Cardiac Physiology Quiz

Cardiovascular Function Assessment

• Learning Outcomes: Students will be able to describe the cardiovascular system's structure and function, demonstrate comprehensive cardiovascular assessments, differentiate normal from abnormal findings through inspection, palpation, percussion, and auscultation, identify diagnostic tools like hemodynamic monitoring (e.g., central venous pressure, pulmonary artery pressure, arterial pressure monitoring), and explain associated nursing implications.

Anatomy of the Heart

• Location: Center of the thorax
• Description: Hollow, muscular organ pumping blood to tissues, supplying oxygen and nutrients
• Weight: Approximately 300 grams
• Layers: Endocardium (inner), Myocardium (middle), Epicardium (outer)
• Pericardium: Fibrous sac composed of visceral and parietal layers
• Pericardial Space: Normally contains around 20 mL of fluid to reduce friction

Layers of the Heart Wall

• Epicardium: Visceral layer of the serous pericardium (outer layer)
• Myocardium: Primarily cardiac muscle (middle layer)
• Endocardium: Endothelium lining heart chambers and valves (inner layer)

Heart Chambers and Valves

• Right Atrium: Receives deoxygenated blood from superior and inferior vena cava, pumps to right ventricle via tricuspid valve.
• Right Ventricle: Pumps deoxygenated blood to lungs through pulmonary artery, protected by pulmonary valve.
• Left Atrium: Receives oxygenated blood from lungs via pulmonary veins, pumps to left ventricle via mitral valve.
• Left Ventricle: Pumps oxygenated blood to body through aorta, protected by aortic valve.

Heart Conduction System

• Sinoatrial (SA) Node: Small cluster of cells initiating electrical impulses, the natural pacemaker.
• Atrioventricular (AV) Node: Receives impulses from SA node, relays them through the bundle of His to the ventricles.
• Bundle of His: Group of fibers extending from the AV node, dividing into left and right bundle branches within the interventricular septum
• Purkinje Fibers: Specialized fibers distributing electrical impulses throughout the ventricular muscle.
• Electrical Impulses: Cause heart muscle contraction for rhythmic beating.

Cardiac Hemodynamics

• Cardiac Output (CO): Volume of blood pumped by the heart per minute. Calculated as stroke volume (SV) multiplied by heart rate (HR). Typical range at rest : 4-8 L/min.
• Stroke Volume (SV): Amount of blood ejected by each ventricle per beat, typically measured in milliliters per beat (mL/beat). Normal Values range : 60–100 mL/beat.
• Heart Rate (HR): Number of times the heart beats per minute.
• Preload: Degree of stretch of heart muscle before contraction, determined by volume and pressure of blood in ventricles at end of diastole.
• Afterload: Resistance heart must overcome to pump blood out ventricles, determined by blood vessel resistance and aortic/pulmonary artery pressure.
• Contractility: Strength of heart muscle contraction, determined by factors like calcium levels in muscle cells and sympathetic nervous system stimulation.
• Ejection Fraction (EF): Percentage of blood ejected from the ventricles with each contraction. A healthy range is approximately 50-70%.

Cardiovascular System Assessment

• Health History: Includes patient's medical history, risk factors, symptoms such as chest pain, dyspnea, edema, fatigue, dizziness, and family history of heart conditions.
• Physical Assessment: Includes monitoring vital signs (pulse pressure, blood pressure), inspecting jugular venous pulsation, assessing arterial pulses, checking skin and extremities, as well as lung and abdominal examination.
• Diagnostic Studies:
  • Laboratory: Complete blood count (CBC), lipid profile, cardiac biomarkers (troponin, CK-MB, BNP), coagulation studies.
  • Radiology: Chest X-ray, echocardiogram, cardiac CT or MRI, electrocardiogram (ECG),
  • Other: Stress test, cardiac catheterization, angiography, Holter monitor.
• Hemodynamic Monitoring: Measuring pressures, central venous pressure (CVP), pulmonary artery pressure (PAP), and intra-arterial blood pressure (BP) for critically ill patients.
• Procedures: Steps for CVP and other hemodynamic monitoring procedures and associated nursing considerations (pre-procedure fasting, post-procedure bed rest, monitoring affected extremity, etc...).