Chronic Aortic Regurgitation
Patients with chronic AR remain asymptomatic for a long time. Palpitations are common and may be due to either awareness of forceful left ventricular contractions or occurrence of premature atrial
or ventricular beats. Angina may occur either from concomitant coronary
disease or from a combination of low diastolic pressure and increased
oxygen demand from ventricular hypertrophy. When left ventricular
dysfunction supervenes, patients initially experience exertional
dyspnea and fatigue. At a later stage, resting heart failure symptoms
occur with orthopnea and paroxysmal nocturnal dyspnea.
On physical examination, visible cardiac pulsations are common. The area of the apical impulse is increased on palpation and is
displaced caudally and laterally. The first heart sound is usually
normal. The aortic component of the second heart sound may be decreased
in conditions where cusp excursion is reduced, such as with valve
calcification. An S4 is often present due to underlying
hypertrophy, and an S3 is audible when ventricular failure
occurs. On auscultation, the characteristic sound of AR is a soft,
high-pitched diastolic decrescendo murmur best heard in the third
intercostal space along the left sternal border at end expiration, with
the patient sitting and leaning forward. In the presence of aortic
root disease, the murmur may be best heard to the right of the sternum.
A systolic ejection murmur may be present at the aortic area due
to the high flow state. Occasionally, a diastolic rumble may be
heard at the apex, referred to as the Austin Flint murmur. The mechanism underlying
this murmur remains unclear. A number of different causes have been
proposed, the most recent being the aortic jet encountering the
mitral inflow resulting in turbulence.
The systolic arterial pressure is increased due to a large stroke volume, whereas the diastolic pressure is decreased due to runoff
from the aorta into both the ventricle and peripheral arteries.
This is the underlying reason for a wide pulse pressure and for
a variety of associated peripheral signs in chronic significant
AR (Table 8–2). However, it must
be remembered that these signs are not specific for AR and may occur
in any high flow state such as occurs in anemia, thyrotoxicosis,
and arteriovenous malformations. With the development of heart failure,
the pulse pressure narrows and the peripheral signs of AR are attenuated.
Table 8–2. Peripheral Signs of Aortic Regurgitation. |Favorite Table|Download (.pdf)
Table 8–2. Peripheral Signs of Aortic Regurgitation.
|Name of Sign||Description|
|Corrigan pulse||Rapid and forceful distention of arterial pulse with quick
|De-Musset sign||To and fro head bobbing|
|Müller sign||Visible pulsation of uvula|
|Quincke sign||Capillary pulsations seen on light compression of nail bed|
|Traube sign||Systolic and diastolic sounds (pistol shots) over the femoral
|Duroziez sign||Bruits heard over femoral artery on light compression by
|Hill sign||Popliteal cuff pressure exceeding brachial pressure by 60
mm Hg or greater|
Acute Aortic Regurgitation
In contrast to chronic AR, most patients with acute severe AR are symptomatic. Initial presentation may vary depending on the
underlying cause, which most commonly is aortic dissection, infective endocarditis,
or trauma. In the presence of associated acute AR, clinical manifestations
of severe dyspnea, orthopnea, and weakness often develop. The onset
of symptoms is sudden, with rapid progression to hemodynamic collapse
if left untreated.
In acute AR, the left ventricle has had no time to adapt to the volume overload state. The peripheral signs associated with chronic
AR are therefore absent. Pulse pressure is usually normal, and hypotension
may be present in severe cases. Bilateral rales are usually present
on examination of the lungs and reflect underlying pulmonary edema.
On precordial palpation, the apical impulse is not shifted. The first
heart sound may be soft or absent due to the premature closure of
the mitral valve. An S3 is often present, but an S4 is
usually absent because there is little or no atrial contribution
to ventricular filling due to high left ventricular end-diastolic
pressure. The typical diastolic murmur of AR is shortened in duration,
often difficult to hear, and easily missed.
Laboratory findings depend on the underlying cause of AR. Elevated white blood cell count and erythrocyte sedimentation rate are seen
in inflammatory conditions, such as infection and aortitis. Abnormal
antinuclear antigen and rheumatoid factor titers may be seen in
patients with rheumatologic disorders. When syphilis is suspected,
serologic tests may be indicated.
