Pulmonary Hypertension in Adults

Introduction

• PH is a multifactorial disease with complex pathophysiology that is associated with high mortality. PH occurs when blood pressure in the pulmonary circulation is elevated and may be idiopathic or caused by vasoconstriction, obstruction of the pulmonary vasculature, left heart disease, or lung disease.
• The classic definition of PH required a mPAP ≥ 25 mmHg and PVR ≥ 3.0 WU. In 2022, the European Society of Cardiology (ESC) and the European Respiratory Society (ERS) updated the definition of PH to include patients with mPAP ≥ 20 mmHg and PVR ≥ 2.0 WU, to identify patients earlier in the disease course, given the elevated mortality risk associated with PH.^1-3
• This summary will focus on PH in adults. Please see the other OA summaries on pediatric PH and PH in pregnant patients.
  • Pulmonary Hypertension in Pregnancy. OA summary. 2025. Link
  • Pediatric Pulmonary Hypertension: Classification, Pathophysiology, and Diagnosis. OA summary. 2025. Link
  • Pediatric pulmonary Hypertension: Anesthetic Considerations. OA summary. 2025. Link

Classification

• PH can be classified by groups designated by the WHO based on etiology and by hemodynamic profile criteria designated by the ESC/ERS.
• The WHO classification of PH by group is listed in Table 1.

• Pre- vs. postcapillary PH is primarily differentiated by whether pulmonary artery wedge pressure (PAWP) or left ventricular end-diastolic pressure (LVEDP) exceeds 15 mmHg. This is in addition to mPAP greater than 20 mmHg.⁴
  • Precapillary PH is caused by pulmonary vascular remodeling → increased PVR (> 2 WU) → RV afterload → RV hypertrophy → RV failure
    • Left heart pressures should be normal → PAWP ≤ 15 mmHg
    • WHO Groups 1, 3, 4, 5
  • Postcapillary PH results from increased pulmonary venous pressure due to elevated left-sided filling pressures.
    • Left heart disease usually present → elevated PAWP (>15 mmHg)
    • WHO Group 2
    • PVR in postcapillary PH can be used to further differentiate between isolated postcapillary PH (ipcPH) and cpcPH
      • ipcPH: PVR ≤ 2 WU
      • cpcPH: PVR > 2WU
  • Exercise-induced PH is observed in patients with normal resting PA pressures who develop PH during exercise.
    • Diagnosis is defined by the relationship between the mPAP and cardiac output (CO) during exercise.
    • mPAP/CO slope more than 3 mmHg/L/min is diagnostic for exercise PH.
    • At this time, the clinical course of exercise PH and whether it should be treated remains under investigation.

Pathophysiology

• The pathophysiologic mechanisms that cause PH are:
  • Increased PVR
  • Caused by pulmonary vasoconstriction, obstruction, inflammation, vascular proliferation, and remodeling
  • Increased pulmonary venous pressure
  • Caused by increased left-sided pressures (i.e., congestive heart failure)
  • Increased pulmonary venous flow
  • Caused by congenital heart disease, presence of atrial or ventricular septal defects, or patent ductus arteriosus
• Long-term prognosis is generally poor because progression of the disease leads to worsening pulmonary arterial pressures → RV dysfunction → heart failure, → death.

Clinical Presentation and Diagnosis

• Presenting symptoms that raise the index of suspicion for PH: exertional dyspnea, fatigue, chest pain, syncope, signs of RV failure (peripheral edema, elevated jugular venous pressure)
• Noninvasive testing is indicated when PH is suspected:⁶
  • Transthoracic echocardiography (TTE):
    • Assess RV size, wall thickness, and function
    • RV/LV basal diameter/area ratio > 1.0
    • Septal flattening on systole (indicative of RV pressure overload)
    • Tricuspid annular plane systolic excursion (TAPSE)/PASP ratio < 0.55 mm/mmHg
  • Measure tricuspid regurgitant jet velocity (TRV) and use that to estimate pulmonary artery systolic pressure (PASP)
    • PH is likely if PASP > 50 mmHg and TRV > 3.4 m/s
    • PH is unlikely if PASP ≤ 36 mmHg and TRV ≤ 2.8 m/s and there are no other suggestive findings of PH on TTE
  • Pulmonary artery diameter ≥ 25 mm
  • Inferior vena cava diameter > 21 mm with decreased inspiratory collapse
  • Note: TTE does not confirm PH, but stratifies likelihood and identifies possible etiology
  • Electrocardiogram: RV hypertrophy, right bundle branch block, right axis deviation, right atrial enlargement
  • Other tests can be considered: chest x-ray, pulmonary function tests, V/Q test, Chest computed tomography, magnetic resonance imaging, etc.
• Invasive testing is used for definitive diagnosis:
  • The gold standard is RHC.
    • RHC can help differentiate between pre- and postcapillary PH by directly measuring intracardiac pressure and help to identify the etiology of PH
    • See Table 2 for diagnostic criteria.

