Pearl 1: Interpreting the pulmonary artery systolic pressure (PASP) on echo
- The PASP is an estimate based on the tricuspid regurgitant jet velocity (TRV).
- Using the Bernoulli equation, the mean pressure difference from the RV to the RA is proportional to 4 x (TRV)2.
- Estimating a PASP requires identifying the TRV on the echo, which can be difficult in patients where getting good echo windows is challenging.
- When compared to the PASP measured on right heart catheterization, the gold standard, echo estimated PASP has been shown to have at most a moderate correlation, though about 50% of the time, echocardiography over- or under-estimates the PASP by at least 10mmHg compared to right heart catheterization measurements.
- The echo estimated PASP gives us a sense of the degree of pulmonary hypertension, but not the underlying etiology.
- When interpreting a PASP remember other clinical variables during acute illness that may alter results:
- Hypoxia can lead to pulmonary vasoconstriction, increasing PASP
- Volume overload can lead to increased tricuspid regurgitation, increasing PASP
- Acute anemia can increase cardiac output, increasing PASP
Chronic anemia can cause PH and remodeling of the vasculature overtime.
Pearl 2: Physiologic framework for pulmonary hypertension
- Abnormalities in any of the following three key hemodynamic components can cause elevated pulmonary artery pressures.
- Increased resistance across the pulmonary vascular system due to primary pulmonary vascular disease:
- Pulmonary arteriole vasculopathy (PAH)
- Chronic lung disease or chronic hypoxemia
- Alteration of the pulmonary vascular bed (ILD, CTEPH, COPD)
- Elevated left-sided filling pressures due to left heart disease:
- Left ventricular systolic or diastolic dysfunction
- Mitral or aortic valve disease
- Increased flow across the pulmonary vascular system:
- Patients will not always fit nicely into only one of these buckets.
- Cirrhosis may cause increased flow from a low SVR state, though portopulmonary hypertension in cirrhosis is due to increased resistance in the pulmonary vascular system.
Pearl 3: Using echo to characterize pulmonary hypertension due to high left-sided filling pressures
- Clear echocardiographic clues of left-sided heart disease include systolic dysfunction, severe aortic stenosis, or mitral valve disease.
- Several elements on an echo can be signs of left-sided diastolic dysfunction that may signal left heart disease:
- Increased left atrial size
- Increased left heart filling pressures with elevated E/e’ >10-12
- The H2FPEF score can be used as a tool to identify diastolic dysfunction in patients with unexplained dyspnea.
Pearl 4: Evaluating pulmonary hypertension due to elevated pulmonary vascular resistance
- If there is no clear evidence of left-sided heart disease, then the elevated PASP may be due to increased resistance (or less commonly increased flow).
- Evidence on septal flattening during systole on an echo may signal increased pulmonary vascular resistance.
- These patients warrant referral to a pulmonary hypertension expert.
- While waiting for the referral, you can start a basic initial work-up:
- Evaluate for PAH
- Ask about autoimmune history, family history, a thorough review of symptoms
- Ask about drug/toxin exposures, specifically methamphetamine
- Evaluate for chronic lung disease or chronic hypoxemia
- Look for prior PFTs or CT scans of the chest
- Start with a chest x-ray
- Order a sleep study
- CTEPH evaluation requires a VQ scan. Make sure you are ordering this at a location where these are commonly done, or wait for the pulmonary hypertension expert to order this.
Contributors
Hannah Robertson, MD – host
Adam Rodman, MD, FACP - host
Noah Schoenberg, MD - guest
Shreya Trivedi, MD, ACP Member - host
Anjali Vaidya, MD - guest
Consultant: Janssen, Bayer Healthcare, United Therapeutics
Reviewers
Cyrus Kholdani, MD
Timothy Fernandes, MD, MPH
Consultant: Actelion, Bayer Healthcare
Those named above, unless otherwise indicated, have no relevant financial relationships to disclose with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients. All relevant relationships have been mitigated.
Release Date: April 6, 2022
Expiration Date: April 6, 2025
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