No specific electrocardiographic abnormalities are characteristic of AR. Signs of left atrial enlargement, left ventricular hypertrophy,
and a “strain pattern” (ST depression with T-wave
inversion in lateral leads) are often seen in chronic significant
AR. Arrhythmias, including ventricular ectopy and ventricular tachycardia, may
occur in advanced cases with left ventricular dysfunction. In acute
AR, sinus tachycardia may be the only abnormality. In cases of infective
endocarditis, inflammation or abscess formation may spread to the
atrioventricular node, resulting in prolongation of the PR interval
or development of atrioventricular block.
Chest radiographic findings are not specific for AR and reflect an estimate of cardiac size and pulmonary vascular changes. In chronic
significant AR, an increase in the size of the cardiac silhouette
is seen. In acute AR, the cardiac size is normal; the lung fields
show increased markings due to pulmonary edema. When AR is due to
aortic dissection, the chest film may show an enlarged ascending
aorta. If calcification of the aortic knob is present, a helpful
sign of dissection is increased separation between the outer margin
of the aorta and the calcific density.
Echocardiography and Doppler Techniques
With recent technologic advances, particularly the introduction of color-flow Doppler, echocardiography has become the method of choice
for evaluating patients with AR. Two-dimensional echocardiography
in combination with various Doppler modalities and, in selected
cases, transesophageal imaging has provided a noninvasive means
for not only diagnosing AR with a high sensitivity and specificity
but also for assessing its etiology and severity. Furthermore, important
information can be obtained on the hemodynamic impact of the regurgitant lesion,
prognosis, and effectiveness of therapy.
Detection of Aortic Regurgitation
Currently, the best noninvasive method for detecting AR is Doppler echocardiography. Doppler techniques are extremely sensitive and
specific in the detection of AR, manifested as a diastolic flow abnormality
arising from the aortic valve, directed toward the left ventricle.
Even trivial regurgitation can be detected, which commonly is not
audible on physical examination. Although most cases of moderate-to-severe
chronic AR have typical findings on physical examination, moderate
lesions may occasionally be missed on examination because of the subtlety
of auscultatory findings. Doppler echocardiography is also extremely
valuable in patients with acute AR when the typical clinical findings
of chronic AR are absent and the murmur can often be missed. Among
the available Doppler techniques (including color Doppler, pulsed
and continuous wave Doppler), color Doppler echocardiography has
proven to be extremely helpful in the evaluation of AR (Figure 8–1). Its major advantage over conventional Doppler is that it provides a spatial orientation of the regurgitant jet arising from the aortic root. A completely
negative color Doppler examination in multiple planes virtually excludes
the presence of AR. Although pulsed and continuous wave Doppler
are almost equally sensitive in the detection of AR, eccentric aortic
insufficiency jets can be missed with these techniques and are better
delineated with color-flow imaging.
Color Doppler echocardiographic frames in diastole from the parasternal long axis view in (A) a patient with mild aortic regurgitation and another with (B) severe regurgitation. The patient with severe aortic regurgitation (B) has
a large ascending aortic aneurysm (Ao Ann). The width of the aortic
regurgitation jet in the left ventricular outflow (between arrows)
provides a good estimate of the severity of aortic regurgitation
by color Doppler echocardiography. Ao, aorta; Ao Ann, aortic aneurysm;
LA, left atrium; LV, left ventricle.
Echocardiographic imaging with M-mode and two-dimensional examinations cannot detect the presence of AR but can provide indirect clues to its presence. These include diastolic fluttering of the anterior
mitral leaflet or septum depending on the impingement of the regurgitant
flow on these structures. These signs, although specific, are not sensitive
for the detection of AR and do not relate to the severity of regurgitation.
Because two-dimensional echocardiography can image cardiac structures,
it provides valuable information on the cause of the AR. Structural abnormalities
of the aortic valve, including calcifications or thickening, congenital
deformities, vegetations, rupture, or prolapse, can be identified.
Dilatation of the aortic root, calcifications, or dissection can
also be evaluated. Although most of these conditions can be assessed
with transthoracic echocardiography, transesophageal echocardiography
has provided high-resolution images that allow for improved detection
of such abnormalities, especially in technically difficult cases
or in conditions such as infective endocarditis. Transesophageal
echocardiography is also routinely performed when an aortic abnormality,
such as aneurysm or dissection, is suspected (Figure
8–2). In patients with AR due to aortic disease, precisely
defining the morphology of the valve and involvement of the aortic
root is important in determining the surgical approach and deciding
whether the valve can be preserved or requires replacement.
