Options for managing severe aortic stenosis: A case-based review
ABSTRACTThe treatment of calcific aortic stenosis is well established and includes careful monitoring of patients who have no symptoms and surgical aortic valve replacement in the patients who do have symptoms. Patients who cannot undergo open heart surgery can now undergo valve replacement via a minimally invasive transcatheter approach. In this article, we use clinical vignettes to illustrate the management of patients with severe aortic stenosis.
KEY POINTS
- Calcific aortic stenosis is the most common acquired valvular disease, and its prevalence is increasing as the population ages.
- Patients who have symptoms should be referred for aortic valve replacement. Patients who are not candidates for open heart surgery may be eligible for transcatheter aortic valve replacement.
- For high-risk patients with multiple comorbidities, “bridging” therapies such as aortic valvuloplasty are an option.
- In patients with aortic stenosis who present with hemodynamic instability and circulatory collapse, time can be gained with the use of intravenous sodium nitroprusside (in the absence of hypotension) or intra-aortic balloon counterpulsation while more definitive treatment decisions are being made.
CASE 6: LIFE-LIMITING COMORBID ILLNESS
Mr. F, age 77, has multiple problems: severe aortic stenosis (aortic valve area 0.6 cm2; peak and mean gradients of 92 and 59 mm Hg), stage IV pancreatic cancer, coronary artery disease status post coronary artery bypass grafting, chronic kidney disease (serum creatinine 1.9 mg/dL), hypertension, and hyperlipidemia. He presents to the outpatient department with shortness of breath at rest, orthopnea, effort intolerance, and peripheral edema over the past several months.
On physical examination rales in both lung bases can be heard. Left heart catheterization shows patent bypass grafts.
How would you manage Mr. F’s aortic stenosis?
Aortic valve replacement is not considered an option in patients with noncardiac illnesses and comorbidities that are life-limiting in the near term. Under these circumstances, aortic valvuloplasty can be offered as a means of palliating symptoms or, if the comorbid conditions can be modified, as a bridge to more definitive treatment with aortic valve replacement.
Since first described in 1986,45 percutaneous aortic valvuloplasty has been studied in several case series and registries, with consistent findings. Acutely, it increases the valve area and lessens the gradients across the valve, relieving symptoms. The risk of death during the procedure ranged from 3% to 13.5% in several case series, with a 30-day survival rate greater than 85%.46 However, the hemodynamic and symptomatic improvement is only short-term, as valve area and gradients gradually worsen within several months.47,48 Consequently, balloon valvuloplasty is considered a palliative approach.
Mr. F has a potentially life-limiting illness, ie, cancer, which would make him a candidate for aortic valvuloplasty rather than replacement. He can be referred for evaluation for this procedure in hopes of palliating his symptoms by relieving his dyspnea and improving his quality of life.
CASE 7: HEMODYNAMIC INSTABILITY
Mr. G, age 87, is scheduled for surgical aortic valve replacement because of severe aortic stenosis (valve area 0.5 cm2, peak and mean gradients 89 and 45 mm Hg) with an ejection fraction of 30%.
Two weeks before his scheduled surgery he presents to the emergency department with worsening fluid overload and increasing shortness of breath. His initial laboratory work shows new-onset renal failure, and he has signs of hypoperfusion on physical examination. He is transferred to the cardiac intensive care unit for further care.
How would you manage his aortic stenosis?
Patients with decompensated aortic stenosis and hemodynamic instability are at extreme risk during surgery. Medical stabilization beforehand may mitigate the risks associated with surgical or transcatheter aortic valve replacement. Aortic valvuloplasty, treatment with sodium nitroprusside, and support with intra-aortic balloon counterpulsation may help stabilize patients in this “low-output” setting.
Sodium nitroprusside has long been used in low-output states. By relaxing vascular smooth muscle, it leads to increased venous capacitance, decreasing preload and congestion. It also decreases systemic vascular resistance with a subsequent decrease in afterload, which in turn improves systolic emptying. Together, these effects reduce systolic and diastolic wall stress, lower myocardial oxygen consumption, and ultimately increase cardiac output.49,50
These theoretical benefits translate to clinical improvement and increased cardiac output, as shown in a case series of 25 patients with severe aortic stenosis and left ventricular systolic dysfunction (ejection fraction 35%) presenting in a low-output state in the absence of hypotension.51 These findings have led to a ACC/AHA recommendation for the use of sodium nitroprusside in patients who have severe aortic stenosis presenting in low-output state with decompensated heart failure.21
Intra-aortic balloon counterpulsation, introduced in 1968, has been used in several clinical settings, including acute coronary syndromes, intractable ventricular arrhythmias, and refractory heart failure, and for support of hemodynamics in the perioperative setting. Its role in managing ventricular septal rupture and acute mitral regurgitation is well established. It reliably reduces afterload and improves coronary perfusion, augmenting the cardiac output. This in turn leads to improved systemic perfusion, which can buy time for a critically ill patient during which the primary disease process is addressed.
Recently, a case series in which intraaortic balloon counterpulsation devices were placed in patients with severe aortic stenosis and cardiogenic shock showed findings similar to those with sodium nitroprusside infusion. Specifically, their use was associated with improved cardiac indices and filling pressures with a decrease in systemic vascular resistance. These changes have led to increased cardiac performance, resulting in better systemic perfusion.52 Thus, intra-aortic balloon counterpulsation can be an option for stabilizing patients with severe aortic stenosis and cardiogenic shock.
Mr. G was treated with sodium nitroprusside and intravenous diuretics. He achieved symptomatic relief and his renal function returned to baseline. He subsequently underwent aortic valve replacement during the hospitalization.
