cardio

Comprehensive Study Guide: Cardiovascular System and Related Alterations

This study guide compiles and expands upon the provided outlines and documents, organizing key concepts from chapters on oxygen transport, blood flow, blood pressure, cardiac function, alterations in cardiac function, heart failure, and cardiac dysrhythmias. It includes filled-in details based on standard pathophysiology knowledge, with structured sections, bullet points, tables for comparisons, and key questions for review. Topics are sequenced by chapter number for logical progression.

Chapter 13: Alterations in Oxygen Transport

What is Blood?

• Blood: A connective tissue composed of:

  • Plasma: Liquid matrix (55% of blood volume) mostly water with proteins, electrolytes, etc.

  • Formed Elements: Cells and cell fragments, including erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets).

• Functions of Blood:

  • Transport of oxygen, nutrients, hormones, and waste.

  • Regulation of body temperature, pH, and fluid balance.

  • Protection via clotting and immune responses.

Erythrocytes

• Structure:

  • RBCs are biconcave disks without nuclei, specialized for gas transport.

  • Contain hemoglobin (Hb), an iron-containing protein that binds oxygen (O2) and carbon dioxide (CO2).

• Carbonic Acid-Bicarbonate Buffer System: Helps maintain blood pH by converting CO2 to bicarbonate.

  • Equation: CO2 + H2O = H2CO3 = H+ + HCO3–.

Erythrocyte Life Cycle:

• Erythropoietin (EPO): Hormone produced mainly by kidneys in response to hypoxia, stimulates RBC production in bone marrow.

• Erythrocyte Production: Occurs in red bone marrow (erythropoiesis), takes about 7 days; regulated by EPO, iron, vitamin B12, and folate.

• Erythrocyte Destruction: Old RBCs (lifespan ~120 days) are phagocytosed by macrophages in spleen/liver; components recycled (e.g., iron for new Hb).

Blood Gas Transport

• Oxygen Transport:

  • 97% bound to Hb in RBCs (oxyhemoglobin); 3% dissolved in plasma.

  • Influenced by O2-hemoglobin dissociation curve (shifts right with acidosis, hyperthermia, high CO2).

• Carbon Dioxide Transport:

  • 70% as bicarbonate (HCO3–) in plasma.

  • 20-30% bound to Hb (carbaminohemoglobin).

  • 7% dissolved in plasma.

Alterations in Transport

• Anemia: Reduced oxygen-carrying capacity due to low RBCs, Hb, or abnormal Hb.

• Hypoxia: Tissue oxygen deficiency; can result from anemia, poor circulation, or lung issues.

• Polycythemia Vera: Overproduction of RBCs leading to increased blood viscosity.

Erythrocyte Disorders

• Anemia:

  • Absolute Anemia: True decrease in RBC mass (e.g., due to loss, destruction, or underproduction).

  • Relative Anemia: Apparent decrease due to plasma volume expansion (e.g., pregnancy, fluid overload).

• General Effects of Anemia:

  • Symptoms include fatigue, pallor, tachycardia, dyspnea.

  • Compensatory increase in cardiac output and respiration.

Physiological Adaptations

• Increased EPO, heart rate, and 2,3-DPG (shifts O2 curve right for better tissue release).

Levels of Anemia:

• Mild: Hb 10-12 g/dL.

• Moderate: Hb 7-10 g/dL.

• Severe - Hb <7 g/dL (life-threatening).

Types of Anemia

Key Questions

• What factors are necessary for normal RBC production? (EPO, iron, B12, folate, functional bone marrow).

• How are oxygen and carbon dioxide transported in the circulation? (O2: mostly on Hb; CO2: bicarbonate, Hb, dissolved).

• How are laboratory tests used to detect anemia and polycythemia? (CBC, reticulocyte count, iron studies, EPO levels, B12/folate).

• What are the general effects of anemia on body systems? (Cardiovascular strain, tissue hypoxia, compensatory mechanisms).

• How are history, clinical manifestations, and laboratory studies used to differentiate the various forms of anemia? (E.g., microcytic vs. macrocytic, iron levels).

• How are history, clinical manifestations, and laboratory studies used to differentiate the various forms of polycythemia? (EPO levels high in secondary, low in vera).

• What are the appropriate treatment measures for each of the common types of anemia and polycythemia? (Refer to above tables).

Chapter 15: Alterations in Blood Flow

What is the Circulatory System?

• Circulatory System: Transports blood, oxygen, nutrients, and removes waste.

