PH (Murray and Nadel) Flashcards
Definition of vasodilator responsiveness (vasoreactivity)
Based on 2009 ACC/AHA and 2015 ESC/ERS guidelines:
At least 10mmHg drop in mPAP AND mPAP less than 40mmHg in response to vasodilator during RHC
Caveats:
- stable or improved cardiac output
- normal oxygenation prior to starting test (so PVR is not a response to improved oxygenation)
When to not do vasodilator testing in RHC
- High risk of pulmonary venous HTN (CHF, elevated PCWP, PVOD) given risk of flash pulmonary edema
- Baseline bradycardia: avoid IV adenosine
3 meds (with dosing and duration) used for vasodilator test
- Inhaled nitric oxide: 20 or 40 ppm for 5 mins (or until positive response)
- IV epoprostenol 2-12 ng/kg/min every 15 mins
- IV adenosine 50-250 mcg/kg/min q2 mins
Meds for vasoreactive PH
CCBs: nifedipine XL or diltiazem
Dihydropyridine (vascular-selective): Nifedipine
-backup amlodipine
Non-dihydropyridine (myocyte-selective): Diltiazem
-avoid verapamil b/c too much negative inotropy
How common is vasoreactivity?
About 10-20% PAH pts who undergo testing have positive vasoreactive response
Only 1/2 who are vasoreactive clinically repsond to CCB
Explain change in PH definition (PASP cutoff) for 6th world symposium on PAH
mPAP cutoff dropped from 25 to 20mmHg because 14 normal (SD 3) so 2 SD above normal is 20ish, felt we’re potentially missing some mild PH cases (which do matter clinically b/c have higher mortality)
Differentiate numerical cutoffs for pre and isolated post-capillary PH
mPAP, PCWP, PVR
Pre-capillary PH: mPAP over 20, PCWP under 15, PVR at or above 3
Pure post-capillary PH: Mpap over 20, PCWP over 14 with PVR below 3
Differentiate numeric cutoffs for isolated postcapillary vs. combined pre/post capillary PH
mPAP, PCWP, PVR
Isolated postcapillary PH (group II): mPAP over 20, wedge over 15, PVR under 3
vs.
Combined pre/post capillary PH (group II and IV): mPAP above 20, PCWP above 15 but PVR above 3
Which WHO group involves
(a) Precapillary PH
(b) Isolated post-capillary PH
(c) Combined pre and post-capillary PH
WHO group for classifying PH
(a) Pre-capillary: I, III, IV, and some V
(b) Isolated post-capillary = groups II and V
(c) Combined- groups II and V
2 most common causes of group I PAH
Group 1 PAH (true PAH)
50% idiopathic PAH
25% connective-tissue disease associated PAH
Other causes of group IV PH aside from CTEPH
Group IV- anything that clogs pulmonary arteries
So can be clot = CTEPH
Also tumor (PA sarcoma, angiosarcoma, mets), vasculitis, congenital pulmonary artery stenosis
Name some etiologies of group V PH
Group V = multifactorial or not well understood etiology
-hematologic disorders: chronic hemolytic anemia, myelodysplasia
-metabolic disease: glycogen storage (Gauchers), sarcoid, PLCH (pulmonary langerhan cell histiocytosis)
PH vs. PAH
PH just means PA pressure above 20, while PAH is from actual pulmonary arterial remodeling/issue
PAH = group I PH
So most of workup for PH is to rule out L. heart disease, other lung disease, CTEPH basically to see if you have PAH (group I)
For which connective tissue diseases are PH screening recommended?
(a) How to screen
PH screening recommend for systemic sclerosis patients, based on DETECT study (2014) that has algorithm given high risk of pts with systemic sclerosis
Also MCTD (mixed connective tissue disease- on systemic sclerosis spectrum with some SLE, RA, and polymyositis
(a) systemic sclerosis, MCTD (sclerosis spectrum disorder) get screening PFT and TTE at start then annually, or with any symptom change
What is MCTD?
(a) Defining antibody
Mixed connective tissue disease = mixed features of systemic sclerosis, SLE, RA, and polymyositis
(a) Defining anti-U1-RNP (antinuclear ribonuclearprotein)
Drugs with definite association with PAH
Drugs/toxins associated with PAH
- Anorexigens- aminorex, fenfluramine, dexfenlfuramine (fenfen)
- methamphetamines
- dasatinib (TKI used for Philadelphia chromosome + ALL and AML)
Describe TR murmur
TR murmur = pansystolic at L sternal border
Why is nocturnal oximetry part of guidelines for PH diagnostic workup?