Management

• Pulmonary hypertension is managed using one or more of the following:¹
  • Avoiding exacerbating activities (i.e., smoking, pregnancy, use of sympathomimetics)
  • Endothelin-receptor antagonists (bosentan, ambrisentan, macitentan)
  • Phosphodiesterase 5 (PDE-5) inhibitors (sildenafil, tadalafil, vardenafil)
  • Prostacyclin analogs (epoprostenol, iloprost, treprostinil)
  • Treat the underlying disorder (for WHO Groups 2-5 PH)
  • Lung transplantation
  • It may be curative but has high morbidity due to potential organ rejection and infection. Lung transplantation is usually reserved for patients with class IV disease (dyspnea at rest).
  • Combined heart-lung transplantation may be required in cases in which severe PH causes end-stage right heart failure.
  • Adjunctive therapy: supplemental O₂, diuretics, anticoagulants
• Treatment of WHO Group 1 PH (pulmonary arterial hypertension [PAH]):
  • Patients with PAH first undergo acute vasoreactivity testing (AVT) to determine if they will benefit from calcium channel blocker (CCB) therapy. AVT is contraindicated in patients with low SBP (<90 mmHg), low cardiac index (<2 L/min/m²), or severe symptoms.
  • AVT is conducted by administering a short-acting vasodilator, such as inhaled nitric oxide (iNO), epoprostrenol, adenosine, or iloprost, and then measuring the hemodynamic response with RHC.
  • AVT is positive if mPAP decreases by ≥ 10 mmHg and to a value of ≤40 mmHg.
    • Patients who test positive are initiated on CCB therapy and reassessed after 3-6 months.
    • Patients who test negative are nonvasoreactive and are treated according to their WHO functional class (Table 3), using single-agent or combination therapy with prostacyclin analogs, PDE-5 inhibitors, and/or endothelin-receptor antagonists.

• Treatment of WHO Group 2-5 PH: treat the underlying etiology
  • Group 2 PH (left-sided heart disease) patients may need surgery.
    • PAH-specific medications (used to treat group 1 PH) have not been shown to provide benefit in Group 2 PH and are not recommended.
  • Group 3 patients with PH (lung disease) may require supplemental oxygen and treatment of the underlying disease.
  • Group 4 (CTEPH) patients with PH may require pulmonary thromboendarterectomy (PTE) or be treated with riociguat. This guanylyl cyclase stimulator reduces dyspnea and PVR in patients who are not surgical candidates.

Anesthesia Considerations

• When taking care of patients with PH, special considerations must be made in the perioperative period to safely take care of these patients
• Preoperative considerations:^7,8
  • Assess baseline cardiac function and severity of PH
  • Assess for signs/symptoms of right heart failure
  • Baseline functional status
  • Any modifiable factors that would optimize the patient’s condition
  • Continue any PH therapies that the patient is on through the perioperative period
  • Optimize volume status – aim for euvolemia to maintain optimal RV output
• Intraoperative considerations:
  • Choose an anesthetic technique that will fulfill procedural requirements and best maintain hemodynamic stability
  • Hemodynamic goals:
  • Avoid increases in PVR:
    • Avoid hypoxia, hypercarbia, acidosis, pain, and high positive end-expiratory pressure (PEEP)
    • Maintain normothermia, normal pO₂, pCO₂
  • Maintain preload, sinus rhythm, and SVR to preserve RV coronary perfusion
  • Monitoring: standard American Society of Anesthesiologists monitors, arterial line, central venous pressure (CVP), and pulmonary artery catheter (PAC)
    • PAC allows for monitoring trends in CVP, PAP, PCWP, CO, and SvO₂
    • Consider TEE for RV assessment
  • Induction:
    • High-risk period due to potential for systemic hypotension and RV decompensation.
    • Ensure adequate preoxygenation
    • Choose agents that maintain hemodynamic stability
  • Maintenance:
    • Consider a balanced anesthetic using sedative-hypnotics and opioids to blunt the sympathetic response
    • Avoid nitrous oxide (can increase PVR and worsen hypoxemia)
    • Avoid excessive concentrations of volatile agents
  • Ventilation management:
    • Avoid hypoxemia, hypercarbia, and acidosis, as these can increase PVR
    • Low tidal volumes to avoid overdistention and hyperinflation
    • Reduce atelectasis by maintaining appropriate lung recruitment
    • PEEP less than 8 cm H₂O
  • Fluid management:
    • Maintain euvolemia (if CVP available, goal is 6-10 mmHg)
  • Have pulmonary vasodilators available as rescue therapy:
    • iNO
    • inhaled epoprostenol
    • Inotropes: IV milrinone or dobutamine
    • Vasopressors: Vasopressin and norepinephrine
  • Emergence:
    • Smooth emergence is paramount to prevent an increase in RV afterload associated with the sympathetic response
    • Ensure adequate pain control
    • Maintain adequate oxygenation and ventilation
    • Ensure normothermia