Aortic Coarctation

Case 1

Case 2

Additional coarctation Images

Background: Coarctation of the aorta is a complex cardiac lesion that requires careful follow-up care through adulthood and pregnancy. Before 1944, no therapy existed for this condition. Since 1972, surgical repair has decreased the mortality rate from 65% to 35%. 

Definition

Coarctation of the aorta is a narrowing of the aorta most commonly found just distal to the origin of the left subclavian artery.

Classification

Most patients with coarctation have juxtaductal coarctation. Older terms such as preductal (infantile-type) or postductal (adult-type) often are misleading.

Pathophysiology: The vascular malformation responsible for coarctation is a defect in the vessel media, giving rise to a prominent posterior infolding (the “posterior shelf”), which may extend around the entire circumference of the aorta. The gross pathology of coarctation varies considerably. The lesion often is discrete but may be long, segmental, or tortuous in nature.

Histology

The coarctated aortic segment reveals an intimal and medial lesion consisting of thickened ridges that protrude posteriorly and laterally into the aortic lumen. The ductus (ie, patent embryonic remnant) or ligamentum arteriosus (closed and fibrosed) inserts at the same level anteromedially. Intimal proliferation and disruption of elastic tissue may occur distal to the coarctation. At this site, infective endarteritis, intimal dissections, or aneurysms may occur. Cystic medial necrosis occurs commonly in the aorta adjacent to the coarctation site and acts as a substrate for late aneurysm formation or aortic dissection in some patients.

Embryology

Coarctation is due to an abnormality in development of the embryologic left fourth and sixth aortic arches that can be explained by 2 theories, the ductus tissue theory and the hemodynamic theory.

In the ductus tissue theory, coarctation develops as the result of migration of ductus smooth muscle cells into the periductal aorta, with subsequent constriction and narrowing of the aortic lumen. Commonly, coarctation becomes clinically evident with closure of the ductus arteriosus. This theory does not explain all cases of coarctation. Clinically, coarctation may occur in the presence of a widely patent ductus arteriosus, and it may occur quite distant from the insertion of the ductus arteriosus, such as in the transverse arch or abdominal aorta.

In the hemodynamic theory, coarctation results from reduced volume of blood flow through the fetal aortic arch and isthmus. In a normal fetus, the aortic isthmus receives a relatively low volume of blood flow. Most of the flow to the descending aorta is derived from the right ventricle through the ductus arteriosus. The left ventricle supplies blood to the ascending aorta and brachiocephalic arteries, and a small portion goes to the aortic isthmus. The aortic isthmus diameter is 70-80% of the diameter of the neonatal ascending aorta.

Based on this theory, lesions that diminish the volume of left ventricular outflow in the fetus also decrease flow across the aortic isthmus and promote development of coarctation. This helps to explain the common lesions associated with coarctation, such as ventricular septal defect, bicuspid aortic valve, left ventricular outflow obstruction, and tubular hypoplasia of the transverse aortic arch. This theory does not explain isolated coarctation without associated intracardiac lesions.

Frequency:

• In the US: This condition represents 5-10% of all congenital cardiac lesions. It represents 7% of critically ill infants with heart disease.

Mortality/Morbidity:

• Patients who are not treated for coarctation of the aorta may reach the age of 35 years; fewer than 20% survive to age 50 years. If coarctation is repaired before the age of 14 years, the 20-year survival rate is 91%. If coarctation is repaired after the age of 14 years, the 20-year survival rate is 79%.

• After repair of the aortic coarctation, 97-98% of patients are New York Heart Association (NYHA) class I. Impaired diastolic left ventricular function and persistent hypertrophy due to increased pressure gradient at the coarctation site during exercise may result in myocardial hypertrophy despite successful hemodynamic results. Overall, left ventricular systolic function is normal or hyperdynamic in these patients.

• Pregnancy: Most women reach childbearing age. If maternal coarctation is not repaired, the risk to fetus and mother is increased. The maternal mortality rate is approximately 3-8%. Even women who have had their coarctation repaired have an increased risk of aortic dissection and rupture of a cerebral aneurysm in the third trimester and peripartum period due to hemodynamic and hormonal changes. All pregnant women with a history of coarctation, either native or repaired, should be considered high risk. Significant stenosis—native, residual, or recurrent—is a contraindication to pregnancy.

Race: Coarctation is 7 times more common in whites than Asian persons. It has a lower incidence among Native Americans than other population groups in Minnesota.

