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Pulmonary Hypertension Diagnostic Tests: Echo, RHC, and V/Q [ Medical Education ](https://mdster.com/blog?category=medical-education) Pulmonary Hypertension Diagnostic Tests: Echo, RHC, and V/Q ============================================================= A practical Internal Medicine overview of how to screen suspected PH, confirm hemodynamics, and avoid missing CTEPH [ MDster Editorial Team ](https://mdster.com/about) · Jul 07, 2026 · 7 min read · 36 [ Reviewed by Dr. Ali Ragab, MBBCH, MSc, MCAI ](https://mdster.com/medical-reviewers/dr-ali-ragab) [Editorial Policy](https://mdster.com/editorial-policy) | [Corrections Policy](https://mdster.com/corrections) [ Internal Medicine ](https://mdster.com/blog?tag=internal-medicine) [ Pulmonary Hypertension ](https://mdster.com/blog?tag=pulmonary-hypertension) [ Right Heart Catheterization ](https://mdster.com/blog?tag=right-heart-catheterization) [ Echocardiography ](https://mdster.com/blog?tag=echocardiography) [ CTEPH ](https://mdster.com/blog?tag=cteph) ![Pulmonary Hypertension Diagnostic Tests: Echo, RHC, and V/Q](https://mdster.com/storage/blog/images/pulmonary-hypertension-diagnostic-tests-echo-rhc-and-vq.jpg) Share this article Share this post On this page 1. [ The three tests, in one glance ](#the-three-tests-in-one-glance) 2. [ Start with echocardiography, but do not stop there ](#start-with-echocardiography-but-do-not-stop-there) 3. [ What echo is good at ](#what-echo-is-good-at) 4. [ Where echo misleads people ](#where-echo-misleads-people) 5. [ Right heart catheterization is the decider ](#right-heart-catheterization-is-the-decider) 6. [ What RHC actually gives you ](#what-rhc-actually-gives-you) 7. [ The practical bedside mindset ](#the-practical-bedside-mindset) 8. [ Never skip the V/Q scan when evaluating unexplained PH ](#never-skip-the-vq-scan-when-evaluating-unexplained-ph) 9. [ Why V/Q still matters ](#why-vq-still-matters) 10. [ What to do with an abnormal scan ](#what-to-do-with-an-abnormal-scan) 11. [ Clinical correlations for the internist ](#clinical-correlations-for-the-internist) 12. [ Key Takeaways ](#key-takeaways) 13. [ Conclusion ](#conclusion) 14. [ Frequently Asked Questions ](#blog-faqs) 15. [ References ](#references-heading) On this page 1. [ The three tests, in one glance ](#the-three-tests-in-one-glance) 2. [ Start with echocardiography, but do not stop there ](#start-with-echocardiography-but-do-not-stop-there) 3. [ What echo is good at ](#what-echo-is-good-at) 4. [ Where echo misleads people ](#where-echo-misleads-people) 5. [ Right heart catheterization is the decider ](#right-heart-catheterization-is-the-decider) 6. [ What RHC actually gives you ](#what-rhc-actually-gives-you) 7. [ The practical bedside mindset ](#the-practical-bedside-mindset) 8. [ Never skip the V/Q scan when evaluating unexplained PH ](#never-skip-the-vq-scan-when-evaluating-unexplained-ph) 9. [ Why V/Q still matters ](#why-vq-still-matters) 10. [ What to do with an abnormal scan ](#what-to-do-with-an-abnormal-scan) 11. [ Clinical correlations for the internist ](#clinical-correlations-for-the-internist) 12. [ Key Takeaways ](#key-takeaways) 13. [ Conclusion ](#conclusion) 14. [ Frequently Asked Questions ](#blog-faqs) 15. [ References ](#references-heading) A patient with progressive dyspnea, edema, and an echo reporting RVSP 58 mmHg does **not** have a complete pulmonary hypertension diagnosis yet. The classic mistakes are still the same: treating an echocardiogram as definitive, skipping invasive hemodynamics, and forgetting the V/Q scan that can uncover potentially treatable **CTEPH**. Contemporary PH guidance still centers diagnosis on hemodynamics, with echo used for probability and right heart catheterization used for confirmation. [\[1\]](#cite-1 "Reference [1]") The three tests, in one glance ------------------------------ TestBest useMain limitationEchocardiographyScreen for PH probability and assess RV structure/functionCannot confirm PH or reliably define subtypeRight heart catheterizationConfirm PH and define hemodynamic phenotypeInvasive and only as good as the measurements obtainedV/Q scanScreen for CTEPH in unexplained or newly diagnosed PHA positive scan needs downstream anatomic workup That table is the board answer and the bedside answer. If you keep the jobs of these tests separate, you will avoid most diagnostic errors. [\[2\]](#cite-2 "Reference [2]") Start with echocardiography, but do not stop there -------------------------------------------------- ### What