  • Components:

  • Heart

  • Blood vessels

  • Blood

• Organization:

  • Closed System: Includes arteries, veins, and capillaries.

  • Lymphatics System: Open system draining interstitial fluid and involved in immune function.

Concepts of Hemodynamics

• Hemodynamics: The study of blood flow dynamics.

• Influenced by:

  • Pressure gradients

  • Vessel compliance

  • Blood viscosity

• Key Factors: Cardiac output, vascular tone, and blood volume.

Physics of Circulation

• Blood Flow: Volume per unit time described by the equation: $Q = \frac{AP}{R}$, where:

  • AP = Pressure difference

  • R = Resistance.

• Blood Pressure: The force exerted by blood on vessel walls.

• Blood Resistance: Opposition to flow, mainly occurring in arterioles.

Laws that Govern Blood Flow

• Length: Longer vessels increase resistance (Poiseuille's law: $R \propto L$).

• Diameter: Resistance is inversely proportional to radius to the fourth power ($R \propto \frac{1}{r^4}$); small changes in arterioles greatly affect flow.

• Viscosity: Thicker blood increases resistance ($R \propto n$).

Turbulence

• Laminar Flow: Smooth, layered flow in healthy vessels.

• Turbulent Flow: Chaotic flow present in aneurysms or stenosis; may cause bruits and thrills.

Capillary Dynamics

• Diffusion: Gases and nutrients cross via concentration gradients.

• Filtration: Fluid movement driven by hydrostatic vs. oncotic pressure (Starling forces).

Central Mechanisms of Blood Flow

• Sympathetic Nervous System: Mediated via norepinephrine and epinephrine leading to vasoconstriction/dilation.

  • Cardiovascular center in the medulla regulates via baroreceptors/chemoreceptors.

  • α1 Adrenergic Receptors: Cause vasoconstriction in arterioles.

  • β2 Adrenergic Receptors: Cause vasodilation in skeletal muscle.

Intrinsic Mechanisms of Blood Flow

• Myogenic Response: Vessels constrict in response to high pressure and dilate with low pressure.

• Metabolic Regulation: Local factors like CO2, H+, adenosine cause vasodilation.

• Endothelial Factors: Nitric oxide for dilation and endothelin for constriction.

Geriatric Considerations

• Reduced vessel elasticity (arteriosclerosis).

• Increased risk of atherosclerosis.

• Orthostatic hypotension due to baroreceptor insensitivity.

• Polypharmacy affecting blood flow.

Alterations of Blood Flow

Blood Vessel Obstructions

• Arterial Obstruction: Reduces distal perfusion.

  • Thrombus: Clot formation based on Virchow's triad: stasis, hypercoagulability, endothelial injury.

  • Etiology: Often related to atherosclerosis, atrial fibrillation.

  • Pathogenesis: Involves platelet aggregation and fibrin mesh formation.

  • Clinical Manifestations: Symptoms includes pain, pallor, and pulselessness (the 6 P's of acute ischemia).

  • Treatment: Can involve the use of anticoagulants, thrombolytics, or surgery.

• Other Causes of Obstruction:

  • Vasospasms: Sudden constriction (e.g., Raynaud's).

  • Emboli: Traveling clots (e.g., from DVT to lungs).

  • Vasculitis: Inflammation (e.g., giant cell arteritis).

  • Mechanical Compression: Due to tumors or compartment syndrome.

Structural Alterations of Blood Vessels

• Arteriosclerosis: Hardening of arteries due to aging/hypertension.

• Atherosclerosis: Plaque build-up in the intima of vessels.

• Aneurysms: Localized dilation (e.g., AAA due to weakened wall).

Atherosclerosis

• Etiology: Resulting from endothelial injury caused by hypertension, smoking.

• Pathogenesis: Involves LDL oxidation, formation of foam cells, and fibrous plaque development.

• Risk Factors:

  • Modifiable: Smoking, unhealthy diet, inactivity, hypertension, diabetes.

  • Nonmodifiable: Age, male gender, family history.

• Clinical Manifestations: Can include angina, claudication, and strokes.

• Treatment: Often includes medications such as statins and antiplatelets, alongside lifestyle changes and revascularization.

Key Questions

• How do the structures of arteries, veins, capillaries, and lymphatics differ, and how do these differences reflect the functions of each? (Arteries have thick walls for high pressure; veins have valves for blood return; capillaries have thin walls for exchange; lymphatics absorb fluid/proteins).