Sex: Male-to-female predominance is 1.3-2:1 in most series.

Age: Age at detection of coarctation of the aorta is dependent on severity of obstruction and coexistence of other lesions.

History:

• Early life: Depending on severity of obstruction and associated cardiac lesions, patients may present with congestive heart failure, severe acidosis, or poor perfusion to the lower body.

• Beyond infancy: Patients are usually asymptomatic. They may present with hypertension, headache, nosebleed, leg cramps, muscle weakness, cold feet, or neurological changes.

Physical: The diagnosis of coarctation generally can be made on physical examination. Blood pressure differential and pulse delay are pathognomonic.

• Physical appearance

• Patients may appear healthy. If coarctation compromises the origin of the left subclavian artery, the left arm is smaller than normal. Otherwise, general development is normal.

• In XO Turner syndrome, a condition frequently associated with coarctation, a phenotypic female has the following features: short stature, webbed neck, absent or scanty axillary and pubic hair, broad chest and widely spaced hypoplastic or inverted nipples, low posterior hairline, small chin, prominent ears, cubitus valgus, short fourth metacarpals and metatarsals, distal palmar triaxial radii, narrow hyperconvex nails, and extensive pigmented cutaneous nevi.

• Arterial pulse: Abnormal differences in upper and lower extremity arterial pulses and blood pressures are clinical hallmarks of coarctation of the aorta. Pulses distal to the obstruction are diminished and delayed. This may be appreciated best by simultaneous arm and leg pulse palpation.

• Auscultation

• A continuous and/or late systolic murmur is best heard posteriorly over the thoracic spine. Collateral arterial murmurs are crescendo-decrescendo in shape and delayed in onset and termination because of their origins in vessels some distance from the heart. The collateral murmurs are present bilaterally.

• If the patient has associated bicuspid aortic valve, an aortic ejection sound, a short midsystolic murmur, and/or early diastolic murmur of aortic regurgitation may be audible.

• Associated cardiac defects

• These are observed in approximately 50% of patients with coarctation.

• The most commonly reported defects are left-sided obstructive or hypoplastic defects and ventricular septal defects. Bicuspid aortic valve is observed in 85% of patients. Also, aortic arch hypoplasia commonly is found in coarctation associated with intracardiac defects.

• Right-sided cardiac obstructive lesions, such as pulmonary stenosis, pulmonary atresia, or tetralogy of Fallot, are observed rarely.

• Extracardiac vascular anomalies

• These occur commonly in patients with coarctation. A right subclavian artery that arises aberrantly from the descending aorta distal to the coarctation occurs in 5% of patients. Rarely, both subclavian arteries originate distal to the coarctation.

• Berry aneurysms of the circle of Willis occur in 3-5% of patients and may result in subarachnoid bleed.

• After years of coarctation, large collateral arteries develop from the upper to lower body (ie, internal mammaries connecting to external iliac arteries and spinal and intercostal arteries connecting to the descending aorta).

• Hemangiomas also have been reported with coarctation.

• Extracardiac nonvascular anomalies

• Extracardiac nonvascular anomalies occur in 25% of patients with coarctation of the aorta. Coarctation of the aorta occurs in 35% of patients with Turner syndrome.

• Abnormalities of the musculoskeletal system, genitourinary system, gastrointestinal system, or respiratory system may be observed in as many as 25% of children with coarctation. In addition, an increasing number of children have head and neck abnormalities observed by ultrasonography.

Causes: The exact etiology of coarctation of the aorta is not known.

• Genetics: Coarctation is 7 times more common in whites than Asian persons. It has a lower incidence among Native Americans than other population groups in Minnesota.

• Environment: Environmental and seasonal variation have been suggested to influence the development of coarctation. A study has shown increased incidence of coarctation in late fall and winter births.

• Gridlock mutation: In 1995, Weinstein et al discovered a recessive mutation in zebrafish that causes a focal malformation resembling coarctation in humans. The mutation, named gridlock, results in failure of vascular channel formation at the site where bilaterally paired dorsal aortas join together and continue posteriorly as a dorsal midline channel, the medial dorsal aorta.

  Lab Studies:
  

  • No specific laboratory tests are necessary.

