aortic valve stenosis

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Aortic Valve Stenosis

 

Definition

When aortic valve stenosis occurs, the aortic valve, located between the aorta and left ventricle of the heart, is narrower than normal size.

Description

A normal aortic valve, when open, allows the free flow of blood from the left ventricle to the aorta. When the valve narrows, as it does with stenosis, blood flow is impeded. Because it is more difficult for blood to flow through the valve, there is increased strain on the heart. This can cause the left ventricle to enlarge and malfunction, resulting in reduced blood supply to the heart muscle and body, as well as fluid build up in the lungs.

Cause and symptoms

Aortic valve stenosis can occur because of a birth defect in the formation of the valve. Calcium deposits may form on the valve with aging, causing the valve to become stiff and narrow. Stenosis can also occur as a result of rheumatic fever. Mild aortic stenosis may produce no symptoms at all. The most common symptoms, depending on the severity of the disease, are chest pain, blackouts, and difficulty breathing.

Diagnosis

Using a stethoscope, a physician may hear a murmur and other abnormal heart sounds. An ECG, also called an electrocardiogram, records the electrical activity of the heart. This technique and chest x ray can show evidence that the left ventricle is enlarged. An x ray can also reveal calcium deposits on the valve, as well as congestion in the lungs. Echocardiography can pick up thickening of the valve, heart size, and whether or not the valve is working properly. This is a procedure in which high frequency sound waves harmlessly bounce off organs in the body. Cardiac catheterization, in which a contrast dye is injected in an artery using a catheter, is the key tool to confirm stenosis and gauge its severity.

Treatment

Treatment depends on the symptoms and how the heart's function is affected. The valve can be opened without surgery by using a balloon catheter, but this is often a temporary solution. The procedure involves inserting a deflated balloon at the end of a catheter through the arteries to the valve. Inflating the balloon should widen the valve. In severe stenosis, heart valve replacement is recommended, most often involving open-heart surgery. The valve can be replaced with a mechanical valve, a valve from a pig, or by moving the patient's other heart valve (pulmonary) into the position of the aortic valve and then replacing the pulmonary valve with an mechanical one. Anyone with aortic stenosis needs to take antibiotics (amoxicillin, erythromycin, or clindamycin) before dental and some other surgical procedures, to prevent a heart valve infection.

Prognosis

The prognosis for aortic valve stenosis depends on the severity of the disease. With surgical repair, the disease is curable. Patients suffering mild stenosis can usually lead a normal life; a minority of the patients progress to severe disease. Anyone with moderate stenosis should avoid vigorous physical activity. Most of these patients end up suffering some kind of coronary heart disease over a 10 year period. Because it is a progressive disease, moderate and severe stenosis will be treated ultimately with surgery. Severe disease, if left untreated, leads to death within 2 to 4 years once the symptoms start.

Prevention

There is no way to prevent aortic stenosis.

Key terms

Aorta — The largest artery in the body, which moves blood from the left ventricle to the rest of the body.
Cardiac catheterization — A procedure in which dye is injected through a tube or catheter into an artery to more easily observe valves or blood vessels seen on an x ray.
ECG — Also called an electrocardiogram, it records the electrical activity of the heart.
Echocardiogram — A procedure in which high frequency sound waves harmlessly bounce off organs in the body providing an image so one can determine their structure and function.
Left ventricle — One of the lower chambers of the heart, which pumps blood to the aorta.
Murmur — An abnormal heart sound that can reflect a valve dysfunction.
Pulmonary valve — The valve located between the pulmonary artery and the right ventricle, which brings blood to the lungs.
Rheumatic fever — A bacterial infection that often causes heart inflammation.

Resources

Books

Bender, Jeffrey R. "Heart Valve Disease." In Yale University School of Medicine Heart Book, edited by Barry L. Zaret, et al. New York: HearstBooks, 1992.

Other

"Aortic Stenosis." Ochsner Heart and Vascular Institute. 〈http://www.ochsner.org/pedcard/as.htm〉.
Rahimtoola, Aly. "Aortic Stenosis." Loyola University Health System Page. http://www.luhs.org.

aortic valve stenosis

Aortic stenosis, see there.

