1Your Heart & Valves

4.3Aortic Wrapping and Aortoplasty

Aortic Wrapping of the ascending aorta is a procedure that is carried out to prevent dissection occurring with or without Valve replacement.

Aortic wrapping with or without aortoplasty may have a beneficial effect not only in dilated ascending aorta but also in all non-dilated BAV patients. Ascending aorta wrapping in BAV patients may preserve the endothelial lining and prevent further dilatation, aneurysm formation, and dissection. Less elastic tissue in the aortas of BAV patients may explain the anecdotal increase in aortic fragility and propensity for aortic dissection, but at this time the suspected portion of the aorta will generally be replaced with a dacron graft, a more established procedure with good data on long term durability. Wrap procedures have met with variable success.

The wrapping of the supracoronary-ascending aorta during AVR should not increase the surgical risk. Fixing the Dacron wrap to the aorta with decreasing diameter prevents dislocation of the wrap and therefore erosion of the aorta.

It is very important for anticipatory surgery for dilatation of the ascending aorta in patients with bicuspid aortic valves compared with patients with tricuspid aortic valves.

5Risk Factors for Patients

5.1Bicuspid Aortic Valve

BAV itself is reported as a risk factor for aortic dissection after AVR. Studies have confirmed the higher risk of late ascending aorta aneurysm or dissection (a tear of the aorta causing blood to flow between the layers of the wall of the aorta and dissects the layers) in patients with BAV, and reinforce the importance of appropriate timing of ascending aorta replacement in cases of AVR or other cardiac procedures in these patients.

Dissection of the ascending aorta is likely in 50% of patients where there is a coexisting bicuspid aortic valve. Research has shown a greater incidence of sudden death and aortic events in the BAV patients (5 times more likely).
Regardless of a seemingly normal ascending aorta at surgery the occurrence of ascending aortic alterations during follow-up could not be predicted at the time of the first operation and was independent of the ascending aorta diameter. In post mortems the dissection entrance tear was always in the ascending aorta, which usually had severe loss of elastic fibres in its media

Patients with BAV seem to have a severe alteration of the aortic wall, which is potentially capable of evolving into acute aortic pathology or progressive dilation of the ascending aorta, independent of valve surgery. Currently there are no diagnostic tests that enable a prediction of which patients with BAV will develop ascending aorta pathology.

Most patients who experience acute aortic syndrome die. Operations for acute aortic dissection or ascending aorta aneurysm after AVR have very high perioperative mortality and morbidity.

5.2Aortic Left Ventricular Ejection Fraction (LVEF)

The left ventricular ejection fraction (LVEF) is an important clinical indicator of the cardiac function and long-term outcome for patients with coronary artery disease.

The left ventricular is assessed by measuring the amount of blood pumped with each heartbeat (the ejection fraction), ventricle filling, and the blood flow into the pumping chamber. A normal ejection fraction is 50% or more. The heart's ejection fraction is one of the most important measures of its performance. Although a marker of survival, ejection fraction looses its prognostic value when it dips under 25% and is above 40-45%.

5.3Aortic Insufficiency (AI, Regurgitation)

Aortic Insufficiency (regurgitation) occurs when there is a leakage of the valve backward into the left ventricle during diastole. This can be caused by structural abnormalities of the valve, similar to those seen in aortic stenosis. Enlargement of the aorta can stretch the valve cusps and produce aortic regurgitation. The acute onset of aortic regurgitation can occur when there is an infection of the aortic valve (called infective endocarditis) or a tear in the aorta.

Chronic aortic regurgitation may be present for decades before any symptoms occur. The left ventricle is able to compensate for the large volume of blood that flows backward by enlarging the cavity and increasing the thickness of the muscle. This mechanism allows the heart to pump out both the amount of blood required by the body and the blood that has gone backward into the left ventricle. When symptoms do occur, patients usually experience shortness of breath or chest discomfort. Long-standing aortic regurgitation may result in irreversible damage to the muscle of the left ventricle, even in the absence of symptoms.

An aortic valve replacement operation should be performed whenever there is severe aortic regurgitation and the patient develops symptoms. Even in the absence of symptoms, aortic valve replacement may be necessary in some patients to prevent the irreversible damage to the heart muscle caused by the extra volume load. If surgery is performed before damage to the heart muscle becomes irreversible, the outlook is excellent, and most patients can return to a normal lifestyle.

5.4Atrial Fibrillation (AF)

Atrial Fibrillation (AF) decreases relative survival substantially. The liability of left ventricular dysfunction with regard to diminished long-term survival is not completely reversed by valve operation. If operation is not performed before left ventricular dysfunction develops, postoperative medical treatment of these dilated, remodelled ventricles should be considered.
The presence of moderate or severe valvular calcification, together with a rapid increase in aortic-jet velocity, identifies patients with a very poor prognosis.
Long term follow up studies consistently report better survival rates in patients undergoing aortic rather than mitral valve replacement. Atrial Fibrillation usually results in the fitting of a pacemaker as the condition worsens.