  Imaging Studies:
  

  • X-ray
  • X-ray findings vary with the clinical presentation of the patient. In coarctation diagnosed early in life, chest x-ray shows cardiac enlargement and pulmonary venous congestion. Associated cardiac defects may mask these findings.
  • In older children, chest x-ray findings are usually normal. The study typically shows a prominent aortic knob, and the stenotic region may be observed as an indentation of the proximal thoracic descending aorta in the shape of a number 3.
  • Rib notching is observed as irregularities and scalloping on the undersurface of the posterior ribs. This finding is unusual in children younger than 5 years and is observed more frequently in patients with significant gradient across coarctation of long standing.
  • Barium esophagram: Barium esophagram shows the classic “E sign,” representing compression from the dilated left subclavian artery and poststenotic dilatation of the descending aorta.
  • Echocardiography
  • Diagnosis of coarctation of the aorta is made by 2-dimensional echocardiography, pulsed-wave Doppler, and color flow mapping. Classic findings are narrowing of the isthmus and posterior indentation or shelf. Blood flow velocities proximal and distal to obstruction, measured by Doppler tracings, can be used to estimate pressure gradient across the coarctation by a modified Bernoulli equation. Color flow mapping shows changes in color at the site of obstruction due to increases in blood velocity and turbulence.
  • In older patients, coarctation may be difficult to diagnose by surface echocardiography. For these patients, MRI, transesophageal echocardiography, or cardiac catheterization with angiogram may be necessary to make the diagnosis.
  • Fetal echocardiography
  • Detection of coarctation in utero is a very difficult task for the echocardiographer.
  • Some features suggest the presence of coarctation: enlargement of right ventricle compared to left ventricle, isthmus and transverse aortic diameters less than 3% for gestational age, hypoplasia of left-sided structures, and decrease or reversal of flow in the foramen ovale.
  • Magnetic resonance imaging
  • MRI is a very sensitive test for location and extent of coarctation as well as involvement of adjacent vessels and presence of collaterals. However, it is very expensive, time consuming, and not universally available.
  • MRI is seldom used as a primary diagnostic tool. It is very useful tool for detecting and monitoring aneurysms and restenosis.
  • Cardiac catheterization
  • If the peak gradient across the coarctation is less than 20 mm Hg, the coarctation is mild.
  • A gradient of greater than 20 mm Hg across the coarctation is suggestive of the need for intervention.

  Other Tests:
  

  • Electrocardiogram
  • Newborns and older children with milder forms of coarctation may have a normal electrocardiogram (ECG). If associated cardiac defects present, then ECG may be abnormal.
  • In older patients, long-standing coarctation of the aorta or a higher gradient across the coarctation stimulates left ventricular hypertrophy.

   

Associations

• Often Isolated
• Turner's Syndrome (XO) - 20% females with coarctation
• Cerebral "Berry" Aneurysms
• Neurofibromatosis I
• William's Syndrome (Congenital Hypercalcemia)
• Sturge-Weber

Medical Care:

• Severe coarctation of the aorta

• Neonates with severe coarctation of the aorta should first have their condition stabilized.

• First, support respiratory collapse with intubation. Second, infuse prostaglandin E₁ to open the ductus arteriosus. Third, correct acidosis. Finally, provide inotropic support to improve symptoms of congestive heart failure.

• Less severe coarctation of the aorta

• Patients presenting with less severe coarctation of the aorta beyond the neonatal period usually have chronically increased afterload and show signs of congestive heart failure. These patients should be treated with digoxin and diuretics.

• Attempts should be made to postpone intervention, such as surgery or balloon dilatation, until the patient is hemodynamically stable.

Surgical Care: No single technique is superior to others in minimizing the rate of restenosis. The preferred method depends on anatomy of the lesion and institutional experience.

• Indication for intervention: At present, 3 specific indications exist for intervention in patients with coarctation of the aorta.

• Significant coarctation or recoarctation of the aorta with long-standing hypertension with or without symptoms

• Hemodynamically significant aortic stenosis

• Female patient contemplating pregnancy

• Types of surgery

• In 1944, Blalock and Park performed the first experimental surgical repair of coarctation of the aorta in animals, which involved use of the left common carotid or subclavian artery to bypass the coarctation with end-to-end anastomosis.

• Resection of the coarctation site and end-to-end anastomosis to repair coarctation was performed first on humans in 1944 by Crafoord, Nylin, Gross, and Hufagel. This is the preferred surgical method even today. In this technique, the aorta is cross-clamped above and below the obstruction, and the discrete narrowing is resected. The advantage of this procedure is that the obstructed site is completely resected. It also avoids use of prosthetic material and maintains a functioning left subclavian artery. The disadvantages of this procedure involve the sacrifice of spinal and intercostal vessels resulting in paralysis. Also, a high rate of restenosis exists with use of continuous running suture or circumferential fibrosis. This problem is overcome by use of interrupted and absorbable sutures, which allows for improved growth of the anastomotic site.