• What is the relationship among vessel resistance, blood pressure, and blood flow? (Flow is inversely proportional to resistance; pressure drives flow).

• How is vascular resistance regulated centrally by the autonomic nervous system and locally by tissues? (Central control by SNS; local regulation by metabolites).

• How do arterial obstructions develop? (Through thrombus or embolus forming on atherosclerotic plaque).

• What are the clinical consequences of acute and chronic arterial obstruction? (Acute leads to ischemia/infarction; chronic leads to claudication/atrophy).

Chapter 16: Alterations in Blood Pressure

What is Blood Pressure?

• Blood Pressure (BP): The force exerted by circulating blood against arterial walls.

  • Systemic Arterial Pressure: Pressure in large arteries.

  • Arterial Blood Pressure (ABP): Measured as systolic/diastolic.

  • Cardiac Output (CO): Volume pumped by the heart per minute, calculated by the equation: $CO = HR \times SV$.

  • Systemic Vascular Resistance (SVR): Opposition to blood flow in vessels, calculated as: $SVR = \frac{(MAP - CVP)}{CO}$.

  • Stroke Volume (SV): Volume ejected per beat, calculated as: $SV = EDV - ESV$.

Blood Pressure Characteristics

• Systolic Blood Pressure (SBP): Peak pressure during ventricular contraction.

• Diastolic Blood Pressure (DBP): Lowest pressure during heart relaxation.

• Pulse Pressure (PP): Defined as SBP - DBP, with a normal range of 30-40 mmHg.

• Mean Arterial Pressure (MAP): Average pressure, calculated by: $MAP = DBP + \frac{(PP)}{3}$ (drives tissue perfusion).

Regulating Blood Pressure

• Regulation Methods:

  • Short-Term Regulation: Involves neural mechanisms (baroreceptors in carotids/aorta signal the medulla for autonomic adjustments) and hormonal factors (e.g. epinephrine for vasoconstriction).

  • Long-Term Regulation: Primarily renal mechanisms (renin-angiotensin-aldosterone system, ADH), manages fluid balance.

• RAAS System: Renin from kidneys leads to angiotensin II, causing vasoconstriction and aldosterone secretion for sodium retention, increasing fluid volume and blood pressure.

Alterations in Blood Pressure

• Normal BP: SBP <120 mmHg and DBP <80 mmHg.

• Elevated BP: SBP 120-129 mmHg and DBP <80 mmHg.

• Grade 1 Hypertension: SBP 130-139 mmHg or DBP 80-89 mmHg.

• Grade 2 Hypertension: SBP 140-179 mmHg or DBP 90-109 mmHg (note: the outlined standard differed, severe defined as >160/100 mmHg).

• Hypertensive Crisis: SBP ≥180 mmHg or DBP ≥120 mmHg.

Hypertension

• Primary Hypertension: Essential/idopathic (90% of cases), often multifactorial in etiology.

• Secondary Hypertension: Due to an identifiable cause, such as renal disease or endocrine disorder.

Primary Hypertension

• Etiology: Genetic and environmental factors lead to vascular remodeling and Na+ sensitivity.

• Risk Factors:

  • Modifiable: Obesity, high salt diet, inactivity, alcohol use, smoking.

  • Nonmodifiable: Age >65, family history, African American race.

• Outcomes: Can lead to cardiovascular disease, stroke, kidney damage, and retinopathy.

• Treatment: Includes lifestyle changes (e.g., DASH diet, exercise) and medications (e.g., ACE inhibitors, beta-blockers, diuretics).

Secondary Hypertension

• Etiology: Can stem from conditions like renal artery stenosis, hyperaldosteronism, pheochromocytoma, or Cushing's syndrome.

• Pathogenesis: Underlying disorder increases systemic vascular resistance or volume (e.g., renal stenosis activating RAAS).

Classifying Hypertension

• Hypertensive Emergency: A crisis with end-organ damage (e.g., encephalopathy, myocardial infarction).

• Hypertensive Urgency: A crisis without acute damage; typically managed on an outpatient basis.

Low Blood Pressure

• Hypotension: Defined as MAP <65 mmHg, which impairs tissue perfusion.

• Orthostatic Hypotension: Characterized by a drop in SBP >20 mmHg upon standing; causes may include dehydration, medications, or autonomic dysfunction.

• Management: Focuses on hydration, compression stockings, and medication adjustments.

