19.1 Heart Failure
3 min read•june 18, 2024
is a complex condition where the heart can't pump blood effectively. It involves impaired , increased , and . These changes lead to decreased and various compensatory mechanisms, including .
Understanding requires knowledge of cardiac function and adaptation. Key concepts include , the , and . Heart failure can manifest as systolic or , each with distinct characteristics and impacts on heart function.
Heart Failure
Mechanisms of heart failure
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- Impaired contractility leads to decreased cardiac output, reduced (percentage of blood pumped out of the ventricle with each contraction), and increased (volume of blood remaining in the ventricle at the end of systole)
- Increased afterload results from increased (resistance to blood flow in the peripheral blood vessels), increased ventricular wall tension, and decreased (volume of blood ejected from the ventricle with each contraction)
- Ventricular remodeling involves (thickening of the heart muscle), (enlargement of the ventricles), and altered ventricular geometry (changes in the shape of the ventricles)
- can lead to further deterioration of heart function over time
- Neurohormonal activation includes:
- (RAAS) activation leads to vasoconstriction (narrowing of blood vessels) and sodium and water retention
- activation causes increased , increased contractility, and vasoconstriction
Cardiac Function and Adaptation
- Preload refers to the volume of blood in the ventricles at the end of diastole, influencing initial stretch of cardiac muscle fibers
- The Frank-Starling mechanism describes how increased preload leads to increased , helping the heart adapt to changes in blood volume
- Cardiac output is the product of stroke volume and heart rate, representing the amount of blood pumped by the heart per minute
- Heart failure can manifest as:
- , characterized by reduced contractility and
- Diastolic dysfunction, where the ventricles have difficulty relaxing and filling properly
- are hormones released by the heart in response to increased wall stress, playing a role in regulating blood volume and pressure
Signs and symptoms of heart failure
- (shortness of breath) manifests as exertional dyspnea (during physical activity), (when lying down), and (sudden episodes at night)
- Fatigue and weakness occur due to reduced cardiac output and decreased oxygen delivery to tissues
- Edema (fluid accumulation) presents as peripheral edema (swelling in the legs and ankles) and (fluid in the lungs)
- is the visible bulging of the jugular veins in the neck, indicating elevated venous pressure
- Cardiac enlargement can be detected by physical examination or imaging studies
- is an abnormal heart sound heard during diastole, often described as a "ventricular filling sound"
- are abnormal lung sounds caused by fluid accumulation in the lungs
- is an increased heart rate, often a compensatory mechanism in heart failure
- Decreased exercise tolerance results from the heart's inability to meet the body's increased oxygen demands during physical activity
Causes and diagnosis of heart failure
- Primary causes:
- leads to (heart attack) and (weakened heart muscle due to inadequate blood supply)
- Hypertension (high blood pressure) increases the workload on the heart
- , such as stenosis (narrowing) or regurgitation (leaking), can cause heart failure
- are diseases of the heart muscle, including dilated (enlarged and weakened), hypertrophic (thickened), and restrictive (stiff and less compliant) types
- (abnormal heart rhythms) can impair cardiac function
- are structural abnormalities present at birth that can lead to heart failure
- Diagnostic methods:
- Physical examination includes for S3 gallop and pulmonary crackles, assessment of jugular venous pressure, and evaluation of peripheral edema
- Chest X-ray can reveal (enlarged heart) and pulmonary congestion (fluid in the lungs)
- (ECG) can detect arrhythmias and provide evidence of myocardial infarction or ischemia
- assesses ventricular function, measures ejection fraction, and evaluates valvular function
- Cardiac biomarkers, such as (BNP) or (NT-proBNP), are elevated in heart failure, while may be elevated in acute settings (e.g., myocardial infarction)
Key Terms to Review (51)
Afterload: Afterload is the pressure the heart must work against to eject blood during systole. It is primarily determined by vascular resistance in the arteries.
Arrhythmias: Arrhythmias refer to any abnormal or irregular heart rhythm that occurs due to disruptions in the electrical activity of the heart. These disturbances in the heart's normal pacing can lead to a wide range of symptoms and potentially serious complications if left untreated.