Transesophageal echocardiographic frames in systole (SYS)
and diastole (DIAST), showing a vegetation attached to the aortic
valve that prolapses into the left ventricular outflow tract during
diastole. In this patient, transthoracic echocardiographic imaging
was difficult and failed to demonstrate the large vegetation.
In addition to the detection of AR, Doppler echocardiography combined with two-dimensional echocardiographic imaging has recently
allowed an assessment of the severity of the lesion. Several methods
have been proposed, including color Doppler assessment of regurgitant
jet size, continuous wave Doppler using the pressure half-time method,
measurements of regurgitant volume and effective regurgitant orifice area derived from two-dimensional echocardiography and pulsed Doppler techniques.
With color-flow Doppler, the AR jet can be spatially oriented in the two-dimensional plane arising from the aortic valve and directed
toward the left ventricle. The ratio of the AR jet diameter just
below the leaflets to that of the left ventricular outflow diameter
has been shown to correlate well with the severity of regurgitation
when compared with the angiographic standard (Table
8–3, see Figure 8–1). Similarly,
a good estimation of AR severity has been found by relating the
cross-sectional area of the jet at its origin to the left ventricular
outflow area. Recently, measurement of the width of the AR jet at
the level of the leaflets (vena contracta) has been used to quantitatively
approximate AR severity. A vena contracta of > 0.6 cm is considered
a sign of severe AR. On the other hand, it is important to note
that the length of the AR jet does not correlate well with AR severity.
This is in part because color Doppler flow mapping is also highly
dependent on the velocity of regurgitation, or the driving pressure,
in addition to the regurgitant volume.
Table 8–3. Grading the Severity of Aortic Regurgitation Using Doppler Techniques Combined with Echocardiography. |Favorite Table|Download (.pdf)
Table 8–3. Grading the Severity of Aortic Regurgitation Using Doppler Techniques Combined with Echocardiography.
|Severity of AR||Color-Flow Doppler JH/LVOH (%)||Continuous Wave Doppler PHT (ms)||Pulsed Doppler Regurgitant Fraction (%)|
|Mild||< 24||> 500||< 20|
|Severe||> 65||< 200||> 50|
Another index of AR severity that has been useful clinically is the pressure half-time derived from continuous wave Doppler recordings
of the AR jet velocity. The velocity of the regurgitant jet is related
to the instantaneous pressure difference between the aorta and left
ventricle in diastole by the modified Bernoulli equation: Δ = 4V2, where ΔP is the pressure gradient
in millimeters of mercury and V is the blood velocity
in meters per second. The pressure half-time index is the time it
takes for the initial maximal pressure gradient in diastole to fall
by 50%. In patients with mild regurgitation, there is a
gradual small drop in the pressure difference in diastole, whereas
with severe AR, a more precipitous drop occurs (Figure
8–3). A pressure half-time greater than 500 ms is
seen in mild AR, but more significant regurgitation is usually associated
with a shorter pressure half-time (see Table 8–3, Figure 8–3). The severity of AR
using this index may be overestimated in patients who have elevated
left ventricular end-diastolic pressure.
Schematic of aortic and left ventricular pressure tracings in (left) a patient with mild and (right) another with severe aortic regurgitation and corresponding examples of
continuous wave Doppler recording of aortic jet velocity in such
patients. In mild aortic regurgitation, a gradual, small drop in
the difference between aortic and ventricular pressures occurs in
diastole, reflected by the small decrease in the velocity of the
aortic regurgitation jet. In contrast, in severe aortic regurgitation,
a more precipitous drop occurs in the pressure gradient and in the
corresponding jet velocity. AR, aortic regurgitation; Ao, aorta;
LV, left ventricle.
The severity of AR can also be assessed using regurgitant volume and regurgitant fraction derived from two-dimensional and pulsed
Doppler echocardiography. This method is based on the continuity
equation, which states that, in the absence of regurgitation, blood
flow is equal across all valves. Stroke volume at the level of a
valve annulus is calculated as the product of the cross-sectional
area obtained by two-dimensional echocardiography and the time velocity integral
of flow recorded by pulsed Doppler. In the presence of AR, stroke
volume at the left ventricular outflow tract is higher than that
across another valve without regurgitation. Therefore, AR volume
can be calculated as the difference between stroke volume at the
left ventricular outflow and that derived at another valve site.
