Pulmonary Circulatory Disorders
Core concepts
Pulmonary circulatory disorders include pulmonary arterial hypertension, pulmonary hypertension due to left heart disease, lung disease or hypoxia, chronic thromboembolic disease, and miscellaneous causes. Group 1 PAH requires exclusion of other groups and may need vasoreactivity testing. Acute PE risk stratification uses hemodynamic stability, RV dysfunction, troponin, and bleeding risk. CTEPH is a treatable cause of PH and warrants evaluation after PE with persistent symptoms. Right ventricular failure from pressure overload can cause congestion, low output, and syncope.
Question traps
Do not start PAH-specific vasodilators in pulmonary hypertension from left heart disease; pulmonary edema can result. Do not confuse chronic thromboembolic disease with acute PE. A normal D-dimer is useful only in low or intermediate pretest probability. RV strain on echocardiography is not the same as hemodynamic instability. Remember that PE can cause troponin elevation and ECG changes mimicking ischemia.
Worked example / rule of thumb
A patient with PE and hypotension receives systemic thrombolysis unless contraindicated; a stable patient with RV dysfunction and elevated troponin is intermediate-high risk and needs close monitoring. Rule: in PE, hypotension equals high risk and drives reperfusion.