Page 11 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

Chapter 1
Figure 2: Using acetylcholine as a pulmonary vasodilator, Paul Wood showed in patients with ‘Primary PH that the administration of acetylcholine leaded to a decrease in pulmonary artery pressure in combination with an increase in cardiac output proving the increased vasoconstriction in this disease.
Wood’s studies using acetylcholine in PH patients also contributed to the classification of PH (Figure 2), which has been modified several times in the last five decades. Approximately 40 causes of PH are now recognized, which are categorized in 5 main groups (Table 1). Left sided heart failure (group 2) is the most common cause of PH [3].
Since the cardiovascular system is a closed loop system, different (patho)physiological hemodynamic changes can initiate an increase in mPAP. The hemodynamic mechanisms resulting in an increase in mPAP are, an increase in pulmonary vascular resistance (PVR), an increase in pulmonary arterial wedge pressure (PAWP) and an increase in cardiac output (CO).
Table 1: Clinical classification of pulmonary hypertension according to guideline (Galie ERJ 2015)
1. Pulmonary arterial hypertension 1.1 Idiopathic
1.2 Heritable
1.2.1 BMPR2 mutation
1.2.2 Other mutations
1.3 Drugs and toxins induced 1.4 Associated with:
1.4.1 Connective tissue disease
1.4.2 Human immunodeficiency virus (HIV) infection 1.4.3 Portal hypertension
1.4.4 Congenital heart disease
1.4.5 Schistosomiasis
1’. Pulmonary veno-occlusive disease and/or pulmonary capillary haemangiomatosis
2. Pulmonary hypertension due to left heart disease
3. Pulmonary hypertension due to lung diseases and/or hypoxia
4. Chronic thromboembolic pulmonary hypertension and other pulmonary artery obstructions 5. Pulmonary hypertension with unclear and/or multifactorial mechanisms
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