Aortic insufficiency
Encyclopedia
Aortic insufficiency also known as aortic regurgitation (AR), is the leaking of the aortic valve
of the heart
that causes blood to flow in the reverse direction during ventricular diastole
, from the aorta
into the left ventricle
.
Aortic insufficiency can be due to abnormalities of either the aortic valve or the aortic root (the beginning of the aorta
).
), which is idiopathic
in over 80% of cases, but otherwise may result from aging
, syphilitic aortitis
, osteogenesis imperfecta
, aortic dissection
, Behçet's disease
, reactive arthritis
and systemic hypertension
. In about 15% the cause is innate bicuspidal aortic valve
, while another 15% cases are due to retraction of the cusps as part of postinflammatory processes of endocarditis
in rheumatic fever
and various collagen vascular diseases. Additionally, aortic insufficiency has been linked to the use of some medications, specifically medications containing fenfluramine
or dexfenfluramine
isotopes and dopamine agonists. Other potential causes that affects the valve directly include: Marfan's syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis
and systemic lupus erythematosus
. In acute cases of aortic insufficiency, the main causes are infective endocarditis
or trauma
.
is higher than the pressure in the aorta
. This allows the blood to be ejected from the left ventricle into the aorta during ventricular systole
. The amount of blood that is ejected
by the heart is known as the stroke volume
. Under normal conditions, 50–70% of the blood in a filled left ventricle is ejected into the aorta to be used by the body (called the 'ejection fraction'). After ventricular systole, the pressure in the left ventricle decreases as it relaxes and begins to fill up with blood from the left atrium
. This relaxation of the left ventricle (early ventricular diastole
) causes a fall in its pressure. When the pressure in the left ventricle falls below the pressure in the aorta
, the aortic valve
will close, preventing blood in the aorta from going back into the left ventricle.
. For instance, if an individual with AI has a stroke volume of 100 ml and during ventricular diastole
25 ml regurgitates back through the aortic valve, the regurgitant fraction is 25%. This regurgitant flow causes a decrease in the diastolic blood pressure in the aorta, and therefore an increase in the pulse pressure
(systolic pressure - diastolic pressure). Thus, physical examination will reveal a bounding pulse
, especially in the radial artery.
Since some of the blood that is ejected during systole
regurgitates back into the left ventricle during diastole
, there is decreased effective forward flow in AI.
Note that while diastolic blood pressure is diminished and the pulse pressure widens, systolic blood pressure generally remains normal or can even be slightly elevated. This is because sympathetic nervous system and the renin-angiotensin-aldosterone axis of the kidneys compensate for the decreased cardiac output. Catecholamines will increase the heart rate and increase the strength of ventricular contraction, directly increasing cardiac output. Catecholamines will also cause peripheral vasoconstriction, which causes increased systemic vascular resistance and ensures that core organs are adequately perfused. Renin
, a proteolytic enzyme, cleaves angiotensinogen to angiotensin
I, which is converted to angiotensin
II, which is also a potent vasoconstrictor. In the case of chronic aortic insufficiency with resultant cardiac remodeling, heart failure will develop, and it is possible to see systolic pressures diminish.
Aortic insufficiency causes both volume overload (elevated preload) and pressure overload (elevated afterload
due to increased stroke volume) of the heart.
The pressure overload (due to elevated pulse pressure and the systemic effects of neuroendocrine hormones) causes left ventricular hypertrophy
(LVH). There is both concentric hypertrophy and eccentric hypertrophy in AI. The concentric hypertrophy is due to the increased left ventricular systolic pressures associated with AI, while the eccentric hypertrophy is due to volume overload caused by the regurgitant fraction.
sequelae of AI are dependent on the rate of onset of AI. Acute AI and chronic AI will have different hemodynamics and individuals will have different signs and symptoms.
