Fig. 1

Pulmonary venous pressures depending on the position of the lesion in relation to the left atrium. If the lesion is located below the level of the atrium, the pulmonary venous pressure at this location is the existing pressure in the left ventricle plus the hydrostatic pressure over the lesion to be biopsied (“T”), defined as the distance from the center of the left atrium to the lesion, marked “A” in the figure. If a pulmonary vein is injured, bleeding occurs here. If the lesion is located above the level of the atrium, the pulmonary venous pressure at this location is the existing pressure in the left atrium minus the hydrostatic pressure below the lesion to be biopsied, defined as the distance from the center of the left atrium to the lesion, marked “B” in the figure. If a pulmonary vein is injured, air enters the pulmonary vein due to the lower viscosity of air compared with blood. LV: Left ventricle; RV: right ventricle; RA: right atrium