Heart failure, or congestive heart failure (CHF), is a very common problem in America. 5.7 million adults in the United States have heart failure. One in nine deaths in 2018 included heart failure as contributing cause. About half of people who develop heart failure die within five years of diagnosis. Heart failure costs the nation an estimated $30.7 billion each year. The frequency of CHF has been increasing steadily. This may be because more people with other forms of heart disease survive longer but are left with damaged hearts, which leads to CHF. Also, as the elderly population increases, there are more people at high risk of developing CHF. Approximately 400,000 new CHF cases occur each year, and it is the most common diagnosis in hospital patients over 65.
The purpose of the heart is to pump blood, which contains oxygen and nutrients, to the rest of the body. CHF is simply the failure of the heart to perform this main function adequately.
CHF occurs when the flow of blood from the heart decreases, or fluid backs-up behind the failing ventricle, or both.
Physicians have several different ways of describing heart failure:
Unilateral heart failure: Because the heart is basically two pumps (right side, left side) in one, either side can fail independently of the other.
• Left-sided heart failure: When the left ventricle can't pump out enough blood, it gets backed up in the lungs, causing pulmonary edema, a buildup of fluid in the lungs. Among other things, this brings about shortness of breath.
• Right-sided heart failure: The right ventricle cannot pump out enough blood, causing fluid to back up in the veins and then in capillaries of the body. Because of the back-up, fluid leaks out of the capillaries and builds up in the tissues, a condition called edema. Edema is especially noticeable in the legs because the lower half of the body drains into the right side of the heart.
Time-dependent heart failure:
• Acute heart failure: This describes heart failure that occurs suddenly. A heart attack can cause acute heart failure if a large enough part of the heart muscle dies. When this happens, the heart cannot pump out enough blood, causing heart failure and pulmonary edema.
• Chronic heart failure: This describes heart failure that develops gradually. The symptoms are subtle at first but become more acute over time.
Phasic heart failure: The heart can fail in either of the two phases of the cardiac cycle — contraction (systole) and rest (diastole).
• Systolic heart failure: The heart has difficulty contracting and pumping out enough blood. This causes weakness, fatigue and decreased ability to exercise. Also known as heart failure with reduced ejection fraction (HFrEF).
• Diastolic heart failure: The heart is unable to fill properly during diastole, usually due to increased filling pressure. This causes systemic or pulmonary edema or both. Also known as heart failure with preserved ejection fraction (HFpEF).
Output vs. demand heart failure:
• High-output heart failure: Cardiac output is normal or a little bit high, but demand for blood flow is abnormally high (hyperthyroidism, anemia, severe infections). The heart is unable to deliver the increased amount of blood and fails.
• Low-output failure: Cardiac output is low, but demand for blood flow is normal. The heart is unable to meet this demand and fails. Low-output failure is more common than high-output failure.
Causes of CHF
CHF is not a specific diagnosis, but is a result of another underlying condition. Finding the underlying condition is important because the treatment often depends on what that condition is. Many conditions can lead to CHF:
High blood pressure (hypertension) increases the work of the heart. The heart has to pump blood against higher resistance and must therefore generate more force. The added strain on the heart muscle can cause failure.
Coronary artery disease causes inadequate oxygen supply to the heart muscle, which can damage or destroy heart muscle tissue, leading to failure.
Valvular heart disease causes improper blood flow through the heart, which increases the heart's workload. There are two main types of faulty heart valves:
• Narrow (stenosis) valves restrict the flow of blood. To generate enough pressure to pump blood through a narrow valve, the heart has to work much harder.
• Leaky (regurgitation) valves allow blood to flow backwards after it has been pumped out. The heart must pump more blood with each heartbeat greatly increasing its workload.
Abnormal heart rhythms (arrhythmias) interrupt the normal filling and pumping cycle. If the heart beats too slow (bradycardia), then not enough blood gets pumped out. If the heart beats too fast (tachycardia), then there is not enough time for the heart to fill with blood. In either case, cardiac output is reduced causing the heart to fail.
A severe decrease in red blood cells (anemia) reduces the supply of oxygen in circulated blood (blood cells carry oxygen). To provide adequate amounts of oxygen to bodily tissues, the heart must circulate blood more frequently. This extra work can cause the heart to fail.
Diseases that affect the heart muscle itself (cardiomyopathy) result in inadequate contraction or weakness of the heart. Diseases that cause cardiomyopathy include:
• Infections (viral, bacterial, AIDS, Lyme disease, rheumatic fever, etc.)
• Toxins (alcohol, cocaine, radiation, chemotherapy, etc.)
• Nutritional deficiencies (thiamine deficiency causing beri-beri)
• Connective tissue disorders (lupus, rheumatoid arthritis, etc.)
• Neuromuscular diseases (muscular dystrophy)
• Infiltrative (amyloidosis, sarcoidosis, cancer)
• Idiopathic (unknown)
• Peripartum cardiomyopathy
Diseases that affect the pericardium (the sac surrounding the heart) restrict the ability of the heart to stretch when it fills. A thickened or scarred sac (constrictive pericarditis) or fluid within the sac (pericardial tamponade) both reduce the ability of the heart to fill.