, there will be a sudden increase in the volume of blood in the left ventricle
. The ventricle is unable to deal with the sudden change in volume. In terms of the Frank-Starling curve, the end-diastolic volume will be very high, such that further increases in volume result in less and less efficient contraction. The filling pressure of the left ventricle will increase. This causes pressure in the left atrium
to rise, and the individual will develop pulmonary edema
.
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.
Acute AI usually presents as florid congestive heart failure
, and will not have any of the signs associated with chronic AI since the left ventricle had not yet developed the eccentric hypertrophy and dilatation that allow an increased stroke volume, which in turn cause bounding peripheral pulses. On auscultation
, there may be a short diastolic
murmur and a soft S1. S1 is soft because the elevated filling pressures close the mitral valve in diastole
(rather than the mitral valve being closed at the beginning of systole
).
and dilatation of the left ventricle, and the volume overload is compensated for. The left ventricular filling pressures will revert to normal and the individual will no longer have overt heart failure.
In this compensated phase, the individual may be totally asymptomatic and may have normal exercise tolerance.
Eventually (typically after a latency period) the left ventricle will become decompensated, and filling pressures will increase. While most individuals would complain of symptoms of congestive heart failure to their physicians, some enter this decompensated phase asymptomatically. Proper treatment for AI involves aortic valve replacement
prior to this decompensation phase.
and circulatory shock.
of an individual with aortic insufficiency involves auscultation
of the heart to listen for the murmur of aortic insufficiency and the S3 heart sound
(S3 gallop correlates with development of LV dysfunction). The murmur of chronic aortic insufficiency is typically described as early diastolic and decrescendo, 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. there is radiation to the right parasternal region, ascending aortic aneurysm has to be excluded. The apex beat
is typically displaced down and to the left
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 concomitant 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 blood returning to the heart (the wrong way) from the aorta through the incompetent aortic valve, although the usefulness of some of the eponymous signs has been questioned:
Also, these are usually less detectable in acute cases.
Less used signs include:
Unfortunately, none of the above putative signs of aortic insufficiency is of utility in making the diagnosis, but they may help as pointers. What is of value is hearing a diastolic murmur itself, whether or not the above signs are present.
, which can provide two-dimensional views of the regurgitant jet, allow measurement of velocity using Doppler, and estimate jet volume.
The findings in severe aortic regurgitation, based on the 2006 American College of Cardiology/American Heart Association guidelines include:
In acute aortic regurgitation, echocardiography may show early closure of the mitral valve.
Chest X-ray
can assist in making the diagnosis, showing left ventricular hypertrophy
and dilated aorta. ECG typically indicates left ventricular hypertrophy
. Cardiac chamber catetherization assists in assessing the severity of regurgitation and any left ventricular dysfunction.
who are asymptomatic is about 0.2 percent per year. Risk increases if the ejection fraction decreases or if the individual develops symptoms.
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 to 50% or below, in the face of progressive and severe left ventricular dilatation, or with symptoms or abnormal response to exercise testing. For both groups of patients, surgery before the development of worsening ejection fraction/LV dilatation, is expected to reduce the risk of sudden death, and is associated with lower peri-operative mortality. Also, surgery is optimally performed immediately in acute cases.
s or angiotensin II receptor antagonist
s, 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.
Other rather conservative medical treatments for stable and asymptomatic cases include low sodium diet
, diuretic
s, digoxin
, calcium blockers and avoiding very strenuous activity
.
In addition, endocarditis prophylaxis is indicated before dental, gastrointestinal or genitourinary procedures.
In mild to moderate cases, echocardiography and cardiac stress test should be followed up every 1–2 years. In severe moderate/severe cases, echocardiography with cardiac stress test and/or isotope perfusion imaging should be performed every 3–6 months.
. 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. Instead, replacement with an aortic valve
homograft should be performed if feasible.
A percutaneous
approach to aortic valve replacement is now feasible, but the main experience has been in the treatment of aortic stenosis.
Aortic valve
The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....
of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
that causes blood to flow in the reverse direction during ventricular diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
, from the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
into the left ventricle
Left ventricle
The left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
.
