PULMONARY ARTERY HYPERTENSION:ETIOPATHOGENESIS,CLINICAL FEATURES AND RECENT ADVANCES

IN MANAGEMENT

PRESENTED BY DR.MAHABALESHWAR CHAIRPERSON: DR.SANTOSH VASTRAD

VENUE:MEDICINE SEMINAR HALLDATE AND TIME:3/2/16 2.30PM

ANATOMY

• The lung has a unique double arterial blood supply from the pulmonary and bronchial arteries

• double venous drainage into the pulmonary and azygos veins.• Each pulmonary artery accompanies the appropriate-

generation bronchus and divides with it down to the level of the respiratory bronchiole.

• Pulmonary arteries are classified as elastic or muscular.

• Pulmonary hypertension is a spectrum of disease involving pulmonary vasculature.

• Increase in pulmonary artery pressure (mPAP) of 25 mmHg or greater at rest,as assessed by right heart cathetarisation.

• Normal PAP-14mmHg

HEMODYNAMICALLY...

• PH is a disease state with increased pulmonary pressures. • Applying Ohm’s law to the pulmonary circulation TPG or pressure difference (mPAP − PCWP) = flow (CO) × resistance (PVR).• Thus, elevated mPAP may be a consequence of elevation in

PCWP, increase in flow, or increase in PVR.• However, pulmonary vessels are highly compliant and capable

of recruitment with progressive reduction in PVR for the increment in flow.

• low-pressure, low-resistance, and high-compliance characteristics of the pulmonary vascular bed

HISTOLOGICALLY...

• PAH is a panvasculopathy predominantly affecting the small pulmonary arteries.

• The initial lesions seem to be intimal hyperplasia and medial hypertrophy (reversible)

• Later stages have irreversible lesions such as intimal fibrosis, thrombosis in situ, inflammation, and plexiform arteriopathy.

• These lesions may be present in various distributions, local or diffuse, in a patient

• Vascular changes in pulmonary arterial hypertension:• Pulmonary arteriole in pulmonary hypertension showing both mild medial hypertrophy and marked intimal

hyperplasia, leading to partial obstruction of the lumen.

• Plexogenic lesion typically found in PAH with smooth muscle cell proliferation and hypertrophy

MOLECULAR AND ENDOTHELIAL ABNORMALITIES

• Various vasoactive molecules play an important role in the pathologic evolution of PAH

1. Prostacyclin/thromboxane A2

2. Endothelin-1 (ET-1)3. Nitric Oxide

PATHOBIOLOGY

• Imbalance in vasoconstriction and vasodilatation,thrombosis, and cell proliferation and remodelling of walls of pulmonary

arteries increased PVR

• Increase in RV afterload

• RV dilatation and hypertrophy

• RV failure with further dilatation

• thinning of the wall and tricuspid regurgitation

• PH secondary to left side heart disease

• Enlarged and thick pulmonary veins

• Pulmonary capillary dilation• Interstitial edema• Alveolar hemorrhage• Lymphatics involved

• PH secondary to lung disease• Obstruction in

emphysematous and fibrotic areas

• CTEPH• Organized thrombi attached

to pulmonary artery medial layer

• Nonoccluded areas-plexiform arteriopathy

GENETICS

• Idiopathic pulmonary hypertension corresponds to sporadic disease without any family history or known triggering factor

• BMPR2 was the first predisposing gene

• Involved in regulation,growth,differentiation,and apoptosis of pulmoanry artery endothelial and smooth muscle cells

• Positive in 70-80 % familial PAH cases

• Positive in 15-20% sporadic cases

• a novel channelopathy caused by mutation in the KCNK3 gene has been identified in familial and idiopathic cases of PAH, thus indicating for the first time that heritable disease may involve factors apparently independent of the TGF-β signaling pathway-Braunwald

• Gender : F>M 2:1• Younger individuals with more hemodynamic compromise• Higher mPAP,lower CO,lower PVR and absent vasodilator

compnent

CLASSIFICATION OF PULMONARY HYPERTENSION

GROUP1.PULMONARY ARTERIAL HYPERTENSION

• Prevalence of group 1--15 to 50 case per million• ETIOLOGY:• Idiopathic Pulmonary Arterial Hypertension

– Most common type of group 1 PAH– Sporadic onset– F:M 2:1

• Heritable PAH– 6-10% patients with PAH

• Drug and Toxin induced PAH– Anorexigens– Fenfluramine– Rapeseed oil,L-tryptophan and methamphetamines– Dasatanib recently

• PAH associated with connective tissue disease:– More prevalent in scleroderma(8-12% cases)– Echocardiography is most common screening tool

• PAH associated with HIV– Incidence is 0.5% and independent of CD4 count or prev opportunistic

infections– Prevalence not changed by ART– Unknown mechanism– Prognosis is improved recently– Routine screening is not adviced-rare

