What are the considerations for spinal anesthesia in a patient with aortic stenosis?

From the Guidelines

Spinal anesthesia should be used with extreme caution in patients with severe aortic stenosis, and is generally not recommended as the first-line anesthetic approach. Patients with aortic stenosis rely on adequate preload and systemic vascular resistance to maintain cardiac output and coronary perfusion. Spinal anesthesia causes sympathetic blockade leading to vasodilation and decreased venous return, which can precipitate profound hypotension and cardiovascular collapse in these patients, as noted in the 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery 1.

Key Considerations

• The mechanism of major adverse cardiac events (MACE) in patients with aortic stenosis likely arises from the anesthetic agents and surgical stress that lead to an unfavorable hemodynamic state, resulting in decreased coronary perfusion pressure, development of arrhythmias or ischemia, myocardial injury, cardiac failure, and death 1.
• Predictors of 30-day death and postoperative MI in patients with moderate or severe AS include high-risk surgery, symptomatic severe AS, coexisting moderate or severe mitral regurgitation, and pre-existing CAD 1.
• If anesthesia is required for a patient with aortic stenosis, general anesthesia with careful hemodynamic monitoring is typically preferred.

Anesthetic Approach

If spinal anesthesia must be used in a patient with mild to moderate aortic stenosis, consider using a low-dose, gradual technique with small incremental doses of local anesthetic. Aggressive fluid preloading should be administered before the block, and vasopressors like phenylephrine should be immediately available to treat hypotension. Invasive arterial monitoring is advisable, and the patient should be positioned carefully to avoid sudden hemodynamic changes. The anesthesiologist should maintain heart rate control, as tachycardia can worsen the condition by decreasing diastolic filling time.

Monitoring and Management

• Invasive hemodynamic monitoring and optimization of loading conditions are crucial in patients with aortic stenosis undergoing noncardiac surgery 1.
• Options for patients who meet indications for aortic valve replacement before noncardiac surgery but are considered high risk or ineligible for surgical AVR include proceeding with noncardiac surgery with invasive hemodynamic monitoring, percutaneous aortic balloon dilation as a bridging strategy, and transcatheter aortic valve replacement (TAVR) 1.

From the Research

Considerations for Spinal Anesthesia

• Patients with aortic stenosis are at increased risk of perioperative morbidity and mortality 2, 3
• Perioperative invasive monitoring is advised for patients with an aortic valve area <1.0 cm(2) or a mean aortic valve gradient >30 mmHg to avoid hypotension and arrhythmias 2
• Continuous spinal anesthesia with minimally invasive hemodynamic monitoring can be a valid alternative to general or epidural anesthesia in patients with severe aortic stenosis undergoing lower limb surgery 2
• Combined spinal-epidural anesthesia with closely monitored, careful titration of the local anesthetic dose can be an efficient and safe anesthetic method for managing patients with severe aortic stenosis 4

Anesthetic Management

• General anesthesia can be riskier than neuraxial anesthesia for severe aortic stenosis patients undergoing spinal surgeries in the prone position 4
• Selected patients with severe aortic stenosis can undergo noncardiac procedures at a reasonably low risk with careful monitoring of anesthesia 3
• Appropriate choice of anesthetic technique and agent can optimize anesthetic management of patients with aortic stenosis 5
• Spinal anesthesia can be successfully used in patients with aortic stenosis, as reported in a case of a 94-year-old male patient who underwent orthopedic surgery under spinal anesthesia with no complications 5

Hemodynamic Considerations

• Patients with severe aortic stenosis are at increased risk of hypotension and hypoperfusion during surgery 6
• General anesthesia can result in a decrease in cardiac index and stroke volume index compared to preoperative values 6
• Dobutamine infusion and fluid bolus can increase cardiac index, but the effect on stroke volume index is highly variable and associated with baseline left ventricular ejection fraction 6