Aortic insufficiency can be due to abnormalities of either the aortic valve or the aortic root (the beginning of the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
).
Etiology
About half of the cases of aortic insufficiency are due to the aortic root dilatation (annuloaortic ectasiaAnnuloaortic ectasia
Annuloaortic ectasia is a dilatation of the proximal ascending aorta and aortic annulus. It may cause aortic regurgitation, thoracic aortic dissection, aneurysm and rupture. It is often associated with Marfan syndrome. It can also be a complication due to tertiary syphilis...
), which is idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
in over 80% of cases, but otherwise may result from aging
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...
, syphilitic aortitis
Syphilitic aortitis
Syphilitic aortitis is a disease of the aorta associated with the tertiary stage of syphilis infection. SA begins as inflammation of the adventia, including the vessels that supply the aorta itself with blood, the vasa vasorum...
, osteogenesis imperfecta
Osteogenesis imperfecta
Osteogenesis imperfecta is a genetic bone disorder. People with OI are born with defective connective tissue, or without the ability to make it, usually because of a deficiency of Type-I collagen...
, aortic dissection
Aortic dissection
Aortic dissection occurs when a tear in the inner wall of the aorta causes blood to flow between the layers of the wall of the aorta and force the layers apart. The dissection typically extends anterograde, but can extend retrograde from the site of the intimal tear. Aortic dissection is a medical...
, Behçet's disease
Behçet's disease
Behçet's disease is a rare immune-mediated systemic vasculitis that often presents with mucous membrane ulceration and ocular involvements...
, reactive arthritis
Reactive arthritis
Reactive arthritis , is classified as an autoimmune condition that develops in response to an infection in another part of the body. Coming into contact with bacteria and developing an infection can trigger the disease. Reiter's syndrome has symptoms similar to various other conditions collectively...
and systemic hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
. In about 15% the cause is innate bicuspidal aortic valve
Bicuspid aortic valve
A bicuspid aortic valve is most commonly a congenital condition of the aortic valve where two of the aortic valvular leaflets fuse during development resulting in a valve that is bicuspid instead of the normal tricuspid configuration. Normally the only cardiac valve that is bicuspid is the mitral...
, while another 15% cases are due to retraction of the cusps as part of postinflammatory processes of endocarditis
Endocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
in rheumatic fever
Rheumatic fever
Rheumatic fever is an inflammatory disease that occurs following a Streptococcus pyogenes infection, such as strep throat or scarlet fever. Believed to be caused by antibody cross-reactivity that can involve the heart, joints, skin, and brain, the illness typically develops two to three weeks after...
and various collagen vascular diseases. Additionally, aortic insufficiency has been linked to the use of some medications, specifically medications containing fenfluramine
Fenfluramine
Fenfluramine is a drug that was part of the Fen-Phen anti-obesity medication . Fenfluramine was introduced on the U.S. market in 1973. It is the racemic mixture of two enantiomers, dextrofenfluramine and levofenfluramine...
or dexfenfluramine
Dexfenfluramine
Dexfenfluramine, marketed as dexfenfluramine hydrochloride under the name Redux, is a serotoninergic anorectic drug: it reduces appetite by increasing the amount of extracellular serotonin in the brain...
isotopes and dopamine agonists. Other potential causes that affects the valve directly include: Marfan's syndrome, Ehlers–Danlos syndrome, ankylosing spondylitis
Ankylosing spondylitis
Ankylosing spondylitis , previously known as Bekhterev's disease, Bekhterev syndrome, and Marie-Strümpell disease is a chronic inflammatory disease of the axial skeleton with variable involvement of peripheral joints and nonarticular structures...
and systemic lupus erythematosus
Systemic lupus erythematosus
Systemic lupus erythematosus , often abbreviated to SLE or lupus, is a systemic autoimmune disease that can affect any part of the body. As occurs in other autoimmune diseases, the immune system attacks the body's cells and tissue, resulting in inflammation and tissue damage...