• PAH associated with Portal Hypertension– Also called portopulmonary hypertension– No relation with severity of liver disease or degree of portal

hypertension– 2-6% prevalance,but may be high in patients referred for liver

transplant• PAH associated with congenital heart disease:

– Congenital systemic to pulmonary shunts cause PAH– Eisinminger syndrome initially produces progressive pulmonary

vasculopathy with PAHand later reversal of shunt and central cyanosis

– Better survival compared to IPAH

PAH associated with Schistosomiasis– South America and Sub saharan Africa– More common with chronic S. mansoni or S. japonicum infection– Granulomatous inflammation occludes distal pulmonary arterial

branches and eventually produces a rise in pulmonary arterial pressure– Present in 5% of patients with hepatosplenic schistosomiasis

• Pulmonary venoocclusive disease and pulmonarycapillary hemangiomatosis– PAH plus pulmonary venous hypertension,including pulmonary

hemosiderosis,interstitial edema and lymphatic dilation– Recessive mutations in EIF2AK4– Lung transplant is treatment of choice

• Clinical diagnosis:• Symptoms• Dyspnea : 90% • Syncope : 20%• Chest Pain: 20%- 30% • Edema: 30 -50%

Accentuated pulmonary component of High pulmonary pressure in creasesSeconal heart sound (audibe at apex in force of pulmonary valve closure>90% of patients)

Early systolic click Sudden interruption of opening Pulmonary valve into high pressure artery

MIdsystolic ejection murmur Turbulent transvalvular pulmonary outflow

Left Parasternal lift High right ventricular pressure and Right ventricular fourth heart hypertrophySound (in 38% of purtients)

Increased jugular a wave High right ventricular filling pressure

SIGN PATHOPHYSIOLOGY

MODERATE TO SEVERE PULMONARY HYPERTENSION

Holosytolic murmur that increases Tricuspid regurgitationwith inspiration Increased Jugular V wavePulsarile Liver

Diastolic murmur Pulmonary regurgitation

Hepatojugular reflux High central venous pressure

SIGN PATHOPHYSIOLOGY

ADVANCED PULMONARY HYPERTENSION WITH RIGHT VENTRICULAR FAILURE

Right Ventricular third heart sound Right ventricular dysfunction (in 23% of patients)

Marked distention of jugular veins Right ventricular dysfunction or tricuspid Hepatomegaly regurgitation or bothPeripheral edema (in 32% of partients)Ascites

Lowblood pressure,diminished Reduced cardiac output,peripheralPulse pressure,cool extremities vasoconstriction

Sign Pathophysiology

Central Cyanosis Hypoxemia ,right-to-left shuntClubbing Congenital heart disease,pulmonary venopathy

Cardiac auscultatory finding Congenital or acquired heart or valvular Including systolic murmurs,diastolic diseasemurmurs,opening snap,and gallop

Rales,dillness or decreased breath sound Pulmonary congestion or effusion (or both)

Fine rales,accessory muscle use,wheezing Pulmonary parenchymal diseaseProtractive expiration productive cough

Obesity,kyphoscoliosis,enlarged tonsils Risk factors for disordered ventilation

Sclerodactyly,arthritis,rash Connective tissue disorder

Peripheral venous insufficiency or Possible venous thrombosisobstruction

Sign Pathophysiology

• other signs• Venous stasis ulcers• Pulmonary vascular bruits• Signs of liver failure

APPROACH TO PAH

• Biomarkers– Uric acid levels – elevated plasma troponin T levels (> 150 pg/mg) have

been associated with worse outcomes– BNP levels– Similarly, NT-proBNP below cutoff levels < 1,400 pg/mL has

been associated with better outcomes. – BNP/NT-proBNP plasma levels should be checked for the

initial risk stratification– Low and stable or decreasing BNP/NT-proBNP may be a

marker of successful disease control in PAH.

ECG

ECG

CHEST X RAY

ECHOCARDIOGRAM

• By using the Doppler technique, peak velocity of the tricuspid regurgitation jet can be measured.

• From this measured velocity, the pressure difference between right ventricle and right atrium can be estimated by employing the simplified Bernoulli equation (ΔP = 4v2).

• Estimation of pulmonary artery pressure from tricuspid regurgitant velocity • JVP: Jugular venous pressure; TR: Tricuspid regurgitation; RA: Right atrium;

RV: Right ventricle; PA: Pulmonary artery

Four-chamber view. Right atrial (RA) enlargement, right ventricular (RV) enlargement. The left atrium (LA) and left ventricle (LV)

are small and underfilled.

Short axis view. RV enlargement is present. Flattening of the intraventricular septum (IVS) results from pressure and volume overload of the RV

RIGHT HEART CATHETERISATION

• RHC is required to confirm the diagnosis of PH, to assess the etiology and severity, and to test for vasoreactivity of the pulmonary circulation.

