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Show Notes

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, one study found that about 50% of the time, echocardiography over- or under-estimates the PASP by at least 10mmHg compared to right heart catheterization measurements.
  • Assessing changes in RV function is is helpful for monitoring disease progression and treatment response.

Pearl 2: Confounding Clinical Scenarios 

  • When interpreting a PASP, remember other clinical variables during acute illness that may alter results
  • Hypoxia and acute respiratory illness can lead to pulmonary vasoconstriction via autoregulation or loss of the vascular bed, increasing PASP.
    • This may include disease states such as pneumonia, pleural effusion, or pneumothorax
  • Volume overload can lead to increased tricuspid regurgitation, increasing PASP. 
  • Acute anemia can increase cardiac output, increasing PASP.

Pearl 3: 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.
    • Example: 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 4: Signs of 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 5: Elevated pulmonary vascular resistance

  • If there is no clear evidence of left-sided heart disease, as above, 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
      • Screen for HIV and liver disease
      • 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
        • If unavailable, 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.

Transcript

S: This is Dr. Shreya Trivedi, an internist at Beth Israel Deaconess Medical Center 

A: This is Dr. Adam Rodman, also a general internist at BIDMC, and this is Dr. Hannah Robertson, a resident at BIDMC. This is the CORE IM 5 pearls podcast bringing you high-yield evidence-based pearls.

H: Today I’m super excited to delve into pulmonary hypertension and unpack what the echo can tell us about pulmonary HTN, also known as “PH.”

A: Oh man, Hannah, I love this because sometimes I feel like, I don’t know, 50% of the echos that order come back with a mention of some sort of mild to moderate pulmonary hypertension.

H: Yeah, I 100% echo that feeling Adam, pun intended. But in all seriousness … sometimes I feel like it can be easy to underappreciate these findings.

S: I hear you guys, but then again, pulmonary hypertension can be such a big deal to overlook.

Vaidya: A patient of mine yesterday told me her exact words were, “I would rather feel pain than not being able to breathe this much.” And I mean, I just listened to her and felt a fire of motivation inside of me, for us to try to do better by these patients. And so there’s the suffering, there’s the human component of it.

H: That’s Dr. Anjali Vaidya, a cardiologist and co-director of the pulmonary hypertension program at Temple University Hospital and she’s gonna help us all do better by these patients.

A: Alright so let’s get into those pearls we’ll be covering in the episode. Test yourself by pausing after each of the 5 questions. 

S: Remember, the more you test yourself, the deeper your learning gains.

H: Pearl 1: Interpreting the pulmonary artery systolic pressure (PASP) on echo

  • S: How reliable is the PASP on the echo and what should you be trending over time on the echo?

H: Pearl 2: Confounding clinical scenarios 

  • S: What are some acute clinical scenarios that might affect the PASP on the echo?

H: Pearl 3:  Physiologic framework for pulmonary hypertension

  • S: What are 3 pathophysiologic insults that cause increased pulmonary artery pressures? 

H: Pearl 4: Signs of high left-sided filling pressures

  • S: What can you look for on an echo to suggest diastolic dysfunction? 

H: Pearl 5: Elevated pulmonary vascular resistance

  • S:  What are the best practices to evaluate causes of increased pulmonary vascular resistance?  

Pearl 1: Interpreting the pulmonary artery systolic pressure (PASP) on echo

Vaidya: I think that we have all been taught to look at the PA systolic pressure or the RV systolic pressure estimation on echo, um, as the sort of initial clue or diagnosis for pulmonary hypertension and that, and that’s never going to go away and it’s so incredibly valuable, but I have learned over the course of many years now it is also the least specific. 

S:  That’s a good point. But what is that PASP an estimation of?

Vaidya: It’s an estimation. It’s not an absolute direct measurement of a number and there’s some very wonderful physics and math that goes behind it using Doppler with the modified Bernoulli equation.

S: Oh interesting, so the PASP is derived from an equation?! It’s not someone sitting in a dark room measuring the diameter of those pulmonary arteries?

H: No so actually that number, the PASP or what we call sometimes RVSP – right ventricular systolic pressure – is derived from actually looking at  the tricuspid regurgitant jet velocity, so essentially looking for tricuspid regurgitation, or TR, and then inputting that into this modified Bernoulli equation.

