Pulmonary hypertension (PH) is a serious condition characterized by high blood pressure in the arteries of the lungs. This elevated pressure makes it harder for the heart to pump blood through the lungs, particularly affecting the right side of the heart. To assess and screen for PH, healthcare providers often use echocardiography, commonly known as an echo. This non-invasive ultrasound of the heart is a primary tool for estimating the likelihood of PH due to its ability to visualize cardiac structures and blood flow.
Understanding Pulmonary Hypertension and Echocardiography
Pulmonary hypertension occurs when the blood vessels in the lungs become narrowed, blocked, or destroyed, making it difficult for blood to flow through them. This resistance causes blood pressure to rise in the pulmonary arteries, forcing the heart’s right ventricle to work harder to push blood into the lungs. Over time, this increased workload can enlarge and weaken the right ventricle, potentially leading to right-sided heart failure.
An echocardiogram uses high-frequency sound waves to create moving pictures of the heart. A technician places a probe on the chest, which emits sound waves that bounce off the heart’s structures and return as echoes to a computer, forming real-time images. This imaging technique allows doctors to visualize the heart’s chambers, valves, and the direction and speed of blood flow. This technique provides immediate, detailed information about the heart’s function and structure.
Key Echocardiographic Indicators of Pulmonary Hypertension
Echocardiography provides several specific measurements and visual signs that suggest the presence of pulmonary hypertension. These indicators help estimate the likelihood and severity of the condition.
- Tricuspid Regurgitation (TR) velocity: Measures the speed of blood leaking backward through the tricuspid valve. This allows for an estimation of the right ventricular systolic pressure (RVSP), which closely reflects the pulmonary artery systolic pressure (PASP). A TR velocity greater than 2.8 m/s, especially if over 3.4 m/s, strongly suggests PH.
- Right Ventricular (RV) size and function: An enlarged or thickened right ventricle (RV dilation or hypertrophy) indicates it is working harder against high pressure. Reduced systolic function and an RV-to-left ventricle (LV) ratio greater than 1.0 also raise suspicion for PH.
- Interventricular Septum (IVS) shape: High pressure in the right ventricle can cause the septum to bulge into the left ventricle, creating a “D-shaped” appearance. This indicates increased pressure overload on the right side of the heart.
- Dilated Pulmonary Artery (PA): An enlarged main pulmonary artery suggests sustained high pressure.
- Inferior Vena Cava (IVC) size and collapsibility: An enlarged IVC that collapses minimally with breathing indicates elevated right atrial pressure, supporting PH suspicion.
Confirming the Diagnosis Beyond the Initial Echo
While echocardiography is an excellent tool for screening and estimating the probability of pulmonary hypertension, it is not definitive for a formal diagnosis. The “gold standard” for confirming PH and precisely measuring pulmonary artery pressures is right heart catheterization (RHC). During this invasive procedure, a thin, flexible tube is inserted into a vein, typically in the neck or groin, and guided into the heart’s right side and pulmonary artery to directly measure blood pressure.
Other diagnostic tests often follow an initial echo to determine the underlying cause of PH. These may include blood tests to check for various conditions, a chest CT scan to look for lung conditions or clots, or pulmonary function tests to assess lung capacity. These additional evaluations help understand the cause of PH and guide specific treatment strategies.