. In acute cases of aortic insufficiency, the main causes are infective endocarditis
Infective endocarditis
Infective endocarditis is a form of endocarditis, or inflammation, of the inner tissue of the heart, such as its valves, caused by infectious agents. The agents are usually bacterial, but other organisms can also be responsible....
or trauma
Trauma (medicine)
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
.
Physiology
In individuals with a normally functioning aortic valve, the valve is only open when the pressure in the left ventricleLeft ventricle
The left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
is higher than the pressure in the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
. This allows the blood to be ejected from the left ventricle into the aorta during ventricular systole
Systole (medicine)
Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...
. The amount of blood that is ejected
Ejection fraction
In cardiovascular physiology, ejection fraction is the fraction of Blood pumped out of the Right Ventricle of the heart to the Pulmonary Circulation and Left Ventricle of the heart to the Systemic Circulation with each Heart beat or Cardiac cycle...
by the heart is known as the stroke volume
Stroke volume
In cardiovascular physiology, stroke volume is the volume of blood pumped from one ventricle of the heart with each beat. SV is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat from the volume...
. Under normal conditions, 50–70% of the blood in a filled left ventricle is ejected into the aorta to be used by the body (called the 'ejection fraction'). After ventricular systole, the pressure in the left ventricle decreases as it relaxes and begins to fill up with blood from the left atrium
Left atrium
The left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
. This relaxation of the left ventricle (early ventricular diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
) causes a fall in its pressure. When the pressure in the left ventricle falls below the pressure in the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
, the aortic valve
Aortic valve
The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....
will close, preventing blood in the aorta from going back into the left ventricle.
Pathophysiology
In aortic insufficiency (AI), when the pressure in the left ventricle falls below the pressure in the aorta, the aortic valve is not able to completely close. This causes a leaking of blood from the aorta into the left ventricle. This means that some of the blood that was already ejected from the heart is regurgitating back into the heart. The percentage of blood that regurgitates back through the aortic valve due to AI is known as the regurgitant fractionRegurgitant fraction
Regurgitant fraction is the percentage of blood that regurgitates back through the aortic valve to the left ventricle due to aortic insufficiency, or through the mitral valve to the atrium due to mitral insufficiency...
. For instance, if an individual with AI has a stroke volume of 100 ml and during ventricular diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
25 ml regurgitates back through the aortic valve, the regurgitant fraction is 25%. This regurgitant flow causes a decrease in the diastolic blood pressure in the aorta, and therefore an increase in the pulse pressure
Pulse pressure
Pulse Pressure is most easily defined as being the amount of pressure required to create the feeling of a pulse. Measured in millimeters of mercury , the pressure difference between the systolic and diastolic pressures give you the amount of pressure change to create the pulse, which is the pulse...
(systolic pressure - diastolic pressure). Thus, physical examination will reveal a bounding pulse
Bounding pulse
Bounding pulse is a medical sign characterized as a leaping and forceful pulse that quickly disappears. To feel a bounding pulse, the radial artery is lightly palpated at the distal palmar edge. It is best detected when the arm is held aloft....
, especially in the radial artery.
Since some of the blood that is ejected during systole
Systole (medicine)
Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...
regurgitates back into the left ventricle during diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
, there is decreased effective forward flow in AI.
Note that while diastolic blood pressure is diminished and the pulse pressure widens, systolic blood pressure generally remains normal or can even be slightly elevated. This is because sympathetic nervous system and the renin-angiotensin-aldosterone axis of the kidneys compensate for the decreased cardiac output. Catecholamines will increase the heart rate and increase the strength of ventricular contraction, directly increasing cardiac output. Catecholamines will also cause peripheral vasoconstriction, which causes increased systemic vascular resistance and ensures that core organs are adequately perfused. Renin
Renin
Renin , also known as an angiotensinogenase, is an enzyme that participates in the body's renin-angiotensin system -- also known as the Renin-Angiotensin-Aldosterone Axis -- that mediates extracellular volume , and arterial vasoconstriction...
