Pulmonary Arterial Hypertension (PAH)

Patients with pulmonary arterial hypertension (PAH) can develop several complications with the progression of the disease or as a result of hemodynamic imbalance. Some of these complications include cardiac arrest/sudden death, right ventricular failure (RVF), syncope, hypoxemic respiratory failure, arrhythmias, hemoptysis, pulmonary embolism, chest pain/left main compression syndrome, and infection.1

Cardiac Arrest/Sudden Death

PAH patients have limited reserves to compensate for hemodynamic imbalances. PAH patients with critically compromised hemodynamics or decompensated right heart failure (RHF),2 which is characterized by World Health Organization (WHO) as functional class (FC) IV symptoms with reduced blood supply to other organs, may not overcome acute decompensation resulting in cardiac arrest or sudden death. Those who require cardiopulmonary resuscitation have a poor outcome. A study found that cardiopulmonary resuscitation was not successful in 79% of cases and only 8 patients survived for more than 90 days.1    

Right Heart Failure

Right heart failure (RHF) is one of the most common causes of mortality in PAH patients. As the disease progresses, continuously elevated pulmonary vascular resistance (PVR) causes pressure overload on the right ventricle (RV) that responds with hypertrophy and eventual distension. With time, RV adaptation is impaired, resulting in systolic and diastolic dysfunction of both left and right ventricles, increased risk of dysrhythmias and eventually RHF.1,3


Syncope is a transient loss of consciousness with rapid onset, short duration, and spontaneous recovery. It occurs as a result of low cardiac output and subsequently low cerebral perfusion. Patients can injure themselves during syncope due to falling down. Syncope is a serious complication since it indicates disease worsening and increased risk of death. PAH patients experiencing syncope should be urgently evaluated to assess disease progression by their PH health care provider and determine if there’s a need for right heart catheterization to assess hemodynamic status.4

Hypoxemic Respiratory Failure

Hypoxemic respiratory failure is rare in PAH patients and mainly occurs in the presence of congenital heart disease (CHD) or a right-to-left cardiac shunt or concomitant interstitial lung disease. Hypoxemia occurs in PAH patients due to low mixed venous oxygenation, alterations in the ventilation/perfusion relationship and reduced arterial carbon dioxide level from hyperventilation.1


Arrhythmias are frequent and serious complications in PAH patients that require immediate attention. In these cases, clinical deterioration necessitating hospitalization or sudden death may occur. Supraventricular arrhythmias such as supraventricular tachycardia (SVT), atrial fibrillation, or atrial flutter, are the most common types of arrhythmias. In advanced PAH, SVTs may develop due to increased atrial stretch and myocardial fibrosis. In PAH patients with CHD, SVTs often result from previous surgical incisions or right atrial dilatation. Ventricular arrhythmias usually occur in PAH patients with CHD.4


Hemoptysis, or coughing up blood or blood-stained mucus, in PAH patients occurs usually through bronchial circulation (in 90% of cases) rather than pulmonary circulation. In a minority of cases, the source of bleeding is the aorta or systemic arterial supply to the lungs. Sudden death following severe hemoptysis is rare but the mortality rate can be more than 50% if the patients do not receive immediate appropriate treatment. Pathological changes, hypoxic vasoconstriction and intravascular thrombosis, in PAH patients reduce pulmonary circulation that results in bronchial artery enlargement and proliferation. In patients with severe PAH, there are prominent collateral vessels and hypertrophy of bronchial collateral arteries that can sometimes induce extravasation into the respiratory tract causing significant hemoptysis.4

Pulmonary Embolism

Another fatal complication in PAH patients is acute pulmonary embolism (PE) that causes obstruction of the pulmonary vasculature, as well as release of vasoconstrictors, leading to an acute increase in PVR. The increased resistance results in rapid increase in RV pressure and volume overload, which eventually leads to RV dilation and dysfunction. Together with systemic hypotension, it may lead to ischemia or even myocardial infarction.5

Chest Pain/Left Main Compression Syndrome

Chest pain is a frequent complication experienced by patients with PAH. The most common cause of chest pain is RV dilation and hypertrophy leading to increased myocardial oxygen demand which may result in angina. Less commonly, chest pain is caused by progressive pulmonary artery dilation, which may cause extrinsic compression of the left main coronary artery. Left main compression syndrome (LCMS) may result in left ventricular dysfunction and sudden cardiac death.1


PAH patients are sensitive to even small infections (bacterial or fungal) that can cause hypoxemia and worsen RHF, which may lead to death. The common cause of infection in patients receiving intravenous (IV) prostacyclin treatment is the central venous catheter line, which should not be flushed or used for blood draws.1


  1. Hohsfield R, Archer-Chicko C, Housten T, Harris Nolley S. Pulmonary arterial hypertension emergency complications and evaluation: practical guide for the advanced practice registered nurses in the emergency department. Adv Emerg Nurs J. 2018;40(4):246-259. doi:10.1097/TME.0000000000000210
  2. Olsson KM, Halank M, Egenlauf B, et al. Decompensated right heart failure, intensive care and perioperative management in patients with pulmonary hypertension: updated recommendations from the cologne consensus conference 2018. Int J Cardiol. 2018;272S:46-52. doi:10.1016/j.ijcard.2018.08.081
  3. Price LC, Dimopoulos K, Marino P, et al. The CRASH report: emergency management dilemmas facing acute physicians in patients with pulmonary arterial hypertension. Thorax. 2017;72(11):1035-1045. doi:10.1136/thoraxjnl-2016-209725
  4. Demerouti EA, Manginas AN, Athanassopoulos GD, Karatasakis GT. Complications leading to sudden cardiac death in pulmonary arterial hypertension. Respir Care. 2013;58(7):1246-1254. doi:10.4187/respcare.02252
  5. Smulders YM. Pathophysiology and treatment of haemodynamic instability in acute pulmonary embolism: the pivotal role of pulmonary vasoconstriction. Cardiovasc Res. 2000;48(1):23-33. doi:10.1016/s0008-6363(00)00168-1

Article reviewed by Kyle Habet, MD, on July 1, 2021.