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Biomedical subjects

R H Samson

Publications and source records attributed to R H Samson.

At least 37 records · Page 2Linked to original sources
PubMed1985

Collateral back pressure--is it a valid predictor of infrainguinal bypass graft patency?

While it is generally thought that collateral back pressure (CBP) is a reliable predictor of graft patency, this correlation has not yet been validated. We have used a new, simple technique to measure CBP without direct puncture of the recipient artery. After the distal anastomosis is completed, the graft is filled with saline and clamped proximally. A transducer connected needle is then inserted into the distal portion of the graft for CBP measurements (mm Hg). These were obtained in 84 grafts (43 femoropopliteals [FP] and 41 femorodistals [FD]). Outflow resistance (OR) measurements (mm Hg/ml/min) were also obtained in 70 (36 FP; 34 FD) of these grafts by a previously described technique. The mean CBP for FP and FD bypasses was 41 +/- 17 and 26 +/- 19 mm Hg, respectively (P less than 0.001). Although early graft patency (3 months) (13 occluded, 71 patent) did not correlate with angiographic findings of popliteal runoff or integrity of pedal arch, it did significantly relate to CBP. Mean CBP for occluded grafts was 22 +/- 17 mm Hg and for patent grafts it was 36 +/- 19 mm Hg (P less than 0.01). Similarly, mean OR was significantly related to patency, 1.29 +/- 0.23 mm Hg/ml/min for occluded grafts and 0.36 +/- 0.23 mm Hg/ml/min for patent grafts (P less than 0.0001). Moreover, only OR was a significant predictor of infrapopliteal graft patency (P less than 0.01). OR was found to be a better predictor of graft patency than CBP by stepwise logistic regression analysis (P less than 0.0001). We conclude that CBP is a more reliable predictor of graft outcome than angiographic criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1985

Perioperative noninvasive hemodynamic ankle indices as predictors of infrainguinal graft patency.

Of 129 femoropopliteal bypasses, 40 closed in 0 to 42 months. Early and late closures were not predicted by pre- or postoperative ankle/brachial pressure index (ABPI) or ankle pulse volume recording amplitude (APVR) or their increments (delta). Of 141 femorotibial bypasses, 60 closed in 0 to 12 months, with 46 closing early (less than 1 month). Early failure occurred in 19 of 52 limbs (37%) with pre-ABPI less than 0.2 and 17 of 89 limbs (19%) with pre-ABPI greater than 0.2 (p less than 0.025). Similar significant differences in early patency occurred between limbs with pre-APVR less than 5 and greater than 5 mm (29 of 94 [34%] vs. 7 of 47 [15%], respectively). Late closure was not predicted by either value. Thus in the 44 limbs with pre-ABPI greater than 0.2 and pre-APVR greater than 5 mm, only 11 grafts closed (25%), whereas if pre-ABPI was less than 0.2 or pre-APVR less than 5 mm, 49 of 97 grafts (51%) occluded within 17 months (p less than 0.025). Postoperative or delta indices had no predictive value. Preoperative ABPI less than 0.2 or APVR less than 5 mm was associated with twice the risk of early femorotibial graft closure; however, cumulative life-table patency was still 39% at 24 months.

Ankle↗
PubMed1985

Tibiotibial vein bypass grafts: a new operation for limb salvage.

Tibiotibial bypasses were performed with short (8 to 33 cm) segments of reversed autologous vein in 14 patients who did not have longer segments of usable vein. All patients faced imminent amputation unless they had an effective revascularization. Two patients died, one within 1 month of operation. One patient required below-knee amputation despite a patent bypass. Eleven patients (79%) have a patent bypass and a functional limb 6 to 50 months after operation. These good patency results even with several grafts inserted into isolated segments of tibial arteries, some with incomplete plantar arches, suggest that these short vein grafts may be superior to other vein grafts. Tibiotibial bypasses may improve limb salvage results in otherwise difficult circumstances.

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PubMed1985

Combined segment arterial disease.

