Atherosclerosis is the primary process leading to myocardial infarction, stroke, chronic mesenteric ischemia, renovascular hypertension, extremity ischemia, and aneurysmal disease. These pathologic states occur years after the slow onset of plaque formation in the vascular wall. The precise mechanism of final injury is 1 or more of the following: (a) plaque enlargement reducing blood flow; (b) complete occlusion of arteries at sites of advanced plaques; and (c) arterial embolism of plaque-associated thrombi or atheromatous debris.
The assessment of the surgical patient undergoing vascular surgery is a complex process that requires integration of multiple areas of expertise. The classic concept of clearing a patient for surgery has been replaced with an integrated approach of interdisciplinary cooperation that focuses on assessment of existing disorders, optimization of resilience and reserve in anticipation of increased preoperative demand, avoidance of therapeutic conflicts, and identification of potential procedure-specific risks.
Patients presenting for major vascular surgery usually have either overt or occult involvement of several organ systems. The vascular patient population has a high incidence of significant coronary artery disease (CAD), for example, left ventricular systolic dysfunction (left ventricular ejection fraction less than 40%) is 5 times more common in patients with cerebrovascular disease or peripheral arterial disease compared with matched controls.
The current standards for preoperative cardiac evaluation of these patients are the guidelines published by the American College of Cardiology and the American Heart Association initially in 1996 and revised in 2002 and in 2007. As stated in these guidelines, "patients who require vascular surgery appear to have an increased risk for cardiac complications because (a) many of the risk factors that contribute to peripheral vascular disease (eg, diabetes mellitus, tobacco use, and hyperlipidemia) are also risk factors for CAD; (b) the usual symptomatic presentation for CAD in these patients may be obscured by exercise limitations imposed by advanced age, intermittent claudication, or both; and (c) major open vascular surgery may be associated with substantial fluctuations in intravascular/extravascular fluid volumes, cardiac filling pressures, systemic blood pressure, heart rate, and thrombogenicity."
Vascular surgery patients require intensive perioperative monitoring for 2 primary reasons: (a) these patients often have systemic manifestations of atherosclerotic vascular disease and are at risk for cardiac, cerebral, renal, and spinal cord ischemia, all of which can be diagnosed and treated using appropriate monitors; and (2) vascular procedures involve major physiologic changes, including significant third-space losses, blood loss, and the complications of transfusion (coagulopathies, hypocalcemia, hypothermia, and acidosis). There can also be significant changes in the hemodynamic profile associated with the application and release of vascular clamps.
Monitoring of the awake patient is the gold standard for neurologic assessment during carotid endarterectomy (CEA) and may allow for the prompt identification of patients who would benefit from shunt placement. Change in contralateral strength or consciousness in the setting of adequate mean arterial pressure is an indication for shunt placement.
One of the goals of anesthesia for CEA is to avoid hemodynamic extremes during induction, incision, surgical manipulation, emergence, and extubation. The blood ...