AORTIC STENOSIS

AORTIC STENOSIS

AORTIC STENOSIS

Aortic valve stenosis or aortic stenosis occurs when the heart’s aortic valve narrows. The valve doesn’t open fully, which reduces or blocks blood flow from your heart into the main artery to your body (aorta) and to the rest of your body.

There are two common clinical scenarios in which aortic stenosis is prevalent. The first is due to a congenitally abnormal unicuspid or bicuspid valve, rather than tricus­pid. Symptoms can occur in young or adolescent individu­als if the stenosis is severe, but more often emerge at age 50–65 years when calcification and degeneration of the valve become manifest. A dilated ascending aorta, due to an intrinsic defect in the aortic root media and the hemo­dynamic effects of the eccentric aortic jet, may accompany the bicuspid valve in about half of these patients.

Coarctation of the aorta is also seen in a number of patients with congenital aortic stenosis. Offspring of patients with a bicuspid valve have a much higher inci­dence of the disease in either the valve, the aorta, or both (up to 30% in some series).

A second pathologic process, degenerative or calcific aortic stenosis, is thought to be related to calcium deposi­tion due to processes similar to those that occur in athero­sclerotic vascular disease. Approximately 25% of patients over age 65 years and 35% of those over age 70 years have echocardiographic evidence of aortic valve thickening (sclerosis). About 10–20% of these will progress to hemo­dynamically significant aortic stenosis over a period of 10–15 years. Certain genetic markers are associated with aortic stenosis (most notably Notch 1), so a genetic com­ponent appears a likely contributor, at least in some patients. Other associated genetic markers have also been described.

Symptoms and Signs

Slightly narrowed, thickened, or roughened valves (aortic sclerosis) or aortic dilation may contribute to the typical ejection murmur of aortic stenosis.

In mild or moderate cases where the valve is still pliable, an ejection click may precede the murmur and the closure of the valve (S2) is preserved.

The characteristic systolic ejection murmur is heard at the aortic area and is usually transmitted to the neck and apex. In severe aortic stenosis, a palpable LV heave or thrill, a weak to absent aortic second sound, or reversed splitting of the second sound is present.

In some cases, only the high-pitched components of the mur­mur are heard at the apex, and the murmur may sound like mitral regurgitation (the so-called Gallaverdin phenome­non). When the valve area is less than 0.8–1.0 cm2 (normal, 3–4 cm2), ventricular systole becomes prolonged and the typical carotid pulse pattern of delayed upstroke and low amplitude is present.

A delayed upstroke, though, is an unreliable finding in older patients with extensive arterio­sclerotic vascular disease and a stiff, noncompliant aorta. LVH increases progressively due to the pressure overload, eventually resulting in elevation of ventricular end-diastolic pressure.

Cardiac output is maintained until the stenosis is severe. LV failure, angina pectoris, or syncope may be pre­senting symptoms of significant aortic stenosis; impor­tantly, all symptoms tend to first occur with exertion.

Risk factors

Risk factors of aortic valve stenosis include:

  • Older age
  • Certain heart conditions present at birth (congenital heart disease) such as a bicuspid aortic valve
  • History of infections that can affect the heart
  • Having cardiovascular risk factors, such as diabetes, high cholesterol and high blood pressure
  • Chronic kidney disease
  • History of radiation therapy to the chest

Complications

Aortic valve stenosis can cause complications, including:

  • Heart failure
  • Stroke
  • Blood clots
  • Bleeding
  • Heart rhythm problems (arrhythmias)
  • Infections that affect the heart, such as endocarditis
  • Death

Prevention

Some possible ways to prevent aortic valve stenosis include:

  • Taking steps to prevent rheumatic fever. You can do this by making sure that you see your doctor when you have a sore throat. Untreated strep throat can develop into rheumatic fever. Fortunately, strep throat can usually be easily treated with antibiotics. Rheumatic fever is more common in children and young adults.
  • Addressing risk factors for coronary artery disease. These include high blood pressure, obesity and high cholesterol levels. These factors may be linked to aortic valve stenosis, so it’s a good idea to keep your weight, blood pressure and cholesterol levels under control if you have aortic valve stenosis.
  • Taking care of your teeth and gums. There may be a link between infected gums (gingivitis) and infected heart tissue (endocarditis). Inflammation of heart tissue caused by infection can narrow arteries and aggravate aortic valve stenosis.

Treatment for aortic stenosis

Treatment for aortic stenosis may include:

  • monitoring – for asymptomatic or mild cases
  • hospitalisation – for moderate to severe cases
  • lifestyle patterns such as maintaining physical activity while avoiding hard physical exercise, control of weight and avoidance of smoking
  • procedures or surgery to replace or repair the valve.

Surgical procedures for aortic stenosis

There are three main surgical procedures for treating aortic stenosis:

  • aortic valve replacement
  • transcatheter aortic valve implantation (TAVI) 
  • balloon valvuloplasty.

Aortic valve replacement

If the aortic valve is too damaged to be repaired, it may be surgically replaced with an artificial or tissue valve. This is known as aortic valve replacement. Sometimes, the person’s own pulmonary valve may be used. This is known as a pulmonary autograft or Ross operation.

Transcatheter aortic valve implantation (TAVI)

TAVI is a procedure that involves a new valve being inserted without the need for open heart surgery. It can also be known as transcatheter aortic valve replacement (TAVR). A TAVI or TAVR is usually only suitable for older people who are too high risk for conventional surgical replacement. 

Balloon valvuloplasty

When performing balloon valvuloplasty, a catheter is inserted into a blood vessel in the groin and threaded up to the heart. The tip of the catheter is placed inside the aortic valve and then a balloon is inflated. This helps to stretch and widen the valve and improve blood flow into the aorta. 

The balloon is then deflated and it and the catheter are then removed.

Balloon valvuloplasty doesn’t cure the condition and further surgical treatment may be needed later in life. This procedure is usually used as a temporary measure or to relieve symptoms when other options are not available. 

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