Patients undergoing vascular surgery frequently have multiple comorbid conditions that should be optimized prior to surgery.

1. Cardiovascular system. Major adverse cardiac events (MACE) such as stroke, myocardial infarction (MI), cardiac arrest, and death are the leading cause of morbidity and mortality in patients undergoing vascular surgery. MI accounts for about one-half of early postoperative deaths. Accurate risk stratification based on preoperative patient characteristics remains a significant challenge in vascular surgery. Commonly used risk calculators such as the Revised Cardiac Risk Index (RCRI) and Gupta Myocardial Infarction or Cardiac Arrest have reduced performances in vascular surgery. Alternate scoring systems such as the Geriatric-Sensitive Perioperative Risk Calculator, Vascular Surgery Group of New England Cardiac Risk Index, and Vascular Quality Initiative Cardiac Risk Index tools have been proposed to address these shortcomings, but have their own limitations. Below are some specific considerations with regard to vascular surgical patients.
   1. Cardiac stress testing. For nonemergent cases, in patients estimated to be at elevated risk (>1% risk of perioperative MACE) with poor functional capacity (<4 METS), noninvasive cardiac stress testing should be carried out if the results will impact patient care. Dobutamine stress echocardiogrpahy or myocardial perfusion imaging will be necessary for patients with physical limitations such as claudication or disability from prior stroke. The need for coronary artery catheterization is determined based on the results of the stress test, in consultation with a cardiologist.
   2. Echocardiography may be indicated if the patient has a new murmur, dyspnea of unknown etiology, valvular heart disease, or heart failure with new or worsening symptomatology.
   3. Blood pressures should be measured in both arms to determine whether there is a difference. Due to the systemic nature of atherosclerosis, patients may have subclavian or axillary arterial stenoses. Blood pressure should be monitored in the extremity with the higher reading.
   4. Coronary revascularization should be carried out only if medically indicated. According to the Coronary Artery Revascularization Prophylaxis trial, coronary revascularization in advance of major vascular surgery has not been shown to improve outcome when compared with medical management. This trial excluded patients with left main coronary artery disease, ejection fraction less than 20%, and severe aortic stenosis.
   5. β-Blocker therapy should be maintained in patients already on chronic therapy. Initiation of β-blocker therapy is reasonable in patients with three or more RCRI risk factors or in patients with reversible ischemia on preoperative testing. However, improper timing and dose titration may increase risk of stroke and mortality. β-Blocker therapy should be started at least 2 days prior to surgery; 7 days is preferred. Therapy should be started at a low dose and titrated slowly to achieve target heart rate of 60 to 80 bpm and should be held for hypotension.
   6. Antiplatelet therapy.Aspirin therapy should be continued in patients with coronary stents, cerebrovascular disease, or high-risk coronary artery disease. Continuation should be considered in all vascular surgical procedures in discussion with the surgical team. Aspirin therapy is associated with an increased risk of bleeding. POISE-2, a randomized, controlled trial of 10,000 patients undergoing noncardiac surgery, did not show a benefit of aspirin initiation or continuation with respect to MACE or death. However, it excluded patients who had recently received coronary stents and those undergoing carotid endarterectomy (CEA). Furthermore, only a small proportion of the study population underwent vascular surgery. Continuation of clopidogrel therapy depends on patient factors (eg, presence and type of coronary stents and when they were placed) as well as surgical factors.
   7. Statins should be continued perioperatively. The initiation of statin therapy is reasonable in patients undergoing vascular surgery. The statin should ideally be started 1 week to 30 days prior to the surgical procedure. There is evidence that statins decrease coronary inflammation regardless of low-density lipoprotein level. Withdrawal prior to surgery has been associated with increased cardiac events.
   8. Warfarin, depending upon the indication and in consultation with the surgical team and prescribing provider, should be discontinued at least 3 to 5 days before surgery, and heparin therapy initiated.