• Patch aortoplasty was first performed by Vossculte in 1961 to repair coarctation of the aorta. This technique involves cutting across the obstruction and augmenting the area with a patch of prosthetic material. The advantages of this procedure include the ability to repair a long segment of coarctation; sparing of the left subclavian, intercostal, and spinal arteries; and preserving native aortic tissue to allow for growth. The disadvantage of this procedure is that it uses prosthetic material, which may gradually result in aneurysm formation.

• Left subclavian flap angioplasty, introduced in 1966 by Waldhausen and Nahrwold, involves ligating the left subclavian artery and dividing it distally. A longitudinal incision is made from the descending aorta to the coarctation superiorly into the origin of the left subclavian artery. The subclavian artery is turned down and used to enlarge the narrowing. To prevent subclavian steal phenomena, the vertebral artery is ligated. The advantages to this procedure include preservation of native vascular tissue and avoidance of circumferential sutures, which allows for better growth of the involved area. The disadvantage to this procedure is the sacrifice of a major artery to the left arm, resulting in poor growth of that extremity.

• Bypass graft repair bridges the ascending and descending aorta. The major disadvantage of this procedure is that prosthetic material does not grow as the child grows, and it becomes calcified and narrow with time.

   

• Catheter-based intervention consists of primary ballooning and/or stenting and rapidly is becoming an accepted form of management of native coarctation. Ballooning and stenting is emerging as the treatment of choice for residual or recurrent stenosis. Most cardiologists who treat adults with congenital cardiovascular defects prefer catheter-based intervention. The unacceptably high incidence of paralysis makes surgical intervention on the adult patient much less desirable (see Complications).

Consultations:

Activity: As with all aortopathies and aortic valve problems, significant and prolonged isometric activities are contraindicated. The risk of dissection, even in repaired coarctation, remains significant and may be increased with isometric activity.

Further Outpatient Care:

• According to the Canadian Adult Congenital Heart Association, all patients with coarctation of the aorta need to be monitored by a cardiologist.

• Patients should have at least one MRI or angiogram following repair of the coarctation.

• Close surveillance and aggressive management are necessary for residual hypertension, heart failure or intracardiac disease, associated bicuspid aortic valve, recurrent coarctation of the aorta, or significant arm-leg blood pressure gradient at rest or with exercise.

• Ascending aortic dilation in the presence of a bicuspid aortic valve, new or unusual headache from berry aneurysm formation, late dissection proximal or distal to the repair site, and aneurysm formation at the site of coarctation repair are late sequelae of this disease.

Complications:

• Postoperative complications

• Patients may present with hoarseness due to damage to the recurrent laryngeal nerve as it loops around the patent ductus arteriosus or ligamentum.

• Ipsilateral diaphragmatic paralysis may result from injury to the phrenic nerve.

• Chylothorax can occur due to damage to the thoracic duct that crosses behind the aortic arch and left subclavian artery.

• Serious postoperative hemodynamic collapse may result from hemorrhage due to injury to the chest wall collaterals.

• Rebound and paradoxical hypertension is observed frequently and may be related to the baroreceptor-mediated increase in sympathetic activity and reflex vasospasm in the vascular territory distal to the coarctation.

• Postcoarctectomy syndrome is a unique problem early in the postoperative period. Increases in blood flow and pressure in the mesenteric arteries after repair of coarctation may result in abdominal distention and pain, vomiting, and decreased bowel sounds. This syndrome may be masked because of poorly controlled postoperative hypertension and early enteral feeding. By aggressively controlling postoperative hypertension and delaying enteral feeding for 2 days after surgery, incidence of postcoarctectomy syndrome may be reduced.

• The most serious complication associated with repair of coarctation is paralysis of the lower body resulting from spinal cord injury. Because of complex collateral formation, ischemia of the spinal cord is often difficult to predict and, therefore, may be unavoidable.

• Long-term complications: The most common long-term complication is systemic hypertension. This may be accentuated by exercise, creating a need to exclude residual or recurrent obstruction.

Prognosis:

• Patients who are not treated for coarctation of the aorta may reach the age of 35 years; fewer than 20% survive to age 50 years. If coarctation is repaired before the age of 14 years, the 20-year survival rate is 91%. If coarctation is repaired after the age of 14 years, the 20-year survival rate is 79%.