Vaidya: But inherent in that equation and that technique are potential areas for error, including the angle with which we’re measuring the velocity relative to the Doppler probe, including the completeness of the tricuspid regurgitation jet. And so, when all of those things are used together in one equation, there is certainly potential for error.

H: The other thing that clouds the picture is in a lot of patients with interstitial lung disease or COPD, they have difficult anatomy and it can be really hard to get a good echo window. ‘

S: Yeah I can think of so many times you get an echo report back and it says “couldn’t estimate the PASP” but that doesn’t mean that they don’t have high pulmonary artery pressures. It just means it couldn’t be estimated. 

A: This is really interesting to me because most people, really referring to myself here, you know the echo readings seem like they’re scientific proof and I just accept them without much questions, but how skeptical should I actually be about these numbers?

Vaidya: And this has been shown in data for many years where the accuracy of Doppler echo in the hemodynamic assessment of pulmonary hypertension can be off by over 10 millimeters of mercury in up to half of patients that are getting an echocardiogram. Um, it’s been shown in studies where actually echo and cath were done within an hour. So really no change in physiology and underlying condition. And that error can happen as an overestimation or an underestimation with a very similar frequency.

H: Wow now that is humbling, but a good reminder that no test is perfect. But when I looked into it, the estimated PASP is actually not so bad compared to a right heart cath, which is the gold standard for measuring this value..

A: Yeah, at this point there are multiple studies showing a moderate correlation between the PASP and right heart cath numbers.

H: Maybe more importantly though, once pulmonary artery pressures are high it’s high and maybe this error doesn’t make much of difference.

Vaidya: I consider the PASP estimation on echo to often represent what I think of as like t-shirt sizes, like small, medium, large, like, we’re not specific here. It’s just, how big is it? And there’s no great consensus on what is mild versus moderate versus severe.

H: Exactly, and what was a new teaching point for me is that it’s really not that helpful to trend the PASP on echo. 

Vaidya: And so I have learned to tell the patients this in advance because we love our patients and they will, of course, come back to me and say, okay, doc, what was my pressure on this echo? What was my PA, how am I doing? What was the pressure on the echo? And then they look at you like, you’re insane when the honest answer is it doesn’t matter. And it’s very hard for them and us initially, even to accept and recognize that the pressure estimation is not the marker of the disease, a phenotype or characterizing it, nor is it the marker of response to treatment. 

S: Guys, I gotta say, I am a huge fan of trending things, like the internist in me, so it is hard for me not to read into changes of those pulmonary artery pressures too much. 

A: Well Shreya, turns out you’re not the only person who loves trending. One thing we learned from Dr. Noah Schoenberg, a pulmonologist here at BIDMC, is that it’s really important in these patients to trend the RV size and function.

Schoenberg: I use the echocardiographic description of RV function as a much more detailed description of what’s going on with the pulmonary circulation and the underlying pathophysiology. Over time, progressive dilatation is very concerning, just like progressive dilatation on the left side is very concerning. It speaks to an RV that is failing to compensate for the pressures it is dealing with.

H: Ok so what I’m getting here is the PASP may be an initial signal of something going on, but what we really should be tracking overtime is how the RV is handling that high PA pressure. 

A: Yeah like seeing if there’s RV hypertrophy? Is the RA enlarged? Are those pressures high enough to open up a PFO?

Schoenberg: Certainly as the RV dilates, if it fails, you can also see decreased function. It becomes more hypokinetic the RVF falls. And you know, that sort of implies that your cardiac output is likely also drop. 

H: Yeah and once the RV starts to fail and can’t generate that squeeze the the PASP counterintuitively actually goes down 

S: Yeah that reminds me, I had a patient once who had really severe pulmonary hypertension, and her repeat echo comes back and the PASP actually is almost normal and I remember like scratching my head like oh did we just improve her all of a sudden? Uh but no, her RV dysfunction actually just got worse. 

A: I think that’s a really prescient lesson Shreya, because yes, numbers are numbers but a lot of things can throw them off and at the end of the day it’s how the person in front of you is doing. So I’m going to try to recap our takeaway here: the PASP on echo is calculated based on the tricuspid regurgitant velocity and at best it’s an estimate. So the PASP kind of gives us a ballpark of how the pressures are but the most important thing in these patients is to see how the right side of the heart is actually handling those elevated pressures.

Pearl 2: Confounding clinical scenarios 

A: In my personal experience, we often look at the PASP number but then miss the boat on taking into account what else is going on with patients and how that’s impacting that PASP number we’re seeing.

