Systolic heart failure
Systolic heart failure is a more common type of heart failure than diastolic heart failure. Whereas diastolic heart failure occurs as a result of the heart's inability to relax, systolic heart failure results from the heart's inability to contract. Having an enlarged heart (cardiomegaly) is a common contributing factor to systolic heart failure.
Definition & Facts
There are four chambers in the heart: two ventricles and two atria, and there are four heart valves regulating the flow of blood between the various chambers and blood vessels of the heart. The right side of the heart consists of the right ventricle and right atrium and the left side consists of the left atrium and left ventricle.
The cardiac cycle involves de-oxygenated blood flowing back from the venae cavae into the right atrium. The right atrium, once full of blood, contracts and blood flows into the right ventricle. When the right ventricle becomes engulfed with blood, it contracts and this contraction propels blood into the pulmonary artery where it then travels into the lungs.
When blood returns from the lungs through the pulmonary veins, it is full of oxygen and fills the left atrium. The left atrium contracts and pushes blood into the left ventricle, which then contracts and pushes blood rich with oxygen out into the aorta. The right atrium concurrently fills with de-oxygenated blood, repeating the cycle.
Systole is the part of the cardiac cycle in which the heart contracts. Systole occurs in response to electrical impulses and has two components: atrial systole and ventricular systole. Atrial systole occurs when the cardiac muscles of the right and left atria contract whereas ventricular systole involves the contraction of the cardiac muscles of the right and left ventricle.
Systolic heart failure typically affects the left side of the heart and the inability of the left ventricle to contract, which means that oxygen rich blood cannot reach vital organs. Left ventricle systolic failure is the most common type of heart failure, accounting for 60% of heart failure cases according to the Cleveland Clinic.
Symptoms & Complaints
The back up of blood also results in blood and fluid accumulating and depositing in various tissues, causing swelling of the legs, ankles, and other extremities (edema). Due to impaired function of the kidneys, the filtration process is compromised, and water and sodium retention occur.
Additional symptoms include increased heart rate (tachycardia) because of the heart pumping faster to increase the volume of blood that is circulating in order to compensate for the weakness of the heart's contractions. A person may become mentally disoriented (confusion) and experience memory loss because of reduced blow flow to the brain.
Systolic heart failure has its basis in the weakening of the heart muscle and a wide array of heart abnormalities and diseases can cause this weakening. A leading cause of such weakening of the heart muscle is coronary artery disease. When atherosclerosis – which is the narrowing of the arteries due to build up of arterial plaque – occurs in the coronary arteries, there is reduced blood flow to the cardiac muscles, which causes them to become weakened and less able to contract.
Valvular heart diseases may also cause systolic heart failure. Types of valvular heart disease include aortic valve stenosis and mitral valve stenosis in which the aortic and mitral valves, respectively, cannot open properly. Mitral valve regurgitation and aortic valve regurgitation occur when the respective valves cannot close properly.
Sometimes the heart muscle is weakened due to inflammation– a condition called myocarditis. This can occur due to infections with various viruses and bacteria though most often occurs due to viral infections. Such viral infections known to cause myocarditis include Epstein-Barr virus infection and HIV. Streptococcus bacteria can also cause myocarditis as can certain autoimmune diseases like lupus and rheumatoid arthritis in which the body's immune system perceives its own tissues as invaders and attacks them.
Diagnosis & Tests
Echocardiography is a standard diagnostic test in assessing heart disease. An echocardiogram can distinguish between diastolic heart failure and systolic heart failure. It can show the presence of an aneurysm of the left ventricle which would indicate that heart failure occurred due to the lack of adequate oxygen to the heart muscles.
Cardiac catheterization is another diagnostic tool that can diagnose coronary artery disease as an underlying cause of the systolic heart failure. An angiography will be performed as part of the cardiac catheterization in which a contrast dye is injected into the veins and is then visible in X-rays. These tests locate blockages, analyze blood pressure in the heart, determine the ability of the heart muscles to contract, and can also be used to take a biopsy if a tissue sample is needed.
A BNP (brain natriuretic peptide) test involves taking a blood sample and testing it with a machine for the presence of BNP in the blood, which is a substance secreted in response to stretching of the heart muscles which occurs during heart failure. The process can take under 15 minutes and is successful in detecting heart failure over 80% of the time.
Treatment & Therapy
Systolic heart failure can be addressed through a variety of lifestyle changes, medications, and procedures. People with systolic heart failure should consume a low sodium diet. They should certainly quit smoking. Maintaining a healthy weight is also crucial for recovery and cardiac rehabilitation.
Angiotensin-converting-enzyme ACE inhibitors is a standard, universally prescribed medication for patients with systolic heart failure. These medications are antihypertensive drugs which lower high blood pressure. Beta blockers are also prescribed and improve outcomes; they work to counteract cardiac arrhythmias. Diuretics help address any edema caused by the blockages of blood and fluid in the body's lungs and tissues by encouraging fluid removal.
Prevention & Prophylaxis
Another important preventative tool is getting regularly screened if a family history of heart disease exists or if one already has a pre-existing condition that increases one's risk of systolic heart failure. Getting vaccinated for certain viruses and pursuing prompt treatment if ill with an upper respiratory tract infection can help decrease the risk of myocarditis which underlies some cases of systolic heart failure.