echo is good at Transthoracic echo is the first-line noninvasive test in suspected PH. It does two clinically useful things: it estimates the **probability** of PH and it shows whether the RV is already paying the price. [\[2\]](#cite-2 "Reference [2]") High-yield echo clues include: - peak TRV >2.8 m/s as the entry point for abnormal probability assessment - RV/LV basal diameter ratio >1 - interventricular septal flattening - RA enlargement - dilated IVC with reduced inspiratory collapse - pericardial effusion in more advanced disease These are not trivia. They tell you whether the patient may already be on the RV-failure side of the interface, which should lower your threshold for urgent referral. [\[2\]](#cite-2 "Reference [2]") ### Where echo misleads people Echo alone is insufficient to confirm PH. The guideline language is direct: PH diagnosis requires **RHC**. [\[2\]](#cite-2 "Reference [2]") Why? Because the TR jet is imperfect. TRV can underestimate PH in severe tricuspid regurgitation and overestimate it in high-flow states or with technical error, and there is no single echocardiographic parameter that reliably establishes PH or its cause. [\[2\]](#cite-2 "Reference [2]") > **Clinical Pearl:** An elevated RVSP on echo is a reason to think harder, not a reason to label the patient with PAH. Echo screens; cath decides. [\[2\]](#cite-2 "Reference [2]") Board pitfall: do not equate “high RVSP” with group 1 disease. Left-sided heart disease, lung disease, thromboembolic disease, and mixed physiology can all produce an abnormal echo. [\[1\]](#cite-1 "Reference [1]") Right heart catheterization is the decider ------------------------------------------ ### What RHC actually gives you RHC confirms PH and supports treatment decisions, especially when PAH or CTEPH is suspected. It should be performed in experienced centers and should include a complete hemodynamic dataset obtained with standardized technique. [\[2\]](#cite-2 "Reference [2]") For Internal Medicine, the must-know numbers are simple: - **PH:** mPAP >20 mmHg - **Precapillary PH:** mPAP >20 mmHg, PAWP ≤15 mmHg, PVR >2 WU - **Isolated postcapillary PH:** mPAP >20 mmHg, PAWP >15 mmHg, PVR ≤2 WU - **Combined post- and precapillary PH:** mPAP >20 mmHg, PAWP >15 mmHg, PVR >2 WU Those measurements are why RHC matters. They separate pulmonary vascular disease from pulmonary venous hypertension and keep you from giving PAH drugs to the wrong patient. [\[2\]](#cite-2 "Reference [2]") ### The practical bedside mindset Ask one question before every cath: *Will invasive hemodynamics change management?* In suspected PAH or CTEPH, the answer is usually yes. In mild PH with obvious left-sided or lung disease and no therapeutic consequence, RHC may be less useful; in contrast, when the phenotype is unclear, severe, or RV failure is emerging, do not delay. [\[2\]](#cite-2 "Reference [2]") Another exam pearl: borderline wedge pressures are dangerous. If PAWP is 13-15 mmHg and the phenotype smells like HFpEF, exercise or fluid challenge may uncover postcapillary physiology. That is exactly the patient in whom premature PAH labeling causes harm. [\[2\]](#cite-2 "Reference [2]") Never skip the V/Q scan when evaluating unexplained PH ------------------------------------------------------ ### Why V/Q still matters In patients with unexplained PH, a ventilation/perfusion scan is recommended to assess for **CTEPH**. This remains true even in the CT era because V/Q is the most effective screening tool for excluding chronic thromboembolic disease. [\[2\]](#cite-2 "Reference [2]") The board-level fact is worth memorizing: in the absence of parenchymal lung disease, a normal perfusion scan essentially excludes CTEPH, with a reported negative predictive value of 98%. That is why a normal prior CTPA does **not** let you skip V/Q when the PH workup is underway. [\[2\]](#cite-2 "Reference [2]") ### What to do with an abnormal scan A mismatched perfusion defect is not the end of the workup; it is the trigger for referral and anatomic imaging. Contemporary algorithms pair abnormal perfusion imaging with echo, CTPA, and ultimately RHC in expert PH/CTEPH centers. [\[2\]](#cite-2 "Reference [2]") This matters because CTEPH is the PH subtype you most hate to miss. It has a distinct management pathway, including evaluation for operability and other interventional options, so the diagnostic miss is not academic. [\[3\]](#cite-3 "Reference [3]") Clinical correlations for the internist --------------------------------------- When