• After repair of coarctation of the aorta, 97-98% of patients are NYHA class I. Impaired diastolic left ventricular function and persistent hypertrophy due to increased pressure gradient at the coarctation site during exercise may result in myocardial hypertrophy despite successful hemodynamic results. Overall, left ventricular systolic function is normal or hyperdynamic in these patients.

• Pregnancy

• Most women reach childbearing age. If maternal coarctation is not repaired, risks to fetus and mother are increased. The maternal mortality rate is approximately 3-8%.

• Despite repair, women have an increased risk of aortic dissection and rupture of cerebral aneurysm in the third trimester and peripartum period due to hemodynamic and hormonal changes.

• All pregnant women with a history of coarctation, either native or repaired, should be considered high risk.

• Significant stenosis—native, residual, or recurrent—is a contraindication to pregnancy.

Patient Education:

• Most adults with coarctation have undergone repair; however, continued education regarding exercise, endocarditis and endarteritis prevention, and pregnancy issues is necessary.

• For the rare adult with uncorrected coarctation, extensive patient education is necessary on issues ranging from pathology and repair to lifestyle modification and follow-up care.

• The medical practitioner must understand that coarctation is a complex lifelong condition that may be repaired but is never truly corrected.

Bicuspid aortic valve

Background: The bicuspid aortic valve has been recognized as a common congenital abnormality for centuries. Leonardo da Vinci was one of the first to call attention to the aortic valve with 2 leaflets. He recognized the superior engineering advantages of the normal trileaflet valve. Considering that it is a common abnormality, bicuspid aortic valve is mentioned only briefly in many pediatric and cardiology textbooks. 

Definition 

A congenitally bicuspid aortic valve has 2 leaflets. Most have 2 complete commissures. Approximately half of cases have a low raphe. Not included are stenotic or partially fused valves caused by inflammatory processes, such as rheumatic fever. 

Embryology 

The embryonic truncus arteriosus is divided by the spiral conotruncal septum during development. The normal right and left aortic leaflets form at the junction of the ventricular and arterial ends of the conotruncal channel. The nonseptal leaflet (posterior) cusp normally forms from additional conotruncal channel tissue. Abnormalities in this area will lead to the development of a bicuspid valve, often through incomplete separation (or fusion) of valve tissue. 

Bicuspid aortic valve often is seen with either coarctation of the aorta or interrupted aortic arch, suggesting a common developmental mechanism. 

Anatomy 

The bicuspid valve is composed of 2 leaflets or cusps, usually of unequal size. The larger leaflet is referred to as the "conjoined" leaflet. Two commissures are present; usually neither is partially fused. The presence of a partially fused commissure, which has also been called a "high" raphe, probably predisposes toward eventual stenosis. At least half of all congenitally bicuspid valves have a low raphe, which never attains the plane of the attachments of the two commissures and which never extends to the free margin of the "conjoined" cusp. Redundancy of a conjoined leaflet may lead to prolapse and insufficiency. 

Valve leaflet orientation can vary. Anterior-posterior orientation of the commissures, with "right (conjoined)" and left leaflets, occurs in approximately 50-65% of cases. The conjunction is of tissue that would normally form the right-noncoronary commissure. Horizontal (left-right) orientation of the commissures, with "anterior (conjoined)" and posterior leaflets is seen in 30-45% of cases. The conjunction is of tissue which would normally form the left-right commissure. For unclear reasons, conjunction of tissue normally destined to form the left-noncoronary commissure is rare. 

Coronary arteries may be abnormal. A "left dominant" coronary system (ie, posterior descending coronary artery arising from the left coronary artery) is seen more commonly with bicuspid aortic valve. The left main coronary artery may be up to 50% shorter in patients with bicuspid aortic valve. 

The aortic root may be dilated. This has been attributed to "poststenotic" dilatation. However, the aortic root may be inherently abnormal (e.g., it may have decreased connective tissue). 


Pathophysiology: With degeneration of aging valves, sclerosis and calcification can occur. The bicuspid valve also may be completely competent, producing no regurgitant flow. However, redundancy and prolapse of cusp tissue can lead to valve regurgitation. Although bicuspid aortic valve is a common abnormality, complications may arise in as many as one third of patients over their lifetimes; this disorder, therefore, deserves close attention and medical follow-up. 