Auscultation: Auscultation is the act of listening to the internal sounds of the body, such as the heart, lungs, and other organs, using a stethoscope or other medical device. It is a crucial diagnostic tool in healthcare, particularly in the context of heart failure assessment.
B-type Natriuretic Peptide: B-type natriuretic peptide (BNP) is a hormone produced primarily by the ventricles of the heart in response to increased wall stress and pressure. It is a biomarker used to diagnose and monitor heart failure, as its levels rise when the heart is under strain.
Cardiac output: Cardiac output is the volume of blood the heart pumps per minute. It is a critical parameter in assessing cardiovascular health and function.
Cardiac Output: Cardiac output is the volume of blood pumped by the heart per minute. It is a critical measure of the heart's pumping ability and a key determinant of tissue perfusion and oxygen delivery throughout the body. This term is essential in understanding the fundamental mechanics of the cardiovascular system and its role in various cardiovascular conditions and their management.
Cardiac Remodeling: Cardiac remodeling refers to the structural and functional changes that occur in the heart in response to various pathological conditions, such as heart failure, hypertension, or myocardial infarction. This process involves alterations in the size, shape, and composition of the heart, which can ultimately impact its ability to effectively pump blood throughout the body.
Cardiomegaly: Cardiomegaly is the medical term used to describe an abnormal enlargement or thickening of the heart muscle, often as a result of various underlying conditions affecting the cardiovascular system. This term is particularly relevant in the context of heart failure, as cardiomegaly can be both a cause and a consequence of this disorder.
Cardiomyopathies: Cardiomyopathies are a group of diseases that primarily affect the heart muscle, causing it to become enlarged, thick, or rigid. These structural and functional changes in the heart can impair its ability to pump blood effectively, leading to heart failure and other complications.
Congenital Heart Defects: Congenital heart defects are structural abnormalities of the heart or major blood vessels that are present at birth. These defects can range in severity from minor to life-threatening, and they can affect the heart's ability to pump blood effectively throughout the body, leading to various complications related to heart failure.
Contractility: Contractility is the intrinsic ability of cardiac muscle fibers to contract at a given fiber length. It is a crucial determinant of the heart's pumping efficiency.
Coronary Artery Disease: Coronary artery disease is a condition in which the major blood vessels that supply the heart become damaged or diseased, often due to a buildup of fatty deposits called plaque. This can restrict blood flow to the heart muscle, leading to various cardiovascular complications and potentially life-threatening events.
Diastolic Dysfunction: Diastolic dysfunction refers to the impaired ability of the heart's ventricles to fill with blood during the relaxation (diastolic) phase of the cardiac cycle. This can lead to a reduction in the heart's pumping efficiency and contribute to the development of heart failure.
Dyspnea: Dyspnea is the medical term for shortness of breath or difficulty breathing. It is a subjective experience of an uncomfortable or labored breathing sensation that can arise in various medical conditions affecting the respiratory, cardiovascular, or neuromuscular systems.
Echocardiography: Echocardiography is a non-invasive imaging technique that uses high-frequency sound waves, or ultrasound, to produce real-time images of the heart's structure and function. It is a crucial diagnostic tool in the evaluation and management of various cardiovascular conditions, including heart failure and fluid volume excess associated with renal disorders.
Ejection fraction: Ejection fraction (EF) is the percentage of blood pumped out of the left ventricle with each heartbeat. It is a key measure in diagnosing and assessing the severity of heart failure.
Ejection Fraction: Ejection fraction is a measure of the percentage of blood that is pumped out of the heart's main pumping chamber, the left ventricle, with each contraction. It is a crucial indicator of the heart's overall pumping ability and is commonly used to assess cardiac function in various cardiovascular conditions.
Electrocardiogram: An electrocardiogram (ECG or EKG) is a diagnostic test that records the electrical activity of the heart. It is a crucial tool used to assess heart health and detect various cardiac conditions, including dysrhythmias, hypertension, and heart failure.
End-Systolic Volume: End-systolic volume (ESV) refers to the amount of blood remaining in the ventricles of the heart at the end of the systolic phase, or the contraction phase of the cardiac cycle. It is an important measure of cardiac function and a key indicator in the assessment of heart failure.
