Echocardiography in Pulmonary Hypertension

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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:
    • Anemia
    • AV fistula in hemodialysis
    • Low systemic vascular resistance (SVR) state in Cirrhosis
• 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

CME Credit

This activity has been planned and implemented in accordance with the accreditation requirements and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint providership of the American College of Physicians and Core IM.  The American College of Physicians is accredited by the ACCME to provide continuing medical education for physicians.

The American College of Physicians designates this enduring material (podcast) for 0.5 AMA PRA Category 1 Credit™.  Physicians should claim only the credit commensurate with the extent of their participation in the activity.

ABIM Maintenance of Certification (MOC) Points

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 0.5 medical knowledge MOC Point in the American Board of Internal Medicine’s (ABIM) Maintenance of Certification (MOC) program.  Participants will earn MOC points equivalent to the amount of CME credits claimed for the activity. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.

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After listening to the podcast, complete a brief multiple-choice question quiz. To claim CME credit and MOC points you must achieve a minimum passing score of 66%. You may take the quiz multiple times to achieve a passing score.