Dividing the regurgitant volume by stroke volume across the aortic
valve gives an estimate of regurgitant fraction. A regurgitant fraction
of less than 30% is usually mild, whereas regurgitant fraction
greater than 50% denotes severe AR (see Table
8–3). A similar approach to estimating severity of
AR can be achieved using pulsed Doppler echocardiography in the
proximal descending aorta. In patients with significant AR, a large
reversal of flow is observed in diastole toward the aortic arch
and ascending aorta. This simple method should be used routinely
to qualitatively grade the severity of regurgitation and can also be
used quantitatively to derive a regurgitant fraction.
Proximal flow convergence is more difficult to identify in AR, but when it is present, the proximal isovelocity surface area method
can be used to determine the effective regurgitant orifice area.
This method is less accurate in eccentric jets and aortic root dilatation.
Although color-flow Doppler allows a good estimation of the severity of AR in most patients, its accuracy depends on optimization of
the color Doppler examination, including gainsettings, frame rate,
and interrogation of multiple tomographic planes. The availability
of other independent Doppler indices of AR severity further allows
the corroboration of color Doppler findings. This is particularly
helpful in patients with eccentric AR jets, for which severity may
be difficult to assess by color-flow Doppler alone. A detailed transthoracic
examination usually provides all the necessary information. When
the transthoracic approach is inadequate or inconclusive, transesophageal
echocardiography can be performed in this setting for the diagnosis
and assessment of severity of the lesion.
Another important caveat in classifying the severity of AR is that it is in part dependent on hemodynamic status, including preload
and, more importantly, afterload. Raising blood pressure may significantly
increase AR severity.
Assessment of Hemodynamic Effects
The hemodynamic effects of AR are assessed with both echocardiographic imaging and Doppler echocardiography. Two-dimensional echocardiography provides quantitation of ventricular size and function, in addition
to the degree of left ventricular hypertrophy and ventricular mass.
End-diastolic and end-systolic left ventricular dimensions and volumes
as well as left ventricular ejection fraction provide important measures
of the hemodynamic effects of AR and help identify patients at higher
risk. In patients with acute AR, premature closure of the mitral
valve can be demonstrated by both two-dimensional and M-mode imaging.
In these situations, diastolic mitral regurgitation can also be
detected by Doppler echocardiography, reflecting the rapid rise
of left ventricular pressure in diastole, exceeding that of left
atrial pressure. These findings indicate severe AR. In patients
with chronic AR, assessment of the ventricular and atrial filling dynamics
at the mitral and pulmonary venous inflow, respectively, allows
for noninvasive estimation of ventricular diastolic pressure, further
adding to the overall evaluation of the hemodynamic effect of AR
on ventricular function. Newer modalities such as Doppler tissue
imaging further enhance the accuracy of noninvasive assessment of
ventricular diastolic function. Thus, in patients with chronic AR, two-dimensional
echocardiography with Doppler provides serial assessment of left
ventricular volumes, hypertrophy, and function and helps assess
the progression of the disease and optimum timing of surgical intervention.
Cardiac Catheterization and Angiography
Prior to the introduction of Doppler echocardiography, the evaluation of the severity of AR invariably required invasive testing by cardiac
catheterization. With the improvement in the accuracy of noninvasive
tests, routine cardiac catheterization is no longer necessary in
most patients. At catheterization, the detection of AR is achieved
with the injection of radiopaque contrast into the aortic root and
the appearance of dye in the left ventricle (Figure
8–4). In addition, aortography allows evaluation of
the ascending aorta for dilatation or dissection. Some of the structural
abnormalities of the aortic valve may also be identified. The severity
of AR is quantitatively approximated using a grading system that
takes into account the intensity of contrast dye in the left ventricle
and its clearance (Table 8–4). This grading system has been helpful clinically in the assessment of AR severity. However, it is important
to emphasize that, similar to other diagnostic techniques, a number of technical factors may also affect interpretation. Positioning the catheter too close to the valve may itself cause regurgitation. The volume and rapidity of contrast injection, ventricular function, and type of catheter used are important factors that may affect the interpretation of AR severity.
Aortic root contrast injection in the left anterior oblique projection in a patient with severe aortic regurgitation, showing
significant opacification of the left ventricle. The aortography
also shows an ascending aortic aneurysm. AoA, aortic aneurysm; Lv,
Table 8–4. Angiographic Grading of the Severity of Aortic Regurgitation. |Favorite Table|Download (.pdf)
Table 8–4. Angiographic Grading of the Severity of Aortic Regurgitation.
|Grade||Degree of LV Opacification||Intensity of Dye||Clearance of Dye from LV|
|I (mild)||Incomplete||Ao > LV||Completely cleared on each beat|
|II (moderate)||Complete but faint||Ao > LV||Incomplete clearance|
|III (moderately severe)||Complete opacification in several beats||Ao = LV||Slow|
|IV (severe)||Complete on first beat||Ao < LV||Slow|
At catheterization, the severity of AR can also be assessed by the determination of regurgitant volume and regurgitant fraction.