Aortic Valve Stenosis

DRG Category:307
Mean LOS:3.3 days
Description:MEDICAL: Cardiac Congenital and Valvular Disorders without Major CC

Aortic stenosis (AS) is a narrowing of the aortic valve orifice, which obstructs outflow from the left ventricle during systole. The left ventricle must overcome the increased resistance to ejection by generating a higher-than-normal pressure during systole, which is achieved by stretching and generating a more forceful contraction. The blood is propelled through the narrowed aortic valve at an increased velocity. Aortic valve stenosis accounts for approximately 5% of all congenital heart defects. About 4 in 1,000 live births have AS, making this condition a relatively common birth defect.

As the stenosis in the aortic valve progresses, two sequelae occur. One is that cardiac output becomes fixed, making increases even with exertion impossible. The other is left-sided heart failure. Pressure overload of the heart occurs with concentric hypertrophy of the left ventricle. Left ventricular end-diastolic pressure rises, myocardial oxygen demand increases, and left ventricular mass and wall stress are increased. The increase in left ventricular pressure is reflected backward into the left atrium. Because the left atrium is unable to empty adequately, the pulmonary circulation becomes congested. Eventually, right-sided heart failure can develop as well.

Causes

The predominant causative factor in AS is congenital malformation of the aortic valve. Congenital causes can lead to unicuspid and bicuspid or malformed valves. When they become calcified, symptoms may occur. Stenosis can also occur with narrowing of the subvalvular outflow tract by fibroelastic membranes or muscle tissue. Acquired valvular stenosis results from rheumatic heart disease and degenerative calcification. Risk factors for degenerative stenosis include hypertension, elevated cholesterol, diabetes mellitus, and smoking. The patient’s age when the condition manifests itself usually suggests the cause. Congenital stenosis is usually seen in patients younger than 30 years old. In patients between the ages of 30 and 70 years, the cause is equally attributed to congenital malformation and rheumatic heart disease. Atherosclerosis and degenerative calcification of the aortic valve are the predominant causes for stenosis in people older than 70 years.

Genetic considerations

There is considerable evidence supporting a genetic component for congenital AS. Bicuspid aortic valve, which can result in AS, is often found among relatives of persons affected with other left ventricular outflow tract malformations. AS occurs as a feature of rare genetic diseases such as Williams syndrome, which has autosomal dominant transmission, characteristic facial features, and mental retardation. Mutations in the NOTCH1 gene can lead to aortic valve calcification, among other congenital aortic valve defects, in an autosomal dominant inheritance pattern.

Gender, ethnic/racial, and life span considerations

AS can occur at any age, depending on the cause. Among children born with AS, 75% are male, and overall approximately 80% with AS are male. Degenerative aortic stenosis is most common in males older age 75. Ethnicity and race have no known effect on the risk of AS.

Global health considerations

Rheumatic heart disease and subsequent valvular disease is a continuing problem in developing nations, where up to 60% of all admissions for cardiovascular illnesses are related to the condition. Prevalence may be as low as 1 per 100,000 children in Costa Rica to as high as 150 per 100,000 children in China. Areas of particular concern are Southeastern Asia, Central America, North Africa, and the Middle East.

Assessment

History

A history of rheumatic fever suggests possible cardiac valvular malfunction; however, many patients who have had rheumatic fever do not remember having had the condition. The diagnosis therefore is usually based on symptoms. Given the potential genetic causes, a family history of AS can be significant.

Physical examination

The classic symptoms of aortic stenosis are chest pain, fainting on exertion (syncope), and labored breathing on exertion due to heart failure. Inspection of the thoracic wall may reveal a thrusting apical pulsation. A systolic thrill (vibrations felt from turbulent blood flow) may be palpated over the second intercostal space to the right of the sternum. A lift or heave may be palpated over the apex of the heart.

Auscultation of heart sounds reveals a harsh systolic crescendo-decrescendo murmur. The murmur, referred to as diamond shaped, is considered the hallmark of AS. Auscultation of breath sounds may reveal fine crackles (rales) if pulmonary congestion is present in left-sided heart failure. The pulmonary congestion will vary with the amount of exertion and severity of stenosis.

Psychosocial

Because the symptoms of AS are usually gradual, most people have already made adjustments in their lifestyle to adapt and do not seek treatment until the symptoms become debilitating. Assess what the patient has already done to cope with this condition. In addition, assess the patient’s degree of anxiety about a diagnosed heart condition and potential treatment.

