Aortic regurgitation
| Aortic regurgitation | |
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| Aortic Valve Insufficiency: Gross, mitral and aortic valve calcification with partially ruptured cusp. Aortic insufficiency with nice kangaroo pouches. (An excellent example). Image courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editors-in-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Keri Shafer, M.D. [3]
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Synonyms and related words: Aortic regurgitation, AI, AR
Aortic Insufficiency refers to retrograde or backwards flow of blood from the aorta into the left ventricle during diastole.[1] [2] [3] [4]
Epidemiology and Demographics
There are two broad underlying causes of aortic regurgitation:
- Disease of the aortic valve itself and
- Disease of the aortic root leading to dilation and regurgitation of the aortic valve
Aortic regurgitation secondary to dilation of the ascending aorta has overtaken valvular aortic disease as the most common cause of aortic regurgitation.
Pathophysiology
Aortic Valve Disease
A full list of causes of aortic regurgitation can be found in the differential diagnosis section below.
One of the most common causes of aortic valvular disease in the past has been rheumatic fever in which case the aortic cusps are infiltrated with fibrous tissue. This then leads to retraction of the cusps and prevents their apposition during diastole. The cusps may also fuse and this may cause a component of aortic stenosis. It is therefore not uncommon for these patients to have mixed aortic regurgitation and aortic stenosis. Often these patients will have involvement of the mitral valve as well.
In the modern era, a more common cause of acquired aortic valve regurgitation is degenerative disease of the aorta and aortic valve in which case there is calcification and fibrosis of the cusps. As is the case with rheumatic fever, there is similar retraction of the cusps that results in aortic insufficiency.
A third not uncommon cause of acquired aortic regurgitation is infective endocarditis. In this disease state, regurgitation develops as a result of a hole or perforation that develops in the leaflet, or alternatively the cusps may not oppose each other due to a vegetation lying between the cusps which prevents their apposition.
A final not uncommon cause of acquired aortic insufficiency is trauma in which case there is distortion of the valve architecture leading to failure of the cusps to oppose.
Congenital conditions such as congenital bicuspid aortic stenosis or a ventricular septal defect can also result in aortic insufficiency.
Aortic Root Disease
Aortic root disease as a cause of aortic insufficiency has overtaken acquired forms of valvular disease and congenital forms of valvular disease as the leading cause of aortic regurgitation. The following is a list of those conditions that lead to dilation of the aortic root and thereby cause aortic insufficiency:
Hemodynamic Consequences of Aortic Insufficiency
Chronic Aortic Regurgitation
The hemodynamic impact of aortic regurgitation is to cause progressive dilation and hypertrophy of the left ventricle. The mitral valve ring may also dilate which may lead in turn to mitral regurgitation. The left atrium may dilate as a result of the mitral regurgitation.
It has been said that 'aortic regurgitation begets aortic regurgitation'. The high oscillatory shear associated with aortic regurgitation may lead to further dilation of the aorta, which in turn may lead to further aortic regurgitation.
Volume overload associated with aortic regurgitation leads to left ventricular hypertrophy. The sarcomers replicate in series and there is elongation of the myocytes and myocardial fibrils. As a result of this hypertrophy the ratio of the ventricular wall thickness to cavity radius remains normal and therefore wall stress is normal. In aortic regurgitation there is eccentric hypertrophy where as in aortic stenosis there is concentric hypertrophy where there is replication of the sarcomers in parallel. Once wall thickening fails to keep up with the hemodynamic load, end systolic wall stress rises and at this point the left ventricle fails. The dramatic enlargement of the heart that is seen with aortic regurgitation is called cor bovinum. Over time the left ventricle will decompensate and there will be increasing interstitial fibrosis and a stiffening or a reduction in the compliance of the left ventricular wall. At this point the patient will experience a rise in the end diastolic pressure and volume. The first decline is seen with exercise and then the patient begins to have a reduction in forward output at rest.
Patients with chronic aortic insufficiency may also develop myocardial ischemia. This is due to the fact that they have an increase in demand due to an increased thickness of the LV and also a reduction in the supply due to a lower perfusion pressure during diastole.
