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Rapid ReviewPracticeSeries 2 · Video 3 of 14

Cardiac Output — Preload, Afterload & Contractility

39 min5 chaptersPosted Feb 2026↻ 100% watched
A
Dr. Amara Osei-Bonsu
RN, MSN, CCRN · Senior Nursing Educator
⚡ Flashcards

Focused clinical teaching on cardiac output — preload, afterload & contractility, with bedside interpretation, nursing cues, and quick mental models for revision.

What you'll learn

  • The anatomy and function of the SA node, AV node, Bundle of His, and Purkinje fibres
  • How to trace a normal electrical impulse through the heart step by step
  • The ECG correlates of each phase of conduction, from the P wave through the QRS complex
  • What happens when conduction is delayed or blocked and how to recognise it clinically
  • Nursing priorities when a patient develops a new conduction abnormality or perfusion change

Recommended for NCLEX revision, cardiovascular systems review, and quick bedside reinforcement before rhythm-interpretation practice.

  • 0:00
    Chapter 01
    Introduction & Overview
    What the conduction system is and why it matters clinically
    0:00
  • 9:48
    Chapter 02 · Now Playing
    The SA Node — The Heart's Natural Pacemaker
    Automaticity, rate control, and what happens when the SA node fails
    9:48
  • 20:33
    Chapter 03
    AV Node, Bundle of His & Purkinje Fibres
    The gating function of the AV node and the ventricular conduction pathway
    20:33
  • 33:10
    Chapter 04
    ECG Correlates of Conduction
    Reading the electrical impulse on a 12-lead ECG — P, PR, QRS, QT
    33:10
  • 46:55
    Chapter 05
    When Conduction Fails — Clinical Nursing Response
    Heart blocks, escape rhythms, and your priorities as a nurse
    46:55

Related Study Notes

  • Cardiac Conduction — quick note summary
  • ECG Interpretation: reading the 12-lead with bedside cues
  • Dysrhythmias: recognition, causes, escalation, and nurse-first response
18:22Now, the SA node fires spontaneously. This is what we call automaticity, and it establishes the rhythm before any atrial depolarisation reaches the AV node.
18:48That impulse spreads across the atria and becomes the P wave on ECG. Think of it as an electrical wavefront moving right to left through the atrial muscle.
19:12The signal then reaches the AV node and deliberately slows down. That delay gives the atria time to finish filling the ventricles before ventricular contraction begins.
19:45A prolonged PR interval tells you AV nodal conduction is delayed. That may be benign, but it can also signal medication effects, ischemia, or conduction system disease.
20:18From the AV node, the impulse travels down the Bundle of His, divides into left and right bundle branches, and finally disperses through Purkinje fibres.
20:55A wide QRS suggests ventricular conduction is abnormal. That changes the bedside urgency and should shape how you interpret the rhythm strip.
21:30At the bedside, the first nursing question is whether every P wave is followed by a QRS. That determines whether the issue is sinus, AV nodal, or ventricular.
22:05Once you identify the pattern, you can connect the rhythm to symptoms, perfusion, and escalation priorities instead of just naming the ECG finding.

Current excerpt

Now, the SA node fires spontaneously. This is what we call automaticity, and it establishes the rhythm before any atrial depolarisation reaches the AV node.