Abstract
BACKGROUND: Pulmonary hypertension (PH) is a life-threatening condition that can be triggered by pulmonary thromboembolism (PTE), which causes abrupt increases in pulmonary artery pressure and resistance. Although Doppler echocardiography is a useful screening tool, its ability to accurately reflect rapid hemodynamic changes during acute PTE remains limited. The Flowire catheter allows for real-time assessment of intravascular flow and may offer better insight into these changes. AIMS: The aims were to investigate changes in pulmonary artery hemodynamics measured using a Flowire catheter and to validate the accuracy of Doppler echocardiography in assessing these changes in dogs with acute pulmonary thromboembolism (PTE). METHODS: Hemodynamic and echocardiographic data were obtained from 10 anesthetized female beagles using a Flowire catheter and echocardiography at three preload conditions: baseline, bolus loading, and an acute pulmonary hypertension state induced by a 300-μm dextran microsphere injection. RESULTS: With increases in pulmonary artery pressure and pulmonary vascular resistance, the proximal and distal pulmonary artery flow peak measured using the Flowire catheter significantly decreased during the acute pulmonary hypertension period. Echocardiography did not accurately capture these hemodynamic changes and tended to overestimate pulmonary artery flow peak in the distal pulmonary artery. CONCLUSION: Doppler echocardiography has limitations in accurately reflecting complex hemodynamic changes during acute PTE. In contrast, Flowire catheterization provides additional and precise local hemodynamic information.