dyspnea, edema, syncope, rising natriuretic peptides, or unexplained RV dysfunction show up together, do not order tests randomly. Use a sequence: **echo to screen, V/Q to exclude CTEPH, RHC to define the physiology**. [\[1\]](#cite-1 "Reference [1]") After acute PE, persistent or new exercise limitation should reopen the CTEPH question, especially once the patient is beyond the early anticoagulation window. That is a common boards scenario and a common real-world miss. [\[2\]](#cite-2 "Reference [2]") Key Takeaways ------------- - Echo is the **first** test in suspected PH, but it only assigns probability. [\[2\]](#cite-2 "Reference [2]") - Do not diagnose PH or PAH from echo alone; confirmation requires **right heart catheterization**. [\[2\]](#cite-2 "Reference [2]") - RHC defines whether physiology is precapillary, postcapillary, or mixed by using mPAP, PAWP, CO, and PVR. [\[2\]](#cite-2 "Reference [2]") - In unexplained PH, order a **V/Q scan** to screen for CTEPH; a normal perfusion scan makes CTEPH very unlikely. [\[2\]](#cite-2 "Reference [2]") - A positive V/Q scan does not finish the diagnosis; it should push referral, anatomic imaging, and RHC. [\[2\]](#cite-2 "Reference [2]") - The biggest exam and clinical pitfall is confusing an abnormal screening test with a hemodynamic diagnosis. [\[2\]](#cite-2 "Reference [2]") Conclusion ---------- In PH, the tests are not interchangeable. Respect the workflow: **echo raises suspicion, V/Q protects you from missing CTEPH, and RHC tells you what disease the patient actually has**. [\[2\]](#cite-2 "Reference [2]") Frequently Asked Questions ---------------------------- ### Can echocardiography diagnose pulmonary hypertension by itself? No. Echo is the first-line screening test and estimates PH probability, but definitive diagnosis requires right heart catheterization. [\[2\]](#cite-2 "Reference [2]") ### What makes right heart catheterization so important in suspected PH? RHC provides the hemodynamic data that classify PH: mPAP, PAWP, cardiac output, and PVR. Those numbers distinguish precapillary from postcapillary or mixed disease. [\[2\]](#cite-2 "Reference [2]") ### Why is a V/Q scan preferred for screening for CTEPH? Because V/Q scanning is the recommended screening test for CTEPH and a normal perfusion scan, in the absence of significant parenchymal lung disease, effectively excludes it. [\[2\]](#cite-2 "Reference [2]") ### If a patient had a prior negative CTPA, can I skip the V/Q scan during PH workup? No. A negative prior CTPA does not replace V/Q screening when evaluating unexplained PH, because chronic thromboembolic disease can still be missed without perfusion imaging. [\[2\]](#cite-2 "Reference [2]") References (8) ------------------ 1. 1. [ pubmed.ncbi.nlm.nih.gov/39209475 ](https://pubmed.ncbi.nlm.nih.gov/39209475/) [↩](#cite-ref-1-1 "Back to text") 2. 2. [ www.ishlt.org/docs/default-source/standards-guidelines/2022\_endorsement\_esc\_ers\_phguidelines.pdf?sfvrsn=a6cbfe7\_1 ](https://www.ishlt.org/docs/default-source/standards-guidelines/2022_endorsement_esc_ers_phguidelines.pdf?sfvrsn=a6cbfe7_1) [↩](#cite-ref-2-1 "Back to text") 3. 3. [ pubmed.ncbi.nlm.nih.gov/35643802 ](https://pubmed.ncbi.nlm.nih.gov/35643802/) [↩](#cite-ref-3-1 "Back to text") 4. 4. Humbert M, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J. 2022;43:3618-3731. 5. 5. Kovacs G, Bartolome S, Denton CP, et al. Definition, classification and diagnosis of pulmonary hypertension. Eur Respir J. 2024;64(4):2401324. 6. 6. Best Practices for Right Heart Catheterization in the Diagnosis of Pulmonary Hypertension. CHEST. 2025. 7. 7. The Role of Echocardiography in the Diagnosis and Prognosis of Pulmonary Hypertension. 2024. 8. 8. The Role of Lung Ventilation/Perfusion Scan in the Management of Chronic Thromboembolic Pulmonary Hypertension. 2024. Keep going Turn reading into Internal Medicine performance ------------------------------------------------- - System‑based, exam‑style questions + explanations - Smarter review to reinforce weak topics - Build confidence with measurable progress [ Start practicing ](https://mdster.com/user/dashboard) [ Explore Internal Medicine ](https://mdster.com/speciality/internal-medicine) [ View pricing ](https://mdster.com/pricing) [ Explore features ](https://mdster.com/features) No credit card required. Full access to all features\*. No commitment. Cancel anytime. \*AI SOE Examiner is limited to 10 cases monthly for Advanced & Bundle subscribers. 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