Symptoms of Pulmonary Arteriovenous Malformations (PAVMs)
Many patients with pulmonary AVMs (25-58%) are completely asymptomatic before catastrophic complications occur, making screening essential in high-risk populations, particularly those with hereditary hemorrhagic telangiectasia. 1
Respiratory Symptoms
- Hypoxemia is the most common symptomatic presentation, occurring in 27-71% of patients with PAVMs, manifesting either at rest or during exercise 1
- Dyspnea on exertion affects approximately 67% of symptomatic patients 2
- Orthodeoxia and platypnea (worsening oxygen levels and shortness of breath when upright) are characteristic presentations because 65-83% of PAVMs are located in the lower lung lobes 1
Neurological Complications
The loss of the pulmonary capillary bed's filtering function creates a direct pathway for emboli to reach the systemic circulation, leading to serious neurological events:
- Transient ischemic attacks (TIAs) and cerebral strokes occur in 3.2-55% of patients with PAVMs due to paradoxical embolization 1, 3
- Cerebral abscesses develop in 0-25% of cases when systemic bacterial infections bypass pulmonary filtration 1, 4
- Major neurologic events were the presenting symptom in 33% of patients in one surgical series 2
These neurological complications represent the most serious morbidity and mortality risk from untreated PAVMs and are the primary indication for treatment 1.
Hemorrhagic Complications
- Massive hemoptysis and hemothorax are rare (0-2%) but represent life-threatening emergencies 1
- Pregnancy dramatically increases hemorrhage risk due to hormonal and hemodynamic changes, making this a critical consideration in women of childbearing age 1, 5
Associated Condition: Hereditary Hemorrhagic Telangiectasia (HHT)
- 70-90% of pulmonary AVMs occur with HHT, an autosomal dominant disorder 1, 3
- Epistaxis (nosebleeds) is a hallmark of HHT and often present in the patient's history 6
- Patients may have a family history of HHT 6
Clinical Presentation Patterns
The symptoms depend on the size, number, type (complex versus simple), and flow through the malformations 1:
- Solitary large PAVMs typically cause more pronounced hypoxemia and may improve after treatment 2
- Multiple bilateral PAVMs may present with more severe symptoms requiring staged or palliative treatment 2
- Migraines can occur as a presenting symptom 3
Critical Clinical Pitfall
The high rate of asymptomatic presentation (25-58%) before catastrophic complications mandates aggressive screening in high-risk populations, especially patients with HHT or family history of HHT. 1 Waiting for symptoms to develop before diagnosis can result in preventable strokes, brain abscesses, or fatal hemorrhage. Transthoracic contrast echocardiography with agitated saline has 98-99% sensitivity for detecting PAVMs and should be used as a screening tool in at-risk patients 6.