CSAD provides a challenge for the vascular surgeon. Patients are older, sicker, and at greater risk than are patients with unisegmental disease. Similarly, symptoms are more severe and limb loss is more frequent. A multitude of different reconstructive techniques are available, but their injudicious or untimely use can not only fail to improve the patient but can also cause limb loss or death. Their use must be predicated by a differentiation of which arterial segments are hemodynamically involved, yet this determination may not be possible even after extensive noninvasive and invasive investigation. To optimize the approach to these patients, the following principles should be employed. First, incapacitating claudication is a valid indication for a suprainguinal inflow procedure in a good-risk patient. However, indications for surgery should usually be limited to limb salvage, especially if an infrainguinal procedure is contemplated. Medical conditions such as heart failure and diabetes should be improved before arteriography. The latter should delineate the entire infrarenal arterial system, with special attention to the iliac, deep femoral, and pedal arteries. Oblique views may be of critical importance. Noninvasive hemodynamic tests should be used to confirm the need for arterial reconstruction and help delineate areas of functional stenosis. Direct pull-through pressure measurements may be required for ultimate confirmation. If proximal disease is thus defined, as proximal inflow operation should usually be sufficient unless there is extensive gangrene of the foot, in which case synchronous distal grafts may be required. If the proximal graft alone is performed, the patient must be followed closely since approximately 10% of patients may need subsequent distal reconstructions. The role of the "runoff" segments such as the deep femoral artery, popliteal trifurcation, and pedal arteries may be critical. Every effort should be made to ensure flow through these vessels. Profundoplasty alone is seldom indicated but is often a valuable adjunct to other reconstructive procedures. Lumbar sympathectomy is seldom required. PTA is becoming a valuable adjunct to treatment of CSAD, and intraoperative dilatation also has potential attributes. If such an approach is followed, lasting limb salvage with minimal morbidity should be achieved in most patients with CSAD.

Aging↗
PubMed1985

Comparison of axillounifemoral and axillobifemoral bypass operations.

Routine use of axillobifemoral (ABF) bypass has been advocated because this operation is thought to achieve better patency than the axillounifemoral (AUF) procedure. In 5 years we performed 34 AUF and 22 ABF bypass operations for limb salvage in high-risk patients using 6 mm polytetrafluoroethylene grafts. Five-year cumulative life table patency rates for AUF bypasses were 71% with reoperation (secondary patency) and 44% without reoperation (primary patency). These values were not significantly different (p greater than 0.5) from those for ABF bypasses (77% and 50%, respectively). Five-year limb salvage results (AUF 73%; ABF 89%) were also not significantly different (p greater than 0.1). Correlation of arterial outflow characteristics with graft patency revealed that 78% of the patients who never had graft occlusion had occluded superficial femoral arteries (SFA) demonstrated at the first operation, while 79% of the patients who experienced graft closure had comparable SFA occlusions. Our aggressive approach to graft thrombosis included angiographic study of the inflow arterial system. This revealed that 16% of the failed grafts were associated with hemodynamically significant stenosis of the donor subclavian artery. Our results indicate that AUF bypass is the procedure of choice for unilateral limb ischemia in high-risk patients who require an axillary source and that patency of the SFA does not affect outcome. These results also emphasize the need to obtain angiographic evaluation of the inflow system.

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PubMed1984

Inadequacy of the noninvasive hemodynamic evaluation of percutaneous transluminal angioplasty.

The role of noninvasive hemodynamic tests in the evaluation of percutaneous transluminal angioplasty success or failure was studied. The ankle-brachial pressure index and pulse volume recording amplitude were measured before and after 37 iliac and 46 femoropopliteal angiographically successful percutaneous transluminal angioplasties. Immediate evidence of hemodynamic improvement was seen in 53 percent of angiographically successful dilatations using the ankle-brachial pressure index and in 60 percent using the pulse volume recording amplitude alone. A better correlation was seen when improvement was noted on either test but was still only 71 percent. Twelve primary iliac percutaneous transluminal angioplasties were considered to be successful immediately by angiography, yet no hemodynamic improvement was recorded. Nine primary iliac percutaneous transluminal angioplasties, however, had continued clinical success and limb viability. Twelve angiographically successful femoropopliteal percutaneous transluminal angioplasties also showed no improvement in hemodynamic values, yet three have continued clinical evidence of patency. Thus, although noninvasive hemodynamic tests are important and must be carried out, they are only one of many ways to assess the effectiveness of angioplasty.

Adult↗
PubMed1984

Evaluation of graft patency utilizing the ankle-brachial pressure index and ankle pulse volume recording amplitude.