B/c of high association btwn OSA and PH, allllso because treating the OSA can improve cardiopulmonary outcomes
Differentiate significance of interventricular septal flattening in systole vs. diastole
interventricular septum flattening
in systole = RV pressure overload
in diastole = RV volume overload
Clinically/treatment wise not much difference…
EKG signs of RV hypertrophy
(a) RV thickness on TTE cutoff for hypertrophy
(a) RV thickness more than 4mm = hypertrophy on TTE
On EKG: see large R-wave in V1 (R:S more than 1) and large S-wave in V5/6 (R:S less than 1)
Formula for PVR
V = IR, so R = V(voltage) / I (current)
PVR (pulmonary vascular resistance) = delta P (mPAP - PCWP) / CO (cardiac output)
change in pressure/flow
Serious events associated with RHC
RHC adverse events
Access- hematoma
Catheter advancement- SVT
Vasoreactivity- hypotension
obv the feared and dreaded PA perforation
How to see shunt on RHC (why we take VBGs throughout cath sometimes)
If see PaO2 (or SpO2) rise as you move from vena cava to PA indicative of L to R shunt somewhere
Define vasoreactivity response on RHC
Vasoreactivity definition: (typically use iNO)
Reduction in mPAP by at least 10mmHg to mPAP of 40mmHg or below WITH an increase or no change (basically no decrease) in cardiac output
- so when put on iNO, watch mPAP, then re-shoot cardiac output numbers
Described definition for exercise-induced PH
Exercise induced PH- mPAP at rest under 21, then with maximal exercise mPAP raises to above 30 with TPR (total pulmonary resistance) over 3 U
- doesn’t differentiate pre and post-capillary disease
- TPR = mPAP/CO (while PVR is mPAP-PCWP/CO)
Formula for TPR (total pulmonary resistance)
(a) Why this value may be more helpful than trending mPAP during exercise to elicit exercise-induced PH
Total pulmonary resistance = mPAP/CO (don’t subtract wedge from meanPAP which would give you PVR)
(a) Trend mPAP/CO during exercise b/c adjusts for increase in cardiac ouptut
Where does BNP come from?
Pro-BNP released by R and L ventricular myocytes in response to stress and stretch. Then cleaved into NT-proBNP (inactive) and BNP (active)
Minimal important difference of 6MWT in PH patients
MCID = 30m for 6MWT in PH patients
6MWT not used for diagnosis (obv so non-specific) but used to monitor response to treatment
Higher or lower associated with worse outcomes in PH on CPET
(a) VO2max
(b) VE/VCO2
CPET results associated with worse mortality
(a) Lower VO2max (lower oxygen consumption at max)
(b) Higher ventilatory equivalent (>35 generally), meaning need more ventilation to excrete same amount of CO2
Are most group II isolated or combined pre-capillary PH?
(a) Isolated or combined has better mortality?
Most group II-PH is isolated post-capillary
(a) combined pre and post has worse prognosis than isolated post, each increase in PVR by 1 Woods unit associated with 9% increase in mortality
Mechanism by which aortic stenosis causes PH
vs. MR
L sided valvular heart disease => PH
-AS by diastolic dysfunction due to pressure overload of LV
So severity of PH in AS correlates with degree of diastolic dysfunction
vs.
-MR by LA volume overload/dilation
So severity of PH in MR correlates directly with severity of regurg
Data to argue why not to use PAH-specific meds in group II PAH
(a) Flolan
(b) Macitentan
No proven benefit (and potentially signal of harm) for PH-specific medications in group II
(a) RCT of severe HFrEF-PH: IV epoprostenol (flolan) vs. placebo (FIRST = Flolan International Randomized Survival trial), American Heart Journal 1997- stopped early given trend towards reduced survival in epoprostenol
(b) MELODY-1 (ERJ 2018) macitentan in PH due to LV dysfunction vs. placebo for combined pre- and post (PVR over 3) macitetan vs. placebo
-worse fluid retention and functional class w/ macitentan w/o signal of benefit in secondary outcomes
6th WSPH statement of pulmonary vasodilators in group 2 PH
6th World Symposium of Pulmonary Hypertension statement (2019)- no role for pulmonary vasodilators
-some small studies showing possible benefit of PDE5 inhibitors but overall not convincing
-RCTs of harm from macitentan and flolan (IV epoprostenol)
List mechanisms by which sickle cell disease can cause PH
Sickle cell disease => group V (multifactorial or undetermined PH)
-hypoxia
-chronic hemolysis impairing nitric oxide release
-chronic clotting of vessels through sickling
-high cardiac output from anemia
Which hematologic disorder is an indication for routine PH screening?
