|Year : 2020 | Volume
| Issue : 2 | Page : 88-90
Pulmonary arteriovenous malformations with pulmonary artery hypertension: Therapeutic implication
Jayachandra, BS Meghana, Yoganand
Department of Medicine, BMC and RI, Bengaluru, Karnataka, India
|Date of Submission||16-Sep-2019|
|Date of Decision||02-Nov-2019|
|Date of Acceptance||06-Nov-2019|
|Date of Web Publication||18-Apr-2020|
Dr. B S Meghana
Department of Medicine, BMC and RI, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Pulmonary arteriovenous malformations (PAVMs) are rare pulmonary vascular anomalies and represent fistulous connection between arterial and venous branches without customary intervening capillary network that is vital for gas exchange. The incidence is 2–3/100,000. Typically, PAVMs are associated with a normal or low pulmonary vascular resistance as the direct arteriovenous communications are low-resistance circuits. However, pulmonary artery hypertension is uncommon in PAVMs. Treatment of choice for PAVM is embolization. However, it abolishes low-resistance pathways for pulmonary blood flow and therefore can elevate pulmonary artery pressure. For majority of patients with severe PAH, risks of PAVM embolization outweigh potential benefits.
Keywords: Embolization, pulmonary arteriovenous malformations, pulmonary hypertension
|How to cite this article:|
Jayachandra, Meghana B S, Yoganand. Pulmonary arteriovenous malformations with pulmonary artery hypertension: Therapeutic implication. APIK J Int Med 2020;8:88-90
|How to cite this URL:|
Jayachandra, Meghana B S, Yoganand. Pulmonary arteriovenous malformations with pulmonary artery hypertension: Therapeutic implication. APIK J Int Med [serial online] 2020 [cited 2020 Aug 13];8:88-90. Available from: http://www.ajim.in/text.asp?2020/8/2/88/282848
| Introduction|| |
Pulmonary arteriovenous malformations (PAVMs) were first described in the late 19th century; Churton reported the autopsy findings in a young boy with cyanosis in 1897. Size varies from too small to be seen by radiography or angiography to more than 5 cm in diameter. 65% of PAVMs are located in the lower lobes. Transforming growth factor β (TGF-β) plays a critical role in endothelial cell homeostasis. Downregulation of TGF-β permits excessive endothelial cell proliferation and increases blood vessel formation. TGF-β under the influence of proangiogenic signals from VEGF forms persistent direct arteriovenous connections. Direct arteriovenous connections are low-resistance circuits [Figure 1]. When PAVMs coexist with significant pulmonary artery hypertension (PAH), caution must be exercised with PAVM embolization as sudden obliteration of low-resistance circuit could significantly increase the pulmonary resistance and unsettle an already fragile right ventricle or lead to other hemorrhagic complications.
| Case Report|| |
An 80-year-old female presented with progressive exertional breathlessness of 15-year duration. There was no history of other cardiac or respiratory symptoms. On examination, tachypnea with SpO2 was 88% in room air and no orthodeoxia. On systemic examination, CVS and RS: Grade II parasternal heave, epigastric pulsations seen. Grade II parasternal heave, epigastric pulsations of RV type felt. Apex beat present in left 5th ICS lateral to midclavicular line, continuous thrill was felt in right costal margin in infrascapular area. Left 2nd intercostal space was dull to percuss, pansystolic murmur of grade 3/6 heard in mitral area, loud P2 present and pulmonary bruit was heard over right infrascapular area. Complete blood count, liver function test, and RFT were normal [Figure 2]. Two-dimensional echocardiography revealed rheumatic heart disease with mild mitral regurgitation, mild aortic regurgitation, mild tricuspid regurgitation, and pulmonary hypertension (PASP 61 mmHg). Secondary causes of PAVM were ruled out by history and other relevant investigations. Pulmonary bruit was evaluated with computed tomography [Figure 3]. Pulmonary angiogram showed PAVM in the right lower lobe. Feeding artery was segmental branch of the right pulmonary artery. Draining vein was segmental branch of pulmonary vein in the right lower lobe. It also showed features of corpulmonale secondary to PAVM.
|Figure 3: Computed tomography pulmonary angiogram showing pulmonary arteriovenous malformation|
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| Discussion|| |
PAVMs are rare vascular anomalies. The patient presented with one of the most common symptoms, dyspnea on exertion (seen in 27%–71% of patients). Other symptoms of PAVM are platypnea, orthodeoxia, hemoptysis (4%–18%), chest pain (6%), epistaxis (32.85%), headache (43%), transient ischemic attack (57%), and cerebrovascular accident (CVA) (18%). The patient had hypoxemia and pulmonary bruit (seen in 10%–58%). Other clinical features of PAVM are clubbing (32%) and telangiectasia (66%), more common on face, followed by lips, nares, tongue, ears, hands, chest, and feet. Complications of PAVM are hemoptysis (<10%), hemothorax (<2%), pulmonary hypertension (uncommon), CVA, brain abscess, migraine, and cerebral arteriovenous malformations. PAVMs are low-resistance circuits due to the absence of intervening capillaries. PAH is a rare complication of PAVM. It is important to note impact of concurrent cardiovascular disease in patients with PAVM. PAVM risks differ in the presence of PAH.
Treatment of choice for PAVMs is embolization and is an effective means of reducing lifetime risks of paradoxical embolic stroke and cerebral abscess, improving oxygenation and treating PAVM-induced hemoptysis. The most common indications for PAVM embolization are to reduce the risk of paradoxical embolic stroke and for individuals with hypoxemia to improve dyspnea and exercise tolerance. Embolization usually carries minimal risk in expert hands and, as a result, is generally offered to patients with PAVMs of a size amenable to embolization, irrespective of the presence of respiratory symptoms. PAVMs themselves are lower vascular resistance circuits than that of the surrounding normal lung, due to the absence of a microvascular network of capillary vessels. The presence of PAVMs does not modify the treatment of PAH; however, the presence of PAH needs modification in recommended treatment for PAVMs. Because the risk of paradoxical embolic stroke is substantially lower in individuals with higher PPA [Figure 4] and symptomatic relief from dyspnea should not be expected for patients with PH and SpO2 of 90%, as was the case in all four patients with severe PH in a recent study, Shovlin et al.,, suggested that for the majority of patients with preexisting severe PAH, the risks of PAVM embolization outweigh potential benefits. Hence, when PAVMs coexist with significant PAH, caution must be exercised with PAVM embolization as sudden obliteration of low-resistance circuit could significantly increase the pulmonary resistance and unsettle an already fragile right ventricle or lead to other hemorrhagic complications. As PAVM with PAH is relative contraindication for surgery, the patient was managed conservatively.
|Figure 4: Comparison of complications in patients having pulmonary arteriovenous malformation without pulmonary hypertension and pulmonary arteriovenous malformation with pulmonary hypertension|
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| Conclusion|| |
PAH is uncommon in patients with PAVM. Treatment of choice for PAVM is embolization. However, as embolization abolishes lowresistance pathways for pulmonary blood flow, it causes increase in pulmonary artery pressure. Hence is more hazardous and fatal. Temporary balloon occlusion does not predict subsequent rise in pulmonary artery pressure. For majority of patients of PAVM with PAH embolization risks outweigh potential benefit. This case is being reported as is a rare complication of PAVM and to emphasize on its therapeutic implication.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]