. Furthermore, the certainty of an above-the-knee amputation healing is not present in these patients; therefore, a hemodynamic assessment of the healing potential of an above-the-knee amputation is required.

Aged↗

PubMed1991

Venous valvular insufficiency: influence of a single venous valve (native and experimental).

This report evaluates the ability of a single competent (native or experimental) superficial femoral vein valve to correct canine hindlimb venous insufficiency. The time to maximal ankle venous pressure after standing (VFT) and to 90% of that time after exercise (VRT90), and the minimal pressure after exercise (AVP) were measured in 17 greyhounds before intervention, after only the superficial femoral vein valve remained (n = 5), and after complete lower limb venous valvulotomy (n = 17). Three weeks later, 12 dogs underwent a native (n = 4) or experimental (n = 8) autogenous venous valve transplantation. Immediately and at 3 weeks after transplantation, venous pressure measurements were obtained. The manual strip test confirmed valve competence at the time of sacrifice. Only one valve transplant became incompetent. Immediately after single superficial femoral vein valve construction, VFT, AVP, and VRT90 measurements were not significantly different from normal. Three weeks after transplantation the AVP measurements were consistent with an insufficient venous system, whereas the VRT90 measurements were between and statistically different from both the control and totally incompetent system (p less than 0.05). After the native valve but not the experimental valve transplantations VFT normalized. These data suggest that insertion of a single competent superficial femoral vein valve into an incompetent lower limb venous system corrects venous pressure measurements initially but soon provides only a partially competent system. The experimental valve, although competent, is less responsive than a native valve.

Animals↗

PubMed1991

Arteriovenous fistulas as adjuncts to venous bypass grafts.

A canine model of occlusive hindlimb venous hypertension was used to determine which of two different, clinically applicable, adjunctive arteriovenous fistulas (AVFs), sequential or peripheral, would augment flow in autogenous cross-femoral venous bypass grafts (CFBs) with the least alteration of hindlimb hemodynamics. Unilateral venous hypertension was produced by iliofemoral venous ligation in three groups of five dogs: group I, venous ligation only (controls); group II, venous ligation followed by CFB with a sequential AVF; and group III, venous ligation with CFB and peripheral AVF. Bilateral hindlimb venous and arterial pressures and flows, and graft flows, were measured preoperatively and for 4 h postoperatively. Insertion of a CFB eliminated the venous hypertension in all 10 bypass dogs. Graft flow was augmented by addition of the sequential AVF (to 1167 +/- 309 mL/min from 92 +/- 12.3 mL/min: p less than .0001). However, this was accompanied, both in the limb ipsilateral to the AVF and in the contralateral limb, by the return of significant venous hypertension (p less than .001) and significant reduction (even reversal) of femoral vein flow caudad to the CFB (p less than .005). In contrast, adding the peripheral AVF augmented graft flow (to 200 +/- 62 mL/min from 65 +/- 43.7 mL/min; p less than .0001), but did not elevate venous pressure or impair venous flow in either hindlimb. The data from this short-term canine model suggest that a peripheral adjunctive AVF may effectively augment CFB graft flow without the potential for detrimental effects on venous hemodynamics characteristic of the sequential AVF.

Animals↗

PubMed1991

Outcome predictors in selection of balloon angioplasty or surgery for peripheral arterial occlusive disease. Veterans Administration Cooperative Study No. 199.

In a selected group of men, surgical bypass and percutaneous balloon angioplasty (PTA) are equally effective therapy for ileo-femoropopliteal occlusive disease, provided immediate PTA failures are disregarded. Can we predict those patients likely to experience immediate PTA failure? Do any preintervention factors exist that favor PTA or surgical bypass for the remaining patients? Logistic regression analysis determined variables predictive of failure for the 19 immediate PTA failures and for the 17 patients with PTA and the 24 patients with surgical bypass who failed after initial intervention but before the end of 2 years. Two hundred sixty-three patients were enrolled. The analysis evaluated patient characteristics (age, weight, smoking status, diabetic status, and sickness impact profile score) as well as lesion site, percent lesion stenosis, runoff status, hemodynamic parameters, and indications. Two independent predictors of immediate PTA failure were diastolic hypertension (p = 0.032) and percent stenosis of study site (p = 0.035). The probability equation defined by the logistic regression analysis delineates patients at high risk for immediate PTA failure. Interestingly, no factor uniquely predicted delayed PTA or surgical failure. These data suggest that selected patients with diastolic hypertension and a severely stenotic or occluded artery are poor candidates for PTA. Either PTA or surgical bypass is effective therapy for the remaining patients.