Acute aortic insufficiency
Acute aortic insufficiency is often secondary to either trauma or infective endocarditis. While the heart can accommodate the changes of chronic aortic insufficiency over time, the acute changes of acute aortic insufficiency are not well accommodated by the left ventricle.
The rapid rise in left ventricular pressure causes the mitral valve to close earlier during diastole. This early closure fortunately prevents backwards flow of blood into the pulmonary vascular bed. The very high left ventricular end diastolic pressure often keeps the aortic diastolic pressure from falling too low and thus there is often not a wide pulse pressure. Indeed absence of a wide pulse pressure in the patient with acute aortic insufficiency should alert the clinician to potential failure of the left ventricle.
Diagnosis
Differential Diagnosis of the Etiologies of Aortic Insufficiency
Acute Aortic Insufficiency
- After prosthetic valve surgery
- Aortic dissection
- Bacterial Endocarditis
- Chest trauma
- Myxomatous aortic valve
- Other valvular disease
- Rheumatic Fever
Chronic Aortic Insufficiency
- After prosthetic valve surgery
- Aortic Dissection
- Ankylosing Spondylitis
- Arteriosclerosis
- Bacterial Endocarditis
- Bechterew's Disease
- Bicuspid aortic valve
- Cystic medianecrosis of aorta
- Ehlers-Danlos Syndrome
- Hypertension
- Marfan Syndrome
- Myxomatous aortic valve
- Polymyalgia Rheumatica
- Pseudoxanthoma Elasticum
- Reiter's Syndrome
- Rheumatic Fever
- Rheumatoid Arthritis
- Sinus of Valsalva Aneurysm
- Syphilis
- Systemic Lupus Erythematosus
- Traumatic
- Turner's Syndrome
- Ventricular Septal Defect
- Weight loss medications
History
Physical Examination
The physical examination of an individual with aortic insufficiency involves auscultation of the heart to listen for the murmur of aortic insufficiency and the S4 heart sound (which would indicate left ventricular filling against a hypertrophied LV wall). The murmur of chronic aortic insufficiency is typically described as early diastolic and decresendo, which is best heard at aortic area when the patient is seated and leans forward with breath held in expiration. The murmur is usually soft and seldom causes thrill. If there is radiation to the right parasternal region, ascending aortic aneurysm has to be excluded.
If there is increased stroke volume of the left ventricle due to volume overload, an ejection systolic 'flow' murmur may also be present when auscultating the same aortic area. Unless there is concomittant aortic valve stenosis, the murmur should not start with an ejection click.
There may also be an Austin Flint murmur, a soft mid-diastolic rumble heard at the apical area. It appears when regurgitant jet from the severe aortic insufficiency renders partial closure of the anterior mitral leaflet.
Peripheral physical signs of aortic insufficiency are related to the high pulse pressure and the rapid decrease in blood pressure during diastole due to the AI, although usefulness of some of the eponymous signs has been questioned:[5]
- large-volume, 'collapsing' pulse
- bounding peripheral pulses; also known as Watson's water hammer pulse
- low diastolic and increased pulse pressure
- Corrigan's pulse (rapid upstroke and collapse of the carotid artery pulse)
- de Musset's sign (head nodding in time with the heart beat)
- Quincke's sign (pulsation of the capillary bed in the nail)
- Traube's sign (systolic and diastolic murmurs described as 'pistol shots' heard over the femoral artery when it is gradually compressed)
- Duroziez's sign (a double sound heard over the femoral artery when it is compressed distally)
Rarer signs include [6]:
- Lighthouse sign (blanching & flushing of forehead)
- Landolfi's sign (alternating constriction & dilatation of pupil)
- Becker's sign (pulsations of retinal vessels)
- Müller's sign (pulsations of uvula)
- Mayen's sign (diastolic drop of BP>15 mm Hg with arm raised)
- Rosenbach's sign (pulsatile liver)
- Gerhardt's sign (enlarged spleen)
- Hill's sign - a ≥ 20 mmHg difference in popliteal and brachial systolic cuff pressures, seen in chronic severe AI. Considered to be an artefact of sphygmomanometric lower limb pressure measurement.[7]
- Lincoln sign (pulsatile popliteal)
- Sherman sign (dorsalis pedis pulse is quickly located & unexpectedly prominent in age>75 yr)
- Ashrafian sign (Pulsatile pseudo-proptosis)[8]
Unfortunately, none of the above putative signs of aortic insufficiency is of utility in making the diagnosis.[9] What is of value is hearing a diastolic murmur itself, whether or not the above signs are present.
