Aortic Stenosis
Aortic stenosis is characterized by the narrowing of the aortic valve opening and the exertion of the left ventricle to increase pressure to drive blood through the opening. The added workload increases the demand for oxygen, while diminished cardiac output reduces coronary artery perfusion, causes ischemia of the left ventricle, and leads to heart failure.
Signs and symptoms of aortic stenosis may not appear until the patient reaches ages 50 to 70, even though the lesion has been present since childhood. Incidence increases with age. Aortic stenosis is the most significant valvular lesion seen among elderly people. About 80% of patients with aortic stenosis are male.
Causes
Aortic stenosis may result from congenital aortic bicuspid valve (associated with coarctation of the aorta), congenital stenosis of pulmonary valve cusps, rheumatic fever or, in elderly patients, atherosclerosis.
Complications
Aortic stenosis leads to left ventricular failure, usually after age 70. It typically occurs within 4 years after the onset of signs and symptoms and is fatal in up to two-thirds of patients.
Sudden death, possibly caused by an arrhythmia, occurs in up to 20% of patients, usually around age 60.
Assessment
Even with severe aortic stenosis (narrowing to about one-third of the normal opening), the patient may be asymptomatic. Eventually, the patient will complain of dyspnea on exertion, fatigue, exertional syncope, angina, and palpitations. If left ventricular failure develops, the patient may complain of orthopnea and paroxysmal nocturnal dyspnea.
Inspection may reveal peripheral edema if the patient has left-sided heart failure.
Palpation may detect diminished carotid pulses and pulsus alternans. If the patient has left-sided heart failure, the apex of the heart may be displaced inferiorly and laterally. If the patient has pulmonary hypertension, you may be able to palpate a systolic thrill at the base of the heart, at the jugular notch, and along the carotid arteries. Occasionally, it may be palpable only during expiration and when the patient leans forward.
The murmur is low-pitched, rough, and rasping and is loudest at the base in the second intercostal space. In stenosis, the murmur is at least grade 3 or 4. It disappears when the valve calcifies. A split S2 develops as aortic stenosis becomes more severe. If the examiner places a hand over the base of the heart, a vibration may be felt. The vibration is the result of blood flow across the narrowed valve opening. An S4 reflects left ventricular hypertrophy and may be heard at the apex in many patients with severe aortic stenosis.
Pediatric pointerAuscultation may uncover an early systolic ejection murmur in children and adolescents who have noncalcified valves. The murmur begins shortly after S1 and increases in intensity to reach a peak toward the middle of the ejection period. It diminishes just before the aortic valve closes. In addition, children with aortic stenosis may be asymptomatic but may have exercise intolerance. Children who have severe aortic stenosis should be instructed to avoid strenuous activities.
