Symptomatic Pulmonary Arterial Hypertension After Mitral Valve Surgery

Most patients with mitral valve disease are symptomatic with shortness of breath and a
limited activity level prior to mitral valve surgery. Despite surgical repair or replacement
of the mitral valve, many patients remain symptomatic with an impaired ability to live an
active lifestyle. Often after extensive evaluation, no other pulmonary, left ventricular
dysfunction, or valvular heart disease is responsible for the continued symptoms, and some
of these patients will be limited by persistent pulmonary hypertension (PH) at rest or with
exertion that is responsible for limiting their activity level and impacting their quality
of their life.

It is our goal in the proposed study to systematically characterize symptomatic and
asymptomatic patients greater than six months after mitral valve surgery using clinical
data, echocardiographic evaluation, laboratory assessment, and in some patients, invasive
hemodynamic measurements. The investigators will screen asymptomatic and symptomatic
patients with resting echocardiography and also with echocardiography during exercise, as
many patients will exhibit exercise-induced PH following mitral valve surgery. Pulmonary
artery (PA) pressure will be estimated from echocardiography using Doppler-derived
calculations. If elevated PA pressures are observed with echocardiography, then symptomatic
patients will undergo right heart catheterization for invasive pressure measurement, which
is the gold-standard for the diagnosis of PH. When PH is present and there is a normal wedge
pressure (PCWP) during invasive pressure measurement, further assessment to identify
potential candidates for PH therapy will be performed. This involves having patients breathe
inhaled nitric oxide, a rapid-acting, pulmonary vasodilator with a short half-life. While
breathing inhaled nitric oxide, blood pressure, PA pressure, PCWP, and cardiac output will
be monitored to characterize individuals who could benefit symptomatically from
pharmacotherapy to treat underlying PH. It is important to note that only a small minority
of patients exhibit a positive vasodilator response and those with PH and a normal PCWP
without an initial vasodilator response would still be identified as candidates for chronic
PH therapy.

The information generated from this proposed research will make a significant contribution
to the understanding of PH in a group of patients in whom it has not been previously
studied. Scientific reports on the evaluation of patients with PH after mitral valve surgery
are almost nonexistent from the modern era. Furthermore, patients with PH due to mitral
valve disease have been excluded from clinical trials of agents currently approved by the
U.S. Food and Drug Administration (FDA) to treat PH. Therefore, this work will carefully
characterize PA pressures in an objective manner in a group of patients following mitral
valve surgery who remain limited with respect to their activity levels. In addition, the
investigators will gain a better understanding of the frequency with which patients have PH
and a normal PCWP, which identifies a cohort of patients who could have an improvement in
their symptoms and quality of life with chronic vasodilator treatment.