Angioplasty, Balloon↗

PubMed1991

Hemodynamic effects of varied graft diameters in the venous system.

Both in vivo and mathematical models of venous hypertension were used to evaluate the hemodynamic effects of 4, 6, 8, and 10 mm diameter cross-femoral venous bypass grafts (CFBs). Eighteen grafts (length 138 +/- 3.4 mm) were tested in paired sequential fashion (four grafts, 4 and 8 mm; five grafts, 6 and 10 mm) in nine greyhounds (femoral vein diameter, 7.7 +/- 0.09 mm). Bilateral hindlimb venous pressures and flows were measured before and after unilateral iliofemoral venous ligation, 30 minutes after CFB insertion, and for 5 minutes after venous flow augmentation induced by stimulated muscle contraction. CFBs of all sizes were equally effective at relieving the occlusive venous hypertension at rest. Muscle contraction elevated venous pressure in all ligated hindlimbs (p less than 0.0001); however, the pressure returned to baseline by 3 minutes in dogs with 6, 8, and 10 mm grafts but remained elevated (p less than 0.05) with the 4 mm grafts even after 5 minutes. Peak graft flow (first 90 seconds after contraction) was significantly greater through the 8 mm grafts than through the 4 mm grafts (p less than 0.01), although no difference was noted in flow rates between 6 and 10 mm grafts. The pressure gradient across the graft as predicted by the mathematic model for 6 to 10 mm conduits was less than 5 mm Hg for flows up to 1000 ml/min, although the pressure gradient of the 4 mm graft exceeded 5 mm Hg at 200 ml/min and approached 30 mm Hg at 1000 ml/min. Therefore, data from both canine and mathematical models agreed that, at rates approximating human resting flow (1000 ml/min), no adverse short-term hemodynamic consequences result from CFB conduits of 6 to 10 mm diameter.

Animals↗

PubMed1991

Acute mesenteric venous thrombosis. Revisited in a time of diagnostic clarity.

Historically, mesenteric venous thrombosis (MVT) has been found during laparotomy or at autopsy. Improvements in computed tomography (CT) and ultrasound (U/S) may identify patients earlier in their clinical course. How has this altered the treatment strategy of the authors? This 10-year retrospective study of acute MVT consisted of 12 men and three women (average age 43). Presenting signs and symptoms were nonspecific in 10/15 patients resulting in multiple diagnostic tests. All CT scans (10) and angiograms (4) revealed mesenteric clot. U/S exams detected clot in 6/9 patients. The remaining five patients exhibited clinical signs requiring operations rather than diagnostic studies. The only consistent laboratory abnormality was an elevated white blood cell count in 12/15 patients. Management of MVT varied. Five patients, heparinized once the diagnosis was made, did not experience dysfunction from MVT. Ten patients were not initially treated with heparin and were divided into three groups. Three patients received neither heparin nor surgery and have had no sequelae. MVT contributed to the death of two patients. The remaining five patients were diagnosed in the operating room following bowel resection. Two of these patients received postoperative heparin and had a favorable outcome. Two of the three patients not heparinized after surgery suffered additional bowel infarction. MVT can present as nonspecific abdominal pain, but also as peritonitis requiring operation. CT and U/S can identify patients with early MVT. It appears that heparin has both a primary therapeutic role in early disease and a postoperative adjunctive role in advanced disease. With such care, these patients can expect an acceptable prognosis (86% survival).

Acute Disease↗

PubMed1991

Inadequacy of saphenous vein grafts for cross-femoral venous bypass.

