Congestive Heart Failure

Heart failure, sometimes also called congestive heart failure, is a condition that occurs when the heart can’t pump enough blood to meet the body’s demands. Heart failure can be either systolic or diastolic, and it can affect the right, left, or both sides of the heart. In systolic heart failure, the heart is unable to effectively contract to push blood out of the ventricles; whereas with diastolic failure, the ventricles become stiff and unable to relax between beats, so they can’t fill with blood properly.

Now, the heart acts as a pump to move deoxygenated blood through the right side of the heart, to the lungs for oxygenation, back to the left side of the heart, and then out to the body. Each beat of the heart has two phases: systole and diastole. Systole is when the heart is contracting and pumping blood, and diastole is when the heart is relaxed and filling with blood.

The amount of blood pumped by the heart in one minute is called cardiac output, and it’s an important indicator of heart function. Cardiac output is determined by four factors: contractility, preload, afterload, and heart rate.

Contractility is the heart’s ability to contract and eject blood during systole, which enhances the force of contraction during systole. Preload is the amount of stretch in the ventricles at the end of diastole as the ventricles fill with blood. In general, the more the preload, the stronger the contraction. On the other hand, afterload is the resistance the ventricles must push against during systole. Less afterload can decrease workload on the heart. Lastly, heart rate is the number of times the heart beats per minute.

Okay so, cardiac output is calculated by multiplying the heart rate by stroke volume, which is the amount of blood pumped by the heart during systole. Now, the amount of blood within the ventricles at the end of diastole is called the end-diastolic volume; and the stroke volume is just a portion of the end-diastolic volume. Similarly, the percentage of the end-diastolic volume pushed out of the ventricles with each contraction is called the ejection fraction.

A normal ejection fraction can vary, but it typically ranges between 50 and 70 percent. It’s calculated by dividing the stroke volume by the end-diastolic volume and multiplying by 100 to get a percentage. In general, the higher the ejection fraction, the more blood is being pumped to the body.

The cause of heart failure is usually secondary to another condition that impairs the heart’s ability to contract or relax effectively. These include coronary artery disease, hypertension, or valvular heart disease.

Risk factors for heart failure can include advanced age and history of cardiac disease.