Sickle cell disease- screen patients with TTE (looking specifically for tricuspid regur velocity > 2.5 m/s) every 1-3 years given high mortality associated
Treatment of Sickle cell disease-related PH
(a) What to avoid
Sickle cell disease PH- strong indication with hydroxyurea
-can consider PH-specific drugs including trial of prostacyclin or ERA
(a) Avoid PDE5i given signal of harm in prior study
-no data on riociguat
TTE finding associated with higher mortality in SCD-PH patients and how to measure it
Tricuspid regurg velocity over 2.5 m/s
-continuous wave doppler over tricuspid valve, see max velocity of regurg jet (under x-axis)
Explain which type of doppler (and why) is used to measure tricuspid regurg velocity
Tricuspid regurg velocity can be fast (over 2 m/s) which will exceed the Nyquist limit and cause aliasing if use pulse wave doppler => use continuous wave doppler
Pulse wave doppler- one crystals sends out and receives signal from specific area of interested (‘gate window). Limited by pulsed repetition frequency (how fast crystal can send out and receive signal) so will get aliasing over 2 m/s
Continuous wave doppler- different crystal emits sound wave than receives => not limited by prf and can detect faster flows
General cutoff for speed requiring certain type of doppler (pulsed wave vs. continuous)
Pulse wave doppler- one crystals sends out and receives signal from specific area of interested (‘gate window). Limited by pulsed repetition frequency (how fast crystal can send out and receive signal) so will get aliasing over 2 m/s
Continuous wave doppler- different crystal emits sound wave than receives => not limited by prf and can detect faster flows
What is the nyquist limit? Which type of doppler is limited by this
Nyquist limit- maximum doppler shift frequency (velocity of blood) that can be correctly measured w/o aliasing in color or pulse waved doppler
-b/c in pulsed wave doppler same crystal emits and receives => has a max pulsed repetition frequency
Limits ability of pulse wave doppler to detect flow => need to use continuous wave doppler for speeds generally exceeding 2 m/s
ex] for higher flows, such as tricuspid regurg velocity, use continuous wave doppler
Which two chronic hemolytic anemias carry increased risk of PH?
Hematologic disorders fall into group V (unclear multifactorial mechanism) of PH
-sickle cell disease
-beta-thalassemia
Name some etiologies of group V PH
(a) Hematologic
(b) Systemic
Group V PH
(a) Hematologic
-chronic hemolytic anemias: sickle cell and beta-thal
-myelodysplasias: polycythemia vera, essential thrombotycosis, CML, myelofibrosis
(b) Systemic
-sarcoidosis
-PLCH (rare cystic smoker-associated ILD)
-NF1 (aut dom)
-Gauchers
-Glycogen storage disease
-LAM
Proposed mechanism of PH in chronic renal failure patients
Mostly due to L heart failure and fluid overload
-also may be due to increased cardiac output due to AV fistula formation
Describe how drug-induced PH might affect specific subgroup of patients with group V PAH
Buzzword for drug-induced PH = dasatinib (TKI) used to treat myelodysplasias (can cause group V PH)
-discontinuation of dasatinib associated with improved
Congenital heart disease- which PH group?
Predominantly group I
-if L heart involved can have component of group 2
-‘complex’ cases can be considered group V (unclear multifactorial mechanisms)
Describe how fibrosing mediastinitis can cause group V PH
Fibrosing mediastinitis (histoplasmosis, sarcoidosis, Tb, radiation) due to benign proliferation of fibrous tissue in the mediastinum, causing encasing of mediastinal structures including vasculature => compression of pulmonary arterioles
Rule of thumb- numeric difference btwn PCWP and LVEFP
Overall- PCWP underestimated LVEDP by about 3mmHg (2.9mmHg)
Dos aortic or mitral valve disease cause more severe PH?
In general mitral valve disease (both stenosis/regurg) causes more severe PH than aortic but both cause PH
In normal pt what prevents large rise in PA pressures with exercise
At rest- substantial portion of capillary bed in unrecruited
With exercise- unopened capillaries are recruited => lowering PVR so PA pressures dont skyrocket
In PAH pts vs. health baseline
(a) NO production
(b) Plasma endothelin levels
(c) Endogenous prostacyclin levels
PAH pts have
(a) Less (impaired) endogenous NO production
(b) Higher (elevated) endothelin levels
(c) Lower endogenous prostacyclin levels
Effect of alpha-adrenergic tone on pulmonary vasculature
(a) Effect of sympathetic nerve stimulation vs. NO and PI pathways on pulmonary vasculature
Alpha-adrenergic activation => vasoconstriction of pulmonary vasculature (hence why phenylephrine isn’t a great drug in PH)
(a) But NO and PI pathways/release considered to have a way more potent (predominant) affect than sympathetic nerve stimulation => minimizing the vasoconstrictor effect of sympathetic nerve stimulation
3 main classes of drugs implicated in drug and toxin-induced PAH
- Weight loss agents- aminorex, fenfluramine, benfluorex
- Ampheatmines/methamphetamine
- Dasatinib- TKI (tyrosine kinase inhibitor) used
Differentiate mechanism of sildenafil and riociguat
Both work on NO pathway- to increase cGMP levels => dilation of pulmonary vascular smooth muscle cells
Sildenafil = PDE5i inhibit the metabolism of cGMP
Riociguat = soluble guanine cyclase stimulator increases synthesis of cGMP
Prognosis compared to IPAH
(a) Portopulmonary HTN
(b) Schistosomiasis associated PAH
(a) POPH has a worse prognosis than IPAH, prognosis related to the severity of the liver and pulmonary vascular disease
-Estimate 3-year survival of 40% (vs. ~50% for IPAH without treatment)
(b) Sch-PAH typically has a more benign prognosis than
About 30% of PH pts in Brazil!
-Estimated 3-year mortality 15% (survival 85%)
What percent of pts with portal hypertension develop PAH
About 6% of portal hypertension pts develop PAH
-worse prognosis than PAH
