Heart failure is a progressive medical condition characterized the heart's inability to pump the amount of blood that the rest of the body needs to function properly. According to the part of the heart affected – heart failure can be left or right-sided, and according to the pathophysiology of the disease, heart failure can be systolic or diastolic.
What is systolic heart failure?
The heart is divided into four chambers, each with its role in helping the body function. Systolic heart failure means that the heart’s ventricular muscle is too weak to pump blood normally. There could be a number of reasons that lead to systolic heart failure. The most common series of events is that the ventricular muscle first becomes too thick because of intense efforts to pump out blood. Eventually, the heart muscle becomes too demanding for its own blood supply and the coronary arteries can no longer fulfill its needs. Subsequently, the ventricles sort of start to “surrender” and become dilated, while the heart becomes enlarged. This process results in progressive lowering of the ejection fraction (the percentage of blood pumped out of a ventricle during systole).
What is diastolic heart failure?
After each beat (systole), the heart needs to relax. Between two beats, in a healthy person, the ventricles should be able to fill with blood. In people who suffer from diastolic heart failure, the heart's ventricles lack the capacity to fill with blood as they should.
Diastolic heart failure is also known as heart failure with preserved systolic function or heart failure with normal ejection fraction. There is a lot of debate around this terminology, because some scientists find it inadequate. Remember that the ejection fraction is a percentage of the blood pumped out of a ventricle. In diastolic heart failure, the ventricles do not receive enough blood during the diastole and that is why this percentage remains normal. A normal percentage doesn’t mean a normal amount, and that is why other parameters are measured using cardiac ultrasound, to make the right diagnosis.
Similarities between systolic and diastolic heart failure
Systolic and diastolic heart failure share two main causes: high blood pressure and coronary artery disease. The former is responsible for making the heart to work under pressure, while the second makes the coronary arteries stiff, narrow, or even blocked, which prevents blood from reaching and supplying the heart muscle.
It’s also important to note that both systolic and diastolic left-sided heart failure can eventually contribute to the development of right-side heart failure, so immediate diagnosis and treatment are required to prevent this progression.
Another similar thing is the diagnostic approach. In order to determine which type of heart failure you have, doctors will measure your ejection fraction, as well as other important parameters of heart function, primarily using cardiac ultrasound imaging.
When a person’s ejection fraction is below 40 percent, they are likely to have systolic heart failure. However, if a person has a normal ejection fraction but still shows signs of heart failure, they more likely have diastolic heart failure.
Systolic and diastolic heart failure can also share similar medical interventions as part of a person’s treatment plan. If they are caused by hypertension and/or coronary artery disease, the treatment of these conditions can help slow down the progression of the heart failure. Coronary bypass and stent placement are most commonly used to treat coronary artery disease, while hypertension can be kept under control with medications.
If any of these conditions advances beyond the point of treatment, patients might be up for a heart transplant.
Some of the medications that can be used in both types of heart failure include ACE inhibitors, inotropes, digoxin, mineralocorticoid receptor antagonists, Angiotensin II Receptor Blockers (ARBs) and others. The dosage and combination of these medications are very carefully planned, and they must be determined by a cardiologist, individually for each patient.
Differences between systolic and diastolic heart failure
To best explain the differences between the two different types of heart failure, imagine that in systolic heart failure, the heart ventricles can receive blood, but do not have enough power to pump it out, while in diastolic heart failure, the ventricles are unable to receive enough blood in the first place.
Another specific feature of diastolic heart failure is that aging represents a very important risk factor. With aging, the amount of collagen fibers in the heart muscle reduces, and much like the skin, the heart loses its elasticity and flexibility. It becomes more rigid, and therefore prevents normal relaxation of the ventricular muscle during the diastole.
Conclusion
Both systolic and diastolic heart failure are serious medical conditions. Luckily, they can be easily assessed and patients can start with the treatment early in the process. Although systolic and diastolic heart failure have very similar risk factors, signs, and symptoms, their pathophysiology is still very different, and each patient requires an individual approach.
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