Pulmonary Hypertension

Aka: Pulmonary Hypertension

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II. Epidemiology

  1. Prevalence increases with age
    1. Prevalence estimated at 10% in age >65 years

III. Definitions

  1. Pulmonary Hypertension
    1. Pulmonary artery systolic pressure >30 mmHg
    2. Pulmonary artery mean pressure >20 mmHg at rest (by cardiac catheterization)
  2. Pulmonary Arterial Hypertension (Previously known as Primary Pulmonary Hypertension)
    1. Idiopathic Pulmonary Hypertension (rare, high mortality)
  3. Secondary Pulmonary Hypertension
    1. Secondary to one of Pulmonary Hypertension Causes
  4. Cor Pulmonale
    1. Right Ventricular Failure
    2. Secondary to respiratory cause of Pulmonary Hypertension

IV. Pathophysiology

  1. Pulmonary vascular bed pressures (25/10) are typically much lower than systemic pressures (120/80)
    1. Low pressures are adequate to perfuse thin walled gas exchange capillaries with little resistance
    2. Thin-walled right ventricle has adequate output to perfuse a normal, low pressure system
  2. Right-sided pressures increase with primary or secondary disease
    1. See Pulmonary Hypertension Causes
    2. Idiopathic Pulmonary Arterial Hypertension (PAH)
    3. Secondary to cardiopulmonary disease, autoimmune or metabolic disorders or thromboembolic disease
  3. Pulmonary vasculature changes in response to increased pressure
    1. Pulmonary artery medial hypertrophy
    2. Intimal fibrosis
    3. Fibrinoid necrosis
    4. Intravascular thrombus formation
  4. Right Ventricular Strain results from increased pulmonary circuit pressures
    1. Progressive Right Heart Failure develops

V. Types: Acute Pulmonary Hypertension

  1. Acute increase in main pulmonary artery pressures
  2. May result from many acute insults (e.g. Hypoxia, hypercapnia, acidosis, Left Heart Failure)

VI. Types: Chronic Pulmonary Hypertension (replaces old system of primary versus secondary Pulmonary Hypertension)

  1. Pulmonary artery Hypertension (WHO Group 1)
    1. Least common Pulmonary Hypertension type, but most specific management options
    2. Mechanism
      1. Progressive distal pulmonary artery narrowing
    3. Causes
      1. Idiopathic or familial
      2. Includes Persistent Pulmonary Hypertension of the Newborn
      3. Risk factors include Collagen vascular disease including Systemic Sclerosis, as well as HIV Infection
  2. Pulmonary Hypertension associated with left heart disease (WHO Group 2)
    1. Most common cause of Pulmonary Hypertension
    2. Mechanism
      1. Increased left atrial pressures increases pulmonary pressures
      2. Pulmonary venous congestion with Vasoconstriction and venous remodeling
    3. Causes
      1. Left-sided valvular heart disease
      2. Left-sided atrial or ventricular heart disease
      3. Left Heart Failure (Up to 72-83% have Pulmonary Hypertension)
  3. Pulmonary Hypertension associated with lung disease, Hypoxemia or both (WHO Group 3)
    1. Second most common cause of Pulmonary Hypertension (esp. COPD)
    2. Mechanism
      1. Increased pulmonary vascular resistance
        1. Alveolar capillary bed destruction
        2. Vasoconstriction of pulmonary arterioles secondary to chronic Hypoxia
    3. Causes
      1. Chronic Obstructive Lung Disease
        1. Pulmonary Hypertension is found in 5% of COPD patients
        2. Pulmonary Hypertension in 20% of hospitalized COPD and 50% of end-stage COPD
      2. Interstitial Lung Disease
      3. Sleep Apnea
      4. Chronic high altitude exposure
  4. Pulmonary Hypertension associated with chronic thromboembolic disease (WHO Group 4)
    1. Mechanism
      1. Vasoconstriction and pulmonary arterial bed remodeling in response to large vessel obstruction
    2. Causes
      1. Thromboembolism of proximal or distal pulmonary arteries (3.8% with PH at 2 years after PE)
      2. Thromboembolism not due to thrombi (e.g. tumor, Parasites)
  5. Miscellaneous Pulmonary Hypertension (WHO Group 5)
    1. See Pulmonary Hypertension Causes
    2. Sarcoidosis
    3. Pulmonary vessel compression

VII. Causes

  1. See Pulmonary Hypertension Causes

VIII. Associated Conditions

  1. Chronic Hemolytic Anemia
  2. Congenital Heart Disease
  3. Connective Tissue Disease
  4. Human Immunodeficiency Virus (HIV Infection)
  5. Portal Hypertension
  6. Persistent Pulmonary Hypertension of the Newborn
  7. Sickle Cell Disease
  8. Stimulant Abuse (Cocaine, Methamphetamine)
  9. First degree relative with Pulmonary Hypertension (Family History)