To determine femoropopliteal graft patency, the ankle-brachial pulse index and the ankle pulse volume recording amplitude were measured. Fourteen healthy volunteer subjects were tested on two occasions over 24 hours (ankle-brachial pressure index 1.14+:-0.16, change 0.03+:-0.05; ankle pulse volume recording amplitude 25+:-7 mm, change 5+:-4 mm). In the second control group, hemodynamic function in the unoperated limb was studied before and after surgery in 40 patients undergoing infrainguinal bypass on the contralateral side (preoperative ankle-brachial pressure index 0.66+:-0.3, change 0.02+:-0.12; preoperative ankle pulse volume recording amplitude 8+:-7 mm, change 1+:-3 mm). After 119 patent femoropopliteal bypasses ankle-brachial pressure index and ankle pulse volume recording amplitude increased by 0.41+:-0.26 and 11+:8 mm, respectively.

Ankle↗
PubMed1984

Quantitative assessment of outflow resistance in lower extremity arterial reconstructions.

Graft patency is thought to correlate with resistance in the runoff bed or outflow resistance. However, accurate measurement of this parameter has been difficult. A simple and reproducible method for direct measurement of outflow resistance following completion of the distal anastomosis of a bypass graft has been developed. This method employs injection of a fixed amount of normal saline through the proximal end of the graft and measurement of the resulting integrated pressure increment by an analog computer. Division of this pressure integral by the volume injected is a measure of the outflow resistance expressed in resistance units (mm Hg/ml/min). The median outflow resistance in 31 femoropopliteal bypasses was 0.29 units with a range of 0.08-1.38 units. The median outflow resistance in 33 femorodistal bypasses was 0.7 units with a range of 0.18-2.34 units. All bypasses with an outflow resistance of 1.1 units or less remained patent for 3 months. There were 51 grafts in this group (30 femoropopliteal; 21 femorodistal) and their outflow resistance ranged from 0.08 to 1.1 units. All bypasses with an outflow resistance of 1.2 units or higher thrombosed within the first postoperative month. There were 13 grafts in this group (1 femoropopliteal; 12 femorodistal) and their outflow resistance ranged from 1.2 to 2.38 units. Eight of the 13 grafts that failed originally were subjected to thrombectomy, which was uniformly unsuccessful. Although this method does not yet allow bypass surgery to be denied to any patient, it does define a group of patients in whom thrombectomy will not be effective and should not be attempted.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1984

Components of outflow resistance and their correlation with graft patency in lower extremity arterial reconstructions.

We have used a simple reproducible method to measure total outflow resistance (OR) and its proximal and distal components in 101 bypasses (46 femoropopliteal [FP] and 55 femorodistal [FD]). All bypasses with a distal OR greater than 1.2 mm Hg/ml/min failed within 3 months and all with distal OR less than 1.2 mm Hg/ml/min remained patent for at least 3 months. To evaluate the contribution of vasospasm to OR and its role in graft failure, 60 bypasses (29 FP, 31 FD) had OR measurements before and after local infusion of papaverine hydrochloride (60 mg). Within 3 months, nine grafts (all FD) occluded and 51 remained patent. All nine failures had distal OR greater than 1.2 mm Hg/ml/min before papaverine infusion. After infusion, the mean percentage decrease in both total and distal OR for all grafts was 30% and 31%, respectively. However, there was no significant difference between these papaverine-induced decreases in OR and 3-month graft failure or success. Moreover, in three bypasses, even though papaverine lowered the distal OR from greater than 1.2 to less than 1.2 mm Hg/ml/min, early occlusion occurred. In six grafts (1 FP, 5 FD) when total and distal OR before and after papaverine was greater than 1.2 mm Hg/ml/min, the graft was extended to a second distal artery as a sequential bypass. These six grafts have remained patent over 3 months. Thus measurement of OR and particularly distal OR is a most accurate predictor of early graft success or failure. Pharmacologic manipulation does not enhance the predictive value of the OR measurement. OR measurements also help to select those FD bypass cases in which extension to a second distal artery as a sequential bypass improves patency.

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PubMed1984

Management of angioplasty complications, unsuccessful procedures and early and late failures.

