Hospital Medicine

Pulmonary Hypertension

Pulmonary Hypertension

I. Problem/Condition.

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure ≥25 mm Hg at rest, measured during right heart catheterization. PH may either be primary or secondary to cardiac disease, pulmonary disease, thrombotic causes, or primary arterial hypertension.

Regardless of the cause, PH will lead to right ventricular failure and high mortality. Since symptoms develop very gradually, many patients will present late. Prognosis will depend on severity of symptoms.

II. Diagnostic Approach.

A. What is the differential diagnosis for this problem?

The world health organization (WHO) classified pulmonary hypertension into five major groups.

Group 1 includes disorders in which the PH is related to disorder in arterioles (i.e., pulmonary arterial hypertension [PAH]). It includes idiopathic, hereditary, connective tissue, drugs or toxins, human immunodeficiency virus (HIV), portal hypertension, congenital heart disease, hemoglobinopathies, and schistosomiasis.

Group 2 includes disorders related to left heart disease.

Group 3 includes disorders related to lung disease and hypoxia.

Group 4 includes disorders related to chronic thromboembolic disease.

Group 5 includes disorders with unclear multifactorial mechanism such as sarcoidosis, hematologic disorders, glycogen storage disease, and thyroid disorders.

Many mechanisms can lead to elevation of pulmonary pressures. In PAH, progressive narrowing of the pulmonary arterial bed results from an imbalance of vasoactive mediators, such as prostacyclin, nitric oxide, and endothelin-1. This leads to an increased right ventricular afterload, right heart failure, and premature death. Although around 11-40% of patients with idiopathic PAH and 70% of patients with a family history of PAH carry a mutation in the gene encoding bone morphogenetic receptor-2 (BMPR2), only 20% have lifetime risk of developing pulmonary hypertension. In group 2 WHO, raised left atrial pressures result in secondary elevation of pulmonary pressure. In group 3 WHO, raised pulmonary arterial pressures result from mechanisms such as vascular destruction and hypoxic vasoconstriction. In group 4 WHO, mechanical obstruction of the pulmonary vascular bed is the primary process. For a classification of pulmonary hypertension, see Figure 1.

Figure 1.

Classification of pulmonary hypertension

B. Describe a diagnostic approach/method to the patient with this problem.

PH should be suspected from patient symptoms and physical examination. Electrocardiography, chest radiography, and pulmonary function tests may identify an alternative cause of breathlessness. Initial noninvasive testing should be used to screen for PH such as transthorathic echocardiography (TTE). Underlying diseases should be evaluated with appropriate tests. PH including hemodynamic profile should be confirmed with right heart catheterization. Primary PH is a diagnosis of exclusion.

1. Historical information important in the diagnosis of this problem.

The following are standard questions in the historical evaluation of PH:

Do you have shortness of breath? Does it occur on exertion or at rest?

Do you have chest pain?

Do you feel dizzy?

Do you feel tired?

Do you take any illicit drugs/medications?

Do you know your HIV status?

Do you have joint pain or swelling?

Have anyone of your family been diagnosed with connective tissue disease?

Have you been diagnosed with sleep apnea, or do you know if you snore?

Have you or anyone of you family been diagnosed with deep vein thrombosis (DVT) or pulmonary embolism?

Did anyone of your family has PH? If yes, at what age?

2. Physical Examination maneuvers that are likely to be useful in diagnosing the cause of this problem.

Heart auscultation may reveal prominent pulmonary component of second heart sound, right ventricular heave, murmur of tricuspid regurgitation, and right ventricular gallop.

Signs of right heart failure including peripheral edema, ascites, hepatomegaly, jugular vein distension.

Look for digital clubbing and peripheral cyanosis.

Examine tonsils for enlargement and assess mallampati score.

Examine skin and joint for connective tissue disease.

3. Laboratory, radiographic and other tests that are likely to be useful in diagnosing the cause of this problem.

Work-up should be focused on ruling out secondary causes of PH as primary PH is diagnosis of exclusion.

