An absolute contraindication to thrombolytic therapy is:
Patients with small-vessel occlusion are poor candidates for surgery because they lack distal target vessels to use for bypass. These patients should be offered a trial of thrombolysis, unless they have contraindications to thrombolysis or their ischemia is so severe that the time needed to achieve adequate lysis is considered too long. The major contraindications of thrombolysis are recent stroke, intracranial primary malignancy, brain metastases, or intracranial surgical intervention. Relative contraindications for performance of thrombolysis include renal insufficiency, allergy to contrast material, cardiac thrombus, diabetic retinopathy, coagulopathy, and recent arterial puncture or surgery.
Contraindications to thrombolytic therapy:
The term chronic limb ischemia (CLI) is reserved for patients with objectively proven arterial occlusive disease and symptoms lasting for more than:
The term chronic limb ischemia (CLI) is reserved for patients with objectively proven arterial occlusive disease and symptoms lasting for more than 2 weeks. Symptoms include rest pain and tissue loss, such as ulceration or gangrene. The diagnosis should be corroborated with noninvasive diagnostic tests, such as the ABI, toe pressures, and transcutaneous oxygen measurements. Ischemic rest pain most commonly occurs below an ankle pressure of 50 mm Hg or a toe pressure less than 30 mm Hg.2 Ulcers are not always of an ischemic etiology.
Clinica l categories of chronic limb ischemia:
aFive minutes at 2 miles per hour on a 12% incline of treadmill exercise. bGrades II and Ill, categories 4, 5, and 6, are encompassed by the term chronic critical ischemia. AP = ankle pressure; PVR = pulse volume record ing;TM = transmetatarsa i;TP = toe pressure.
Symptoms and signs of neuropathic ulcer versus ischemic ulcer:
The percentage of patients with vein grafts that will develop intrinsic stenosis within the first 18 months following implantation is:
Fifteen percent of vein grafts will develop intrinsic stenoses within the first 18 months following implantation. Consequently, patients with vein grafts were entered into duplex surveillance protocols (scans every 3 months) to detect elevated (>300 cm/s) or abnormally low ( <45 cm/s) graft velocities early. Stenoses greater than 50%, especially if associated with changes in ABI, should be repaired to prevent graft thrombosis. Repair usually entails patch angioplasty or shortsegment venous interposition, but PTA/stenting is an option for short, focal lesions. Grafts with stenoses that are identified and repaired prior to thrombosis have assisted primary patency identical to primary patency, whereas a thrombosed autogenous bypass has limited longevity resulting from ischemic injury to the vein wall.
The following are true of cryopreserved grafts EXCEPT:
Cryopreserved grafts are usually cadaveric arteries or veins that have been subjected to rate controlled freezing with dimethyl sulfoxide (DMSO) and other cryopreservants. Cryopreserved vein grafts are more expensive than prosthetic grafts and are more prone to failure. The endothelial lining is lost as part of the freezing process, making these grafts prone to early thrombosis. Cryopreserved grafts are also prone to aneurysmal degeneration. Despite the fact that these grafts have not performed as well as prosthetic bypasses and autogenous vein bypasses in clinical practice, they can still play a role when revascularization is required following removal of infected prosthetic bypass grafts, especially when the autogenous vein is unavailable to create a new bypass through clean tissue planes.
When lower extremity occlusive disease extends to involve the popliteal artery or tibial vessels, the appropriate outflow vessels for performing bypass in order of descending preference are:
When the disease extends to involve the popliteal artery or the tibial vessels, the surgeon must select an appropriate outflow vessel to perform a bypass. Suitable outflow vessels are defined as uninterrupted flow channels beyond the anastomosis into the foot. Listed in order of descending preference, they are as follows: above-knee popliteal artery, below-knee popliteal artery, posterior tibial artery, anterior tibial artery, and peroneal artery. In patients with diabetes, it is frequently the peroneal artery that is spared. Although it has no direct flow into the foot, collateralization to the posterior tibial and anterior tibial arteries makes it an appropriate outflow vessel.
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