Frequency: 


In the US: Bicuspid aortic valves may be present in up to 1-2% of the population. Since the bicuspid valve may be entirely "silent" during infancy, childhood, and adolescence, these incidence figures generally are not included in the overall incidence of congenital heart disease. 
Internationally: Incidence does not appear to be affected by race or geography. 

Sex: Male-to-female ratio is 2:1 or greater. Sex is not a predictive variable in the natural history of bicuspid aortic valve. 

Age: Bicuspid aortic valve may be identified at any age from birth through the 11th decade; it also may be only an incidental finding at autopsy. Bicuspid aortic valve may remain "silent" and be discovered as an incidental finding on echocardiographic examination of the heart. 


"Critical" aortic stenosis and infective endocarditis may be considered relatively early sources of morbidity for patients with bicuspid aortic valve. Critical aortic stenosis may occur in infancy and may be associated with a bicuspid valve. 
Occasionally, bicuspid aortic valve will be diagnosed after a patient has developed infective endocarditis with systemic embolization. Infective endocarditis, when it occurs, is usually seen in children or young adults.
Stenosis of the bicuspid aortic valve is more likely to develop in persons older than 20 years and is caused by progressive sclerosis and calcification. High levels of serum cholesterol have been associated with more rapidly progressive sclerosis of the congenitally bicuspid aortic valve.
Younger individuals who develop pathologic changes in the bicuspid aortic valve are more likely to develop "pure" valve regurgitation than stenosis.

Clinical

History: Patients with bicuspid aortic valves may be completely asymptomatic. If symptoms are present, they relate to the development of aortic stenosis, aortic insufficiency, or both. Occasionally, a congenitally bicuspid aortic valve may be the cause of critical aortic stenosis, with symptoms of severe congestive heart failure presenting in early infancy. This critical form of stenosis is associated more frequently with a unicommissural valve. In patients in whom a bicuspid aortic valve is seen in association with other types of left heart obstruction (coarctation or interrupted aortic arch), the bicuspid valve generally functions well, and symptoms usually are caused by the associated disorder. 

Inheritance: Although bicuspid aortic valve is generally sporadic, familial clusters have been identified, with incidence as high as 10-17% in first-degree relatives of probands.

Associated syndromes

Coarctation or interrupted aortic arch (bicuspid aortic valve present in >50% of patients with these lesions).
Williams syndrome (bicuspid aortic valve, associated with supravalvular aortic stenosis in 11.6%)
Patent ductus arteriosus, also associated with hand anomalies
Erdheim cystic medial necrosis (familial aortic dissection)
Turner syndrome (bicuspid aortic valve in 30% of patients)

Physical: Since the bicuspid aortic valve is frequently a clinically "silent" condition, findings of a general examination are usually normal. 

Typical features of Turner syndrome (short stature in females with webbed neck and broad chest) or Williams syndrome ("elfin" facies, mild retardation) may suggest the possibility of bicuspid aortic valve.

Cardiac examination

The precordium is usually normal to palpation, and there is no evidence of cardiomegaly.

The first heart sound is unaffected. The second heart sound splits normally with inspiration, with absent or minimal outflow gradient. With increasing aortic stenosis gradient, the splitting of the second sound will be less apparent or may be absent. With severe stenosis, the second sound will be split "paradoxically" (ie, with expiration). This splitting differs from normal splitting of the first heart sound (ie, with tricuspid and mitral valve closures) in that normal splitting is best appreciated at the lower left sternal border and is a softer, lower-pitched sound than the click of a bicuspid aortic valve.

The most common abnormal sound heard with bicuspid aortic valve has been described as a systolic ejection "click." This sound is actually a less distinct, medium-pitched sound heard well at the apex with the diaphragm of the stethoscope. It is heard in all phases of respiration just after the first heart sound, and its timing does not vary with maneuvers (eg, hand-grip, Valsalva, squatting). The ejection sound also may be heard in the aortic area (upper right sternal border), where it takes on a brighter and sharper quality. 

In contrast, the click of pulmonary valvular stenosis is intermittent (heard best during expiration) and located closer to the left sternal border. It is a bit less distinct than the aortic valve click. The click of mitral valve prolapse also may be heard at the apex but is softer, occurs later, and is less distinct than the bicuspid aortic valve click. The mitral prolapse click often will vary in timing with changes in position or isometric handgrip and may be followed by the murmur of mitral regurgitation. Multiple showers of clicks are common, and the sound has been likened to crinkling cellophane.

