Heart valve disease module 9: surgery for heart valve disease

Indications for TAVI

A TAVI procedure can be considered for severe symptomatic aortic stenosis if:

• Life expectancy as a result of co-morbidity is expected to be >12 months
• Quality of life not critically limited by comorbidities
• There is no co-existent valve or coronary disease significantly contributing to symptoms and requiring surgery

TAVI is then indicated if:

• Surgery contraindicated e.g. porcelain aorta, repeat thoracotomy for a ‘re-do’ judged excessively hazardous
• Surgery judged by a ‘TAVI team’ to be less favourable

Mitral surgery at the time of AV replacement

Mitral regurgitation is common in association with severe aortic stenosis and may improve as the LV reduces in size and intracavity pressures fall. Concomitant mitral surgery is required if:

• There is organic disease of the mitral valve and moderate or worse regurgitation
• There is severe functional regurgitation

Aortic regurgitation

Abnormal LV size or function

The response of the LV to volume load is dilatation with eccentric hypertrophy. This leads to subendocardial fibrosis and the results of AVR in the presence of significant dilatation are less good than for AS. The current criteria for surgery are:

• LV ejection fraction <50%
• LV systolic diam >50 mm (25 mm/m² indexed to BSA)
• LV diastolic diam > 70 mm

Aortic dilatation

Even if the regurgitation is not severe, surgery should be considered for dilatation at any level of the sinus, sinotubular junction or ascending aortic with thresholds depending on the underlying condition:

• Arteriosclerotic dilatation – ≥55 mm
• Marfan – ≥45 mm (with risk factors)
• Bicuspid valve – ≥50 mm (with risk factors)

Risk factors include:

• family history of aortic dissection
• systemic hypertension
• coarctation

These guideline thresholds should also be modified if there is a rapid increase in diameter taken as 5 mm in a year and if there are symptoms.

If aortic valve replacement is required, the threshold for simultaneous aortic replacement is 40 mm for a patient with Marfan syndrome and 45 mm for those with a bicuspid aortic valve.

Asymptomatic with normal LV

There is no indication for surgery in the absence of a dilated aorta. There is some suggestion that CMR grading may be better than echocardiography in predicting the need for surgery.

It may be difficult to know what to do at the time of CABG or intervention for other valves in the presence of mild or moderate aortic regurgitation.

In rheumatic disease, the rate of progression of mild or moderate AR is slow so it is reasonable to leave these untreated whilst performing balloon valvotomy for mitral stenosis. When performing CABG it is usual to perform aortic valve replacement for moderate AR while leaving mild AR.

Mitral stenosis

Intervention is indicated for symptoms despite adequate rate control and diuretic therapy. Implanting a replacement valve carries a relatively high risk of around 5% and balloon valvotomy (see figure 17) is the procedure of choice when feasible (see table 3²⁰).

In patients in whom valvotomy is feasible, it is important to exclude symptoms on exercise testing and also check for pulmonary hypertension.

Indications for balloon valvotomy are:

• Symptoms and orifice area <1.5 cm² and
• Valve anatomically suitable for balloon valvotomy (class I) or
• Conventional surgery contraindicated and valve not ideal but in which balloon valvotomy is not absolutely contraindicated (class IIa)
• No symptoms but high-risk of progression
  • PA pressure >50 mmHg at rest
  • Impending non-cardiac surgery or pregnancy

Mitral replacement is indicated for significant symptoms and acceptable risk in a valve not suitable for valvotomy.