22.1 Introduction to Cardiac Emergencies and Shock
2 min read•june 18, 2024
Cardiac emergencies and can be life-threatening. These conditions involve problems with blood flow to the heart or throughout the body. Quick recognition and action are crucial for saving lives and preventing long-term damage.
Understanding the signs and causes of heart attacks, , and different types of shock is key. From chest pain to low blood pressure, these symptoms can help identify emergencies fast. Knowing the underlying issues, like blocked arteries or severe infections, guides proper treatment.
Pathophysiology and Clinical Manifestations of Cardiac Emergencies and Shock
Acute myocardial infarction and unstable angina
occurs when a coronary artery becomes completely blocked, causing myocardial (reduced blood flow) and (tissue death) due to rupture of an (buildup of fatty deposits) with subsequent formation (blood clot), leading to decreased and potential
is caused by partial occlusion of a coronary artery, leading to myocardial without necrosis, which may be due to atherosclerotic plaque rupture, vasospasm (narrowing of blood vessels), or increased myocardial oxygen demand, and can progress to AMI if left untreated
Clinical manifestations of cardiac emergencies and shock
Chest pain or discomfort that may radiate to the jaw, neck, back, or left arm, often described as pressure, squeezing, or tightness
Shortness of breath or
(excessive sweating)
Nausea and vomiting
Lightheadedness or (fainting)
(rapid heart rate) or (slow heart rate)
(low blood pressure)
Altered mental status or confusion
Cool, clammy skin
Decreased urine output (oliguria)
Four main types of shock and their underlying causes
caused by failure of the heart to pump effectively, leading to decreased , which may be due to AMI, (weakened heart muscle), or severe valvular disease (heart valve problems)
occurs when there is a significant loss of (blood or fluid loss), with causes including (bleeding), , or severe burns
characterized by inappropriate (widening of blood vessels) and decreased (reduced blood pressure), with types including:
caused by severe infection leading to systemic inflammation
caused by severe allergic reaction (e.g., to medications or food)
caused by loss of sympathetic tone (nerve function) due to spinal cord injury
occurs when there is an obstruction to blood flow outside of the heart, with causes including:
: blockage of pulmonary arteries by a blood clot (thrombus)
: collapse of the lung and compression of the heart due to air in the pleural space (chest cavity)
: compression of the heart due to fluid accumulation in the pericardial sac (protective covering around the heart)
Key Terms to Review (55)
Acute myocardial infarction: Acute myocardial infarction, commonly known as a heart attack, occurs when blood flow to a part of the heart is blocked for an extended period. This results in damage or death of the heart muscle due to lack of oxygen.
Acute Myocardial Infarction (AMI): Acute myocardial infarction (AMI), commonly known as a heart attack, is a serious medical condition that occurs when the blood supply to a part of the heart muscle is suddenly blocked, typically by a blood clot. This disruption in blood flow leads to damage or death of the affected heart muscle tissue.
American Heart Association: The American Heart Association (AHA) is a non-profit organization dedicated to fighting cardiovascular diseases and promoting heart health through research, education, and advocacy. It plays a crucial role in setting guidelines for the management of cardiovascular conditions.
Anaphylactic Shock: Anaphylactic shock is a severe, whole-body allergic reaction that can be life-threatening. It is a medical emergency characterized by a sudden drop in blood pressure, constriction of the airways, and other potentially fatal symptoms triggered by exposure to an allergen.
Angina: Angina is chest pain or discomfort caused by reduced blood flow to the heart muscle. It is often a symptom of coronary artery disease.
Atherosclerotic Plaque: Atherosclerotic plaque is a buildup of fatty deposits, cholesterol, and other substances within the walls of the arteries, leading to the narrowing and hardening of the blood vessels. This condition is a key contributor to the development of cardiovascular diseases, including heart attacks and strokes.
Bradycardia: Bradycardia is a slower than normal heart rate, typically defined as fewer than 60 beats per minute in adults. It can be a sign of an underlying health issue or a side effect of certain medications.
Bradycardia: Bradycardia is a condition characterized by an abnormally slow heart rate, typically less than 60 beats per minute. This term is relevant in the context of various cardiovascular and pharmacological topics, as it can be a side effect or complication associated with certain medications and disease states.
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 Tamponade: Cardiac tamponade is a life-threatening condition in which fluid accumulation within the pericardial sac, the protective membrane surrounding the heart, causes increased intrapericardial pressure that impairs the heart's ability to fill and pump blood effectively. This disruption of normal cardiac function can lead to shock and cardiovascular collapse if not promptly recognized and treated.
Cardiogenic shock: Cardiogenic shock is a critical condition where the heart fails to pump enough blood to meet the body's needs, often due to severe heart damage. This leads to inadequate oxygen delivery and can result in organ failure.