, a proteolytic enzyme, cleaves angiotensinogen to angiotensin
Angiotensin
Angiotensin, a peptide hormone, causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure. Angiotensin also stimulates the release of aldosterone, another hormone, from the adrenal cortex...
I, which is converted to angiotensin
Angiotensin
Angiotensin, a peptide hormone, causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure. Angiotensin also stimulates the release of aldosterone, another hormone, from the adrenal cortex...
II, which is also a potent vasoconstrictor. In the case of chronic aortic insufficiency with resultant cardiac remodeling, heart failure will develop, and it is possible to see systolic pressures diminish.
Aortic insufficiency causes both volume overload (elevated preload) and pressure overload (elevated afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
due to increased stroke volume) of the heart.
The pressure overload (due to elevated pulse pressure and the systemic effects of neuroendocrine hormones) causes left ventricular hypertrophy
Left ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
(LVH). There is both concentric hypertrophy and eccentric hypertrophy in AI. The concentric hypertrophy is due to the increased left ventricular systolic pressures associated with AI, while the eccentric hypertrophy is due to volume overload caused by the regurgitant fraction.
Hemodynamics
The hemodynamicHemodynamics
Hemodynamics, meaning literally "blood movement" is the study of blood flow or the circulation.All animal cells require oxygen for the conversion of carbohydrates, fats and proteins into carbon dioxide , water and energy in a process known as aerobic respiration...
sequelae of AI are dependent on the rate of onset of AI. Acute AI and chronic AI will have different hemodynamics and individuals will have different signs and symptoms.
Acute aortic insufficiency
In acute AI, as may be seen with acute perforation of the aortic valve due to endocarditisEndocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
, there will be a sudden increase in the volume of blood in the left ventricle
Left ventricle
The left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...
. The ventricle is unable to deal with the sudden change in volume. In terms of the Frank-Starling curve, the end-diastolic volume will be very high, such that further increases in volume result in less and less efficient contraction. The filling pressure of the left ventricle will increase. This causes pressure in the left atrium
Left atrium
The left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the pulmonary veins, and pumps it into the left ventricle, via the mitral valve.-Foramen ovale:...
to rise, and the individual will develop pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...
.
Severe acute aortic insufficiency is considered a medical emergency
Medical emergency
A medical emergency is an injury or illness that is acute and poses an immediate risk to a person's life or long term health. These emergencies may require assistance from another person, who should ideally be suitably qualified to do so, although some of these emergencies can be dealt with by the...
. There is a high mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
rate if the individual does not undergo immediate surgery for aortic valve replacement
Aortic valve replacement
Aortic valve replacement is a cardiac surgery procedure in which a patient's failing aortic valve is replaced with an alternate healthy valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky or partially blocked...
. If the acute AI is due to aortic valve endocarditis
Endocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
, there is a risk that the new valve may become seeded with bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
. However, this risk is small.
Acute AI usually presents as florid congestive heart failure
Congestive heart failure
Heart failure often called congestive heart failure is generally defined as the inability of the heart to supply sufficient blood flow to meet the needs of the body. Heart failure can cause a number of symptoms including shortness of breath, leg swelling, and exercise intolerance. The condition...
, and will not have any of the signs associated with chronic AI since the left ventricle had not yet developed the eccentric hypertrophy and dilatation that allow an increased stroke volume, which in turn cause bounding peripheral pulses. On auscultation
Heart sounds
Heart sounds, or heartbeats, are the noises generated by the beating heart and the resultant flow of blood through it...
, there may be a short diastolic
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
murmur and a soft S1. S1 is soft because the elevated filling pressures close the mitral valve in diastole
Diastole
Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...
(rather than the mitral valve being closed at the beginning of systole
Systole (medicine)
Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...
).