Birth defects in the formation of the heart (congenital heart disease) produce an additional workload on the heart eventually causing it to fail. These defects involve abnormal formation of the walls between different chambers of the heart (hole in the heart), abnormal formation of the heart valves, or abnormal positions of the blood vessels that bring blood to or from the heart.
Many factors can place an extra burden on an already failed heart. Identifying the precipitating factors is important for directing proper treatment. Precipitating factors include:
• Stopping prescribed medications
• Excessive intake of fluids or salt
• Uncontrolled hypertension
• Heart attack
• Ischemia (lack of blood to heart muscle)
• Cardiac arrhythmia (abnormal heart rhythm)
• Pulmonary embolus (blood clot in lung)
• Hyperthyroidism (overactive thyroid)
• Hypoxia (low level of oxygen in blood usually due to lung disease)
• New heart valve malfunction
When the heart begins to fail, the first thing the body does is activate the sympathetic nervous system. Sympathetic nerve stimulation increases the heart rate and the force of contraction and constricts the body's veins. These factors work together to increase cardiac output. However, sympathetic nerve stimulation also constricts arteries, which increases blood pressure. The increase in pressure forces the heart to work harder and use more oxygen, which is thought to cause further deterioration of the heart over time.
Treatment of CHF
The goal of treatment in CHF is to control the symptoms and treat the underlying cause as well as the precipitating cause. Before prescribing medications, your physician may want you to lose weight and stop smoking. These measures may reduce the workload on the heart as well as control some of the causes of CHF (high blood pressure, coronary artery disease). In addition, reducing the intake of salt and water can improve symptoms and may reduce the need of some medications. Exercise may be helpful to improve overall fitness.
• Diuretics (water pills) are medications used to increase the amount of sodium (Na+) and water released by the kidneys. This reduces the blood volume and the amount of blood that the heart has to pump, helping to reducing its workload. The goal is to maintain ideal weight by eliminating edema.
A major side effect of diuretics is a low potassium (K+) level, which can cause muscle cramping and abnormal heart rhythms. Potassium supplements or potassium-sparing diuretics can be used either alone or in combination with other diuretics.
• Vasodilators are groups of medications that dilate or enlarge blood vessels. During CHF, the blood vessels are often constricted due to the activation of the sympathetic nervous system. When vasodilators are used, they decrease the resistance and blood pressure against which the heart must beat, thus improving heart function. Angiotensin converting enzyme inhibitors (ACE inhibitors) are very effective vasodilators. This is one of the few medications that have actually been shown to prolong life in CHF patients.
• Nitroglycerin dilates veins and can be taken under the tongue, intravenously, by mouth, or by skin patches.
• Calcium channel blockers dilate blood vessels and are sometimes used to treat CHF, especially when clogged arteries to the heart are present. These drugs also tend to decrease the force of the heart's contraction.
• Hydralazine is a vasodilator that acts on arteries. It is used less frequently since ACE inhibitors have been found to be more effective.
• Digitalis medications (digoxin, Lanoxin) increase the force of contraction of the heart muscle and also control abnormal heart rhythms, especially atrial fibrillation and atrial flutter. Therefore, digitalis is most useful when someone with atrial fibrillation or atrial flutter has CHF
• Beta blockers have been found to be useful for CHF. By blocking the beta-adrenergic receptors of the sympathetic nervous system, the heart rate and force of contraction are decreased.
Occasionally, there are circumstances when surgery can treat CHF. The most common surgical procedures are:
• Heart valve replacement: When a heart valve malfunctions, valve replacement can reverse the symptoms. In some cases, this can be a life-saving procedure.
• Congenital heart defect correction: Surgical repair of congenital heart defects is frequently used to restore normal functioning as much as possible.
• Coronary artery bypass surgery: If Coronary artery disease (CAD) is the cause of CHF, then correcting the CAD with coronary artery bypass grafts can be useful.
• Pacemaker/Defibrillator: In special circumstances, a certain type of pacemaker/defibrillator may be used to improve the efficiency and function of the heart by “resynchronizing” the way the heart contracts. These devices are called Biventricular implantable cardioverter defibrillators or BiV-ICD.
• Heart transplant: When CHF persists and worsens despite maximum therapy, then a heart transplant can be an option. Patients considered for transplants usually suffer from severe symptoms and have one year survival rates of 50 percent. The improvement in anti-rejection drugs (especially cyclosporine) have increased survival from this procedure. There are also some devices that assist the severely failed heart, such as an intra-aortic balloon pump and a left ventricular assist device. These are used as bridges to keep a person alive until a donor heart can be found.
Questions and or comments regarding this week’s health column please contact, Anthony Navone, MD, Non-Invasive Cardiologist at International Heart Institute practicing in the Marcus Daly Cardiology Center at 1200 Westwood Drive, Hamilton, MT 59840. Working together to build a healthier community, visit mdmh.org to learn about the many medical providers at Marcus Daly Memorial Hospital.