cardiogenic pulmonary edema

Cardiogenic pulmonary edema is the lung flooding caused by a failing left heart. Picture the left ventricle as a pump that should clear the blood arriving from the lungs; when it cannot keep up, blood backs up behind it, pressure rises in the lung veins and capillaries, and fluid is squeezed out into the air sacs, like water rising behind a dam that can no longer let enough through.

This back-pressure mechanism distinguishes it from non-cardiogenic edema, where the capillaries leak because they are injured rather than overpressured. The cause may be a heart attack weakening the muscle, a leaking or narrowed valve, a sudden surge in blood pressure, or a fast irregular rhythm. Often it comes on quickly, sometimes overnight, producing severe breathlessness, a sense of drowning, and frothy sputum.

Recognising the cardiac origin matters because treatment targets the heart and the excess pressure: drugs to offload fluid and dilate vessels, control of blood pressure and rhythm, and breathing support such as non-invasive ventilation. The wedge pressure measured at right heart catheterization, or simpler bedside clues, help confirm that raised left-heart pressure, not lung injury, is to blame.