IX. Symptoms

  1. Common
    1. Progressive Dyspnea on mild exertion or Exercise intolerance (60%)
    2. Fatigue or generalized weakness (19%)
    3. Syncope or Presyncope, especially with exertion (13%)
  2. Less Common
    1. Hoarseness (Oertner Syndrome)
      1. Pulmonary artery compress left recurrent laryngeal
    2. Angina-type exertional Chest Pain
  3. Rare
    1. Cough
    2. Hemoptysis (advanced disease)
    3. Raynaud's Phenomenon (2%)

X. Signs

  1. Findings are primarily of developing Right-Sided Heart Failure
  2. Heart sounds
    1. Fixed Split S2 Heart Sound
      1. Accentuated second pulmonic valve component (P2)
        1. P2 is louder than the aortic second sound (A2)
      2. A2 remains louder as stethoscope moved to apex
    2. Right atrial Fourth Heart Sound (S4 Heart Sound)
    3. Right ventricular Third Heart Sound (S3 Heart Sound)
      1. Indicates advanced disease
      2. Associated with poor prognosis
  3. Murmurs
    1. Pulmonic ejection Systolic Murmur
    2. Pulmonic early Diastolic Murmur (graham steel murmur)
      1. Diastolic decrescendo murmur
    3. Tricuspid insufficiency pansystolic murmur
      1. More prominent as right ventricle dilates
  4. Other findings
    1. Jugular Vein distention
    2. Prominent right ventricular impulse
    3. Hepatomegaly
    4. Peripheral Edema
    5. Ascites
    6. Weight gain
    7. Prolonged Capillary Refill
    8. Decreased Oxygen Saturation

XI. Diagnosis

  1. See Pulmonary Hypertension Diagnosis
  2. Challenging diagnosis
    1. Diagnosis is often delayed 2-4 years after symptom onset
      1. Despite multiple primary care and specialist visits
      2. Have a high index of suspicion in patients with comorbid Associated Conditions (see above)
    2. More significant cases may present with Right Heart Failure
      1. Lower Extremity Edema
      2. Jugular Venous Distention
  3. Mean Pulmonary Artery Pressure (PAP)
    1. Normal: <15 mmHg
    2. Pulmonary Hypertension
      1. Rest: 25 mmHg or higher
      2. Exercise: 30 mmHg or higher
  4. Pulmonary capillary wedge pressure (PCWP)
    1. PCWP <15 mmHg: Pre-capillary Pulmonary Hypertension
      1. All Causes of Pulmonary Hypertension
      2. EXCEPT those due to left heart disease (WHO Groups 1,3,4,5)
    2. PCWP >15 mmHg: Post-capillary Pulmonary Hypertension
      1. Left heart disease related causes (WHO Group 2 Pulmonary Hypertension)

XII. Labs: Initial Dyspnea Evaluation

  1. Complete Blood Count (CBC)
    1. Evaluate for Anemia (high output Heart Failure)
  2. Comprehensive Metabolic Panel (Electrolytes, Renal Function tests, Liver Function Tests)
  3. B-Type Natriuretic Peptide (BNP)
  4. Serum Troponin
  5. Thyroid Stimulating Hormone (TSH)
    1. Evaluate for Hyperthyroidism (high output Heart Failure)
  6. Other tests to consider at initial presentation
    1. HIV Test
    2. Oximetry (6 Minute Walk Test)

XIII. Imaging

  1. Chest XRay
    1. Cardiomegaly
    2. Right atrial enlargement
    3. Mediastinal narrowing (lateral view)
      1. Right Ventricular Hypertrophy
      2. Pulmonary vasculature pruning (vessels taper off quickly at hilum)
  2. CT Chest
    1. Consider CT Pulmonary Embolism
    2. Consider High Resolution CT in suspected Restrictive Lung Disease

XIV. Diagnostics

  1. See Pulmonary Hypertension Diagnosis
  2. Electrocardiogram (EKG)
    1. See Right Ventricular Strain EKG Pattern
    2. Right Ventricular Hypertrophy
    3. Right Bundle Branch Block
    4. Right strain pattern (S1-Q3-T3 pattern)
    5. T Wave Inversion V1-V4
    6. ST Elevation in aVR
    7. Sinus Tachycardia
    8. Atrial Fibrillation
      1. New onset rate control may be challenging in Pulmonary Hypertension and risk decompensation
  3. Echocardiogram
    1. First-line testing for suspected cases
    2. Refer patients for positive results (even when incidental on echo performed for other reasons)
    3. Peak tricuspid regurgitation velocity >2.8 m/s
      1. High probability if associated with other suggestive echo findings, or peak velocity >3.4 m/s
    4. Estimated pulmonary pressure >35 to 40 mmHg is consistent with Pulmonary Hypertension
    5. Also evaluates right ventricular function
    6. Right Ventricular Hypertrophy
      1. Right ventricular wall thickening (suspicious if >5mm, RVH if >10mm)
      2. Right ventricle pushes into left ventricle on PSAX View (D Sign)
  4. Pulmonary Function Tests
    1. Evaluate for other Dyspnea Causes (COPD, Asthma or Restrictive Lung Disease)
  5. Six minute walk test (with oximetry)
    1. Evaluates WHO functional class status
    2. Predicts mortality in all Pulmonary Hypertension types
  6. Right Heart Catheterization
    1. Indicated Pulmonary Hypertension classification
    2. Further evaluation of Pulmonary Arterial Hypertension and chronic thromboembolic Pulmonary Hypertension
    3. Optional when Pulmonary Hypertension has a clear cardiopulmonary cause (e.g. lung disease, left sided heart disease)
    4. Measures pulmonary artery wedge pressure (left atrial pressure)
      1. Normal in precapillary pulmonary vascular bed causes (e.g. Pulmonary Arterial Hypertension)
      2. Wedge pressure is increased in postcapillary causes (e.g. left-sided Heart Failure)
    5. Measures pulmonary vascular resistance (PVR)
      1. Calculate PVR as the difference between mean pulmonary artery pressure and left atrial pressure
      2. PVR is increased in Pulmonary Arterial Hypertension (normal in Heart Failure)