Vaidya: You know, pulmonary processes and hypoxia alone can lead to pulmonary vasoconstriction. And so I will often encourage folks not to necessarily discount the presence of pulmonary hypertension if it’s found in that clinical context, but to just recognize the potential impact.

A: Even if they’re not hypoxemic, significant atelectasis or effusion, or also PTX can cause elevated pulmonary pressures because you’re losing some vasculature. 

H: Ok wait so actually walk me through how that makes the pulmonary pressures go up?

Schoenberg: You can actually have loss of vascular bed because part of the lung is collapsed there. And so you just aren’t able to push blood through those areas. Um, the other relates to pulmonary auto regulation when an area is not ventilating, the blood vessels constrict. And when you have constricted blood vessels, it is harder for blood to flow through them. You have increased pulmonary vascular resistance. So whether it is due to, uh, a pneumothorax causing partial collapse of the lung, so that lung isn’t ventilating, or whether it’s a pleural effusion having the same effect or even a pneumonia where that lung isn’t aerated well, um, the blood vessels constrict and it is, um, shunt blood elsewhere that ideally is that are ventilated, but now it is harder for blood to flow when the pulmonary vascular resistance goes up.

S: Hah, so basically any big acute respiratory process can make the pulmonary pressures go up – what else can do it?  

Vaidya: Anemia can lead to changes in cardiopulmonary physiology too, in terms of affecting stroke volume and cardiac output. And so if a patient is acutely anemic, that’s not the time to interpret their PAs P estimation on the echocardiogram because they’re probably slightly high in a high output state, which can also contribute to pulmonary hypertension. But that said a few times a year, a new pulmonary hypertension referral to me is anemia. And that’s all it is.

H: That’s so crazy but it makes a lot of sense that an acute drop in hemoglobin can put people in a high cardiac output state and then really mess up that PASP estimate. 

S: Yeah. Makes you think about all the patients that we have who are in heart failure and are volume overloaded, we often get echos on them. How much can we trust those PASPs?

Vaidya: Volume status can have some effect. Um, it doesn’t generally overall impact right heart function, but it can certainly have a significant impact on the degree of valvular regurgitation and tricuspid regurgitation. And so volume status of hypoxia can be important parameters that can affect the interpretation.

A: There’s some nuance here. So its not that volume overload itself makes the PASP artificially elevated. If you’re overloaded and you also have tricuspid regurgitation, especially moderate to severe to TR, the PASP can be artificially high. Why? Well if you remember, we actually use the tricuspid regurgitant jet to estimate the PASP in the first place. But if someone is overloaded without significant degrees of TR, the PASP will not be as impacted. 

S: Nice, uh. That was some great spaced repetition Adam on how the tricuspid is actually used to calculate the pulmonary systolic pressure, so props. So with that, why don’t we recap the times that we should interpret the pulmonary artery pressures with a bit of a grain of salt. So that’s gonna be in patients with one, acute respiratory illnesses, profound acute anemia, and lastly volume overload. 

Pearl 3: Physiologic framework for pulmonary hypertension

A: I can think of so many examples of being on the inpatient side of things when I get a patient’s echo back, an echo that I ordered, and it shows a pulmonary artery systolic pressure of 40 or so. But you know, they presented with something, I got the echo, and they get better. And that’s that. What do I do with that number? 

H: Yeah Adam, and I totally agree, and I’ve definitely seen this as a transitional issue when I’m seeing patients in clinic also. Maybe we repeat the echo if we didn’t think they were in some steady state physiology and the PASP is still high. So now that we know that the PASP is more or less just a signal, we then still have to figure out what’s actually going on.

Vaidya: The underlying hemodynamics of pulmonary hypertension is always going to be one of three things. And so I start with that concept because when the pressure estimation is high on echo or measured in the cath lab, the real question for us as the physician is which of those three things is the cause and the culprit of the pressure being high.

S: Whoa, whoa wait a minute guys –  one of 3 things?! I don’t know about you guys but I feel like the 5 different WHO groups were hammered into my head with pulmonary hypertension.

H: Hey hey ok so hear her out! I actually found this way of thinking of pulmonary hypertension way more intuitive, and its a good starting point to figure out what kind of physiology our patient might have.

Vaidya: So always think physiology first and then go to the WHO groups second. So physiology first is at a high flow. Is it high left atrial pressure or is it high resistance?