Cardiogenic Shock: Cardiogenic shock is a life-threatening condition in which the heart is unable to pump enough blood to meet the body's needs, leading to organ failure and potential death. It is a critical complication that can arise from various cardiac emergencies.
Cardiomyopathy: Cardiomyopathy is a group of diseases that affect the structure and function of the heart muscle, making it harder for the heart to pump blood effectively throughout the body. It can lead to various cardiac emergencies and states of shock.
Cardiovascular System: The cardiovascular system is the network of organs and vessels responsible for circulating blood, oxygen, and nutrients throughout the body. It is a vital system that supports the body's overall health and function by delivering essential components to tissues and removing waste products.
Coronary Artery Disease (CAD): Coronary artery disease (CAD) is a condition in which the major blood vessels that supply the heart become damaged or diseased, typically due to a buildup of fatty deposits called plaque inside the arteries. This can restrict blood flow to the heart, leading to chest pain, heart attack, and other cardiovascular complications.
Defibrillation: Defibrillation is a medical procedure used to restore a normal heartbeat by sending an electric pulse or shock to the heart. It is commonly used in life-threatening situations such as cardiac arrest, where the heart is experiencing ventricular fibrillation or pulseless ventricular tachycardia.
Dehydration: Dehydration refers to the condition where the body loses more fluid than it takes in, resulting in an imbalance of water and electrolytes. This term is particularly relevant in the context of osmolality, cardiac emergencies and shock, laxatives and stool softeners, diuretics, and osmotic diuretics, as these topics all involve the regulation and imbalance of bodily fluids.
Diaphoresis: Diaphoresis is the medical term used to describe excessive sweating or perspiration, often associated with various medical conditions or physiological responses.
Distributive shock: Distributive shock is a type of shock that results from an abnormal distribution of blood flow in the smallest blood vessels, leading to inadequate supply of oxygen and nutrients to tissues. It often involves severe systemic vasodilation.
Distributive Shock: Distributive shock is a type of shock characterized by the abnormal distribution of blood flow throughout the body, leading to inadequate tissue perfusion and oxygenation. It occurs when the body's regulatory mechanisms fail to maintain proper blood pressure and blood flow to vital organs.
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.
Dysrhythmia: Dysrhythmia is an abnormality in the rhythm of the heartbeat, which can result from irregular electrical activity in the heart. It can lead to complications such as decreased cardiac output and increased risk of stroke.
Dysrhythmias: Dysrhythmias, also known as cardiac arrhythmias, are abnormal heart rhythms that occur when the electrical signals that coordinate the heart's contractions are disrupted. These irregularities in the heart's rhythm can affect the efficiency of the heart's pumping action, potentially leading to various cardiac emergencies and shock.
Hemodynamics: Hemodynamics refers to the study of the dynamics of blood flow and pressure within the cardiovascular system. It encompasses the principles that govern the movement and distribution of blood throughout the body, including the factors that influence cardiac output, blood pressure, and peripheral resistance.
Hemorrhage: Hemorrhage refers to severe or uncontrolled bleeding, often from a ruptured blood vessel or an organ. It is a critical medical emergency that requires prompt intervention to prevent life-threatening complications in the context of cardiac emergencies and shock.
Hypotension: Hypotension is a medical condition characterized by an abnormally low blood pressure, where the systolic blood pressure falls below 90 mmHg and the diastolic blood pressure falls below 60 mmHg. This can have significant implications on the body's ability to circulate blood and deliver oxygen and nutrients to vital organs.
Hypovolemic shock: Hypovolemic shock is a critical condition where severe blood or fluid loss makes the heart unable to pump enough blood to the body. It can lead to organ failure and requires immediate medical intervention.
Hypovolemic Shock: Hypovolemic shock is a life-threatening condition that occurs when there is a severe loss of blood or fluid volume, leading to inadequate tissue perfusion and oxygenation. This term is crucial in understanding concepts related to fluid volume, intravenous fluid therapy, cardiac emergencies, and shock drugs.
Infarction: Infarction is the death of tissue due to a lack of blood supply, often caused by a blockage in an artery. It commonly occurs in the heart (myocardial infarction) or brain (cerebral infarction).
Intravascular Volume: Intravascular volume refers to the total volume of blood circulating within the blood vessels of the body. It is a critical factor in maintaining proper cardiovascular function and ensuring adequate tissue perfusion.
Ischemia: Ischemia is a condition characterized by insufficient blood flow to tissues, causing a shortage of oxygen and nutrients needed for cellular metabolism. It can lead to tissue damage or dysfunction, particularly in vital organs like the heart.
Ischemia: Ischemia is a condition characterized by a reduced or interrupted blood supply to a specific tissue or organ, leading to a lack of oxygen and nutrient delivery. This term is particularly relevant in the context of cardiac emergencies and the use of nitrates as a therapeutic intervention.
