Pulmonary Hypertension Pathology Study Guide

Pulmonary Hypertension Pathology Video

Pulmonary Hypertension

Pulmonary hypertension refers to a form of high blood pressure that affects the pulmonary circuit (mean arterial pressure > 25 mmHg; normal is 10 mmHg).

Pulmonary hypertension condition is characterized by atherosclerosis of the pulmonary trunk, smooth muscle hypertrophy of pulmonary arteries, and intimal fibrosis.

Plexiform lesions are seen with severe, long-standing pulmonary hypertension.

Extreme pulmonary hypertension may lead to right ventricular hypertrophy with eventual cor pulmonale characterized by exertional dyspnea or right-sided heart failure.

Pulmonary hypertension is classified either as primary or secondary based on etiology.

Pulmonary Hypertension Pathology. Micrograph showing arteries in pulmonary hypertensive with marked thickening of the walls. Yale Rosen. Not altered. CC BY-SA 2.0
The pulmonary vasculature in lung tissue from four patients with severe pulmonary hypertension is shown. The patients were characterized clinically as Category 1 (IPAH), Category 2 (left ventricular failure), Category 3 (interstitial lung disease), and Category 4 (chronic thromboembolic disease). However, each specimen reveals similar changes in the pulmonary arteriole showing medial hypertrophy and intimal proliferation. What is pulmonary arterial hypertension?: Rich S - Pulmonary circulation (2012). Not altered. CC.
(a and b) Histological section showing prominence of the intracinar arterioles with medial hypertrophy corresponding to Grade I pulmonary hypertension (Heath-Edwards grading system), (H and E ×100 (a), ×200 (b). (c) Elastic von-Gieson's (EVG) stain highlighting the prominent intracinar arterioles (EVG ×100). (d and e) Muscle hypertrophy along with proliferation of intimal cells in the arterioles corresponding to Grade II pulmonary hypertension (Masson's trichrome ×100 (d), ×400 (e). Severe pulmonary artery hypertension following intracardiac repair of tetralogy of Fallot: An unusual finding. Kumar B, Puri GD, Manoj R, Gupta K, Shyam KS - Pulmonary circulation (2011 Jan-Mar). Not Altered. CC.

Primary Pulmonary Hypertension

Primary pulmonary hypertension most prevalent among young female adults.

The cause of primary pulmonary hypertension is unknown.

Some familial forms of primary pulmonary hypertension are attributed to the inactivating mutations of BMPR2, causing the proliferation of vascular smooth muscle.

Obstructive remodelling of a small pulmonary artery in pulmonary arterial hypertension (increased thickness of the three vessel layers and severe lumen reduction are shown) and ongoing pathobiological processes in the different layers of the vessel wall (yellow boxes) and in the blood. Asterisks indicate the potential processes involved. Corrective interactions of the related approved therapeutic interventions are also reported (green boxes). *Vasoconstriction; †Proliferation/migration; ‡Inflammation; §Thrombosis. B-FGF, basic fibroblast growth factor; BMPR, bone morphogenetic protein receptor; [Ca2+], intracellular calcium concentration; K+ch, membrane potassium channels; SMC, smooth muscle cells; MFB, myofibroblasts; MMP, matrix metalloproteases; PDE-5, phosphodiesterase type 5; PDGF, platelet-derived growth factor; TxA2, tromboxane A2; VEGF, vascular endothelial growth factor; VIP, vasoactive intestinal peptide. The pathological picture is a courtesy of Dr Carol Farver, Cleveland Clinic. Pulmonary arterial hypertension: from the kingdom of the near-dead to multiple clinical trial meta-analyses. Galiè N, Palazzini M, Manes A - European heart journal (2010). Not Altered. CC.

Secondary Pulmonary Hypertension

Secondary pulmonary hypertension is caused by underlying diseases or other known risk factors.

The most common causes are of secondary pulmonary hypertension include:

Hypoxemia (lung diseases)
Increased volume in the pulmonary circuit (e.g., congenital heart disease)

Secondary pulmonary hypertension may also arise with recurrent pulmonary embolism.

Secondary Pulmonary Hypertension. Is a complication of many cardiac, pulmonary, and extrathoracic conditions. Robina Weermeijer. Not altered. CC.