S: Huh, so it sounds like all elevated pulmonary pressures are due to one of three pathophys insults, first being high flow through the pulmonary system, second being high left sided filling pressures backing up into the pulmonary system, and the last being high vascular resistance within the pulmonary system.

H: To cement those 3 pathophys insults, Dr. Schonberg actually uses a garden hose analogy – that he uses both for teaching & explains it to patients.

Schonberg: Ultimately, pulmonary hypertension is a little bit like trying to water your garden with a garden hose hooked up for spigot on a house, high flow through the hose will raise the pressure, having a nozzle on the end causing water to back up will raise the pressure and having a kink in the hose or a constriction will raise the pressure. But all of those represent different kinds of pulmonary hypertension and different pathophysiologies. 

S: Great I think im getting it but to really sink it in lets break down those 3 pathophys buckets a bit more

A: So bucket number one, we think of things that alter the pulmonary vascular bed itself and increase resistance.

S: Yeah so going back to that hose analogy, these are all different kinks or constrictions within the hose that raise the pressures so I’m guessing things like pulmonary arterial hypertension in WHO group 1, or all the chronic lung disease in WHO group 3, or WHO group 4 chronic thromboembolic pulmonary hypertension aka CTEPH. These are all things that link back to some kind of change in the pulmonary vascular bed and increase the resistance within that pulmonary system.

H: So then the next physiologic bucket is the elevated left-sided filling pressures – so basically this is pulmonary hypertension related to left-sided heart disease. This is the nozzle at the end of the hose.

Vaidya: The overwhelmingly common majority cause is going to be the left sided filling pressures that are high.

S: And then the third and last pathophys insult that can cause high pulmonary pressures is going to be increased flow, so this is turning up the nozzle of that hose. It sounds like high cardiac output states can do it, and I know we mentioned severe anemia can get us to that high output state, but I gotta be honest guys, it’s a little less intuitive for me. Why don’t we go over some other high output states that can increase flow.

H: So let’s think about all of our patients with end-stage renal disease who have an AV fistula for dialysis — that’s something that can actually cause high pulmonary pressures also.

Vaidya: Particularly fistulas that have been present for many years, not usually a brand new one, that’s just within the last year or two and particularly AV fistulas that are large in size, which tends to be ones above the elbow, as opposed to in the forearm, because they just have the potential to grow bigger and have more shunting through that fistula.

S: Whoa I’ve seen so many elevated pulmonary pressure in patients who are on dialysis. But ESRD patients could have a lot of reasons to have pulmonary hypertension – they’ve got chronic anemia – they’ve got left-sided heart disease. How would we know the fistula is the culprit??

Schoenberg: What we’ll do in the cath lab is we’ll actually close down the fistula and see what happens to the cardiac output and the pulmonary pressures. And sometimes they won’t change. Sometimes they’ll drop, and if they drop significantly to a non pathologic state, then we’ll start investigating the actual flow through the fistula.

H: Yeah and some studies have even shown these patient’s PASPs then go down after kidney transplant when the fistulas are closed.

S: Whoa this so is eye-opening – i hadn’t really considered fistulas messing up the flow and as contributing to pulmonary HTN in dialysis patients on top of all the other reasons they could develop PH

Schoenberg: The reality though, is that echocardiographic pulmonary hypertension is an ominous finding those patients have significantly increased mortality, um, as compared to patients who have normal echo choreography. 

S:  Yeah these patient can be so sick – there is one other patient population whose physiology often causes them have high pulmonary pressure – and thats patients with cirrhosis. 

Vaidya: And then you realize they have advanced liver disease and cirrhosis. And they’ve had a variceal bleed chronically, and they have high output physiology from a low SVR state because they have cirrhosis and they’re anemic and you examine them and they have low, normal, low jugular venous pressure. And they have bounding arterial pulses that you realize this, this patient has a high cardiac output physiology, secondary to underlying chronic conditions. And the pulmonary hypertension is a secondary manifestation of what we already know and does not represent any new physiology or information.

A: This is such a good example, I feel like I’ve taken care of this exact patient on the wards.

H: Yeah and the physiology in these patients is super interesting – YES, there can be this high output state BUT there is also the other bucket at play, increased resistance. These pts can also develop something called portopulmonary hypertension which causes remodeling that increases resistance.  So patients with cirrhosis can have either elevated resistance or high flow or even both playing a role. 

S: Another humbling reminder that patients do not go into just one of these three physiologic insult buckets and can have multiple forces at play.

