Breathlessness (dyspnea) is another important symptom at heart disease. It can occur at rest or with exercise. Breathlessness at rest usually indicates a more severe disease. It is the most common symptom which is used to grade the functional class of the individual. Breathlessness in heart disease often indicates heart failure, though it can also occur due to myocardial ischemia (anginal equivalent).
New York Heart Association (NYHA) functional class
Class I: No symptoms or limitation of ordinary physical activity.
Class II: Mild symptoms on ordinary physical activity.
Class III: Moderate symptoms on less than ordinary physical activity.
Class IV: No physical activity possible without symptoms. Often symptomatic at rest.
Symptoms included in NYHA classification are fatigue, palpitation, dyspnea and angina.
Dyspnea occurring in supine position and relieved on sitting up is known as orthopnea. It is usually a symptom of advanced heart failure.
Paroxysmal nocturnal dyspnea
Paroxysmal nocturnal dyspnea (PND) is breathlessness which occurs a few hours after the onset of sleep, typically in the very early morning hours. It subsides spontaneously after sitting up for a few minutes. It is a typical symptom of left heart failure including mitral stenosis (narrowing of the mitral valve) and left ventricular failure. It may be noted that there is no left ventricular failure in mitral stenosis, though left atrial and pulmonary venous pressures are elevated, leading to pulmonary congestion.