Ear Nose and Throat
The uvula may bob
Heart
Extremities
The pulses are bounding with a "water hammer pulse"
Laboratory Findings
Electrocardiogram
Chest X Ray
Echocardiography
- Increased duration between E and A peaks
- Fluttering of the anterior mitral valve leaflet due to AI jet turbulence
- Clinical setting to decide mechanism
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Severe aortic insufficiency 1
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Severe aortic insufficiency 2
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Severe aortic insufficiency 3
Severe acute aortic insufficiency is considered a medical emergency. There is a high mortality rate if the individual does not undergo immediate surgery for aortic valve replacement. If the acute AI is due to aortic valve endocarditis, there is a risk that the new valve may become seeded with bacteria. However, this risk is small. [10]
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Severe aortic insufficiency in patient after aortic valve replacement 1
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Severe aortic insufficiency in patient after aortic valve replacement 2
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Severe aortic insufficiency in patient after aortic valve replacement 3
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Severe aortic insufficiency in patient after aortic valve replacement 4
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Severe aortic insufficiency in patient after aortic valve replacement 5
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Severe aortic insufficiency in patient after aortic valve replacement 6
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Severe aortic insufficiency in patient after aortic valve replacement 7
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Severe aortic insufficiency in patient after aortic valve replacement 8
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MRI and CT
Diagnostic evaluation
The most common test used for the evaluation of the severity of aortic insufficiency is the echocardiogram, which can provide two-dimensional views of the regurgitant jet, and allow measurement of the velocity and volume of the jet.
The echocardiographic findings in severe aortic regurgitation include:
- An AI color jet dimension > 60 percent of the left ventricular outflow tract (LVOT) diameter (may not be true if the jet is eccentric)
- The pressure half-time of the regurgitant jet is < 250 msec
- Early termination of the mitral inflow (due to increase in LV pressure due to the AI.)
- Early diastolic flow reversal in the descending aorta.
- Regurgitant volume > 60 ml
- Regurgitant fraction > 55 percent
Quantification of Aortic Insufficiency by Aortography
The pigtail catheter is placed a few centimeters above the aortic root. Grading the amount of regurgitation is based on the amount of opacification of the ventricle 2 complete cardiac cycles after injection compared to that of the aortic root.
Grade 1
Brief and incomplete ventricular opacification. Clears rapidly.
Grade 2
Moderate opacification of the ventricle that clears in less that 2 cycles. Never greater than aortic root opacification.
<googlevideo>2835396102193538399&hl=en</googlevideo> 2+ AI Marfan Syndrome
Grade 3
Opacification of the ventricle equal to aortic root opacification within 2 cycles. Delayed clearing of ventricle over several cycles.
<googlevideo>-7844772248158567311&hl=en</googlevideo> 3+ AI
Grade 4
Opacification of the ventricle almost immediately that is greater than that of the aortic root with delayed clearing of the ventricle.
<googlevideo>1323435585463870537&hl=en</googlevideo> 4+ AI
Treatment
| Symptoms | Ejection fraction | Other information |
|---|---|---|
| NYHA class III - IV | ≥ 50 % | |
| NYHA class II | ≥ 50 % | Progression of symptoms or worsening parameters on echocardiography |
| CHA class ≥ II angina | ≥ 50 % | |
| Regardless of symptoms | 25 - 49 % | |
| Cardiac surgery for other cause (ie: CAD, other valvular disease, ascending aortic aneurysm) | ||
Aortic insufficiency can be treated either medically or surgically, depending on the acuteness of presentation, the symptoms and signs associated with the disease process, and the degree of left ventricular dysfunction.