Key Questions

• How do changes in cardiac output and systemic vascular resistance affect blood pressure? (BP = CO × SVR; increases in either raise BP).

• How is blood pressure regulated on both short- and long-term bases? (Short-term: Neural/hormonal; Long-term: Renal/volume).

• What are the risk factors for developing primary hypertension? (As discussed above).

• How is secondary hypertension defined, and what are common etiologies? (Identifiable causes, e.g., renal or endocrine disorders).

• How is hypertension detected, classified, and managed? (Multiple readings; staged per guidelines; involves both lifestyle and medication interventions).

• What are the end-organ consequences of inadequately controlled hypertension? (Heart failure, stroke, chronic kidney disease, aneurysms).

• What is the distinction between hypertensive emergency and urgency, and what are their management strategies? (Emergency: Requires IV meds in an ICU; urgency: Managed with oral medications gradually).

• What are the risk factors for orthostatic hypotension, and how is the condition managed? (Age, medications, dehydration; management includes fluids and slow position changes).

Chapter 17: Cardiac Function

1. ### Cardiovascular Anatomy

• Heart consists of:

  • Endocardium: Inner lining.

  • Myocardium: Muscle layer responsible for contractions.

  • Epicardium: Outer surface.

  • Pericardial Sac: Protective sac surrounding the heart.

• Blood Flow:

  • Right heart pumps deoxygenated blood to the lungs.

  • Left heart pumps oxygenated blood to systemic circulation.

1. ### Cardiac Cycle

• Phases:

  • Ventricular filling (diastole).

  • Isovolumic contraction.

  • Ventricular ejection.

  • Isovolumic relaxation.

• Atrial Pressure Waves:

  • 'a' = Atrial contraction.

  • 'c' = AV valve bulging.

  • 'v' = Atrial filling.

1. ### Coronary Circulation

• Coronary Arteries: Arise from the aortic root.

  • Right coronary artery supplies the right heart structures.

  • Left coronary artery branches into left anterior descending (LAD) and circumflex arteries.

• Most coronary blood flow occurs during diastole.

1. ### Cardiac Myocytes

• Two cell types:

  • Mechanical: Pumping cells.

  • Electrical: Impulse conduction cells.

• Cells act as a syncytium via gap junctions, allowing coordinated contractions.

1. ### Molecular Basis of Contraction

• Sliding Filament Mechanism: Actin and myosin interactions shorten sarcomeres during contraction.

• Relaxation requires active calcium removal from the cytoplasm.

1. ### Cardiac Energy Metabolism

• Primary Energy Sources: Include fatty acids and glucose.

• Creatine Phosphate: Serves as an immediate ATP reserve for muscle contraction.

1. ### Cardiac Electrophysiology

• Resting Membrane Potential: Approximately -90 mV.

• Action Potential Phases: Involves movement of Na+, Ca2+, and K+ ions.

• Conduction Pathway:

  • SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers.

1. ### Electrocardiography (ECG)

• P Wave: Represents atrial depolarization.

• PR Interval: Indicates AV conduction time.

• QRS Complex: Represents ventricular depolarization.

• T Wave: Represents ventricular repolarization.

1. ### Determinants of Cardiac Output

• Cardiac Output: Determined by the formula $Cardiac Output = Heart Rate \times Stroke Volume$.

• Stroke Volume Determinants: Depend on preload, contractility, and afterload.

1. ### Diagnostic Tests

• Technologies to assess cardiac structure and function include:

  • ECG

  • Echocardiography

  • MRI

  • CT scan

  • Nuclear cardiography

  • Cardiac catheterization

Chapter 18: Alterations in Cardiac Function

1. Coronary Heart Disease (CHD)

• CHD results from insufficient oxygen delivery to the myocardium due to atherosclerosis.

• Risk Factors: Include age, male gender, family history, hyperlipidemia, diabetes, smoking, hypertension, and obesity.

• Atherosclerosis begins with:

  • Endothelial injury

  • Inflammation

  • LDL oxidation, leading to foam cell and plaque formation.

• Clinical Syndromes: Can manifest as:

  • Stable angina: Chest pain with exertion relieved by rest, without permanent damage.

  • Unstable angina: Results from plaque disruption and partial occlusion.

  • Myocardial infarction (MI): Prolonged ischemia resulting in myocardial necrosis.

• Symptoms of MI: Severe chest pain, nausea, diaphoresis, dyspnea, inflammation.

• Diagnosis involves assessing ECG changes and biomarkers (Troponin I/T, CK-MB, myoglobin).