Minimal or mild stenosis may produce a soft and fairly harsh ejection murmur at the upper right sternal border with possible radiation into the carotids. Increasing severity of stenosis produces a longer, louder, and harsher murmur with definite radiation into the carotids and possibly into the posterior shoulder. With more severe stenosis, a thrill may be felt in the suprasternal notch.

In the presence of a typical opening sound or click, the high-pitched sound of subtle aortic valve insufficiency may be heard at the third left intercostal space with the diaphragm of the stethoscope. A variety of maneuvers may be helpful in auscultation, including isometric handgrip, having patients lean forward in a seated position (to bring the aortic area closer to the chest wall), and having patients hold their breath in expiration (also decreases the distance between the stethoscope and the left ventricle).

Differentials

Aortic Stenosis, Subaortic 
Aortic Stenosis, Supravalvar 
Aortic Stenosis, Valvar 
Aortic Valve Insufficiency 
Cardiomyopathy, Hypertrophic 
Mitral Valve Prolapse 
Pulmonary Stenosis, Valvar 
Rheumatic Heart Disease 

Work-up

Lab Studies: 


Total and high-density lipoprotein (HDL) cholesterol or fasting lipid profile should be measured in children older than 3 years.
Elevated low-density lipoprotein (LDL) cholesterol may accelerate sclerosis of the bicuspid aortic valve.
In the case of a child with bicuspid aortic valve and family history of hypercholesterolemia or early coronary artery disease, baseline cholesterol may be helpful in recommending dietary modification.

Imaging Studies: 


Chest x-ray may show mild prominence of the ascending aorta in the posteroanterior projection along the superior right heart border; this is due to "poststenotic" dilation. Left ventricular enlargement would imply progressive aortic valve insufficiency. 

Two-dimensional echocardiography provides accurate confirmation of a bicuspid aortic valve.
Imaging can show the bicuspid aortic valve in multiple planes. Most important information is obtained from the parasternal long- and short-axis views.

Long-axis view shows the typical systolic "doming" due to limited valve opening. An approximation of valve orifice diameter can be obtained at peak systole. This view is also important for sizing the sinus of Valsalva, sinotubular junction, and ascending aorta.

Short-axis view is used to examine commissures, leaflet morphology, mobility, and presence or absence of a low raphe. Diameter or area of valve opening generally is overestimated in this view, since the true orifice usually lies above this plane.

Doppler measurements of peak and mean systolic velocities and gradients can be recorded from the apical "5-chamber," the suprasternal, or the high right parasternal views. Doppler signal should be lined up as closely as possible and parallel to the "jet" to provide accurate estimates of flow velocities. Estimates of flow velocity from the apical view sometimes can be improved by moving the transducer more medially toward the sternum.

Parasternal long- and short-axis views also can be used for color Doppler studies, which evaluate for aortic insufficiency. The severity of aortic valve insufficiency can be assessed by several methods. One of the simplest and most reliable is to measure the insufficiency jet diameter at the aortic valve annulus and compare this diameter to the annulus diameter.
False-positive diagnosis of bicuspid aortic valve may arise from incomplete demonstration of all 3-valve closure lines. The typical normal (trileaflet) aortic valve shows a rotated "Mercedes sign" on closure. The bicuspid valve may not be recognized if there is a high raphe seen with valve closure.

Angiography
The bicuspid aortic valve is viewed best in the anterior-posterior 30 degree right anterior oblique (RAO) projection. Injection is into the left ventricle and also into the aortic root. 

Typical finding is systolic "doming" of the valve margins due to incomplete opening. 

Aortic insufficiency can be looked for on the aortic root injection.

Magnetic resonance imaging: MRI generally is not helpful for the diagnosis of bicuspid aortic valve alone, but may be helpful for complete assessment of the thoracic aorta in cases of coarctation, Turner syndrome, or Williams syndrome.

Other Tests: 


Electrocardiogram
ECG generally is normal for an isolated bicuspid aortic valve without stenosis or insufficiency.
Progression of stenosis or insufficiency will lead to left atrial enlargement and left ventricular hypertrophy.

Procedures: 


Transesophageal echocardiography may be necessary to define valve commissures and vegetations in adolescents or young adults in whom bicuspid aortic valve is suspected on clinical grounds (particularly those with symptoms or findings that suggest infective endocarditis).

Treatment

Medical Care: No specific medical care is required for individuals with bicuspid aortic valve, unless they have progressive deterioration or infection. Serial follow-up evaluations are important for early recognition of potential complications. 

Surgical Care: Surgery specifically for bicuspid aortic valve is not necessary unless progressive complications ensue. 

