Background: Aortic stenosis (AS) is the obstruction of
blood flow across the aortic valve. AS has several etiologies: congenital
unicuspid or bicuspid valve, rheumatic fever, and degenerative calcific
changes of the valve.
Pathophysiology: When the aortic valve becomes
stenotic, resistance to systolic ejection occurs and a systolic pressure
gradient develops between the left ventricle and the aorta. Stenotic
aortic valves have a decreased aperture that leads to a progressive
increase in left ventricular systolic pressure. This leads to pressure
overload in the left ventricle, which, over time, causes an increase in
ventricular wall thickness (ie, concentric hypertrophy). At this stage,
the chamber is not dilated and ventricular function is preserved, although
diastolic compliance may be affected.
Eventually, however, the left ventricle dilates. This, coupled with a
decrease in compliance, is associated with an increase in left ventricular
end-diastolic pressure, which is increased further by a rise in atrial
systolic pressure. A sustained pressure overload eventually leads to
myocardial decompensation. The contractility of the myocardium diminishes,
which leads to a decrease in cardiac output. The elevated left ventricular
end-diastolic pressure causes a corresponding increase in pulmonary
capillary arterial pressures and a decrease in ejection fraction and
cardiac output. Ultimately, congestive heart failure (CHF) develops.
- In the US: This is a relatively common congenital
cardiac defect. Incidence is 4 in 1000 live births.
Mortality/Morbidity: Sudden cardiac death occurs in
3-5% of patients with AS. Adults with AS have a 9% mortality rate per
year. Once symptoms develop, the incidence of sudden death increases to
15-20%, with average survival duration of less than 5 years. Patients with
exertional angina or syncope survive an average of 3 years. After the
development of left ventricular failure, life expectancy is slightly
greater than 1 year.
Sex: Among children, 75% of cases of AS are in males.
Age: AS usually is not detected until individuals are
school aged. AS exists in up to 2% of those who are younger than 70 years.
The etiology of AS in those aged 30-70 years can be rheumatic disease or
calcification of a congenital bicuspid valve. In those older than 70
years, degenerative calcification is the primary cause of AS. Among people
older than 75 years, 3% have critical AS.
History: AS usually has an asymptomatic latent period
of 10-20 years. Symptoms develop gradually. Ultimately, patients
experience the classic triad of chest pain, heart failure, and syncope.
Typical symptoms include the following:
- Fatigue (may be an early symptom among children)
- Gradual decrease in physical activity with insidious progression of
fatigue and dyspnea on exertion
- Patients may have a higher incidence of nitroglycerin-induced
syncope than the general population.
- Always consider AS as a possible etiology for a patient in the ED
with particular hemodynamic sensitivity to nitrates.
- Syncope during exertion: Proposed mechanisms include arrhythmias and
left ventricular failure with an abrupt decline in cardiac
- Symptoms of left ventricular failure (eg, dyspnea on exertion,
nocturnal cough, orthopnea, paroxysmal nocturnal dyspnea, hemoptysis)
may occur. This is due to an elevation of the pulmonary capillary
pressure from left ventricular dilation and reduced compliance.
- Palpation reveals a laterally displaced apex reflecting the presence
of left ventricular hypertrophy.
- A systolic thrill may be palpable at the base of the heart, in the
jugular notch, and along the carotid arteries.
- Crescendo-decrescendo systolic ejection murmur begins shortly after
the first heart sound. The intensity increases toward midsystole, then
decreases, and the murmur ends just before the second heart sound. It is
generally a rough, low-pitched sound that is loudest at the base of the
heart and most commonly is appreciated in the second right intercostal
space. An ejection click may be auscultated. This is associated with
- An audible fourth heart sound indicates the presence of left
ventricular hypertrophy in severe AS. Once the left ventricle dilates
and fails, a third heart sound may be audible.
- Pulsus parvus et tardus: This is an arterial pulse with a delayed
and plateaued peak, decreased amplitude, and gradual downslope. A
high-pitched, diastolic blowing murmur may be present if the patient has
associated aortic regurgitation.
Causes: The ventricular pressure required to deliver a
certain cardiac output at the required perfusion pressure is the pressure
gradient across the valve in systole. This pressure gradient defines the
degree of aortic valve obstruction.
- Newborns with significant AS develop CHF within the first week of
life. The left ventricle is often too small to be compatible with life.
The newborn heart develops left-to-right shunting through the patent
foramen ovale, which leads to worsening CHF.
- Congenital AS caused by a congenital unicuspid or bicuspid aortic
valve is usually asymptomatic in the otherwise healthy developing child.
It often is diagnosed on routine physical examination, although a child
may present with angina pectoris with exercise.
- As rheumatic fever decreases in frequency, so does rheumatic
fever–induced AS. These patients have a fibrous contracture with
shortening of the cusps due to recurrent inflammation from rheumatic
carditis. Adjacent cusps tend to fuse at the commissures. This causes a
form of acquired unicuspid or bicuspid aortic valve. Calcifications may
develop, but the primary cause of stenosis is the adhesions that fuse
the cusps. In patients older than 70 years, the most common cause of AS
is degenerative calcification of the valve. Mönckeberg senile calcific
AS occurs in elderly patients in whom all 3 cusps are highly
- Calcific AS also occurs in older patients with congenital or
acquired bicuspid valves. Congenital bicuspid valves cause calcific AS 4
times more frequently than acquired forms do.
