Anesthesia Considerations for Aortic Stenosis

Aortic stenosis (AS) is the narrowing of the valve opening that channels blood from the heart to the rest of the body. This serious condition affects 3.4% of U.S. adults over 75.¹ As the population ages, it is important to consider the complications that AS patients may face when undergoing noncardiac surgery (NCS), which can include myocardial infarction, heart failure, and ventricular arrythmia.² Aortic stenosis patients often have hypertrophy and reduced compliance of the left ventricle, making them more sensitive to anesthesia-induced decreases in oxygen and coronary perfusion pressure.³ As the American College of Cardiology Foundation and the American Heart Association, Inc. (ACC/AHA) emphasize, patients with undiagnosed severe AS undergoing NCS have an estimated rate of cardiac complications between 10 and 30%.⁴ 

Thus, a preoperative assessment for those with AS or at risk of AS is essential. Routine auscultation can help identify patients with undiagnosed AS, whose symptoms include angina, dyspnea, and syncope.² The severity of AS should be carefully assessed, as Kertai et al. and others have shown the severity of stenosis is proportional to the level of risk.⁵ 

For decades, cardiologists have grappled with whether or not AS patients undergoing surgery should pursue aortic valve replacement (AVR) beforehand, although AVR can come with its own clinical risks.¹ An April 2020 paper by Luis et al reported that 491 severe AS patients undergoing NCS had significantly lower rates of major adverse cardiac events when AVR was done beforehand (5.4% versus 20.5%).⁶ Importantly, it is becoming more feasible to conduct AVR, as less-invasive procedures like transcatheter aortic valve implantation (TAVI) become more prevalent. TAVI is shown to have a lower procedural mortality rate and shorter recovery time, which can facilitate early NCS after the procedure.¹  

In December 2020, the ACC/AHA updated its guidelines to make the transcatheter valve, rather than the surgical valve, the primary recommended treatment for severe aortic stenosis. The updated guidelines state that while there is “a lack of data on the efficacy or safety of TAVI” in AS patients undergoing NCS, “TAVI is a reasonable option to avoid delay of semi-urgent noncardiac surgery.” More broadly, valve replacement “will prevent hemodynamic instability during, as well as after, noncardiac surgery.”⁴ Other options for AS patients whose risks prevent them from undergoing AVR include balloon aortic valvuloplasty.^4, 7 

For AS patients undergoing NCS, the primary concerns for anesthesia management are the maintenance of hemodynamic stability and cardiac output. Because aortic stenosis patients usually have constricted blood vessels, they can easily have low blood pressure under anesthesia. Low blood pressure can lead to a spiral of low coronary perfusion pressure, ischemia (inadequate blood supply) in the heart muscles, ventricular dysfunction, and ultimately, cardiovascular collapse. Thus, alpha-adrenergic agonists like phenylephrine are often an essential tool in maintaining coronary perfusion.² These are the agents of choice for treating low blood pressure because they do not significantly increase heart rate.³ 

The patient’s blood pressure, fluid status, cardiac output, contractility, and more should all be carefully monitored during surgery, and because of the heterogeneity of complications that may arise, there is little research supporting one anesthetic technique over another. As Goel et al., note in a 2018 article describing two NCS case studies in severe aortic stenosis patients: “Very few studies have compared general versus epidural anesthesia for noncardiac surgery in severe aortic stenosis patients.” The two patients in the paper were both administered general anesthesia. They received fentanyl, propofol, and atracurium, and after induction, phenylephrine was used to maintain mean arterial pressure above 65 mmHg.⁸ Anesthesiologists often promote using general anesthesia over regional anesthesia for AS patients to control blood pressure with greater precision.² 

Some experts consider spinal anesthesia to be contraindicated for AS patients undergoing surgery. The sympathetic blockade can quickly lead to low blood pressure; epidural anesthesia can also be contraindicated, but the more gradual decline in blood pressure can allow physicians to respond accordingly, and it has been used successfully for surgeries such as hip replacements.² Thus, Goel et al. conclude that “the question whether to give general or epidural depends totally on anesthesiologist’s discretion, [taking] into consideration [a] patient’s perioperative condition, severity of AS, [and] type of surgery.”⁸ 

Overall, aortic stenosis patients undergoing NCS should receive careful hemodynamic monitoring, selection of anesthesia, treatment for rapid changes in blood volume status and arrythmia, and assiduous perioperative care.¹ With proper collaboration from cardiologists, surgeons, and anesthesiologists, physicians can minimize risks for AS patients undergoing surgery.² 

References 

1.  Kennon S, Archbold A. Expert opinion: Guidelines for the management of patients with aortic stenosis undergoing non-cardiac surgery: Out of date and overly prescriptive. Interv Cardiol. 2017;12(2):133-136. 

2.  Phillips D. Aortic stenosis: a review. American Association of Nurse Anesthetists: AANA. Published 2006. https://www.aana.com/docs/default-source/aana-journal-web-documents-1/p309-315.pdf?sfvrsn=4b115ab1_6 

3.  Raleigh L. Aortic Stenosis in Noncardiac Surgery Patients. Medscape.com. Published 2019. https://emedicine.medscape.com/article/2500069-overview 

4.  Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: A report of the American college of cardiology/American heart association joint committee on clinical practice guidelines. Circulation. 2021;143(5):e72-e227. 

5.  Kertai MD, Bountioukos M, Boersma E, et al. Aortic stenosis: an underestimated risk factor for perioperative complications in patients undergoing noncardiac surgery. Am J Med. 2004;116(1):8-13. 

6.  Luis SA, Dohaei A, Chandrashekar P, et al. Impact of aortic valve replacement for severe aortic stenosis on perioperative outcomes following major noncardiac surgery. Mayo Clin Proc. 2020;95(4):727-737. 

7.  Sawhney R, Abraham M, Ganjoo P, Tandon MS. Anesthetic considerations in a patient with severe aortic stenosis for craniotomy. J Neurosurg Anesthesiol. 2003;15(2):151-154. 

8.  Goel N, Kumar MG, Barwad P, Puri GD. Noncardiac surgery in two severe aortic stenosis patients: General or epidural anesthesia? Saudi J Anaesth. 2018;12(2):367-369.