Plasma brain natriuretic peptide, platelet parameters, and cardiopulmonary function in chronic obstructive pulmonary disease

Table 1 World Health Organization criteria for evaluating cardiac function in patients with pulmonary arterial hypertension

Grade	Symptom
I	Daily manual activity is unrestricted.
II	Physical activity is mildly restricted, and the symptoms disappear after taking rest; symptoms of shortness of breath and fatigue gradually develop after performing daily general activities.
III	Physical activity is clearly constrained, and there are no apparent symptoms after taking rest; performing activities that require greater strength than that for daily activities could induce shortness of breath, fatigue, and palpitation.
IV	No physical activity is allowed, especially in those with right heart failure syndrome; resting can also trigger anhelation and fatigue symptoms, and any physical activity can aggravate the abovementioned symptoms.