Acute Coronary Syndrome
Mitral Valve Prolapse
- Chest radiographs may show cardiac enlargement. Minimal
enlargement and more subtle signs of concentric hypertrophy without
dilatation are present, including mildly enlarged heart size, rounding
at the cardiac apex, and slight backward displacement of the heart as
seen in lateral view.
- In later, more severe stages of AS, roentgenographic signs of left
atrial enlargement, pulmonary artery enlargement, right-sided
enlargement, and pulmonary congestion are evident.
- Two-dimensional transthoracic echocardiography can confirm the
clinical diagnosis of AS and provide specific data on left ventricular
function. It can show the structure and function of the other valves
- The following 3 significant findings can help define the severity
of the disease and describe the current hemodynamic significance:
- An echo-dense aortic valve with no cusp motion is indicative of
severe AS. This may be unreliable in congenital or rheumatic
- A decrease in the maximal aortic cusp separation (<8 mm in
the adult) is also indicative of severe AS.
- The presence of otherwise unexplained left ventricular
hypertrophy implies significant AS.
- Utilizing echo-Doppler techniques, the systolic pressure gradient
across the aortic valve can be assessed. Doppler techniques also can
help visualize any mitral or aortic regurgitation that might be
- Generally, ECG is not a reliable test because of the wide
variations seen in AS and other cardiac conditions.
- An ECG of a patient with significant AS most likely shows evidence
of left ventricular hypertrophy with or without a strain
- While the degree of severity of ECG changes does not correlate
well with the degree of hemodynamic instability, the ECG, if performed
as a serial study, is valuable in demonstrating the progression of the
- Approximately 25% of patients with significant AS may not show
clear ECG evidence of ventricular hypertrophy. This population
includes the elderly who have significant myocardial fibrosis and
adolescents who may experience ST-segment changes before QRS
- Of patients with significant AS, 13% have conduction defects seen
on ECG. These can include first-degree heart block, left bundle-branch
block, and any other conduction defects.
- The presence of left atrial enlargement suggests an associated
mitral valve process.
- Cardiac catheterization and coronary arteriography
- Perform cardiac catheterization and coronary arteriography on
patients who may have surgery, are suspected of having coronary artery
disease, or are older than 40 years (even without significant
- These patients have a 50% incidence of underlying coronary artery
disease. This is a significant consideration if the patient may have
- Other considerations in the complete workup of AS include
radionuclide studies to evaluate myocardial perfusion at rest and during
exertion and exercise studies. Perform these tests cautiously on
symptomatic patients. Surgery is recommended routinely in patients with
a valve cross-sectional area of 0.8-1.9 cm. However, with improvements
in aortic valve replacement, this parameter is becoming more
Emergency Department Care:
- Prehospital and ED management is focused on acute exacerbations of
the symptoms of AS.
- As always, assess and address airway, breathing, and
- If the patient is in cardiopulmonary arrest, perform resuscitation
according to the recommendations of the American Heart Association in
their Advanced Cardiac Life Support guidelines.
- A patient presenting with uncontrolled CHF should be treated
supportively with oxygen, cardiac and oximetry monitoring, intravenous
access, loop diuretics, nitrates (remembering the potential nitrate
sensitivity of patients with AS), morphine (as needed and tolerated),
and noninvasive or invasive ventilatory support (as
- Diagnostic studies in the ED should include ECG, chest radiograph,
serum electrolytes, cardiac enzymes, CBC, and arterial blood gases (if
hypoxemia or a mixed respiratory disease state is suspected). Emergency
formal ultrasound may be useful in centers that have this
- Vasodilators should be used judiciously in patients with AS, as they
may cause a significant drop in blood pressure.
- Patients with heart failure due to AS that is resistant to medical
management should be considered for emergent surgery.
- A patient presenting with angina pectoris requires monitoring and
studies as listed above. Measures should be taken to relieve the chest
discomfort. This may include administration of nitrates, oxygen, and
- Nitroglycerin-induced syncope occurs more often in patients with AS
than in those without AS. This information should be obtained through
the history at presentation.
- Syncope in the face of AS should be assessed and treated as in any
patient presenting with a syncopal episode.
- A patient with AS may present initially with one or more of the
above complaints. A thorough history and physical should be obtained in
addition to baseline laboratory studies, a chest radiograph, and an ECG.
Hospital admission, telemetry/intensive care unit admission, and
cardiology consultation all should be considered. If available, an
echocardiogram may be indicated in the ED.
- Atrial fibrillation in the setting of AS is considered a medical
emergency and should be converted urgently in patients who are
hemodynamically unstable. Associated symptoms also should be treated
- The main issue to recognize with AS is that the possible symptoms
(chest pain or syncope) often are attributed to other disease processes.
This is a diagnosis often missed in the ED and only discovered during a
more extensive workup.