Chronic aortic insufficiency
If the individual survives the initial hemodynamic derailment that acute AI presents as, the left ventricle adapts by eccentric hypertrophyLeft ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
and dilatation of the left ventricle, and the volume overload is compensated for. The left ventricular filling pressures will revert to normal and the individual will no longer have overt heart failure.
In this compensated phase, the individual may be totally asymptomatic and may have normal exercise tolerance.
Eventually (typically after a latency period) the left ventricle will become decompensated, and filling pressures will increase. While most individuals would complain of symptoms of congestive heart failure to their physicians, some enter this decompensated phase asymptomatically. Proper treatment for AI involves aortic valve replacement
Aortic valve replacement
Aortic valve replacement is a cardiac surgery procedure in which a patient's failing aortic valve is replaced with an alternate healthy valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky or partially blocked...
prior to this decompensation phase.
Symptoms
Symptoms of aortic insufficiency are similar to those of heart failure and include dyspnea on exertion, orthopnea and paroxysmal nocturnal dyspnea. Palpitations and angina pectoris may also be felt. In acute cases there may be cyanosisCyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
and circulatory shock.
Physical examination
The physical examinationPhysical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
of an individual with aortic insufficiency involves auscultation
Auscultation
Auscultation is the term for listening to the internal sounds of the body, usually using a stethoscope...
of the heart to listen for the murmur of aortic insufficiency and the S3 heart sound
Third heart sound
The third heart sound or S3 is a rare extra heart sound that occurs soon after the normal two "lub-dub" heart sounds .-Physiology:It occurs at the beginning of diastole approximately 0.12 to 0.18 seconds after S2...
(S3 gallop correlates with development of LV dysfunction). The murmur of chronic aortic insufficiency is typically described as early diastolic and decrescendo, 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. there is radiation to the right parasternal region, ascending aortic aneurysm has to be excluded. The apex beat
Apex beat
The apex beat, also called the point of maximum impulse , is the furthermost point outwards and downwards from the sternum at which the cardiac impulse can be felt...
is typically displaced down and to the left
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 concomitant aortic valve stenosis
Aortic valve stenosis
Aortic valve stenosis is a disease of the heart valves in which the opening of the aortic valve is narrowed. The aortic valve is the valve between the left ventricle of the heart and the aorta, which is the largest artery in the body and carries the entire output of blood.-Pathophysiology:The...
, the murmur should not start with an ejection click.
There may also be an Austin Flint murmur
Austin Flint murmur
In cardiology, an Austin Flint murmur is a mid-diastolic or presystolic murmur low-pitched rumbling murmur which is best heard at the cardiac apex...
, 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 blood returning to the heart (the wrong way) from the aorta through the incompetent aortic valve, although the usefulness of some of the eponymous signs has been questioned:
- large-volume, 'collapsing' pulse also known as:
- Watson's water hammer pulseWatson's water hammer pulseWatson's water hammer pulse is the medical sign which describes a pulse that is bounding and forceful, or, in other words, rapidly increasing and subsequently collapsing, as if it were the hitting of a water hammer that was causing the pulse....
- Corrigan's pulse (rapid upstroke and collapse of the carotid arteryCarotid arteryCarotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
pulse)
- Watson's water hammer pulse
- low diastolic and increased pulse pressure
- de Musset's signDe Musset's signde Musset's sign is a condition in which there is rhythmic nodding or bobbing of the head in synchrony with the beating of the heart, in general as a result of aortic insufficiency caused by aortic regurgitation due to aortic valve deficiency. The condition was named after the French poet Alfred de...
(head nodding in time with the heart beat) - Quincke's sign (pulsation of the capillary bed in the nail; named for Heinrich QuinckeHeinrich QuinckeHeinrich Irenaeus Quincke was a German internist and surgeon. His main contribution to internal medicine was the introduction of the lumbar puncture for diagnostic and therapeutic purposes...