A: Ok so lets sum up Pearl 3 which is really a physiological framework that lead to elevated pulmonary artery pressures  – remembering that garden hose, is it a high flow state? Is there high vascular resistance? Or are the left atrial pressures elevated?

S: Yeah, I gotta agree with you. Boiling this down to these 3 physiological insults that can cause high pulmonary pressures makes it much less intimidating and will prolly help me triage a bit sooner what the appropriate work-up might be. 

H: And that’s what we’re gonna cover in our next couple of pearls so keep this framework handy

Pearl 4:  Using echo to characterize pulmonary hypertension due to high left-sided filling pressures

S: Ok so we get our echo back with this high PASP, how do we think about what is this patient’s underlying pathophysiologic insult based on the echo?

H: And honestly the easiest thing to rule out or in what’s common – elevated left sided filling pressures – so the first thing we should see if there are any signs that would point towards this on the echo.

Vaidya: There were some obvious and very readily apparent clues that you might find things like significant systolic dysfunction with a reduced ejection fraction or critical aortic stenosis or severe mitral regurgitation.

A: So that’s easy, if a patient has severe left sided valvular disease or an EF of 20%, especially if its long-standing, there is a good chance that’s causing the elevated pulmonary pressures.

S: But sometimes it’s not so in your face in the impression of the echo and the findings of left sided problems is more subtle. 

H: Yeah and for me I feel like that mostly comes up with diastolic dysfunction and I feel like Sherlock Holmes digging into the report looking for clues but really don’t even know where to start

S:. Dr. Vaidya taught us about FEW clues for diastolic dysfuntion but we’re gonna breakdown two that can give us some insight: the left atrial size and the E/e’ ratio:

Vaidya: So if the left atrium is moderately enlarged or bigger, so moderate or severely enlarged. Then in the context of a patient, having an elevated PASP or RVSP estimation on their echocardiogram, then our brains are immediately going towards suspecting left heart congestion.

A: Let me try and understand here – the teaching point is that chronic progressive dyspnea from pulmonary hypertension related to left heart congestion is not going to exist with a normal left atrial size. So that’s one of the really easy to understand and universally reported features that will give an initial clue.

H: Yep so after you se that large LA on the echo, the next thing we wanna do to is to peak at the E/e’ ratio.  

Vaidya: What that is looking at is a combination of the flow that the velocity of blood flow across the mitral valve in diastole, relative to the velocity of the myocardial motion of the actual tissue around the mitral valve annulus.

 H: If that went over your head the first time around, don’t worry, me too. What helped me was to break down the top and bottom numbers of the ratio, so first off, what’s the numerator E telling us?

A: Ok, so the numerator, E, is really a measure of left-sided pressures – higher pressures result in a greater velocity of blood passively flowing through the mitral valve. Even I got that one. Let’s go to the the denominator, or “e prime,” what’s that telling us?

Vaidya: And so the tissue Doppler measures the stiffness. It sort of represents the compliance and the stiffness of the actual myocytes in the ventricle itself. And if the tissue doppler is moving very slow because of a stiff left side of the heart stiff myocardium, then that tissue Doppler velocity will be a low number. And we’ve referred to that as the E prime.

S: So to put this all together a high E/e’ ratio will signal diastolic dysfunction –  putting that in normal English: Noah’s quote: 

Schoenberg: So at the end of the day, I think of the E/e’ prime ratio as really representing how hard it is for the left atrium to fill the left ventricle, the higher the ed prime ratio, the harder it is for the left atrium to fill the left ventricle. 

H: So at what E/e’ number should I start thinking this looks like diastolic dysfunction?

Vaidya: If you see an E/e prime, that’s greater than 10 in the context of an estimated elevated pulmonary pressure, then our brain is going to left Heart filling pressures are high

A: I’m sure I’ve  scrolled past the E/e’  so many times, and I find that it’s rarely mentioned in the interpretation. It’s a good nugget to have in your back pocket.

H: So true, this is starting to feel like a Rosetta Stone course for the echo but I’m loving it. So to summarize pearl 4, when looking at an echo to better characterize pulmonary hypertension we can start with looking for evidence of elevated left-sided filling pressures like bad aortic stenosis or severe mitral regurg. 