Diagnostic highlights

TestNormal ResultAbnormality With ConditionExplanation
Cardiac catheterizationNormal aortic valveOpening in the aortic valve is obstructed and narrowedAortic valve is narrowed with the pressure gradient across the valve directly related to the degree of obstruction
Two-dimensional and Doppler echocardiographyNormal aortic valveStenosed aortic valveReveals abnormal blood flow patterns

Other Tests: Echocardiography to assess the aortic valve’s structure and mobility; electrocardiogram; chest radiography, radionuclide ventriculography, computed tomography, magnetic resonance imaging

Primary nursing diagnosis

Diagnosis

Activity intolerance related to imbalance between oxygen supply and demand

Outcomes

Endurance; Energy conservation; Self-care; Ambulation: Walking; Circulation status; Cardiac pump effectiveness; Rest; Respiratory status; Symptom severity; Nutritional status: Energy

Interventions

Activity therapy; Energy management; Circulatory care; Exercise therapy: Ambulation; Oxygen therapy; Self-care assistance; Nutrition management

Planning and implementation

Collaborative

medical.
Most patients with AS are placed on activity restrictions to decrease cardiac workload. Patients on bedrest should use the bedside commode because research has shown it creates less workload for the heart than using the bedpan. Fluid restrictions and diuretics may be ordered to reduce pulmonary congestion. Supplemental oxygenation will enhance oxygen levels in the blood to decrease labored breathing and chest pain. Percutaneous balloon valvuloplasty is used as a palliative measure in people who are not surgical candidates or as a bridge in the critically ill before they undergo aortic valve replacement.

surgical.
Surgical repair or replacement is the most common treatment of AS. The average survival rate after the appearance of symptoms is less than 5 years for patients with AS who are treated medically. Surgical treatment increases the survival rate dramatically. The stenotic valve can be replaced with a synthetic valve or a biologic valve, such as a pig valve. The choice of valve type is based on the patient’s age and the potential for clotting problems. The biologic valve usually shows structural deterioration after 6 to 10 years and needs to be replaced. The synthetic valve is more durable but also more prone to thrombi formation. For patients who are not candidates for aortic valve replacement, percutaneous aortic balloon valvuloplasty may reduce some symptoms.

Pharmacologic highlights

Medication or Drug ClassDosageDescriptionRationale
Digoxin0.25 mg PO qdCardiotonicMay be useful in the presence of heart failure and left ventricular dilation and impaired systolic function
Beta-adrenergic receptor blockers (esmolol, metoprolol)Varies with drugBeta-adrenergic receptor blockerUsed to manage angina or elevated blood pressure in patients who are not candidates for surgery or prior to surgery

Other Therapy: Diuretics, nitrates, and other vasodilators are to be avoided if possible because they reduce filling pressures and may lower systolic blood pressure. If the stenotic valve is replaced surgically with a synthetic valve, patients are prescribed long-term anticoagulation therapy, such as warfarin (Coumadin), to prevent thrombi from forming on the synthetic valve. Initially, heparin is given along with the warfarin, and the prothrombin time (PT) is monitored. As the PT value becomes therapeutic, the heparin is discontinued.

Independent

Physical and psychological rest decreases cardiac workload, which reduces the metabolic demands of the myocardium. Physical rest is enhanced by providing assistance with activities of daily living and encouraging activity restrictions. Reducing psychological stress can also be difficult. Decrease the fear of the unknown by providing explanations and current information and encouraging questions. To help the patient maintain or reestablish a sense of control, permit the patient to participate in decisions about aspects of care within his or her knowledge. If the patient decides on surgery, offer to let her or him speak with someone who has already had the surgery.

Discourage sudden changes in position to minimize increased cardiac demand. Instruct the patient to sit on the edge of the bed before standing. Elevate the head of the bed slightly if pulmonary congestion is present, to enhance respiration.

Monitoring physical status is a priority for nursing care. Assess for episodes of dizziness or fainting. The episodes may occur because of decreased cardiac output or cardiac dysrhythmias, so patients should be told to report occurrence of these symptoms promptly. Dizziness and fainting are correlated with sudden death, which, according to recent research, occurs in 10% to 20% of all patients with advanced AS. Maintain a safe physical environment for the patient by removing obstructions in the patient’s room.