• Treatment: Focus on reducing oxygen demand and restoring blood flow (e.g., thrombolysis, angioplasty, bypass).

2. Angina and Acute Coronary Syndromes

• Stable Angina: Pain during exertion, relieved by rest, does not cause lasting damage.

• Unstable Angina: Involves plaque disruption, leading to potential myocardial damage.

• Myocardial Infarction: Extended ischemia resulting in heart muscle death.

3. Cardiac Biomarkers

• Troponin I and T: Most sensitive and specific for myocardial infarction, remain elevated for 3-7 days.

• CK-MB: Rises within 4-6 hours and peaks after 12-24 hours.

• Myoglobin: Rises early but lacks specificity for MI.

4. Endocardial and Valvular Diseases

• Stenosis: Leads to increased pressure workload due to inability of a valve to open fully.

• Regurgitation: Results in increased volume workload due to backward blood flow.

• Common Disorders: Include mitral stenosis, mitral regurgitation, aortic stenosis, aortic regurgitation.

• Rheumatic Heart Disease: Develops from immune reactions following streptococcal infection.

• Infective Endocarditis: Involves microbial colonization of heart valves.

5. Myocardial Diseases

• Myocarditis: Inflammatory condition often of viral origin leading to necrosis and reduced contractility.

• Cardiomyopathies Types:

  • Dilated Cardiomyopathy: Causes ventricular dilation and reduced ejection fraction (EF), often leads to heart failure.

  • Hypertrophic Cardiomyopathy: Characterized by thickened myocardium; has genetic causes and risk of sudden death.

  • Restrictive Cardiomyopathy: Stiff ventricle with impaired diastolic filling.

6. Pericardial Diseases

• Pericarditis: Inflammation of the pericardium causing chest pain and pericardial friction rub.

• Pericardial Effusion: Fluid accumulation in the pericardial sac leading to potential cardiac tamponade.

• Cardiac Tamponade: Life-threatening condition where increased pressure compresses the heart impairing filling.

7. Congenital Heart Diseases

• Present at birth and are among the most common heart disorders in children.

• Two main mechanisms involved:

  • Shunting: Abnormal blood flow between the left and right sides of the heart.

  • Obstruction: Impairs blood flow.

• Acyanotic Defects: Left-to-right shunts (e.g., ASD, VSD, PDA).

• Cyanotic Defects: Right-to-left shunts leading to systemic hypoxemia.

8. Key Pathophysiology Concepts

• The balance between myocardial oxygen supply and demand is critical; increased workload, reduced perfusion or low oxygen content can lead to ischemia.

• Heart failure often develops from progressive ischemic damage.

9. Exam Focus Review Questions

• Explain the process of plaque formation and progression.

• Differentiate between stable angina, unstable angina, and myocardial infarction (MI).

• Compare the effects of stenosis vs. regurgitation on cardiac workload.

• Compare myocarditis and cardiomyopathies.

• Explain the causes and consequences of cardiac tamponade.

• Identify differences between cyanotic vs. acyanotic congenital defects.

Chapter 19: Heart Failure & Cardiac Dysrhythmias

What is Heart Failure?

• Heart Failure: Inability of the heart to pump sufficient blood to meet the body’s needs, leading to both congestion and reduced perfusion.

• Etiology: Includes coronary artery disease (CAD), hypertension, valvular disease, and cardiomyopathy.

• Pathogenesis: Follows the sequence: initial insult → compensation → decompensation.

Cardiac Dysfunction & Compensation

• Dysfunction Types:

  • Systolic Dysfunction: Impaired contraction with low ejection fraction (EF <40%).

  • Diastolic Dysfunction: Impaired relaxation and filling, maintaining a preserved EF with a stiff ventricle.

• Compensation Mechanisms:

  • Myocardial Remodeling: Frank-Starling mechanism leads to volume overload inducing myocardial hypertrophy.

  • Neurohormonal Activation: Enhanced sympathetic nervous system activity increases heart rate and contractility but can become exhaustively maladaptive.

  • Increased Preload: Through RAAS, impacted by fluid retention.

Clinical Manifestations

• Symptoms: Common symptoms include fatigue, dyspnea, and edema.

Types of Heart Failure

• Left-Sided Heart Failure: Results in pulmonary congestion, presenting as dyspnea and orthopnea.

• Right-Sided Heart Failure: Results in systemic congestion with symptoms like edema and jugular venous distension (JVD).

