NREMT Paramedic Practice

What is a primary characteristic of left ventricular failure?

1. Increased cardiac output

2. Decreased end-diastolic blood volume

3. Back pressure into the pulmonary circulation

4. Increased heart rate

The correct answer is: Back pressure into the pulmonary circulation

Left ventricular failure is characterized by the heart's inability to effectively pump blood out of the left ventricle, leading to several physiological changes. One of the primary consequences of this failure is the increase in pressure within the left atrium and subsequently the pulmonary circulation. When the left ventricle fails to eject sufficient blood into the systemic circulation, blood can back up into the lungs, causing increased hydrostatic pressure in the pulmonary capillaries. This back pressure can result in pulmonary congestion and can lead to symptoms such as shortness of breath and pulmonary edema. This characteristic is a direct result of the left side of the heart being impaired, as it is responsible for sending oxygenated blood to the body. The compensatory mechanisms in response to reduced cardiac output also play a role but emphasize the fundamental issue of the heart's inability to handle blood volume effectively, leading to the congestive signs in the lungs. Increased cardiac output, decreased end-diastolic blood volume, and increased heart rate may be seen in other conditions or compensatory states, but they don't highlight the primary mechanism behind left ventricular failure. Thus, the back pressure into the pulmonary circulation is a hallmark of this condition.