In the absence of regurgitation or shunts, the left ventricular
stroke volume derived from contrast ventriculography is equal
to right ventricular stroke volume obtained by the Fick method or thermodilution.
When isolated AR is present, subtracting left ventricular from right
ventricular stroke volume gives the regurgitation volume. Regurgitant
fraction is derived as the regurgitant volume divided by left ventricular
stroke volume. In the presence of concomitant mitral regurgitation,
a total regurgitant volume or fraction can only be assessed using
this method. Because of inherent variability in the determination
of stroke volume, a 10–15% error in these measurements
is not infrequent and is similar to those obtained with Doppler
Cardiac catheterization provides an accurate assessment of the hemodynamic effect of AR. Using contrast ventriculography, preferably
in biplanar projections, accurate determination of left ventricular
volumes and ejection fraction can be performed. Furthermore, direct
measurements of pressures in the various cardiac chambers can be
recorded. In compensated chronic AR, the only abnormality that may
be observed is a widened pulse pressure on the aortic pressure tracing.
As decompensation occurs, left ventricular end-diastolic pressure rises.
In severe, particularly acute AR, aortic and left ventricular pressures
may equalize at end-diastole.
With the improvement in noninvasive testing, routine cardiac catheterization is no longer necessary in most patients for the
sole assessment of the lesion. Currently, cardiac catheterization
is indicated in the assessment of AR severity when noninvasive testing
is equivocal or discordant with the clinical presentation and, more
commonly, in the assessment of coronary artery disease prior to
aortic valve surgery. Preoperative coronary angiography should be
performed prior to elective surgery for AR in men older than 35
years of age, premenopausal women over 35 who have risk factors
for coronary artery disease, postmenopausal women, and any patients
with clinical suspicion of coronary artery disease.
Electrocardiographically Gated 64-Slice Computed Tomography Angiography (CTA)
This test allows rapid diastolic frame rates from which the regurgitant orifice can be planimetered. Studies have shown excellent agreement with echo Doppler measures in the same patients. In addition, the size
of the aorta and left ventricle can be determined as well as ejection
fraction. CTA can also be used to detect significant coronary artery
disease in patients with chest pain or who are being considered
Magnetic Resonance Imaging
Advances in magnetic resonance imaging (MRI) have recently allowed for evaluation of patients with AR. At present, three basic approaches are available: spin echo imaging, gradient echo imaging (cine-MRI),
and phase velocity mapping. Spin echo imaging provides an excellent
approach for depicting cardiac morphology and detecting aortic root
disease. However, aortic valve visualization is poor. Using cine-MRI,
AR is detected as a decrease in the signal intensity in the left
ventricular outflow during diastole. In preliminary studies, the
ratio of area of low-intensity signal to the area of the left ventricular
outflow has provided an accurate estimate of AR severity. Regurgitant fractions
have been determined by comparing right and left ventricular volumes
and stroke volumes. Furthermore, using phase velocity mapping, flow
in a region of interest can be assessed. Regurgitant fraction with
this method can be derived by comparing flows in the ascending aorta
and pulmonary artery.
The use of MRI is promising in the assessment of AR. It is particularly helpful in defining the severity and extent of AR. Imaging can be
performed in any plane, without attenuation from lung or bone. However,
this modality cannot be used in patients carrying metallic objects
such as defibrillators or pacemakers. Its current drawbacks are
lack of availability of cardiac MRI and high cost. It is an alternative
to echocardiography and for centers with expertise in cardiac MRI.
Exercise stress testing can be used to evaluate patients with equivocal symptoms or to guide patients who wish to
participate in athletic activities. Early studies using exercise
radionuclide angiography to assess ejection fraction suggested that
a failure to rise or a fall in ejection fraction correlated with
poor outcomes and was a criteria for considering surgery. However,
when resting ejection fraction and end-diastolic left ventricular
volume were considered, this exercise response in asymptomatic patients had
no independent predictive value. Thus, radionuclide imaging with
exercise in patients has been largely abandoned. In patients with
inadequate echocardiograms, radionuclide imaging can be used to
assess left ventricular size and function, but MRI or CT are probably
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