Aortic stenosis
Aortic stenosis is a condition characterized by the narrowing of the aortic valve, which impedes blood flow from the heart to the rest of the body. It can arise from congenital defects, calcification, or rheumatic disease, though the latter is less common in developed countries. Symptoms often include angina (chest pain), syncope (fainting), and heart failure, which can develop from both systolic and diastolic dysfunction due to the heart's increased workload. Physical examinations typically reveal a characteristic systolic ejection murmur and changes in pulse. Diagnosis predominantly relies on echocardiography, which assesses left ventricular hypertrophy and valve deformities. Unfortunately, there are no effective medicinal treatments for aortic stenosis; therefore, aortic valve replacement is the recommended intervention for symptomatic patients. Prognosis is generally favorable for asymptomatic individuals, while those with symptoms face a significant decline in survival without surgical intervention. Understanding this condition is crucial for timely diagnosis and management to improve patient outcomes.
Aortic stenosis
Disease/Disorder
Anatomy or system affected: Cardiovascular system, heart, brain
Definition: Narrowing of the bicuspid or tricuspid valve, preventing blood flow from the left ventricle to the aorta.
Key terms:
angina: pain in the chest caused by insufficient blood flow to the heart muscle
calcification: the deposit of lime salts in organic tissue, leading to the buildup of calcium in the arterial wall
heart failure: a condition in which the heart cannot pump enough blood to meet the body's needs
hypertrophic left ventricle: enlargement of the muscle tissue of the heart's main pumping chamber
murmur: the sound made by blood flowing backward through a heart valve
syncope: fainting, passing out, temporary loss of consciousness
Epidemiology
Aortic stenosis can be a result of a congenital malformation, calcification, or rheumatic disease. Congenital malformations are sometimes missed early in childhood and need correction during adolescence. Aortic stenosis due to calcification is more typical, generally affects the tricuspid valves, and usually manifests in men in their 60s to 80s. Aortic stenosis resulting from rheumatic disease primarily affects the mitral valve and is rare in developed countries.
Pathobiology
With aortic stenosis, the blood must work harder to get through the calcified or malformed leaflets. In order for this to occur, the muscles of the left ventricle (LV) become thickened and hypertrophic. This increase in muscle thickness preserves the heart's ejection fraction and the cardiac output, allowing the body to receive the necessary blood. Although LV hypertrophy serves as a preserving mechanism, it also leads to some of the pathological symptoms associated with aortic stenosis.
Symptoms
Angina. Chest pain, shortness of breath, and fatigue during exercise can be signs of angina. In order for the hypertrophic LV to maintain its adequate ejection fraction, it must use up the blood supply coming into the heart. Reduced blood flow to the rest of the heart causes angina.
Syncope. Syncope is due to poor blood flow to the brain during exertion. The brain's increased blood demand and the heart's decreased cardiac output due to the narrowing of the tricuspid valves results in inadequate cerebral perfusion, culminating in syncope.
Heart Failure. Heart failure in aortic stenosis is a result of both systolic and diastolic failure. Systolic failure occurs due to the heart's inability to contract properly. Diastolic failure is due to the inability of the hypertrophic LV to relax completely. As aortic stenosis progresses, deposition of collagen on the heart further stiffens the heart muscles, which ultimately leads to heart failure.
Signs
During the physical exam, a systolic ejection murmur is typically heard in the aortic area with a delayed pulse in the carotid artery. The hypertrophic LV is not displaced but is enlarged and demonstrates a bounding pulse. A co-occurring bounding pulse in the apex with a delayed and weak pulse in the carotid is characteristic of aortic stenosis.
Diagnosis
Echocardiography is most diagnostic due to its ability to identify a LV hypertrophy, systolic ejection performance, and any aortic valve deformities. When echocardiography shows severe aortic stenosis and the patient is exhibiting the signs and symptoms mentioned, no further testing is necessary.
Treatment
No medicinal interventions are efficacious in treating aortic stenosis. Avoiding strenuous exercise, careful follow-ups, and periodic echocardiograms are suggested for asymptomatic patients. For symptomatic patients, aortic valve replacement is the only proven treatment. All patients, regardless of age, benefit from valve replacement. Antibiotics are needed in those with mechanical valves undergoing surgical or dental procedures.
Prognosis
In asymptomatic patients, survival is age-matched. With symptomatic patients, survival declines dramatically, averaging at three-year mortality without aortic valve replacement.
For Further Information:
"Aortic Stenosis." MedlinePlus. Natl. Lib. of Medicine, 13 May 2014. Web. 30 Nov. 2015.
Armstrong, Guy P. “Aortic Stenosis.” The Merck Manual: Home Health Handbook for Patients and Caregivers. Merck Sharp & Dohme, n.d. Web. 30 Nov. 2015.
Carabello, A. B. “Valvular Heart Disease.” Goldman's Cecil Medicine. Ed. Lee Goldman and Andrew I. Schafer. Philadelphia: Elsevier Saunders, 2008. 453–457. Print.
Otto, Catherine M. “Clinical Features and Evaluation of Aortic Stenosis in Adults.” UpToDate. Wolters, 26 Mar. 2015. Web. 30 Nov. 2015.
Otto, C. “Calcific Aortic Valve Disease: Outflow Obstruction Is the End Stage of a Systemic Disease Process.” European Heart Journal 30 (2009): 1940–942. Print.
"Problem: Aortic Valve Stenosis." American Heart Association. AHA, 26 Aug. 2015. Web. 30 Nov. 2015.