) - Traube's sign (a 'pistol shot' systolic sound heard over the femoral artery; named for Ludwig TraubeLudwig Traube (physician)Ludwig Traube was a German physician and co-founder of the experimental pathology in Germany.-Biography:...
) - Duroziez's signDuroziez's signDuroziez's sign is a sign of Aortic insufficiency. It consists of an audible diastolic murmur which can be heard over the femoral artery when it is compressed.It is named for Paul Louis Duroziez....
(systolic and diastolic murmurs heard over the femoral artery when it is gradually compressed with the stethescope)
Also, these are usually less detectable in acute cases.
Less used signs include:
- Lighthouse sign (blanching & flushing of forehead)
- Landolfi's sign (alternating constriction & dilatation of pupil)
- Becker's signBecker's signBecker's sign, or Becker's phenomenon, is the presence of visible pulsation of retinal arteries found in patients with aortic insufficiency or Graves' disease.The sign was named after Otto Heinrich Enoch Becker....
(pulsations of retinal vessels) - Müller's signMüller's signMüller's sign is the pulsation or bobbing of the uvula that occurs during systole. It can be seen in patients with severe aortic insufficiency. Müller's sign is caused by an increased stroke volume....
(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.
- Lincoln sign (pulsatile popliteal)
- Sherman sign (dorsalis pedis pulse is quickly located & unexpectedly prominent in age>75 yr)
- Ashrafian sign (Pulsatile pseudo-proptosis)
Unfortunately, none of the above putative signs of aortic insufficiency is of utility in making the diagnosis, but they may help as pointers. What is of value is hearing a diastolic murmur itself, whether or not the above signs are present.
Diagnostic evaluation
The most common test used for the evaluation of the severity of aortic insufficiency is transthoracic echocardiographyEchocardiography
An echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
, which can provide two-dimensional views of the regurgitant jet, allow measurement of velocity using Doppler, and estimate jet volume.
The findings in severe aortic regurgitation, based on the 2006 American College of Cardiology/American Heart Association guidelines include:
- An AI color jet width > 65 percent of the left ventricular outflow tract (LVOT) diameter (may not be true if the jet is eccentric)
- Doppler vena contracta width > 0.6 cm
- The pressure half-time of the regurgitant jet is < 250 msecMillisecondA millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
- Early termination of the mitral inflow (due to increase in LV pressure due to the AI.)
- Holodiastolic flow reversal in the descending aorta.
- Regurgitant volume > 60 ml
- Regurgitant fraction > 50 percent
- Regurgitant orifice area > 0.3 cm2
- Increased left ventricular size
In acute aortic regurgitation, echocardiography may show early closure of the mitral valve.
Chest X-ray
Chest X-ray
In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...
can assist in making the diagnosis, showing left ventricular hypertrophy
Left ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
and dilated aorta. ECG typically indicates left ventricular hypertrophy
Left ventricular hypertrophy
Left ventricular hypertrophy is the thickening of the myocardium of the left ventricle of the heart.-Causes:While ventricular hypertrophy occurs naturally as a reaction to aerobic exercise and strength training, it is most frequently referred to as a pathological reaction to cardiovascular...
. Cardiac chamber catetherization assists in assessing the severity of regurgitation and any left ventricular dysfunction.
Prognosis
The risk of death in individuals with aortic insufficiency, dilated ventricle, normal ejection fractionEjection fraction
In cardiovascular physiology, ejection fraction is the fraction of Blood pumped out of the Right Ventricle of the heart to the Pulmonary Circulation and Left Ventricle of the heart to the Systemic Circulation with each Heart beat or Cardiac cycle...
who are asymptomatic is about 0.2 percent per year. Risk increases if the ejection fraction decreases or if the individual develops symptoms.
