14. History of ischemic heart disease, including previous myocardial infarction, or symptomatic coronary artery disease, or history of left sided myocardial disease as evidenced by a mean PCWP (or a left ventricular end diastolic pressure) > 15 mmHg or left ventricular ejection fraction < 40% as assessed by either multigated angiogram, angiography or echocardiography, or left ventricular shortening fraction < 22% as assessed by echocardiography. Note that patients in whom abnormal left ventricular function is attributed entirely to impaired left ventricular filling due to the effects of right ventricular overload (i.e. right ventricular hypertrophy and/or dilatation) will not be excluded.