• Biventricular Heart Failure: Both left and right sides contribute to symptoms, common in advanced disease.

Classifying Heart Failure

• FACES: Acronym for common symptoms - Fatigue, Activity limitation, Congestion, Edema, Shortness of breath.

• NYHA Classes: Ranges from I (no symptoms) to IV (symptoms at rest).

• ACC/AHA Stages: Ranges from A (at risk) to D (refractory).

Treatments for Heart Failure

• Management of Blood Pressure: Involves the use of ACE inhibitors or ARBs, beta-blockers.

• Managing Contractility: Inotropic agents (e.g., Digoxin) for systolic heart failure; diuretics for volume overload.

Key Questions

• What are the common predisposing factors for the development of heart failure? (CAD, hypertension, myocardial infarction).

• How does heart failure with systolic dysfunction differ from heart failure with preserved systolic function? (Systolic: Low EF; Diastolic: Normal EF, but there are filling issues).

• How do compensatory responses triggered in heart failure work to restore cardiac output, and how might they hasten remodeling progression? (Initial compensations may help but chronic activation then results in hypertrophy and progression to heart failure).

• How are preload, afterload, and contractility therapeutically managed for patients with heart failure? (Diuretics for preload, ACE inhibitors for afterload, inotropes for contractility).

What are Cardiac Dysrhythmias?

• Cardiac Dysrhythmias: Abnormal heart rhythms resulting from issues in impulse generation or conduction.

  • Dysrhythmias may be bradycardic, tachycardic, or irregular.

  • Clinical impacts include palpitations, syncope, and reduced cardiac output.

Electrical Conduction of the Heart

• Conduction System:

  • Sinoatrial (SA) Node: Primary pacemaker of the heart (~60-100 bpm).

  • Atrioventricular (AV) Node: Delays impulse allowing sufficient time for ventricular filling.

  • Bundle of His (AV Bundle): Pathway that splits into left/right bundles leading into Purkinje fibers.

Electrocardiogram (ECG)

• P Wave: Represents atrial depolarization (contraction).

• QRS Complex: Represents ventricular depolarization (contraction).

• T Wave: Represents ventricular repolarization (relaxation).

Types of Dysrhythmias

• Automaticity: Abnormal spontaneous firing of the heart.

• Triggered Activity: Afterdepolarizations causing premature beats (extrasystoles).

• Reentry: Circular impulse propagation causing repetitive firing.

• Abnormal Rate of Impulse:

  • Sinus Tachycardia: Fast heart rate (>100 bpm), often a response to stress or exercise.

  • Sinus Bradycardia: Slow heart rate (<60 bpm), common in athletes or due to high vagal tone.

• Sinus Arrhythmia: Normal variation in heart rate with respiration.

• Sick Sinus Syndrome: Dysfunction in the SA node causing bradycardia-tachycardia.

• Premature Atrial Complexes (PACs): Early atrial beats leading to irregular rhythm.

• Atrial Flutter: Identifiable sawtooth waves typically at 250-350 bpm.

• Atrial Fibrillation: Characterized by irregular rhythms and absence of P waves, leading to ineffective atrial contractions.

• Junctional Escape Rhythms: Occur when the AV node serves as the pacemaker (40-60 bpm).

• Ventricular Escape Rhythms: Result from the Purkinje fibers initiating pacing (20-40 bpm).

• Premature Ventricular Contractions (PVCs): Premature beats with wide QRS complexes.

• Ventricular Tachycardia: Occurs when there are more than 3 PVCs in sequence, presenting wide QRS complexes.

• Ventricular Fibrillation: Chaotic rhythm resulting in no cardiac output.

Conduction Pathway Disturbances

• Atrioventricular Blocks:

  • First-Degree AV Block: Prolongation of PR interval (>0.2 sec).

  • Second-Degree AV Block: Intermittent non-conduction of P waves (Mobitz types I and II).

  • Third-Degree AV Block: Complete dissociation between atrial and ventricular rhythms.

Key Questions

• What are the characteristic features of common cardiac dysrhythmias as seen on ECG? (E.g., Atrial Fibrillation shows no P wave and irregular QRS complexes).

• What are the distinguishing factors that lead to accurately diagnosing various dysrhythmias or conduction pathway disturbances? (Utilize ECG patterns, rate, regularity).

• What is the clinical significance of each common cardiac dysrhythmia, and what are typical treatment approaches? (Examples include: VF requires defibrillation; AFib typically treated with anticoagulants and rate control).