The aortic valve (AV) is the gateway through which the stroke volume is ejected from the left ventricle (LV) into the systemic circulation. Should the gateway be narrowed as in aortic stenosis (AS), the LV hypertrophies concentrically and ejects the stroke volume through the reduced aortic valve orifice. The thickened heart muscle and the increased work of ventricular ejection augments the oxygen demand of the ventricle, which if not met, results in myocardial ischemia. On the other hand, if the valve is incompetent resulting in aortic insufficiency or regurgitation (AR), the left ventricle dilates and develops eccentric hypertrophy to accommodate the increased volume filling the LV cavity during diastole. When the AV is incompetent, diastolic pressure falls and coronary perfusion pressure (CPP) decreases, increasing the risk of ischemia. Providing anesthesia for patients with AV disease undergoing aortic valve surgery or noncardiac procedures can be challenging.
The American Heart Association Task Force on Practice Guidelines reports the current recommendations for the management of patients with AV disease.1 In the past, valvular diseases were most likely the consequence of rheumatic heart disease. Currently, with an increasingly aging population, degenerative diseases of the valves are most frequently diagnosed.2 More than one in eight individuals older than 75 years of age have moderate or severe valvular heart disease of one type or another.2 Life span is reduced in patients with severe valvular disease (Figures 6–1 and 6–2). Additionally, elderly women may have underdiagnosed valvular heart diseases.2 Consequently, it is likely that as the population ages, AV disease will become ever more prevalent in cardiac surgical and noncardiac surgical patients alike. Sometimes, anesthesiologists are the first to diagnose a heart murmur during preoperative assessment.3 Van Klei et al. in a study from the Netherlands found during routine preoperative examination a prevalence of 2.4% for AS in patients greater than 60 years of age scheduled for noncardiac surgery.3
The increasing prevalence of valvular heart disease associated with age in population-based studies (A) and in one U.S. county. (B) Anesthesiologists are increasingly likely to encounter patients with valvular disease as the population ages. [Reproduced with permission from Nkomo VT, Gardin JM, Skelton TN, et al: Burden of valvular heart diseases: a population-based study, Lancet. 2006 Sep 16;368(9540):1005-1011.]
Survival graphs after detection of moderate or severe valvular heart disease demonstrate decreased survival in population-based (A) and community (B) studies of patients with valvular heart disease. Graph A: survival in population-based studies. Graph B: expected versus observed survival in one U.S. county of 971 residents diagnosed with valve disease between 1990 and 1995 compared with the expected survival of an age- and sex-matched population. [Reproduced with permission from Nkomo VT, Gardin JM, Skelton TN, et al: Burden of valvular heart diseases: a population-based ...