S: Exactly, and then diastolic dysfunction is where things get tricky. Do your homework, take a look at the reported LA size and E/e’ ratio if its greater 10-12, you are thinking of diastolic dysfunction

A: And if you determine that elevated left-sided filling pressures is the physiological insult causing your patients pulmonary HTN then the treatment is treating their left sided heart disease and you might not have to do all the workup we are about to talk about in pearl 5.

H: Exactly, and then on the flip side, if you don’t see signs of elevated left sided filling pressure then it may be time to call one of your friendly consultants.

Vaidya: I would start there and say, look, the RVSP is high, the patient is short of breath, left atrial size is normal or only mildly enlarged. And that E/e prime is normal or low that ratio less than 10 or less than eight. If that’s the case, then your spidey sense should be alerted already. And I would say, call me it’s time for me to get involved with this patient, because the likelihood that the patient’s pulmonary hypertension is from a high pulmonary vascular resistance is already much higher because we’ve, we’ve made some progress in lowering the chances that this pulmonary hypertension is coming from the left side of the heart.

Pearl 5: Evaluating pulmonary hypertension due to elevated pulmonary vascular resistance

S. So you know we covered all these things the echo can tell us about the left side of the heart, is there anything we can look at on echo to point us to one of the other buckets, high resistance?

H: Yeah there are some clues on the echo that can point to high resistance, one being septal flattening during systole.

S:  Great, break that down for me a little.

H: Ok let me translate, so “interventricular septal flattening in systole” in the echo report is telling us is that the RV is seeing a high afterload from high pulmonary vascular resistance.

Vaidya: So if you see that septal flattening in systole sometimes described as that D shaped septum in the parasternal short axis of the echocardiogram, think to yourself, this isn’t just pulmonary hypertension. Think this is a high pulmonary vascular resistance, which is much more specific and potentially much more ominous. And it’s literally a sort of a dyssynchrony on the order of milliseconds of the contractility of the RV and the LV because of that high afterload against the right ventricle that it has to face that leads to that appearance of septal flattening in systole.

H: Yeah I’ve definitely heard the “D sign” thrown around in the ED or CCU but good to know that means the pressure and afterload in the pulmonary system is so much that it basically causes the RV and LV to be out of sync actually changing the geometry.

A:  We also see the same pathophys happening in an acute PE where when there’s RV strain and we can see the septal flattening in those cases too.

S: Okay so if we are worried about high vascular resistance im curious how our experts think about this?

Vaidya: So I would say if you have an echocardiogram that is you towards a high pulmonary vascular resistance. So in other words, like you just said left atrial size, normal E/E prime is low. There is septal, flattening in systole. Then we’re going down that road of the evaluation. So I’m thinking now I can go to the who groups, what are the diagnoses and the who groups that would fit that physiology.

H: So when we’re thinking there’s increased resistance, we’re thinking of WHO group 1 which includes pulmonary arterial hypertension, WHO group 3 which are a lot of the chronic lung diseases, and WHO group 4 which is chronic thromboembolic pulmonary hypertension or CTEPH.

A: And just to preface, this next part is just the start of a work-up and is by no means exhaustive for these patients. We’re going to go through them in terms of the WHO groups.

Vaidya: So if we start at the top who group one, pulmonary arterial hypertension, I’m asking, do they have a family history of pulmonary arterial hypertension because of the hereditary form, which is by the way, autosomal dominant and inheritance. There’s a higher penetrance in female. So daughters may manifest disease more than sons. ​​ And there’s also genetic anticipation, which means that the younger generation will manifest the disease earlier and sometimes in a more severe way than parents. So first degree relative family history is what’s important. And if you elicit that, then we refer to genetic counseling and genetic testing.

A: So in addition to asking about family history we also need to ask about symptoms related to a ton of rheumatological disease, so ask about inflammatory joint pain, dry eyes/mouth, fingers turning white in the cold, difficult to control acid reflux that could be a sign of scleroderma. Asking this history and checking an ANA if would be a good start.

Vaidya: And then I’m also asking about exposures to HIV because of HIV associated pulmonary arterial hypertension to any known history or possible cause, but we’re testing everybody and their new evaluation there.

A: The other big thing we often don’t think about is toxin exposure. One of the most common toxin exposures I’ve actually seen is methamphetamine.

Vaidya: And in fact, I have I have learned as an internist and cardiologists that if I don’t specifically ask, if I only say, do you, do you smoke? Do you use IB drugs? Do you use cocaine? I will miss the, the history of methamphetamine. So I’ve learned to be better about that history.