Frank-Starling Mechanism: The Frank-Starling mechanism is a fundamental principle in cardiac physiology that describes the relationship between the volume of blood entering the heart (preload) and the force of contraction of the heart muscle (cardiac output). It explains how the heart can adjust its pumping ability to match the body's changing demands for blood flow.
Heart failure: Heart failure is a condition where the heart cannot pump enough blood to meet the body's needs. It can result from various cardiovascular diseases and requires medical management.
Heart Failure: Heart failure is a condition in which the heart is unable to pump blood effectively, leading to a reduced ability to meet the body's oxygen and nutrient demands. This term is closely connected to the topics of unclassified antidysrhythmics, angiotensin-converting enzyme (ACE) inhibitors, drugs affecting the renin-angiotensin-aldosterone system, oxygenation and gas exchange, and various diuretics, as these medications and physiological processes are often involved in the management and treatment of heart failure.
Heart failure with preserved ejection fraction (HFpEF): Heart failure with preserved ejection fraction (HFpEF) is a condition where the heart's left ventricle retains its ability to contract but has impaired relaxation, leading to insufficient blood filling. Despite normal ejection fraction, patients experience symptoms of heart failure.
Heart failure with reduced ejection fraction (HFrEF): Heart failure with reduced ejection fraction (HFrEF) is a condition where the heart muscle is weakened and cannot pump blood effectively, leading to an ejection fraction of 40% or less. This type of heart failure often results from damage to the heart muscle due to conditions like coronary artery disease or myocardial infarction.
Heart rate: Heart rate is the number of times the heart beats per minute (bpm). It is a crucial indicator of cardiovascular health and is influenced by various factors including medication.
Ischemic Cardiomyopathy: Ischemic cardiomyopathy is a type of heart muscle disease caused by reduced blood flow and oxygen supply to the heart, typically due to coronary artery disease. This impairs the heart's ability to pump blood effectively, leading to heart failure.
Jugular Venous Distension: Jugular venous distension (JVD) refers to the visible bulging or swelling of the veins in the neck, specifically the internal jugular veins, due to an increase in the pressure within these vessels. This is an important clinical sign that can provide valuable information about the underlying cardiovascular and hemodynamic status of a patient, particularly in the context of heart failure.
JVD is a direct reflection of the pressure in the right side of the heart, specifically the right atrium, and can indicate the presence of right heart dysfunction or volume overload.
Myocardial Hypertrophy: Myocardial hypertrophy is the thickening and enlargement of the heart muscle, specifically the myocardium. This condition is often a compensatory response to various cardiovascular stressors, such as high blood pressure or heart valve disorders, and is closely linked to the development of heart failure.
Myocardial Infarction: Myocardial infarction, commonly known as a heart attack, is a condition where the blood supply to a part of the heart muscle is suddenly blocked, typically due to a blood clot. This disruption in blood flow can cause damage or death to the affected heart tissue, impairing the heart's ability to pump blood effectively.
N-terminal pro-BNP: N-terminal pro-BNP (N-terminal pro-brain natriuretic peptide) is a biomarker that is measured to assess heart function and aid in the diagnosis and management of heart failure. It is a precursor to the active hormone BNP, which is released by the heart in response to increased pressure and stretching of the cardiac chambers.
Natriuretic Peptides: Natriuretic peptides are a group of hormones produced primarily by the heart that play a crucial role in regulating fluid and electrolyte balance, as well as cardiovascular function. These peptides are closely associated with the pathophysiology and management of heart failure, a condition characterized by the heart's inability to effectively pump blood throughout the body.
Neurohormonal Activation: Neurohormonal activation refers to the complex interplay between the nervous system and the endocrine system in response to various physiological stressors, particularly in the context of heart failure. It involves the release of hormones and neurotransmitters that help the body adapt to the increased demands placed on the cardiovascular system during heart failure.
Older clients: Older clients are patients typically aged 65 and above who may have unique health considerations due to age-related physiological changes. These changes often necessitate specialized pharmacological approaches.
Orthopnea: Orthopnea is a medical term that describes a condition where a person experiences difficulty breathing when lying flat, and experiences relief when in an upright or semi-upright position. This symptom is often associated with certain medical conditions that affect the cardiovascular or respiratory systems.