A mathematic model of unilateral iliac vein obstruction was used to establish the theoretic basis for selecting saphenous vein or a larger diameter prosthetic cross-femoral venous bypass graft for relief of obstructive venous hypertension. Common femoral vein resting and postexercise peak flows, and common femoral vein and saphenous vein diameters were measured in 18 healthy individuals and used to estimate the pressure gradient (dP) across 20 cm long cross-femoral venous bypass grafts of saphenous vein or 4, 6, 8, 10, and 12 mm prosthetic conduits, in the presence of a transpelvic venous collateral network of varied cross section. The upper limits of normal for the gradients in our model (dPstd) were set at 4 mm Hg for resting flows and 6 mm Hg after exercise. Mean saphenous vein diameter was 4.3 +/- 0.22 mm, which was 36.5% +/- 1.73% of common femoral vein diameter. When the saphenous veins of two thirds of the individuals in our study were used as theoretic cross-femoral venous bypass conduits, greater than 80% of postobstruction peak cross-femoral venous bypass graft flow had to be carried by collaterals to maintain a gradient less than or equal to dPstd. We demonstrated that 4.5 to 6.0 mm diameter saphenous cross-femoral venous bypass grafts would be hemodynamically efficacious in relieving venous hypertension, but only when implanted in parallel with an existing venous collateral network that limited the preoperative dP to 4.5 to 7.5 mm Hg at resting flows and 7.0 to 11.5 mm Hg after exercise; only 44% of saphenous veins were adequate for cross-femoral venous bypass grafts by these criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Venous hemodynamics in a chronic venous valvular insufficiency model.

To develop a large-animal model of chronic venous valve incompetence, 13 greyhound dogs underwent unilateral hindlimb venous valve lysis with a valve cutter apparatus pulled retrograde through the iliac, femoral, and lateral saphenous veins. Bilateral venous pressures in the lateral saphenous vein were recorded before valve lysis, immediately after valve lysis, and at intervals from 1 to 14 weeks after valve lysis, with the dogs in the supine position and elevated 80 degrees semierect, as well as after stimulated hindlimb muscle contraction to empty the hindlimb veins. Passive venous filling time with elevation and 90% venous refilling time after muscle contraction were calculated. From immediately after through 14 weeks after valve lysis, a shortened venous filling time and 90% venous refilling time as well as an elevated poststimulation venous pressure were noted. This valve lysis method successfully produced a hemodynamically verified model of venous valvular insufficiency.

Animals↗

PubMed1990

CO2-welded venous anastomosis: enhancement of weld strength with heterologous fibrin glue.

The milliwatt CO2 laser was used to perform end-to-end anastomoses in canine jugular veins. There was a high disruption rate (50%) in laser-welded veins (n = 10). Fibrin glue (n = 17), formed from human fresh-frozen plasma, enhanced the weld strength decreasing the disruption rate (18%), resulting in an 82% patency which nearly equaled the contralateral sutured vein patency (93%). The bursting strength was improved with fibrin glue. Transmural necrosis was present initially in all groups but extended for a longer distance in the vessel wall in laser-welded anastomoses. Sutured anastomoses exhibited a greater inflammatory response. In laser-welded anastomoses endothelial cells were not as confluent as in sutured anastomoses by six weeks. Carbon dioxide laser-welded end-to-end vein anastomoses appear to be impractical because they disrupt too easily. However, the addition of heterologous fibrin glue to the weld results in a reasonably strong anastomosis with histologic properties that may be beneficial in vein bypass grafts.

Anastomosis, Surgical↗

PubMed1990

An experience with upper-extremity vascular trauma.

In this 6-year study of 101 limbs requiring surgical intervention for upper-extremity vascular trauma, most patients were male, young, and injured by penetrating objects. Injured vessels included 13 axillary/subclavian, 23 brachial, 40 radial, and 25 ulnar arteries. Concomitant injuries included nerve injury in 50 cases, tendon laceration in 29, and bony fracture in 11. Arterial repair was accomplished by primary repair in 54 limbs, vein graft in 26 limbs, and vein patch in 3 limbs. Seventeen arterial injuries were ligated. Ancillary procedures included 30 nerve or 27 tendon repairs. The limb salvage rate was 99%. No functional deficits were noted in those cases with only a vascular injury. In 64% and 25% of patients with nerve or musculoskeletal injury, respectively, the arm was functionally impaired. Prompt diagnosis and surgical intervention eliminate vascular injury as a factor in upper-extremity limb loss or disability. Functional deficits are the result of nerve or orthopedic injuries.

Adolescent↗

PubMed1990

Angioplasty-induced dissections in human iliac arteries: management with Palmaz balloon-expandable intraluminal stents.

