The microbubbles are visualized after 3 to 8 cardiac cycles in the left atrium after initial opacification of the right chambers in patients with an intrapulmonary shunt [1]. TTCE does not provide any information regarding the size and location of the PAVM. Based on the appearance of the bubbles in the left atrium a semiquantitative grading system has been developed [42,43]. The grades are defined as 0 with no opacification, grade 1 with <30 bubbles, grade 2 with moderate filling, and grade 3 with complete opacification of the left atrium. The grading system correlates well with the diagnosis of PAVM, with higher grades associated with larger shunts and cerebral complications [41,44,45]. Usefulness of the grading system to predict treatment of PAVM demonstrates that grades 2 and 3 have a positive predictive value of 0.21 (95% confidence interval [CI], 0.05-0.36) and 0.87 (95% CI, 0.79-0.99), respectively [44]. Adverse events including air embolism are rare with TTCE occurring in <1% [46]. Variant 2: Presenting with shortness of breath, or hemothorax, or hemoptysis. Patient has history of epistaxis and family history of hereditary hemorrhagic telangiectasia (HHT). Suspected PAVM. Initial imaging. Arteriography Pulmonary The real-time nature of pulmonary arteriography allows for high accuracy in delineating the angioarchitecture and detection of flow characteristics such as the early draining vein. In a study comparing the specificity of pulmonary arteriography and CTA, pulmonary arteriography was noted to have a higher specificity for detecting the angioarchitecture compared to CTA (100% versus 78%) [24]. Pulmonary angiography is performed as a part of the treatment procedure and does not have a standalone diagnostic role in detecting PAVM. An exception in which pulmonary angiogram would be helpful as an initial diagnostic imaging tool is in a patient who is hemodynamically unstable with clinical suspicion of pulmonary hemorrhage from a PAVM [25].
Pulmonary Arteriovenous Malformation PAVM . The microbubbles are visualized after 3 to 8 cardiac cycles in the left atrium after initial opacification of the right chambers in patients with an intrapulmonary shunt [1]. TTCE does not provide any information regarding the size and location of the PAVM. Based on the appearance of the bubbles in the left atrium a semiquantitative grading system has been developed [42,43]. The grades are defined as 0 with no opacification, grade 1 with <30 bubbles, grade 2 with moderate filling, and grade 3 with complete opacification of the left atrium. The grading system correlates well with the diagnosis of PAVM, with higher grades associated with larger shunts and cerebral complications [41,44,45]. Usefulness of the grading system to predict treatment of PAVM demonstrates that grades 2 and 3 have a positive predictive value of 0.21 (95% confidence interval [CI], 0.05-0.36) and 0.87 (95% CI, 0.79-0.99), respectively [44]. Adverse events including air embolism are rare with TTCE occurring in <1% [46]. Variant 2: Presenting with shortness of breath, or hemothorax, or hemoptysis. Patient has history of epistaxis and family history of hereditary hemorrhagic telangiectasia (HHT). Suspected PAVM. Initial imaging. Arteriography Pulmonary The real-time nature of pulmonary arteriography allows for high accuracy in delineating the angioarchitecture and detection of flow characteristics such as the early draining vein. In a study comparing the specificity of pulmonary arteriography and CTA, pulmonary arteriography was noted to have a higher specificity for detecting the angioarchitecture compared to CTA (100% versus 78%) [24]. Pulmonary angiography is performed as a part of the treatment procedure and does not have a standalone diagnostic role in detecting PAVM. An exception in which pulmonary angiogram would be helpful as an initial diagnostic imaging tool is in a patient who is hemodynamically unstable with clinical suspicion of pulmonary hemorrhage from a PAVM [25].