XV. Evaluation: Screening of high risk groups

  1. Protocol
    1. Annual Echocardiogram
    2. Reflex to right heart catheterization if positve Echocardiogram for pulmonary artery Hypertension
  2. Indications
    1. BMPR2 gene positive (screen first degree relatives for gene)
    2. HIV Infection
    3. Portal Hypertension (if considering Liver Transplantation)
    4. Prior Appetite Suppressant medication such as Fenfluramine if symptoms
    5. Sickle Cell Disease
    6. Systemic Sclerosis
    7. Congenital Heart Disease with shunt
    8. Recent Acute Pulmonary Embolism with persistent symptoms at 3 months
      1. Consider ventilation-perfusion scan with reflex to Pulmonary Angiography if positive

XVI. Differential Diagnosis

  1. See Causes of Dyspnea with Clear Lung Sounds
  2. Common Causes in the Differential of Dyspnea on Exertion
    1. Congestive Heart Failure
    2. Coronary Artery Disease
    3. Valvular Heart Disease
    4. Obstructive Lung Disease (COPD, Asthma)
    5. Restrictive Lung Disease (e.g. Pulmonary Fibrosis)
    6. Pulmonary Embolism
    7. Anemia

XVII. Management

  1. See Pulmonary Hypertension Management
  2. Specific management for Pulmonary Arterial Hypertension (WHO 1) and chronic Thromboembolism (WHO 4)
    1. Other Pulmonary Hypertension Management is directed at the underlying condition

XVIII. Complications

  1. Increased mortality
    1. Five year mortality: 33 to 36%
    2. Six minute walk test (with oximetry) functional status
      1. Predicts mortality across all Pulmonary Hypertension classes
      2. Gall (2017) J Heart Lung Transplant 36(9): 957-67 [PubMed]
    3. Factors that increase mortality
      1. Higher mortality when Pulmonary Hypertension is secondary to lung disease
      2. Lower mortality in chronic thromboembolic Pulmonary Hypertension
      3. Delayed diagnosis >2 years increases mortality 11%
        1. Khou (2020) Respirology 25(8): 863-71 [PubMed]
    4. In comorbid conditions (e.g. COPD), Pulmonary Hypertension is among greatest risks for increased mortality
  2. Right Ventricular Failure
    1. Common outcome of persistently increased pulmonary artery pressures regardless of cause
      1. Thin walled right ventricle responds poorly to high pressures and leads to Right Heart Failure
    2. Secondary to persistent Pulmonary Hypertension
    3. Cor Pulmonale: Subtype of Right Ventricular Failure
      1. Second to respiratory cause of Pulmonary Hypertension
  3. Pregnancy-Related Complications
    1. Maternal mortality 12%
    2. Pregnancy loss 23%
    3. jha (2020) Eur J Obstet Gynecol Reprod Biol 253: 108-16 [PubMed]

XIX. Resources

  1. Pulmonary Hypertension Association
    1. https://www.phassociation.org/

XX. References

  1. Orman, Greenwood and Swaminathan in Herbert (2016) EM:Rap 16(10): 9-11
  2. Dunlap (2016) Am Fam Physician 94(6):463-9 [PubMed]
  3. Gaine (2000) JAMA 284:3160-8 [PubMed]
  4. Greenwold (2015) Emerg Med Clin North Am 33(3): 623-43 +PMID:26226870 [PubMed]
  5. Latimer (2024) Am Fam Physician 110(2): 183-91 [PubMed]
  6. Nauser (2001) Am Fam Physician 63(9):1789-98 [PubMed]
  7. Rubin (1997) N Engl J Med 336:111-7 [PubMed]
  8. Rubin (1993) Chest 104:236-50 [PubMed]
  9. McLaughlin (2009) Circulation 119(16): 2250-94 [PubMed]
  10. Stringham (2010) Am Fam Physician 82(4): 370-7 [PubMed]

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