Peripheral Bypass Procedures Research Articles

Peripheral vascular surgery with magnetic resonance angiography as the sole preoperative imaging modality

Purpose: Magnetic resonance angiography (MRA) is a developing technique that provides arteriograms without the risks associated with iodinated contrast and arterial puncture or the expense of hospitalization. Prior reports have demonstrated the accuracy of peripheral vessel MRA for evaluation of the aorta through pedal vessels. This study sought to determine whether vascular reconstructions could be planned and accomplished on the basis of MRA alone.Methods: Eighty consecutive candidates for bypass with ischemic rest pain or tissue loss were studied with preoperative outpatient MRA of the juxtarenal aorta through the foot. Confirmation of MRA findings was provided by intraoperative intraarterial pressure measurements for proximal vessels and postbypass arteriography for the runoff. Life-table analysis of graft patency and limb salvage was performed.Results: Two patients could not tolerate MRA and required contrast arteriography, but all others underwent reconstructive procedures on the basis of MRA alone (11 aortobifemoral, 67 infrainguinal). Intraoperative findings regarding suitability of inflow and outflow vessels confirmed the accuracy of the MRAs in every case. MRA indicated that none of the patients undergoing infrainguinal bypass had significant inflow occlusive disease, and this was confirmed at operation with pressure measurements of inflow vessels that were always within 10 mm Hg (peak systolic) of systemic pressure. The results of intraoperative completion arteriography and preoperative MRAs were identical for all but two patients who had minor discrepancies. All aortobifemoral reconstructions remained patent, and all limbs remained intact. The infrainguinal reconstructions had an 84% limb salvage rate and 78% primary graft patency rate at 21 months. Comparison of charges for patients undergoing preoperative MRA versus contrast angiography showed a cost savings of $1288 for each patient treated with preoperative MRA alone.Conclusions: MRA is a noninvasive, cost-effective outpatient imaging technique that, if properly performed and interpreted, is sufficient for planning peripheral bypass procedures. Its use may supplant contrast arteriography in many patients.

Saphenous Vein Endothelium-Dependent Relaxation in Patients with Peripheral Vascular Disease

In vitro vasomotor responses of saphenous veins of 15 patients undergoing peripheral vascular bypass procedures were studied. Vessels were harvested by standard techniques, sectioned into 4 mm rings, and suspended in organ baths under isometric tension. Stimulation with cumulative doses of norepinephrine revealed a -logED50 of 6.85 +/- 0.12 M and maximal tension of 8.64 +/- 1.77 g. Patient characteristics suggesting high maximal response (by univariate analysis) included male sex (male 11.69 +/- 2.49 g versus female 5.08 +/- 1.69 g; p = 0.058). Intact and denuded rings were additionally tested for endothelium-dependent relaxation following submaximal norepinephrine precontraction. The vessels relaxed in response to acetylcholine (maximal relaxation 31.1 +/- 10.7% at 1 x 10(-6) M), calcium ionophore A23187 (85.3 +/- 11.8% at 1 x 10(-5) M), and sodium nitroprusside (150.8 +/- 15.2% at 1 x 10(-5) M), but only acetylcholine relaxation was completely endothelium-dependent. Calcium ionophore A23187 relaxation was partially dependent on the endothelium while sodium nitroprusside relaxation was entirely endothelium-independent. Negligible relaxation was observed in response to adenosine diphosphate (ADP) (12.1 +/- 12.8% at 1 x 10(-5) M) while histamine and serotonin caused additional contraction only. We concluded that, in patients undergoing vascular surgical procedures, the saphenous vein (1) demonstrates variable contractile function which appears to be greater in males following spinal anesthesia, and (2) exhibits moderate endothelium-dependent relaxation in response to acetylcholine and calcium ionophore A23187 but not to ADP, histamine, or serotonin.

Routine intraoperative angioscopy in lower extremity revascularization.

The inability to see through blood remains the main obstacle to the widespread and routine use of angioscopy. Local irrigation with a balanced salt solution is presently the most widely used method to clear the blood. By applying basic principles of irrigation and using a unique, dedicated, irrigation pump, we found that routine angioscopy during lower extremity revascularization that yields consistent high-quality studies is feasible, clinically useful, and safe. Between May 1, 1987, and July 31, 1988, 136 intraoperative angioscopies were performed during 112 peripheral bypass procedures, 15 thrombectomies, 2 embolectomies, and 7 miscellaneous revascularization procedures. Mean total irrigation fluid used in the peripheral bypasses was 398 mL (range, 0 to 1400 mL). Good visual quality was obtained in more than 80% of angioscopies and the failure rate was only 1.8%. On the basis of the findings in 71 of the 136 angioscopies, 78 clinical or surgical decisions were made. No complications were directly attributable to the insertion of the angioscope or use of the pump.

Noninvasive evaluation of peripheral vascular disease using transcutaneous oxygen tension

Transcutaneous oxygen tension (P tcO 2) was used for noninvasive determination of blood supply in 25 patients evaluated for peripheral arterial disease. p tcO 2 values were compared with segmental Doppler pressure, pulse volume recording, pulse reappearance time, and angiography in patients being evaluated for wound healing problems, amputations, and peripheral bypass procedures. P tcO 2 was measured using a heated (45 °C) Clark polarographic electrode to quantitate the oxygen which diffuses from the dermal capillaries to the skin surface. Control P tcO 2 values recorded over the chest or shoulder taken while patients were breathing room air were 78 ± 8 mm Hg. P tcO 2 values greater than 50 mm Hg predicted success for levels of amputation and for wound healing without reconstructive procedures; values of 40 mm Hg or less were associated with continued wound problems and complication after amputation. Increased P tcO 2 values after vascular reconstruction of the legs predicted improved clinical status on follow-up examinations up to 6 months. P tcO 2 predicted the extent of vascular disease as well as the other noninvasive tests and angiography. We conclude that (1) P tcO 2 tension is a simple, accurate, noninvasive method to determine the appropriate level of amputation, wound healing potential, and effectiveness of bypass procedures, and (2) P tcO 2 values correlate well with angiography and noninvasive evaluations.

Digital subtraction angiography of peripheral vascular bypass procedures.

Without premedication or special preparation, digital video subtraction angiography, also known as photoelectronic intravenous angiography, was effectively used for evaluating patients who had undergone peripheral vascular reconstructive procedures. Thirty-eight studies in 20 patients were performed using computer contrast enhancement after an intravenous injection. Patency of arterial grafts was thereby evaluated, thus obviating further routine angiography. Graft patency, even of small complex graft sites, was easily recognized. Occlusions were also readily identified. Patient acceptance was excellent since the procedure is almost painless and can be done on an outpatient basis. The technique is fast, safe, and less expensive than routine angiography.