Arteriovenous fistula of pulmonary vessels - Clinicals, Diagnosis, and Management

Cardiovascular

Clinicals - History

Fact Explanation
Asymptomatic Most patients with small (less than 2cm in diameter) pulmonary arteriovenous fistulae are asymptomatic. Asymptomatic
Most patients with small (less than 2cm in diameter) pulmonary arteriovenous fistulae are asymptomatic.
Epistaxis Epistaxis is the commonest presenting complaint. Patients present with recurrent episodes of epistaxis either spontaneous or secondary to minor trauma. Epistaxis
Epistaxis is the commonest presenting complaint. Patients present with recurrent episodes of epistaxis either spontaneous or secondary to minor trauma.
Dyspnea Dyspnea, the second commonest presenting complain occurs due to right to left shunt of blood. Patients complain of dyspnea on exertion which might progress in to dyspnea on standing upwards (platypnea) as well. Dyspnea
Dyspnea, the second commonest presenting complain occurs due to right to left shunt of blood. Patients complain of dyspnea on exertion which might progress in to dyspnea on standing upwards (platypnea) as well.
Haemoptysis A common complain at presentation, but massive hemoptysis is rarely seen. Haemoptysis
A common complain at presentation, but massive hemoptysis is rarely seen.
Stroke and transient ischemic attacks Patients can develop stroke or recurrent transient ischemic attacks due to increased risk of venous embolization from the pulmonary fistulae. Patients present with dysarthria, facial asymmetry and hemiparesis. Stroke and transient ischemic attacks
Patients can develop stroke or recurrent transient ischemic attacks due to increased risk of venous embolization from the pulmonary fistulae. Patients present with dysarthria, facial asymmetry and hemiparesis.
Symptoms of brain abscess Patients present with prolonged fever, headache, nausea, vomiting and focal neurological signs. Symptoms of brain abscess
Patients present with prolonged fever, headache, nausea, vomiting and focal neurological signs.
Syncope A less common presentation and it is due to hypoxemia. Syncope
A less common presentation and it is due to hypoxemia.
Migraine Although the specific cause is uncertain migraine is known to occur with pulmonary arteriovenous malformations. Migraine
Although the specific cause is uncertain migraine is known to occur with pulmonary arteriovenous malformations.
Congenital Most of the (80%) pulmonary arteriovenous fistula are congenital and very rarely it can be acquired secondary to chest trauma, thoracic surgery, hepatic cirrhosis, metastatic carcinoma, mitral stenosis, infections (actinomycosis, schistosomiasis), Fanconi's syndrome and systemic amyloidosis. Congenital
Most of the (80%) pulmonary arteriovenous fistula are congenital and very rarely it can be acquired secondary to chest trauma, thoracic surgery, hepatic cirrhosis, metastatic carcinoma, mitral stenosis, infections (actinomycosis, schistosomiasis), Fanconi's syndrome and systemic amyloidosis.
Visual disturbances Due to paradoxical embolization from the pulmonary arteriovenous fistula. Visual disturbances
Due to paradoxical embolization from the pulmonary arteriovenous fistula.
Symptoms of congestive cardiac failure Patients develop congestive cardiac failure due to large fistula and subsequent left heart overload. Symptoms of congestive cardiac failure
Patients develop congestive cardiac failure due to large fistula and subsequent left heart overload.

Clinicals - Examination

Fact Explanation
Cyanosis Due to large fistula and increased shunting of blood from left to right. Cyanosis may appear marked in upright position due to increased shunting of blood in the upright position. Cyanosis
Due to large fistula and increased shunting of blood from left to right. Cyanosis may appear marked in upright position due to increased shunting of blood in the upright position.
Clubbing Due to chronic hypoxia. Clubbing
Due to chronic hypoxia.
Telangiectasia Seen in some patients with hereditary hemorrhagic telangiectasia. Telangiectasia
Seen in some patients with hereditary hemorrhagic telangiectasia.
Polycythemia In some patients polycythemia can occur as a compensatory method of chronic hypoxia. Polycythemia
In some patients polycythemia can occur as a compensatory method of chronic hypoxia.
Signs of pulmonary hypertension Patients with arteriovenous fistula of pulmonary vessels can develop pulmonary hypertension. Palpable second heart sound and loud pulmonary component of the second heart sound are characteristic of pulmonary hypertension. Signs of pulmonary hypertension
Patients with arteriovenous fistula of pulmonary vessels can develop pulmonary hypertension. Palpable second heart sound and loud pulmonary component of the second heart sound are characteristic of pulmonary hypertension.
Loud pulmonary systolic bruit This is due to large pulmonary arteriovenous fistula. Murmur is most prominent during the inspiration and when the patient is sitting. Loud pulmonary systolic bruit
This is due to large pulmonary arteriovenous fistula. Murmur is most prominent during the inspiration and when the patient is sitting.
Mucocutaneous telangiectasias Pulmonary arteriovenous fistula are seen in about 24% of patients with HHT. Mucocutaneous telangiectasias are commonly seen in HHT. Mucocutaneous telangiectasias
Pulmonary arteriovenous fistula are seen in about 24% of patients with HHT. Mucocutaneous telangiectasias are commonly seen in HHT.