Treatment
| Symptoms | Ejection fraction | Additional Findings |
|---|---|---|
| Present (NYHA II-IV) |
Any | |
| Absent | > 50 % | Abnormal exercise test, severe LV dilatation (systolic ventricular diameter >55 mm) |
| Absent | <=50 % | |
| Cardiac surgery for other cause (i.e.: 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
Ejection fraction
In cardiovascular physiology, ejection fraction is the fraction of Blood pumped out of the Right Ventricle of the heart to the Pulmonary Circulation and Left Ventricle of the heart to the Systemic Circulation with each Heart beat or Cardiac cycle...
falls to 50% or below, in the face of progressive and severe left ventricular dilatation, or with symptoms or abnormal response to exercise testing. For both groups of patients, surgery before the development of worsening ejection fraction/LV dilatation, is expected to reduce the risk of sudden death, and is associated with lower peri-operative mortality. Also, surgery is optimally performed immediately in acute cases.
Medical treatment
Medical therapy of chronic aortic insufficiency that is stable and asymptomatic involves the use of vasodilators. Small trials have shown a short term benefit in the use of ACE inhibitorACE inhibitor
ACE inhibitors or angiotensin-converting enzyme inhibitors are a group of drugs used primarily for the treatment of hypertension and congestive heart failure...
s or angiotensin II receptor antagonist
Angiotensin II receptor antagonist
Angiotensin II receptor antagonists, also known as angiotensin receptor blockers , AT1-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system...
s, nifedipine
Nifedipine
Nifedipine is a dihydropyridine calcium channel blocker...
, and hydralazine
Hydralazine
Hydralazine is a direct-acting smooth muscle relaxant used to treat hypertension by acting as a vasodilator primarily in arteries and arterioles...
in improving left ventricular wall stress, ejection fraction, and mass. The use of these vasodilators is only indicated in individuals who suffer from hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
in addition to AI. The goal in using these pharmacologic agents is to decrease the afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...
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.
Other rather conservative medical treatments for stable and asymptomatic cases include low sodium diet
Low sodium diet
A low sodium diet is a diet that includes no more than 1,500 to 2,400 mgs of sodium per day. People who follow a vigorous or moderate exercise schedule are usually advised to limit their sodium intake to 3,000 mg per day and those with moderate to severe heart failure are usually advised to...
, diuretic
Diuretic
A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.- Medical uses :...
s, digoxin
Digoxin
Digoxin INN , also known as digitalis, is a purified cardiac glycoside and extracted from the foxglove plant, Digitalis lanata. Its corresponding aglycone is digoxigenin, and its acetyl derivative is acetyldigoxin...
, calcium blockers and avoiding very strenuous activity
Anaerobic exercise
Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass...
.
In addition, endocarditis prophylaxis is indicated before dental, gastrointestinal or genitourinary procedures.
In mild to moderate cases, echocardiography and cardiac stress test should be followed up every 1–2 years. In severe moderate/severe cases, echocardiography with cardiac stress test and/or isotope perfusion imaging should be performed every 3–6 months.
Surgical treatment
The surgical treatment of choice at this time is an aortic valve replacementAortic valve replacement
Aortic valve replacement is a cardiac surgery procedure in which a patient's failing aortic valve is replaced with an alternate healthy valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky or partially blocked...
. 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. Instead, replacement with an aortic valve
Artificial heart valve
An artificial heart valve is a device implanted in the heart of a patient with heart valvular disease. When one of the four heart valves malfunctions, the medical choice may be to replace the natural valve with an artificial valve. This requires open-heart surgery.Valves are integral to the normal...
homograft should be performed if feasible.
A percutaneous
Percutaneous
In surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
approach to aortic valve replacement is now feasible, but the main experience has been in the treatment of aortic stenosis.
External links
- Heart Disease and Life After by Richard Hinkle
See also
- Aortic valve replacementAortic valve replacementAortic valve replacement is a cardiac surgery procedure in which a patient's failing aortic valve is replaced with an alternate healthy valve. The aortic valve can be affected by a range of diseases; the valve can either become leaky or partially blocked...
- Preload
- AfterloadAfterloadAfterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...