Which type of pulmonary hypertension is characterized by constriction of the pulmonary circuit?

Active pulmonary hypertension is characterized by the constriction of the pulmonary circuit due to increased vascular resistance. This condition arises from various factors like hypoxia, inflammation, or vasoconstrictor imbalances, which directly lead to the narrowing of pulmonary arteries and arterioles. This constriction increases the pressure in the pulmonary circulation, thereby making it more difficult for the heart to pump blood through the lungs. Understanding this mechanism is crucial for managing patients with this type of hypertension effectively, as various interventions can target the underlying causes of vascular constriction.

Other types of pulmonary hypertension may involve different pathophysiological processes. For example, passive pulmonary hypertension typically occurs secondary to left heart failure, where increased pressure is transmitted backward into the pulmonary circulation but does not originate primarily from constriction of pulmonary blood vessels. Obstructive pulmonary hypertension often refers to blockages (like pulmonary embolism) that impede blood flow rather than being due to constriction of the vessels themselves. Chronic pulmonary hypertension denotes a long-standing elevation in pressure, which could include various underlying mechanisms, not necessarily limited to active constriction of the vasculature.