Investigations - Diagnosis

Fact Explanation
Full blood count Hemoglobin and hematocrit is elevated in the presence of compensatory polycythemia. Low hemoglobin is rarely seen in patients presenting with massive hemoptysis. Full blood count
Hemoglobin and hematocrit is elevated in the presence of compensatory polycythemia. Low hemoglobin is rarely seen in patients presenting with massive hemoptysis.
Pulse oxymetry Oxygen saturations is usually less than 95% . Orthodeoxia is referred to decrease in oxygen saturation in upright position. Most of the pulmonary arteriovenous fistula are located at the lower lobes of the lung. Once the patient is in upright position, more blood is flowing through the fistula because of the effect of gravity. This further decreases the oxygenation of blood hence oxygen saturation. Pulse oxymetry
Oxygen saturations is usually less than 95% . Orthodeoxia is referred to decrease in oxygen saturation in upright position. Most of the pulmonary arteriovenous fistula are located at the lower lobes of the lung. Once the patient is in upright position, more blood is flowing through the fistula because of the effect of gravity. This further decreases the oxygenation of blood hence oxygen saturation.
Chest X-ray Pulmonary nodules (round or oval mass of uniform density) are characteristically seen in chest X-ray, prominently in the lower lobes. Chest X-ray can be normal in the presence of small fistula. Rarely the feeding artery can be seen in large fistulae. Chest X-ray
Pulmonary nodules (round or oval mass of uniform density) are characteristically seen in chest X-ray, prominently in the lower lobes. Chest X-ray can be normal in the presence of small fistula. Rarely the feeding artery can be seen in large fistulae.
Contrast enhanced CT Contrast enhanced CT can visualize the pulmonary vascular tree. Use of 3D helical CT scan can further increases the sensitivity of the CT. Contrast enhanced CT
Contrast enhanced CT can visualize the pulmonary vascular tree. Use of 3D helical CT scan can further increases the sensitivity of the CT.
Pulmonary angiography This is the gold standard in diagnosing pulmonary arteriovenous fistula. Angiogram can detect and helps in assessing the site and size of the fistula. Circumscribed dilatation of the pulmonary artery or vein is the characteristic feature seen in angiogram. Pulmonary angiography
This is the gold standard in diagnosing pulmonary arteriovenous fistula. Angiogram can detect and helps in assessing the site and size of the fistula. Circumscribed dilatation of the pulmonary artery or vein is the characteristic feature seen in angiogram.
Contrast echocardiography A bubble contrast (micro bubbles of less than 50 microns in diameter) is injected intravenously and the four chambers of the heart is visualized. In normal persons micro bubbles are filtered in the pulmonary capillary bed hence they are not seen in the left atrium and the ventricle. In the presence of pulmonary fistula micro bubbles escape from the pulmonary capillary bed and can be seen in the left atrium and the ventricle. Contrast echocardiography is almost 100% sensitive in detecting pulmonary fistulae. Contrast echocardiography
A bubble contrast (micro bubbles of less than 50 microns in diameter) is injected intravenously and the four chambers of the heart is visualized. In normal persons micro bubbles are filtered in the pulmonary capillary bed hence they are not seen in the left atrium and the ventricle. In the presence of pulmonary fistula micro bubbles escape from the pulmonary capillary bed and can be seen in the left atrium and the ventricle. Contrast echocardiography is almost 100% sensitive in detecting pulmonary fistulae.
Radionuclide perfusion lung scan Technetium 99m–labeled macroaggregated albumin is injected intravenously. These are usually filtered in the pulmonary capillary bed. In the presence of fistulae technetium 99m–labeled macroaggregated albumin escapes from the lungs and it is seen in the capillary network in the brain and the kidney as well. This is considered 100% sensitive in detecting pulmonary arteriovenous fistulae. Radionuclide perfusion lung scan
Technetium 99m–labeled macroaggregated albumin is injected intravenously. These are usually filtered in the pulmonary capillary bed. In the presence of fistulae technetium 99m–labeled macroaggregated albumin escapes from the lungs and it is seen in the capillary network in the brain and the kidney as well. This is considered 100% sensitive in detecting pulmonary arteriovenous fistulae.
MRI MRI has relatively low sensitivity in detecting pulmonary fistulae, but use of phase-contrast cine sequences and MR angiography can enhance the sensitivity of MRI. MRI
MRI has relatively low sensitivity in detecting pulmonary fistulae, but use of phase-contrast cine sequences and MR angiography can enhance the sensitivity of MRI.
Cardiac catheterization Presence of pulmonary hypertension can be detected. Cardiac catheterization
Presence of pulmonary hypertension can be detected.
Shunt fraction measurement Shunt fraction is the fraction of cardiac output that shunts from right to left. If it is more than 5% it indicates a significant shunting of blood. Shunt fraction measurement
Shunt fraction is the fraction of cardiac output that shunts from right to left. If it is more than 5% it indicates a significant shunting of blood.