Myocardial Tissue: Myocardial tissue, also known as the myocardium, is the muscular middle layer of the heart wall that is responsible for the heart's pumping action. It is composed of specialized cardiac muscle cells that contract and relax to circulate blood throughout the body.
Necrosis: Necrosis is the premature death of cells and living tissue in the body, often caused by injury, disease, or lack of blood supply. It is a pathological condition that can occur in various tissues and organs, leading to their destruction and dysfunction.
Neurogenic Shock: Neurogenic shock is a type of distributive shock that occurs due to a disruption in the sympathetic nervous system, leading to vasodilation, decreased peripheral vascular resistance, and reduced venous return to the heart, ultimately resulting in decreased cardiac output and hypotension.
Obstructive shock: Obstructive shock occurs when a physical obstruction impedes blood flow, leading to inadequate tissue perfusion and oxygenation. It is a life-threatening condition requiring immediate medical intervention.
Obstructive Shock: Obstructive shock is a type of shock that occurs when there is a mechanical obstruction to blood flow, preventing the heart from effectively pumping blood to the body's tissues. This disruption in blood flow leads to inadequate tissue perfusion and oxygenation, which can have severe consequences if not promptly addressed.
Palpitations: Palpitations refer to the awareness of an abnormal or irregular heartbeat, often described as a fluttering, pounding, or racing sensation in the chest. This term is particularly relevant in the context of cardiac emergencies, the use of beta-adrenergic blockers, and thyroid disorders.
Pulmonary Embolism: Pulmonary embolism is a serious condition in which a blood clot, usually originating in the deep veins of the legs or pelvis, travels to the lungs and blocks one or more of the pulmonary arteries. This can lead to impaired blood flow and oxygen supply to the lungs, potentially causing life-threatening complications.
Septic Shock: Septic shock is a life-threatening condition that occurs when the body's response to a severe infection leads to a dramatic drop in blood pressure and impaired organ function. It is a critical medical emergency requiring immediate treatment to prevent organ failure and death.
Shock: Shock is a life-threatening condition where blood flow and oxygen delivery to tissues are insufficient, leading to cellular and organ dysfunction. It requires immediate medical intervention to prevent irreversible damage.
Stable angina: Stable angina, also known as effort angina, is chest pain or discomfort that typically occurs with activity or stress and is relieved by rest or nitroglycerin. It is caused by reduced blood flow to the heart muscle due to coronary artery disease.
Syncope: Syncope is a sudden, temporary loss of consciousness caused by a temporary decrease in blood flow to the brain. It is a common medical condition that can occur in a variety of contexts, including Alzheimer's disease and cardiac emergencies.
Systemic vascular resistance: Systemic vascular resistance (SVR) is the resistance offered by the systemic blood vessels to the flow of blood from the heart. It is a crucial determinant of blood pressure and cardiac workload.
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.
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.
Tension Pneumothorax: Tension pneumothorax is a life-threatening condition in which air accumulates in the pleural space, causing the lung to collapse and the mediastinum to shift, leading to impaired venous return and circulatory compromise. This condition is particularly relevant in the context of cardiac emergencies and shock, as it can rapidly progress to cardiovascular collapse if not promptly recognized and treated.
Thrombus: A thrombus is a blood clot that forms inside a blood vessel, obstructing the flow of blood through the circulatory system. This term is particularly relevant in the context of understanding clotting and coagulation, as well as cardiac emergencies and shock, as a thrombus can lead to life-threatening complications if not properly managed.
Tissue Hypoperfusion: Tissue hypoperfusion refers to the inadequate supply of oxygenated blood to the body's tissues, leading to a mismatch between tissue oxygen demand and delivery. This imbalance can result in cellular dysfunction and damage if left unaddressed.
Unstable angina: Unstable angina is a condition characterized by sudden chest pain due to reduced blood flow to the heart. It is a medical emergency and can be a precursor to a heart attack.
Unstable Angina: Unstable angina is a type of coronary artery disease characterized by chest pain or discomfort that is unpredictable, often occurring at rest or with minimal exertion. It represents an acute and high-risk form of ischemic heart disease that requires immediate medical attention.
Valvular Dysfunction: Valvular dysfunction refers to the abnormal functioning of the heart's valves, which are responsible for regulating the flow of blood through the chambers of the heart. This condition can lead to various cardiac emergencies and shock states, as the impaired valve function disrupts the efficient pumping and circulation of blood throughout the body.
Vasoconstriction: Vasoconstriction is the narrowing or constriction of blood vessels, specifically the arteries and arterioles, which leads to a decrease in blood flow and blood pressure. This physiological process is an important mechanism in the regulation of blood flow and blood pressure throughout the body.
Vasodilation: Vasodilation refers to the widening or dilation of blood vessels, particularly the arteries and arterioles. This process leads to increased blood flow and reduced vascular resistance, which can have significant implications in various physiological and pharmacological contexts.