• At experienced centers, morbidity (1.1%) and mortality (0.055%) rates are low

EVOLUTION OF HEMODYNAMIC VARIABLES

• Temporal evolution of the hemodynamic variables with progression of PAH

• As the disease progresses, the right ventricle starts to fail, leading to reduction in CO. As a result, PAP may decrease again.

• false impression of hemodynamic improvement or suggest that there is mild to moderate disease.

• Therefore, it is imperative to measure PVR, which will be high in this situation.

• Usually, the RAP and PCWP also increase, implying RV failure and left ventricular (LV) diastolic dysfunction, respectively.

• The latter is the consequence of ventricular interdependence and abnormal compliance of the left ventricle produced by an enlarged right ventricle

• Vasoreactivity testing in PAH• performed to identify patients who may benefit from long-

term therapy with calcium channel blockers (CCBs). • The agent most often used to test this is inhaled NO, with (i.v.)

epoprostenol and (i.v.) adenosine as alternatives.• positive acute response is defined as a > 10 mm Hg decrease

in mPAP to reach an absolute value of mPAP < 40 mm Hg with an increased or unchanged CO and without significant drop in systemic blood pressure

• It is not useful in other forms of PH (groups 1’, 2, 3, 4, and 5)

PULMONARY TESTING AND ARTERIAL BLOOD GAS (ABG)

• Pulmonary function tests and ABGs are used to identify

underlying airway or parenchymal lung disease.

• Patients with PAH usually have decreased DLCO (typically in

the range of 40% to 80% predicted) and mild to moderate

reduction in lung volumes.

• Pao2 only slightly lower than normal at rest and

• PCO2 is decreased because of alveolar hyperventilation.

SIX-MINUTE WALK DISTANCE

• The 6-minute walk test (6MWT) is the most commonly employed measure of exercise capacity in patients with PH.

• In addition to the distance walked, the degree of dyspnea (Borg score) and oxygen saturation are also measured.

• A 6-minute walk distance of < 332 m and a drop in oxygen saturation by > 10% are suggestive of poor prognosis.

• It is also measured on routine follow-ups and can be indicative of clinical deterioration.

• It may also be used to assess the response to therapy.

• Chest CT and ventilation–perfusion (V/Q) scans are indicated to exclude primary parenchymal or thromboembolic diseases as a cause of PH

Representative computed tomography scan of thechest demonstrating enlarged main pulmonary arteries

TREATMENT

• The treatment of group 1 PH (or PAH) is primarily in the form of pulmonary-specific vasodilator therapy,

• Treatment in groups 2, 3, and 4 PH is mainly oriented toward treating the underlying condition

General measures:(1) Mild physical activity, possibly via exercise rehabilitation, is

beneficial.(2) Routine influenza and pneumococcal vaccinations are

recommended.(3) Contraception should be discussed with females of child-

bearing age, as pregnancy carries a 30% to 50% mortality risk and is contraindicated.

(4) Oxygen supplementation is advised to maintain saturation above 90%

5) Exposure to high altitude should be avoided. If flying, supplemental oxygen should be used if the patient’s preflight saturation is less than 92%.

(6) Diuretic therapy is indicated to manage RV failure with volume overload.

(7) Digoxin may be considered in the case of atrial tachyarrhythmias.

(8) Oral anticoagulation is recommended in CTEPH, in IPAH, and in advanced diseases (e.g., continuous i.v. therapy).

TREATMENT OF PAH

PROSTACYCLIN ANALOGS

• To improve the functional class, exercise tolerance, hemodynamics, and survival in patients with IPAH

• Acutely lower PAPs (as used in vasoreactivity testing) as well as to achieve long-term hemodynamic improvement in patients with PH who are nonresponders.

• Epoprostenol :– continuous i.v. infusion– Early side effects of nausea, headache, flushing, jaw and leg pain,

and diarrhea. – Adverse events related to the delivery system include pump

malfunction, local site infection, catheter obstruction, and sepsis.

• Treprostinil (Remodulin) – can be administered by inhalation, orally, or via continuous

s.c. pump – Infusion site pain is the most common side effect.

• Iloprost (Ventavis)– an aerosol administration and has a proven beneficial

effect in patients with PAH and CTEPH

ENDOTHELIN RECEPTOR ANTAGONISTS (ERAS)

• Bosentan (Tracleer)– oral active dual ETA/ETB receptor antagonist – improves the exercise capacity, functional class,

hemodynamics, and cardiac performance as measured by echocardiography and clinical outcomes.

• Sitaxsentan and ambrisentan are more selective ETA receptor antagonists with similar benefits as bosentan.

• Liver injury and teratogenicity are major concerns and require monthly monitoring

PDE5 INHIBITORS

• Sildenafil (Revatio)– favorable effects on exercise capacity, symptoms, and

hemodynamics.

