Wedged Swan-Ganz catheter causing ventilation-perfusion mismatch. Case report and review of the literature

Thrombosed pulmonary artery aneurysm. A rare cause of a high-probability lung scan

The high-probability ventilation-perfusion lung scan is accepted as supportive of pulmonary embolism and often negates further diagnostic evaluation; however, there are processes that mimic the clinical presentation and radiographic findings of pulmonary emboli, including a unilateral segmental or greater perfusion defect. We present the findings in a patient whose presentation and ventilation-perfusion scans over a three-month course were suggestive of pulmonary embolism, yet pulmonary angiography revealed a thrombosed pulmonary artery aneurysm. The interpretation of a unilateral segmental perfusion defect as high probability does not secure the diagnosis of pulmonary embolism and should not preclude further evaluation for alternative etiologies.

Unusual ventilation-perfusion mismatch in partial anomalous venous return

A 3-year-old girl with a complicated partial anomalous pulmonary venous return presented a scintigraphic pattern characterized by an absence of perfusion of the right lung, contrasting with normal ventilation.

Pulmonary thromboembolism: current status report on the role of nuclear medicine

The normal perfusion study continues indisputably to rule out the presence of pulmonary embolism (PE) with reasonable certainty. However, the abnormal perfusion study requires additional specificity. Many retrospective and one prospective correlation of contrast pulmonary angiography (CPA) have largely substantiated the efficacy of ventilation imaging and increasing specificity, especially with a high-probability (HP) interpretation to approximately a 90% predictive value. In most studies, the predictive value of a low-probability (LP) interpretation also approaches 90%. Intermediate-probability (IP) ventilation-perfusion (V-P) studies are the most frequent reason for performing pulmonary angiography, although LP studies with a stated prior clinical HP should also have CPA. Ventilation imaging technique is not as uniformly established as for perfusion studies, leading to some continued variability in interpretative criteria; yet criteria proposed by Biello and his colleagues have begun to be widely adopted. Aerosol inhalation imaging is developing, but has not been widely used, while problems continue with central airways deposition. The importance of contemporary correlative chest x-rays (CXR) especially when normal, have been emphasized, as well as new findings of the import of serial post-V-P CXRs, especially in HP studies without CPA or negative CPA. CPA continues to be the most specific diagnostic test for PE when properly performed, and is complimented and enhanced by use of prior V-P findings; although it is clear that too few CPAs are being performed. Consequently, there has been too much clinical dependence on V-P imaging. The value of prospective clinical probability estimates in patient management has been better substantiated. Reemphasis on thromboembolism as a systemic disease with use of some objective evaluation of the presence of peripheral thrombosis is becoming a part of clinical rationale, with the integrated long-leg radionuclide venograms (RNV) being one of the reasonable approaches. Multicenter studies have demonstrated, contrary to prior contentions, that V-P imaging leads to a significant net reduction and use of anticoagulants, as well as having overall significant efficacy in effecting patient management in suspected PE. Some of the controversies surrounding V-P imaging are expected to be resolved with the completion of the ongoing multiinstitute Prospective Investigation of Pulmonary Embolic Diagnosis (PIOPED) study.(ABSTRACT TRUNCATED AT 400 WORDS)