Intravascular stent placement may be an effective treatment for percutaneous transluminal angioplasty (PTA)-induced dissection. Among the first 228 patients treated with Palmaz balloon-expandable intraluminal stents (BEISs) for iliac artery stenosis, stents were used to treat PTA-induced dissection in at least 12 iliac arteries in 11 patients. All 12 vessels were shown by angiography to be severely dissected. Stents were placed at the time of PTA in six vessels and as a separate procedure in the other six. An average of three stents per vessel were employed. All arteries showed marked improvement at angiography. Angiographic follow-up was obtained for eight vessels in seven patients at a mean follow-up time of 12.9 months. All had patent stent lumens with neointima formation, although one stented lumen had narrowed, and another clinical failure occurred despite a patent stented vessel and an ankle-arm index (AAI) of 1.35. With a mean clinical follow-up of 9.5 months, the mean AAI for the stented extremities in the nine remaining patients is 0.91 +/- 0.15. Palmaz BEISs are effective in the management of PTA-induced human iliac artery dissection.

Adult↗

PubMed1990

The training of carotid endarterectomy during an era of controversy. A personal experience.

One hundred carotid endarterectomy (CEA) procedures were performed in this teaching institution from August, 1984 to January, 1989 under the direction of the author. Presenting symptoms were TIA (36), CVA (25), amaurosis fugax (17), and asymptomatic carotid stenosis greater than 80 per cent (22). The average age was 61.8 years and 68 per cent were male. The operation was performed through a transverse neck incision with the use of flaps, a shunt was used (96%) and the artery closed primarily (95%). The heparin given was not reversed. There was no operative mortality and the stroke morbidity consisted of one permanent (1%) and one temporary (1%) deficit. Hematoma evacuations were required in four cases; one had a demonstrable bleeding point. The long-term stroke rate was 1.62 per cent, with overall survival of 94 per cent at 42 months. Restenosis following repair was noted in only 5.5 per cent of the cases at one year. When carotid endarterectomy is performed in a teaching institution, excellent early results (2% combined stroke/mortality rate) are maintained long-term. Furthermore, a 50-plus per cent decrease in the risk of stroke at 42 months is demonstrated when this study's results are compared to estimates of the natural history of significant carotid disease.

Adult↗

PubMed1989

The CO2 laser as an intraluminal repair tool.

The CO2 laser can weld vessels together and vaporize plaque. This study evaluates its use as an intraluminal reparative tool. In 17 dogs, a 1-cm circumferential intimectomy with a 1-mm distal intimal flap was performed in both carotids. In each dog, one carotid (CON, control) underwent suture flap repair. On the contralateral side (LR, laser repair), the flap was tacked with 20 250-mW 1-sec pulses and the denuded medium was g-lased for 90 sec (250 mW continuous). Animals were randomized into five groups and sacrificed on the day of surgery (Group I, n = 3), at 3 days (Group II, n = 3), at 1 week (Group III, n = 4), at 2 weeks (Group IV, n = 4), or at 4 weeks (Group V, n = 3). Vessel patencies were 88.2 and 82.4% for CON and LR, respectively. Flap repair appeared similar. No aneurysms were noted. Histology revealed a relative absence of platelet adherence to the g-lased surfaces in Groups I and II when compared to that of mechanical methods (CON). The ratio of the thickness of the regenerated surface to the total wall thickness demonstrated hyperplasia in LR vessels (0.54 +/- 0.12) when compared to that in CON (0.30 +/- 0.15) at 2 and 4 weeks (ANOVA, P less than 0.001). Coverage with endothelial-like cells appeared complete at 4 weeks in both methods. The CO2 laser can effectively repair intimal flaps. However, our results demonstrate a significant increase in medial hyperplasia following g-lasing even in the face of minimal early platelet adherence. This may prove detrimental to the long-term patency of intraluminal CO2 laser-treated vessels.

Animals↗

PubMed1989

Acellular vascular matrix: a natural endothelial cell substrate.

