Heart valve disease module 9: surgery for heart valve disease

Bioprosthetic valve implantation

This video (see figure 13) features an overview from Mr Peter O’Keefe, Consultant Cardiothoracic Surgeon, University Hospital of Wales, Cardiff, UK implanting a Magna Ease Aortic Valve in an 80 year old male patient with diabetes mellitus and who has severe calcific aortic stenosis, and has been symptomatic for a decade. The video lasts for approximately 18 minutes.

Assessing cardiac operative risk

Risk stratification is an essential element in the practice of cardiac surgery. The most widely used scores are EuroSCORE, STS and Ambler. The European System for Cardiac Operative Risk Evaluation (EuroSCORE) identifies a number of risk factors (derived from the original 97 risk factors) which help to predict mortality from cardiac bypass surgery (a risk calculator can be found here). The standard EuroSCORE system consists of three risk groups: low risk (0–2) with an expected mortality under 2%; medium risk (3–5) with an expected mortality under 5%; and high risk (≥6) with an expected mortality greater than 10%, but the logistic Euro-SCORE system tends to be more accurate in high-risk patients.

However no scoring system was derived in patients with valve disease and none is reliable for such patients. All tend to overestimate risk. Therefore scores should only be used as a guide within an integrated and individualised approach to each patient.^15,16

ESC treatment algorithms

Algorithms for the treatment of the valvular heart conditions we discuss in this module (e.g., aortic regurgitation, severe aortic stenosis etc…) can be found here

Aortic stenosis (AS)

Aortic stenosis with impaired LV

Surgery is indicated for an impaired left ventricular ejection fraction (LVEF) <50% when caused by the AS. It is also indicated when there is a myocardial infarction or other cause of LV dysfunction but the AS is unequivocally severe.

If there are apparently moderate gradients in the setting of LV dysfunction, stress echocardiography is usually necessary to determine the severity of the AS and the presence of LV contractile reserve.

With contractile reserve the operative mortality is approximately 5% while with no contractile reserve it is 35%. Long-term recovery may still be good even in the absence of LV contractile reserve and may be better predicted by brain natruretic peptide (BNP) levels <500 pg/ml.

Symptoms and moderate AS

This is a common clinical scenario in which symptoms may be caused by:

• Aortic stenosis if the valve is non-compliant. This means that the valve may fail to open on exercise so that the stenosis becomes more severe on exercise than at rest
• Coexistent coronary disease which is present in up to 50% of cases
• Another co-morbidity e.g. lung disease, obesity, poor mobility from arthritis
• A combination of two or more of the above. This is increasingly common particularly in the elderly

BNP measurement, stress echocardiography and other focused tests e.g. lung function are necessary to resolve these choices

Asymptomatic aortic stenosis

Aortic valve replacement at the time of co-existent coronary artery bypass graft (CABG) is clearly indicated for:

• Severe aortic stenosis because the rate of progression is fast¹⁷
• Moderate aortic stenosis because this is likely to progress to severe within the life of the coronary grafts

Aortic valve replacement may be performed for more mild stenosis on an individual basis after discussion according to a balanced judgment based on:

• The rate of progression. This is thought to be faster if the valve is bicuspid or if all three cusps of a tricuspid valve are involved
• The likely lifespan of the patient based on age and co-morbidity. If less than five years it may not be worth changing the valve
• The chance of coming off bypass with a stenotic valve
• The likely haemodynamics of the replacement valve. If the valve area is likely to be little different then probably not worth replacing