What type of congestion does left heart failure primarily cause?

Left heart failure usually leads to pulmonary congestion.

The heart is divided into the left and right cardiac systems. The four pulmonary veins carry blood from the lungs into the left atrium, which then passes through the mitral valve into the left ventricle. The left ventricle pumps blood under high pressure into the aorta, supplying oxygenated blood to organs throughout the body. In the pulmonary circulation, blood flows from the right ventricle into the pulmonary artery, travels through its various branches, undergoes gas exchange in the capillaries near the alveoli, and finally returns via the pulmonary veins to the left atrium. Pulmonary congestion occurs when left heart failure obstructs blood flow in the pulmonary veins, potentially causing symptoms such as chest tightness, shortness of breath, dyspnea, and inability to lie flat. Patients with left heart failure often experience paroxysmal nocturnal dyspnea, exertional dyspnea, and worsening breathlessness at night. In acute left heart failure, patients may cough up pink, frothy sputum and exhibit bilateral lung crackles (wet rales) upon auscultation. Severe left heart failure can lead to systemic congestion, resulting in hepatosplenomegaly (enlargement of the liver and spleen), ascites, and other related symptoms.

When signs of left heart failure appear, prompt medical evaluation and treatment are essential to prevent disease progression.