   9. If regional anesthesia is planned, anticoagulant and antiplatelet agents should be held according to the most recent American Society of Regional Anesthesia (ASRA) guidelines and in consultation with the surgeon and cardiologist.
2. Respiratory system. Many vascular patients have histories of significant tobacco use and may have compromised pulmonary function (see Chapter 4). Routine pulmonary function testing is not indicated. Aortic cross-clamping and associated ischemia-reperfusion can produce a systemic inflammatory response that may contribute to postoperative lung injury.
3. Renal system. Preexisting renal dysfunction is common. It is related to atherosclerosis, hypertension, diabetes, and advanced age and may exist even in the absence of an abnormal serum creatinine value. Due to a decreased number of functioning glomeruli, these patients have a reduced capacity to autoregulate renal perfusion in the setting of hypotension and are often intolerant to perioperative insults such as ischemia-reperfusion, atheroembolism, and nephrotoxins like contrast dye. Patients with chronically elevated serum creatinine levels (>2 mg/dL) have substantially greater morbidity and mortality following vascular surgery. Open aortic and renal arterial surgeries carry the highest risk for postoperative renal dysfunction. Patients undergoing endovascular procedures are at risk for contrast-induced acute kidney injury (CI-AKI). CI-AKI is diagnosed by an increase in serum creatinine beginning 24 to 48 hours following contrast exposure in a patient with no other reason for AKI. In otherwise healthy patients, the risk of CI-AKI is low and its clinical relevance is debated. The risk of CI-AKI is increased in patients with chronic kidney disease, diabetes, anemia, heart failure, and hemodynamic instability. Procedures using high-osmolar contrast or high volumes of contrast are higher risk. In patients at risk, crystalloid administration and the use of low volumes of iso-osmolar or low-osmolar contrast agents are recommended. Treatment with sodium bicarbonate and N-acetylcysteine has also been used to prevent CI-AKI. However, results of the PRESERVE trial demonstrated neither a benefit of sodium bicarbonate over saline nor a benefit of NAC over placebo in preventing AKI.
4. Central nervous system. Patients should be examined for carotid bruits and questioned for a history of transient ischemic attacks (TIAs) and cerebrovascular accidents. Symptomatic carotid disease may warrant revascularization prior to other elective procedures.
5. Endocrine system. In addition to accelerated atherosclerosis, patients with long-standing diabetes may have extensive microvascular disease resulting in autonomic dysfunction, silent myocardial ischemia, and nephropathy. In consultation with the patient’s endocrinologist, metformin should be discontinued prior to procedures that involve IV contrast dye or renal or hepatic ischemia due to the potential for the development of severe lactic acidosis. It should also be held in patients with preexisting renal dysfunction or heart failure.
6. Hematologic system. The vascular surgical patient is at particularly high risk to develop heparin-induced thrombocytopenia (HIT) due to the need for repeated and occasionally prolonged exposure to heparin (see Chapter 24). This syndrome is characterized by thrombocytopenia and/or thrombosis in the setting of heparin exposure and is due to the formation of antibodies to the heparin-platelet factor 4 (PF4) complex. The 4T score helps determine the pretest probability of a HIT diagnosis and should guide clinical management (eg, suspension of heparin administration if the probability is intermediate or high). Generally, if the pretest probability of HIT is intermediate or high, heparin administration should be suspended and laboratory testing pursued. Anti-PF4 antibody levels are a sensitive but not specific test for HIT and are generally checked first. A negative anti-PF4 antibody test makes HIT unlikely. If anti-PF4 levels are elevated, a serotonin release assay (SRA) is recommended. If the SRA is negative, heparin can be used intraoperatively irrespective of the result of the anti-PF4 antibody test. If both the anti-PF4 antibody test and the SRA are positive, surgery should be delayed or an alternative anticoagulant should be used. The acute management of the patient with HIT includes discontinuation of all heparins, suspension of warfarin, avoidance of platelet transfusions, and the initiation of alternative, nonheparin, anticoagulant therapy.