• Tadalafil (Adcirca) has the same effects, although it also delays the time to clinical worsening.

• Headache, flushing, dyspepsia, and epistaxis are the usual side effects.

• In low-risk patients, oral therapy with ET receptor antagonists or PDE-5 inhibitors is the first choice, whereas i.v. epoprostenol is reserved for the high-risk population

OTHER THERAPIES

• SOLUBLE GUANYLATE CYCLASE INHIBITORS• Riocigut• Stimulates soluble guanylate cyclase independent of NO• Improves 6mw and hemodynamics• Not to be used concurrently with PDE5 inhibitors• Side effects-headache,dyspepsia,peripheral edema

• Fewer than 20% of patients with IPAH are responsive to long-term oral vasodilators

• approximately 65% to 75% maintain sustained clinical improvement with long-term oral therapies or continuous intravenous prostanoid therapy

INTERVENTIONAL THERAPIES

• ATRIAL SEPTOSTOMY• Procedure-graded balon dilation of fossa ovalisover period of

several weeks• patients with severe right ventricular pressure and volume

overload refractory to maximal medical therapy• GOAL- decompress the overloaded right heart and improve the systemic output of the underfilled left ventricle• interatrial communication results in an increased venous

admixture, worsening hypoxemia is an expected outcome• Mortality 9-22%

LUNG TRANSPLANTATION

• Most common performed procedure is bilateral lung or combined heart transplantation

• Single lung transplant-high reperfusion injury• Indication-severe right ventricular dysfunction or complex

CHD• Median survival is 3-5 yrs

PULMONARY HYPERTENSION ASSOCIATED WITH LEFT HEART DISEASE

1. Left heart systolic failure,2. Aortic and mitral valve disease3. Heart failure with preserved ejection fraction (HFpEF)• The hallmark of Group II PH is elevated left atrial pressure

with resulting pulmonary venous hypertension.• Left ventricular failure is the most common cause of

pulmonary hypertension.• The increased pulmonary venous pressure indirectly leads to

a rise in pulmonary arterial pressure

PULMONARY HYPERTENSION ASSOCIATED WITH LUNG DISEASE

• Intrinsic lung disease is the second most common cause of PH• Intrinsic pulmonary diseases1. Airways-chronic bronchitis2. Parenchyma-COPD,pulmonary fibrosis• Disturbances in respiratory muscle function or in the control

of breathing1. Syndromes of alveolar hypoventilation2. Sleep disordered breathing

INTERSTITIAL FIBROSIS

• Pulmonary sarcoidosis, asbestosis, idiopathic fibrosis, and radiation-induced fibrosis

• Dyspnea,tachypnea • Right ventricular failure in late stages• Systemic vasodilators have no proven role• Oxygen prevents hypoxic vasoconstriction• Glucocorticoids and immunosuppressants provide relief• Lung transplantation• Pirfenidone??• Nintedanib??

CHRONIC OBSTRUCTIVE AIRWAY DISEASE

• Chronic bronchitis and emphysema (chronic obstructive pulmonary disease)[COPD]are the most common causes

• Acute Cor Pulmonale-decompensation, which is often due to an acute respiratory infection

• Chronic -when progressive lung disease and worsening gas exchange lead to unremitting vascular remodeling.

• To date, the safest and most effective approach to pulmonary vasodilatation in obstructive lung disease with arterial hypoxemia is the use of supplemental oxygen.

ALVEOLAR HYPOVENTILATION IN PATIENTSWITH NORMAL LUNGS

• primary pathogenetic mechanism is alveolar hypoxia potentiated by respiratoryacidosis.

• Assisted ventilation, particularly during sleep, may be particularlyhelpful in improving oxygenation and reducing hypercapnic

• (eg, continuous positive airway pressure [CPAP]) breathing.

PULMONARY HYPERTENSION ASSOCIATED WITH CHRONIC THROMBOEMBOLIC DISEASE

• The incidence of PH after a single pulmonary embolic event is thought to be quite low and likely increases following recurrent embolism

• Obstruction of the proximal pulmonary vasculature

OTHER DISORDERS AFFECTING THE PULMONARY VASCULATURE

• Sarcoidosis-progressive dyspnea• Sickle Cell Disease– CVS abnormalities are more common– hemolysis, hypoxemia, thromboembolism– chronic high CO, and chronic liver disease.

REFERENCES

• Braunwald’s Heart disease- Textbook of Cardiovascular Medicine – 10th edn

• Hurst’s the Heart-Manual of Cardiology-12th edn• Manual of Cardiovascular Medicine by B.Griffin 4th edn• Harrison’s Principlesof Internal Medicine – 19th edn• Crofton and Douglas’s Respiratory diseases-5th edn

• THANK YOU