Paroxysmal Nocturnal Dyspnea: Paroxysmal nocturnal dyspnea (PND) is a sudden, acute episode of shortness of breath or difficulty breathing that occurs during the night or early morning hours, often waking the individual from sleep. It is a common symptom associated with heart failure, where the heart's inability to effectively pump blood leads to fluid buildup in the lungs, causing respiratory distress.
Preload: Preload is the degree of stretch of the cardiac muscle fibers at the end of diastole, just before contraction. It is influenced by the volume of blood returning to the heart.
Pulmonary Crackles: Pulmonary crackles, also known as rales, are abnormal breath sounds that can be heard during a physical examination of the lungs. They are caused by the sudden opening of small airways and alveoli that have become stiffened or filled with fluid, indicating an underlying respiratory condition.
Pulmonary edema: Pulmonary edema is the accumulation of fluid in the alveoli and interstitial spaces of the lungs, leading to impaired gas exchange. It often results from left-sided heart failure or acute cardiac events.
Pulmonary Edema: Pulmonary edema is a condition where fluid accumulates in the air sacs (alveoli) of the lungs, making it difficult to breathe. This fluid buildup can occur due to various underlying medical conditions, including heart failure, kidney disease, or exposure to certain toxins or medications.
Renin-Angiotensin-Aldosterone System: The renin-angiotensin-aldosterone system (RAAS) is a complex physiological mechanism that regulates blood pressure, fluid balance, and electrolyte homeostasis in the body. It is a crucial system involved in the management of hypertension, heart failure, and other cardiovascular and renal conditions.
S3 Gallop: An S3 gallop, also known as the ventricular gallop, is an abnormal heart sound that occurs during diastole, the filling phase of the cardiac cycle. It is associated with certain cardiovascular conditions, particularly heart failure, and indicates impaired ventricular relaxation and compliance.
Stroke volume: Stroke volume is the amount of blood ejected by the left ventricle of the heart during each contraction. It is a critical measure in understanding cardiac function and overall cardiovascular health.
Stroke Volume: Stroke volume is the amount of blood pumped from the ventricles of the heart with each contraction. It is a critical component of cardiac output, which is the measure of the heart's ability to pump blood throughout the body.
Sympathetic Nervous System: The sympathetic nervous system is a division of the autonomic nervous system that is responsible for the body's fight-or-flight response. It prepares the body to respond to perceived threats or stressful situations by increasing heart rate, blood pressure, and breathing rate, while also diverting blood flow away from the digestive system and towards the muscles.
Systemic Vascular Resistance: Systemic vascular resistance (SVR) is a measure of the resistance to blood flow through the systemic circulation, which includes all blood vessels except those in the pulmonary circulation. It is a crucial factor that influences blood pressure and cardiac output, and is an important consideration in the context of heart failure and shock.
Systolic Dysfunction: Systolic dysfunction refers to the inability of the heart's ventricles to contract effectively and pump blood efficiently throughout the body. This impairment in the heart's pumping ability is a key feature of heart failure, a chronic condition where the heart struggles to meet the body's demands for oxygenated blood.
Tachycardia: Tachycardia refers to a rapid heart rate, typically defined as a resting heart rate exceeding 100 beats per minute. This abnormally fast heart rhythm can have various underlying causes and is an important consideration in several medical conditions and drug therapies.
Troponins: Troponins are a group of regulatory proteins found in the thin filaments of skeletal and cardiac muscle cells. They play a crucial role in the contraction and relaxation of these muscles, making them an important biomarker for the diagnosis and management of heart failure and other cardiovascular conditions.
Valvular Heart Disease: Valvular heart disease refers to any abnormality or malfunction of the heart's valves, which are responsible for controlling the flow of blood through the heart. This can lead to various complications, including heart failure, a key topic in this chapter.
Ventricular Dilation: Ventricular dilation, also known as ventricular enlargement, is a condition where the ventricles of the heart, the lower pumping chambers, become abnormally enlarged or dilated. This can occur as a result of various underlying heart conditions, leading to impaired cardiac function and the development of heart failure.
Ventricular Remodeling: Ventricular remodeling refers to the structural and functional changes that occur in the ventricles of the heart in response to various pathological conditions, such as heart failure or myocardial infarction. This process involves alterations in the size, shape, and composition of the ventricular walls, which can have significant implications for cardiac function and overall cardiovascular health.