Limb-salvage was the indication for 90% of 206 attempted PTAs in 175 patients between 1976 and 1982. Life-table patency rates at 4 years for the angiographically successful iliac PTA and femoropopliteal PTA were 78% and 50%, respectively. PTA of eight iliac, seven femoropopliteal, nine tibial, and two subclavian arteries and one autogenous saphenous vein graft (ASV) were unsuccessful. Of these, 17 subsequently underwent successful bypass grafts and five required below-knee amputations. Ten iliac, 37 femoropopliteal, four tibial, and two ASV graft PTAs failed. Of 20 repeat attempts at PTA, only two have achieved long-term patency. Appropriate surgery allowed limb salvage in 23 of 36 early failures (less than 3 months) and 12 of 14 late failures (greater than 3 months), and usually consisted of the same operation that would have been performed had PTA not been attempted. Fifty-two complications were classified according to the method of treatment. Fourteen warranted surgery, but in 10 this was successfully achieved by the same operation that would have been required had PTA not been performed.

Adult↗
PubMed1984

System for widespread application of microcomputers to vascular surgery.

The application of microcomputers to vascular surgery has been limited because of the lack of software that allows collection and effective evaluation of a large amount of patient-related data. We have developed a microcomputer-based data handling system for evaluating vascular patients that is inexpensive ($6000 to $8000), easy to use, and flexible. Its simplicity for nonprogrammers is achieved through a natural interface with menu-driven operations and descriptive English language messages. With this system eight data entry forms were designed, and data on more than 1000 patients treated for peripheral vascular disease over the last 7 years were entered into the computer by clerical personnel with minimal training. A query language report generator allowed us to obtain reports of results in simple English on any set of selection criteria with all relevant statistical functions, including cumulative life-table patency rates. This system has the following advantages: rapid evaluation of data from several retrospective and prospective studies, such as comparison of graft material, effect of local and systemic risk factors, cost of limb-salvage surgery, and correlation of noninvasive laboratory tests with other parameters; more accurate patient follow-up, with elimination of many of the pitfalls involved in observing large groups of patients frequently; and quantitation of individual surgeon or service results for quality control and self-review, which guide the vascular surgeon to modify treatment protocols, patient selection, and/or surgical techniques. Wider use of this system for data collection and evaluation will help to standardize data reporting and thus allow accurate comparison of data from different centers.

Computers↗
PubMed1984

Staging of arterial complications of cervical rib: guidelines for surgical management.

Subclavian artery compression by a cervical rib is an uncommon but potentially disabling condition. A series of 12 patients with 15 arterial lesions is reviewed and a staging system proposed to provide guidelines for managing patients with this condition. Stage I lesions have only arterial stenosis and minor poststenotic dilatation and are managed by thoracic outlet decompression, usually consisting of cervical rib resection. Stage II lesions have intrinsic arterial damage usually with subclavian aneurysm formation and require rib resection, aneurysmectomy, and arterial reconstruction. Stage III lesions present with distal thromboembolic complications and require thrombectomy or embolectomy in addition to thoracic outlet decompression and arterial reconstruction. The anatomic and pathophysiologic bases of the syndrome are reviewed and clinical and angiographic examples of each stage are presented.

Adult↗
PubMed1983

Limb-threatening vascular disease in patients with coincidental malignancy. An approach to management.

The association of severe peripheral arteriosclerotic occlusive disease and cancer is unusual. Review of 14 patients with both conditions treated by arterial reconstruction demonstrated excellent limb salvage without prejudice of survival or patency. Accordingly, we believe that limb salvage operations should be considered in patients with limb-threatening peripheral vascular disease and an associated cancer.

Adult↗
PubMed1983

A technical aid for the difficult embolectomy.

Occasionally an embolectomy cannot be performed because of failure of the catheter to pass beyond the embolus. We employ a technique that overcomes this problem when it is due to a holdup of the catheter in a branch orifice or atheromatous recess.

Catheterization↗
PubMed1982

Fallibility of intra-operative gram stain in the diagnosis of vascular infection.

Three cases of arterial-graft infection are presented. In all cases the gram stain obtained at surgery demonstrated white blood cells but no bacteria. Cultures obtained at operation subsequently grew Pseudomonas aeruginosa in two patients and Bacteroides fragilis in one patient. Failure to recognize the fallibility of the gram stain in the diagnosis of vascular infection may result in incorrect management decisions.

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