Investigations - Management

Fact Explanation
Contrast echocardiography Contrast echocardiography helps in detecting the recurrence of pulmonary arteriovenous fistule. Contrast echocardiography
Contrast echocardiography helps in detecting the recurrence of pulmonary arteriovenous fistule.
Right heart catheterization Patients are at risk of development of pulmonary hypertension after therapeutic embolization of the fistulae. Presence of pulmonary hypertension can be detected by right heart catheterization. Right heart catheterization
Patients are at risk of development of pulmonary hypertension after therapeutic embolization of the fistulae. Presence of pulmonary hypertension can be detected by right heart catheterization.
Lung function test Lung function tests are indicated to evaluate the degree of dyspnea. Lung function test
Lung function tests are indicated to evaluate the degree of dyspnea.
Exercise ECG This is indicated in the assessment of dyspnea and patient's functionality. Exercise ECG
This is indicated in the assessment of dyspnea and patient's functionality.
Shunt fraction measurement Shunt fraction measurement helps in the assessment of severity of shunt of blood through the fistula. Shunt fraction measurement
Shunt fraction measurement helps in the assessment of severity of shunt of blood through the fistula.

Management - Supportive

Fact Explanation
Basic life support Very rarely some patients can present with shock due to massive epistaxis and hemoptysis. Assessment of airway, breathing and circulation should be done first. Airway patency should be maintained in unconscious patients with oropharyngeal airway or with tracheal intubation. Oxygen should be administered if oxygen saturation is low. Blood should be sent to the emergency grouping and cross-matching as soon as possible. Crystalloids are the intravenous fluid of choice for the initial resuscitation followed by colloids till blood is available for the transfusion. Basic life support
Very rarely some patients can present with shock due to massive epistaxis and hemoptysis. Assessment of airway, breathing and circulation should be done first. Airway patency should be maintained in unconscious patients with oropharyngeal airway or with tracheal intubation. Oxygen should be administered if oxygen saturation is low. Blood should be sent to the emergency grouping and cross-matching as soon as possible. Crystalloids are the intravenous fluid of choice for the initial resuscitation followed by colloids till blood is available for the transfusion.
Antibiotic prophylaxis Antibiotic prophylaxis is indicated in all patients with pulmonary AVMs before surgical or dental procedures to minimize the risk of septicemia and septic embolization. Antibiotic prophylaxis
Antibiotic prophylaxis is indicated in all patients with pulmonary AVMs before surgical or dental procedures to minimize the risk of septicemia and septic embolization.

Management - Specific

Fact Explanation
Conservative management Patients with severe pulmonary hypertension are not eligible for the resection of pulmonary arteriovenous fistula and conservative management is indicated. Conservative management
Patients with severe pulmonary hypertension are not eligible for the resection of pulmonary arteriovenous fistula and conservative management is indicated.
Therapeutic cardiac catheterization Angiographic embolization or balloon occlusion of the feeding artery is one treatment option. Embolization is done with a metal coil. This method does not have a risk of lung parenchymal loss when compared to surgical excision. Induction of tachyarrhythmias, bradyarrhythmias, air embolism and vascular occlusion or rupture is recognized complications. Therapeutic cardiac catheterization
Angiographic embolization or balloon occlusion of the feeding artery is one treatment option. Embolization is done with a metal coil. This method does not have a risk of lung parenchymal loss when compared to surgical excision. Induction of tachyarrhythmias, bradyarrhythmias, air embolism and vascular occlusion or rupture is recognized complications.
Surgical excision Lung parenchymal resection is now rarely done. Ligation of the feeding artery is preferred over parenchymal resection. Video-assisted thoracoscopic resection is practiced for the treatment of small fistulae. Surgical excision
Lung parenchymal resection is now rarely done. Ligation of the feeding artery is preferred over parenchymal resection. Video-assisted thoracoscopic resection is practiced for the treatment of small fistulae.

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