Evidence-Based Practice and Health Policy

Zlotnick, D.M., Ouellette, M.L., Malenka, D.J., DeSimone, J.P., Leavitt, B.J., Helm, R.E., …O’Rourke, D.J. (2013). Effect of preoperative pulmonary hypertension on outcomes in patients with severe aortic stenosis following surgical aortic valve replacement. The American Journal of Cardiology, 112(10), 1635–1640.

  • Aortic valve replacement (AVR) is the gold standard for surgical repair of severe AS; however, management of preoperative pulmonary hypertension may improve postsurgical outcomes for patients undergoing AVR.
  • Among a sample of 1,116 consecutive patients who underwent AVR between 2005 and 2010, pulmonary hypertension was diagnosed in 48% (pulmonary systolic artery pressure [PSAP] > 34 mm Hg).
  • In this sample, increased pulmonary hypertension was associated with a decrease in the 5-year survival rate post AVR (p = 0.006). Patients with severe pulmonary hypertension (PSAP > 59 mm Hg) were four times (p = 0.002) more likely to experience an acute kidney injury postoperatively and almost seven times (p = 0.001) more likely to experience in-hospital mortality post AVR than patients without pulmonary hypertension.

Documentation guidelines

  • Physical findings of systolic murmur, systolic thrill, and rales in the lungs
  • Response to diuretics, nitrates, and rest
  • Reaction to activity restrictions, fluid restrictions, and cardiac diagnosis
  • Presence of complications: Chest pain, bleeding tendencies, labored breathing, fainting

Discharge and home healthcare guidelines

medications.
Be sure the patient understands all medications, including the dose, route, action, adverse effects, and need for routine laboratory monitoring for anticoagulants.

complications of anticoagulants.
Explain the need to avoid activities that may predispose the patient to excessive bleeding. Teach the patient to hold pressure on bleeding sites to assist in clotting. Remind the patient to notify healthcare providers of anticoagulant use before medical, surgical, or dental procedures. Identify foods high in vitamin K (green, leafy vegetables; oats; wheat; rye), which need to be eaten in a consistent amount, not binging, so that the effect of anticoagulants is not reversed.

teaching.
Instruct the patient to report the recurrence or escalation of signs and symptoms of AS, which could indicate that the medical therapy needs readjusting or the replaced valve is malfunctioning. Patients with synthetic valves may hear an audible click like a ticking watch from the valve closure.

prevention of bacterial endocarditis.
Patients who have had surgery are susceptible to bacterial endocarditis, which will cause scarring or destruction of the heart valves. Because bacterial endocarditis may result from dental work, surgeries, and invasive procedures, people who have repaired or replaced heart valves should be given antibiotics before and after these treatments.

Figure 1: The nervous system.

aortic valve stenosis

narrowing of the aortic valve due to disease of the valve cusps. One of the causes of sudden death in sport. See also heart; Figure 1.

Patient discussion about aortic valve stenosis

Q. How does alcohol affect someone who has been diagnosed with aortic valve stenosis? My brother has been diagnosed with aortic valve stenosis and also is a smoker and does drink alcohol on the weekends. He knows that he should stop smoking but what about the effects of alcohol? Does this also contribute to his stenosis?

A. Alcohol changes blood pressure and speed of the heart- that is not a good idea if you have an Aortic stenosis. Could probably makes things worst. I would avoid alcohol… but he should ask GP.

Q. Why does Aortic stenosis causes an enlarged heart? My father was recently diagnosed as suffering from enlarged heart due to his Aortic stenosis. what is the connection between those to conditions? As far as I understand that aortic stenosis mean that the aortic valve is too small not too large...

A. there are several explanations for the enlargement of the heart that occurs due to Aortic stenosis. the most reasonable is that the mechanical power that the heart uses makes it bigger. it easy to see it here: http://www.marvistavet.com/assets/images/aortic_stenosis.gif
this is called Left Ventricular Hypertrophy or LVH in abbreviations.
this is a classic LVH E.C.G.
http://www.frca.co.uk/images_main/resources/ECG/ECGresource39.jpg

More discussions about aortic valve stenosis