The patient with known bicuspid aortic valve will require antibiotic prophylaxis for "invasive" dental or noncardiac surgical procedures.
For noncardiac procedures, preoperative cardiac evaluation may be appropriate, particularly for patients with aortic stenosis or insufficiency.
Diet: Since hypercholesterolemia and other coronary artery disease risk factors may accelerate the sclerosis and deterioration of a congenitally bicuspid aortic valve, a "heart-healthy" diet is recommended for all patients, not only those with recognized risk factors. This diet should limit fat calories to no more than 30% of total calories. Calories from saturated fats should be limited to no more than 10% of total. 

Activity: Patients with normally functioning bicuspid aortic valves (ie, no stenosis or insufficiency) do not require activity restrictions. They may participate in organized competitive sports activities. 

Patients who develop valve insufficiency or stenosis from a congenitally bicuspid aortic valve may require restrictions from strenuous competitive sports.
Strenuous isometric activity, such as weight lifting, rope climbing, and pull-ups, should be avoided by patients with aortic valve insufficiency.

Follow-up

Complications: 


Overall complication rates are variable. In general, bicuspid aortic valve may be a common reason for acceleration of "normal" aging process (eg, valve sclerosis and calcification). Four specific complications are related to the congenitally bicuspid aortic valve.

Aortic stenosis 

Sclerosis of the bicuspid aortic valve generally begins in the second decade of life, and calcification becomes more concerning from the fourth decade. The presence of coronary risk factors (eg, smoking, hypercholesterolemia) may accelerate these processes. 

Approximately 50% of adults with severe aortic stenosis have a congenitally bicuspid valve. 

Historically, rheumatic fever was the most common cause of aortic stenosis. With significantly decreasing incidence of rheumatic fever in "developed" nations, bicuspid aortic valve is the most common cause of aortic stenosis in adults and is probably the most common etiology of valve insufficiency, as well. Acute rheumatic fever and its recurrences are still a major problem in "developing" countries, and in these areas chronic effects of rheumatic fever still are more significant than bicuspid valve in the etiology of aortic stenosis and insufficiency. Rheumatic aortic valve damage can be confirmed only at surgery or autopsy by the presence of Aschoff bodies. 

Aortic insufficiency 

The majority of cases of severe aortic insufficiency are related, either directly or indirectly, to a congenitally bicuspid valve. 

A number of factors may contribute to development of aortic valve insufficiency. These include cusp prolapse, erosion of irregular commissure lines, aortic root dilatation (particularly at the sinotubular junction or supra-aortic ridge), infective endocarditis, and systemic hypertension (particularly with coarctation). 

Bacterial (eg, infective) endocarditis 

The risk of developing infective endocarditis on a bicuspid aortic valve is 10-30% over a lifetime. 

Bicuspid aortic valve is the second most common congenital etiology for infective endocarditis in infants and children; and overall, approximately 25% of endocarditis infections develop on a bicuspid valve. 

Aortic root dissection 

Findings of histologic studies on the aortic root in individuals with bicuspid aortic valve are controversial. Enlargement of the root is often attributed to poststenotic dilatation. However, the root may dilate without significant valve stenosis. 

The risk of aortic root dissection is much higher for individuals with Marfan syndrome (approximately 40%) than for those with bicuspid aortic valve (approximately 5%). Since bicuspid valve is a much more prevalent disorder, dissection of the ascending aortic root more commonly is associated with the valve abnormality. 

Prognosis: 


Overall prognosis for the individual with bicuspid aortic valve is good. Reviews and reports in the past have emphasized the fairly benign course for patients with bicuspid valves. However, more recent reports on the natural history of these valves suggest a number of more serious problems and an acceleration of normal valvular "wear-and-tear."

Patient Education: 


Patient and family education should emphasize the fairly benign course for the child with bicuspid aortic valve.
Older children and adolescents should begin to be made aware of accelerated "aging" processes (ie, progressive stenosis), with particular attention to coronary risk factors.
The importance of bicuspid aortic valve as a potential substrate for infective endocarditis should be emphasized. Good oral and dental hygiene, with appropriate antibiotic prophylaxis for procedures, is important.
The majority of young individuals with bicuspid aortic valve should not require restrictions in physical activity or sports participation, unless they have stenosis or insufficiency.


Medical/Legal Pitfalls: 


The bicuspid aortic valve may fail to be recognized as a source for emboli in cases of unexplained fever and focal central nervous system deficits.