Chest radiography may show enlarge proximal pulmonary vessels.

Electrocardiogram may show right axis deviation, right atrial hypertrophy, and right ventricular hypertrophy.

Echocardiography estimates pulmonary artery pressure as well as assessing for shunt, valvular disease, and ventricular function.

Pulmonary function test (PFT) to identify obstructive and restrictive lung disease.

High resolution computed tomography (HRCT) to identify interstitial lung disease.

Ventilation and perfusion scan (V/Q scan) to identify chronic thromboembolic disease (CTE).

Selected laboratory tests include ANA, RF, ESR, liver enzymes, hepatitis serology, HIV test, and urine drug screen.

Right heart catheterization is essential for confirming diagnosis, accurately measuring mean pulmonary artery, assessing disease severity, and testing for vasodilator responsiveness.

C. Criteria for Diagnosing Each Diagnosis in the Method Above.

Once there is clinical suspicion of PH, patients should be referred for echocardiography to confirm the diagnosis. Blood tests (as described above) should be ordered. Initially, a V/Q scan or spiral CT should be done to evaluate for CTEPH. Following that, HRCT, PFT, and an arterial blood gas (ABG) should be ordered to evaluate for any underlying respiratory disease. Finally, right heart catheterization should be performed to confirm diagnosis and do reversibility studies.

Functional assessment includes classification of functional status according to the New York Heart Association (NYHA) and a 6-minute walk test (6MWT) for treatment.

D. Over-utilized or “wasted” diagnostic tests associated with the evaluation of this problem.

N/A

III. Management while the Diagnostic Process is Proceeding.

A. Management of Clinical Problem Pulmonary Hypertension.

Patients with respiratory distress, hypoxemia, or cyanosis should have oxygen supplementation.

Acute life threatening diseases such as myocardial infarction or pulmonary embolism that cause dyspnea and chest pain should be investigated and treated accordingly.

Patients with family history of PH, scleroderma, congenital heart disease, portal hypertension undergoing liver transplantation assessment, and previous history of pulmonary embolism who have dyspnea after 8-12 weeks of the event should be screened for PH.

Early consult with a pulmonary specialist is recommended.

B. Common Pitfalls and Side-Effects of Management of this Clinical Problem.

Patients with PH due to a primary disease should be referred to appropriate specialist to manage underlying condition.

Patients with PH should avoid anorexigens and decongestant medications.

Women with PH should avoid pregnancy and they are strongly advised to terminate pregnancy if pregnant. PH in pregnancy is associated with a 25-56% maternal mortality, the risk of death being greatest peripartum.

Patients should receive all appropriate vaccinations.

In general, PH prognosis is poor with median survival 2.8 years, but prognosis depends on NYHA functional class, distance walked on 6MWT, presence of pleural effusions, high mean pulmonary artery pressure, and reduced cardiac output.

Therapy of PH due to underlying etiology depends on addressing the primary disease.

For therapy of primary PH, please refer to primary pulmonary hypertension section.

IV. What's the evidence?

Chin, KM, Rubin, LJ. "Pulmonary arterial hypertension". J Am Coll Cardiol. vol. 51. 2008. pp. 1527-1538.

Highland, KB. "Pulmonary arterial hypertension". Am J Med Sci. vol. 335. 2008. pp. 40-45.

McLaughlin, VV, Archer, SL, Badesch, DB. "ACCF/AHA 2009 expert consensus document on pulmonary hypertension: a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents and the American Heart Association developed in collaboration with the American College of Chest Physicians; American Thoracic Society, Inc.; and the Pulmonary Hypertension Association". J Am Coll Cardiol. vol. 53. 2009. pp. 1573-1619.

McGoon, MD, Kane, GC. "Pulmonary hypertension: diagnosis and management". Mayo Clin Proc. vol. 84. 2009. pp. 191-207.

Kiely, DG, Elliot, CA, Sabroe, I, Condliffe, R. "Pulmonary hypertension: diagnosis and management". BMJ. vol. 346. 2013 Apr 16. pp. f2028.

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