Surgical treatment is controversial in asymptomatic patients, however has been recommended if the ejection fraction falls below 50% or in the face of progressive and severe left ventricular dilatation. For both groups of patients, surgery before the development of worse ejection fracture/LV systolic dilatation, is expected to reduce the risk of sudden death, and is associated with lower peri-operative mortality.
Medical treatment
Medical therapy of chronic aortic insufficiency involves the use of vasodilators. Small trials have shown a short term benefit in the use of ACE inhibitors, nifedipine, and hydralazine in improving left ventricular wall stress, ejection fraction, and mass. The use of these vasodilators is only indicated in individuals who suffer from hypertension in addition to AI. The goal in using these pharmacologic agents is to decrease the afterload so that the left ventricle is somewhat spared. The regurgitant fraction may not change significantly, since the gradient between the aortic and left ventricular pressures is usually fairly low at the initiation of treatment.
Surgical treatment
The surgical treatment of choice at this time is an aortic valve replacement. This is currently an open-heart procedure, requiring the individual to be placed on cardiopulmonary bypass.
In the case of severe acute aortic insufficiency, all individuals should undergo surgery if there are no absolute contraindications for surgery. Individuals with bacteremia with aortic valve endocarditis should not wait for treatment with antibiotics to take effect, given the high mortality associated with the acute AI. In stead, replacement with an aortic valve homograft should be performed if feasible.
Percutaneous Aortic Valve Replacement
In the close future, it is hoped that a percutaneous approach to aortic valve replacement will be feasible.
References
- ↑ Connolly HM, Crary JL, McGoon MD; et al. (1997). "Valvular heart disease associated with fenfluramine-phentermine". N. Engl. J. Med. 337 (9): 581–8. doi:10.1056/NEJM199708283370901. PMID 9271479.
- ↑ Weissman NJ (2001). "Appetite suppressants and valvular heart disease". Am. J. Med. Sci. 321 (4): 285–91. doi:10.1097/00000441-200104000-00008. PMID 11307869.
- ↑ Schade R, Andersohn F, Suissa S, Haverkamp W, Garbe E (2007). "Dopamine agonists and the risk of cardiac-valve regurgitation". N. Engl. J. Med. 356 (1): 29–38. doi:10.1056/NEJMoa062222. PMID 17202453.
- ↑ Zanettini R, Antonini A, Gatto G, Gentile R, Tesei S, Pezzoli G (2007). "Valvular heart disease and the use of dopamine agonists for Parkinson's disease". N. Engl. J. Med. 356 (1): 39–46. doi:10.1056/NEJMoa054830. PMID 17202454.
- ↑ Babu AN, Kymes SM, Carpenter Fryer SM (2003). "Eponyms and the diagnosis of aortic regurgitation: what says the evidence?". Ann. Intern. Med. 138 (9): 736–42. PMID 12729428.
- ↑ Ashrafian H. Pulsatile pseudo-proptosis, aortic regurgitation and 31 eponyms. Int J Cardiol. 2006 Mar 8;107(3):421-3.
- ↑ Kutryk M, Fitchett D (1997). "Hill's sign in aortic regurgitation: enhanced pressure wave transmission or artefact?". The Canadian journal of cardiology. 13 (3): 237–40. PMID 9117911.
- ↑ Ashrafian H. Pulsatile pseudo-proptosis, aortic regurgitation and 31 eponyms. Int J Cardiol. 2006 Mar 8;107(3):421-3.
- ↑ Choudhry NK, Etchells EE (1999). "The rational clinical examination. Does this patient have aortic regurgitation?". JAMA. 281 (23): 2231–8. PMID 10376577.
- ↑ al Jubair K, al Fagih MR, Ashmeg A, Belhaj M, Sawyer W (1992). "Cardiac operations during active endocarditis". J. Thorac. Cardiovasc. Surg. 104 (2): 487–90. PMID 1495315.
- ↑ "ACC/AHA guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association. Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease)". J. Am. Coll. Cardiol. 32 (5): 1486–588. 1998. PMID 9809971.
External links
- Heart Disease and Life After by Richard Hinkle
See also
Acknowledgments
Person who first created this page was Editor-In-Chief: C. Michael Gibson, M.S., M.D. [5]