Blood Vessels: The pulmonary arteries
The right ventricle pumps blood through the pulmonary valve and into the main pulmonary artery. This artery subsequently divides into the left and right pulmonary arteries, which collect oxygen from the lungs. By examining the size of and flow through the pulmonary arteries, we can estimate the blood pressure within the lungs. In addition, because raised pressure in the lungs puts the right ventricle under strain, this will often cause a leak (regurgitation) through the tricuspid valve. If we measure the severity of this leak, we can also calculate an approximation of the blood pressure in the lungs (often documented in a scan report as PA(S)P – pulmonary artery (systolic) pressure – or RVSP – right ventricular systolic pressure). Raised blood pressure within the lungs is known as pulmonary hypertension; this is most often caused by lung disease (such as COPD), or by a buildup of pressure further downstream, such as a valve problem in the left side of the heart. However, there are some more uncommon causes of pulmonary hypertension which, if severe, may need further investigation and treatment.