S: Guilty, I’ve definitely done that cursory social history and def did not have methamphetamine on my radar as a link to pulmonary HTN

Vaidya: Um, from a toxin exposure, I would also highlight the tyrosine kinase inhibitor [dasatinib], which is Sprycel is the brand. So our oncology colleagues use this quite a bit, um, and that can actually be a cause of pulmonary arterial hypertension. And so I just want to raise that awareness to connect those dots as we’re going through the med lists

S: And of course, we can’t forget there is one more common and very humbling cause of pulm arterial HTN … 

Vaidya: So those are some of the testing that I’m having in my mind for who group one, pulmonary arterial hypertension, remembering that 40% or so of patients with who group one, pulmonary arterial hypertension are currently ultimately classified as idiopathic, which is not satisfying to any of us as internists.

H: Not satisfying indeed. So switching gears to WHO group 3, I want to know if these patients might have underlying lung disease. So here i am scrolling through prior imaging, especially for prior CTs that may point towards ILD or long-standing emphysema and looking to see if PFTs have been done.

Vaidya: And I would encourage folks to look at PMTs of course, for this barometry and the flow volume loops and the FEV one FEC, all of that, let’s say those things are actually normal pay close attention to the diffusion capacity that DLC, if your DLC is markedly reduced in the context of otherwise relatively normal, PMTs, that’s actually a very important marker of pulmonary vascular disease. It could be PAH or another cause. And so that’s just a quick Pearl of something as internists to keep an eye out for.

H: And then another thing in group 3 that’s super common is OSA. So really all of these patients should be getting a sleep study.

A: And lastly we have our WHO group 4. 

Vaidya: I always say patients do not have PH until they’ve had a VQ scan to rule out chronic thromboembolic, pulmonary hypertension. The VQ scan has a sensitivity that’s greater than 95%, um, to rule out pulmonary to rule out CTEPH, um, and the human dynamics and the symptoms and the echocardiogram and the physical exam of CTEPH can often look so similar, nearly identical to pulmonary arterial hypertension, that we need that additional layer of imaging to rule that out.

H: One thing I found interesting about CTEPH, and I think may be a common misconception is that patients do not have to have a prior history of prior venous thromboembolism to present with new pulmonary hypertension.

S: I definitely don’t think of CTEPH enough – but guys I gotta say a solid pulm HTN work up involves so much 

H: Yeah, thank goodness generalists are definitely not expected to complete all of this work-up and at least get a head start.

Vaidya: So you’re seeing those signs send off the blood work, get ordered the VQ scan while you’re getting the referral underway or calling the consult. You’re sending them as an outpatient, but starting with that is very valuable and can help get the ball rolling.

S: You know to be honest from our reviewers, we heard mixed recommendations about ordering the V/Q scan and making sure you are ordering it at a place where radiologists read V/Q scans often.

A: So to summarize the initial basic work-up for suspected pulmonary hypertension related to increased pulmonary vascular resistance, you want to take a thorough rheum and exposure history and to be explicit here with methamphetamine and tyrosine kinase inhibitors and you might order PFTs and a VQ scan to start an evaluation for CTEPH depending where you are.

S: And lastly, have a low threshold to order that sleep study! And don’t forget the echo, where this whole thing started!

A: Ok so that was a deep DEEP dive into the world of pulmonary hypertension 

S: And we really broke down what the echo can tell us and hopefully everyones feels more empowered to reach out to help sooner – I know I feel more empowered.

Schoenberg: We have a serious referral problem where unfortunately, people sit on bad echos and, and it’s not recognized early enough. So it is, I would always write either someone refers someone early and we say, don’t worry about it. Then someone refer late and we go, Ooh, crap. I wish we’d sort of seen this.

S: And that’s a wrap for today’s episode. If you found this episode helpful, please share with your team and colleagues and give it a rating on Apple podcasts or whatever podcast app you use! It really does help people find us! 

A: If you want to add any of your own tips or share challenges, tweet us and leave a comment on our website page, on instagram or facebook page. Thank you to our peer reviewer Dr. Timothy Fernandes and Dr. Cyrus Kholdani for peer reviewing. 

S: Thank you to Daksh Bhatia for the audio editing and Dr. Kabao Vang for the accompanying graphics. As always we love hearing feedback, email us at hello@coreimpodcast.com. Opinions expressed are our own and do not represent the opinions of any affiliated institutions.

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