Role of serotonin in the pathogenesis of acute and chronic pulmonary hypertension
- aCanterbury Respiratory Research Group, Christchurch School of Medicine, Christchurch, New Zealand, bDepartment of Respiratory Medicine, Western Infirmary, Glasgow G11 6NT, UK
- Dr G I Town, Christchurch School of Medicine, P O Box 4345, Christchurch, New Zealand.
- Received 9 February 1998
- Revision requested 8 May 1998
- Revised 15 June 1998
- Accepted 11 September 1998
The causes of pulmonary hypertension fall into four broad categories: (1) passive increases in pulmonary artery pressure secondary to increased left atrial pressure and left ventricular dysfunction, (2) veno-occlusive disorders, (3) conditions in which the blood flow through the pulmonary arteries is increased beyond the ability of the pulmonary circulation to compensate, and (4) conditions associated with vasospasm or occlusion, resulting in a diminished effective cross sectional area of the pulmonary vascular bed.1 2 In many cases several factors are present simultaneously. Regardless of the initiating cause, severe prolonged pulmonary hypertension appears to result in largely irreversible changes which involve vascular remodelling and often thrombosis.3-5
Because the signs and symptoms of pulmonary hypertension are often very non-specific, patients commonly present late and, until recently, invasive tests were required to establish the diagnosis. Consequently pulmonary hypertension was frequently an important but unrecognised component of other disease states, many of which will be the subject of this discussion.
The main importance of severe pulmonary hypertension is that it may cause right ventricular dysfunction and ultimately death from right heart failure. Pulmonary heart disease, usually associated with pulmonary hypertension, has been estimated to account for at least 10% of all cases of heart disease in the USA.6 The significance of milder pulmonary hypertension is less clear, but it is probably important. A study in Chicago of 1118 subjects who were undergoing coronary angiography for suspected heart disease showed that the finding of pulmonary hypertension, independent of left ventricular dysfunction, was the single most important predictor of the likelihood of death over the subsequent two years.7 Pulmonary hypertension also has important prognostic implications in critically ill surgical patients8 and in those with chronic obstructive pulmonary disease (COPD).9
The changes which take place in pulmonary arteries as a result …