A preliminary assessment was made of the acellular vascular matrix graft as a substrate for endothelial cell seeding, with respect to surface pretreatment (none versus fibronectin and/or serum) and presence of exogenous growth factor. Arteries were harvested from greyhounds and exposed to a sequential detergent extraction process to produce the acellular vascular matrix. Human umbilical vein endothelial cells were grown in tissue culture, harvested in first passage, then seeded at 10(5) cells/cm2 on sections of acellular vascular matrix and on gel-coated polystyrene positive controls. After 18 hour incubation, endothelial cell-seeded acellular matrices were fixed and processed for histologic and planimetric analysis; control wells were fixed and endothelial cells were counted by planimetry. Pretreatment of the acellular vascular matrix was found to have no effect on the percentage of endothelial cell coverage of the matrix. There was significantly better endothelial cell coverage of the acellular matrix than on matched gel-treated polystyrene control wells. Withdrawal of growth factor resulted in a significant reduction in endothelial cell coverage for all acellular vascular matrix groups. Growth factor withdrawal also significantly reduced attachment of endothelial cells on gel-treated polystyrene. Cell surface area was significantly smaller when growth factor was withdrawn from all groups except from the acellular vascular matrix without pretreatment. We conclude that: (1) the acellular vascular matrix is conductive to endothelial cell adherence and spreading even without pretreatment; and (2) sudden withdrawal of exogenous growth factor may impair early coverage of substrates by endothelial cells due to an effect on their adherence or spreading.

Animals↗

PubMed1989

An experimental collagen-impregnated Dacron graft: potential for endothelial seeding.

This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost.

Blood Vessel Prosthesis↗

PubMed1989

Limb salvage in high-risk patients with multisegmental disease.

Is percutaneous iliac angioplasty before distal bypass a logical limb salvage option in a high-risk patient? A retrospective review of 113 iliac angioplasty procedures identified 10 patients in this situation. Angioplasty preceded femoropopliteal bypass (five), femorotibial bypass (three) and, in one case each, femorofemoral bypass or profundoplasty. There were no interventional deaths or complications. Ankle/brachial pressure index improvement followed intervention: 0.28 + 0.2 vs. 0.92 + 0.08, (p less than 0.0005). Limb salvage was 90% at one month, 80% at six months and 70% at one to three years by Life-Table analysis. Two patients with a patent bypass lost limbs from uncontrolled infection within two months. One patient required an amputation 311 days after the only failure of angioplasty and distal bypass. During this study period, 56% of the patients died. This review supports an angioplasty/bypass combined intervention as a valuable treatment option in high-risk patients facing limb loss.

Aged↗

PubMed1988

Carotid plaque morphology: correlation of duplex sonography with histology.

This study attempted to determine whether images obtained during preoperative duplex scanning correlated with histologic studies of carotid endarterectomy plaque and, therefore, might be useful in subsequent studies of the importance of plaque morphology and intraplaque hemorrhage. Forty-six endarterectomy specimens from 44 patients with satisfactory preoperative images were evaluated. The plaques were marked for orientation at the time of removal, and each plaque was imaged by duplex scanning in a saline bath. Magnification radiographs were made. Specimens were embedded in paraffin and slices 6 mu thick were made for staining with hematoxylin and eosin, Masson's trichrome, a modified Verhoeff-vanGieson stain, and von Kossa's stain. Overall, correlation between the preoperative images and the histologic specimens were good to excellent in 42 of 46 specimens. Scanning did not identify three cases of extensive recent intraplaque hemorrhage, however, and one instance of plaque calcification was missed. We conclude that duplex images correlate well with histologic studies except in some cases of recent intraplaque hemorrhage. Duplex imaging is valuable in the correlation of plaque morphology with symptoms for long-term studies. The accuracy of the technique may be improved by using post-processing on static images and in vitro scanning of endarterectomy specimens.

Aged↗

PubMed1988

Lower extremity vascular trauma: a comprehensive, aggressive approach.

During this study, 25 patients (26 limbs) incurred 37 vascular injuries to the lower extremity. The majority were young males injured by penetrating trauma (84%). There were 25 arterial and 12 venous injuries (two isolated). Sixteen patients had soft-tissue injuries, 12 had fractures, and six had peroneal nerve damage. Twenty-two arterial injuries were repaired, the majority (17) by saphenous vein bypass. Three tibial vessels were ligated. All major venous injuries were repaired. No synthetic material was used. Vascular repair took precedence in all but two cases. After repair, the vascular surgeon assisted with stabilization. Thirteen limbs required fasciotomy; nine required subsequent debridements and later plastic reconstruction. Limb salvage was 96%. More important, 21 patients can ambulate independently on the injured extremity (84%). These results support an aggressive approach to lower extremity vascular trauma with repair of all major arterial and venous injuries in conjunction with aggressive debridement and soft-tissue repair.

Adolescent↗