2022 Chapter21 assessment card 4

Chapter 21 Assessment of Cardiovascular Function

Overview of Anatomy and Physiology

• Heart Structure

  • Three layers:

    • Endocardium: thin inner layer

    • Myocardium: muscular middle layer

    • Epicardium: outer protective layer

  • Chambers:

    • Right atrium

    • Right ventricle

    • Left atrium

    • Left ventricle

  • Valves:

    • Atrioventricular valves:

      • Tricuspid (right side)

      • Mitral (left side)

    • Semilunar valves:

      • Aortic

      • Pulmonic

  • Coronary arteries: supply blood to heart muscle

  • Cardiac conduction system: regulates heart rhythm (electrophysiology)

  • Cardiac hemodynamics: study of blood flow through the heart

Cardiac Conduction System

• Primary Pacemaker:

  • Sinoatrial (SA) node

  • Atrioventricular (AV) node serves as backup pacemaker

• Nodal cells make up the pacemakers in the heart

Cardiac Action Potential

• Depolarization:

  • Electrical activation due to sodium influx and potassium efflux

• Repolarization:

  • Return to rest due to potassium reentry and sodium exhaustion

• Refractory Periods:

  • Effective refractory period: cells cannot depolarize

  • Relative refractory period: requires stronger stimulus to depolarize

Cardiac Cycle

• Definition: Events from the beginning to the end of one heartbeat

• Phases:

  • Diastole: heart muscle relaxation

  • Atrial systole: contraction of the atria

  • Ventricular systole: contraction of the ventricles

Cardiac Output

• Ejection Fraction:

  • Percent of end-diastolic volume ejected in a heartbeat

• Cardiac output (CO):

  • Amount of blood pumped by the ventricle per minute

  • Formula: CO = Stroke Volume (SV) × Heart Rate (HR)

Stroke Volume Components

• Stroke Volume (SV):

  • Amount of blood ejected with each heartbeat

• Preload:

  • Degree of stretch of cardiac muscle fibers at end diastole

• Afterload:

  • Resistance the left ventricle must overcome to eject blood

• Contractility:

  • Ability of cardiac muscle to shorten in response to stimulation

Influencing Factors

• Heart Rate Control:

  • Influenced by autonomic nervous system and baroreceptors

• Stroke Volume Control:

  • Preload: determined by Frank–Starling Law

  • Afterload: influenced by vascular resistance

Health History and Assessment

• Key Assessment Areas:

  • Demographics, Family History, Cultural Factors

  • Risk Factors: modifiable and nonmodifiable

• Common Symptoms:

  • Chest pain, shortness of breath, edema, palpitations, nausea

Diagnostic Tests

• Electrocardiography:

  • 12-lead ECG for heart's electrical activity

• Echocardiography:

  • Non-invasive ultrasound examining heart size and motion

• Cardiac Catheterization:

  • Invasive procedure to diagnose heart diseases

  • Right and left heart catheterization

Nursing Interventions

• Monitor catheter site, peripheral pulses, signs of complications

• Post-procedure care: bed rest and patient initiation of safety protocols

Hemodynamic Monitoring

• Measurements: Central venous pressure, pulmonary artery pressure

• Importance in assessing heart function and volume status

Sample Questions & Rationales

• Question #1: What is the primary pacemaker of the heart?

  • Answer: D. Sinoatrial node

• Question #2: Best definition of stroke volume?

  • Answer: Amount ejected per beat

• Question #3: Central venous pressure measures pressure in which area?

  • Answer: B. Vena cava or right atrium