Cardiac Physiology & Pathology – Key Vocabulary

Twenty-two vocabulary flashcards summarising conduction velocities, pacemaker hierarchy, timing intervals, anatomical locations, coronary supply, haemodynamic strategies for valvular disease, characteristic murmurs/pulses, arrhythmia features and key physiological concepts from the lecture notes.

Purkinje Fibres

Cardiac conduction tissue with the fastest velocity (≈4 m/s) because of abundant gap junctions.

Ventricular Muscle Conduction Velocity

≈0.5 m/s, slower than Purkinje fibres but faster than AV-node tissue.

Pacemaker Hierarchy

SA node (70–80 beats/min) > AV node (40–60 beats/min) > His-Purkinje system (15–40 beats/min).

Pacemaker Dominance

The cardiac region with the highest spontaneous firing rate sets the overall heart rhythm.

SA–AV Conduction Time

≈0.03 s for impulses to travel from the SA node to the AV node.

AV Nodal Delay

≈0.13 s total (0.09 s within the AV node + 0.04 s in the AV bundle) allowing ventricular filling.

Total A–V Conduction Time

≈0.22 s from SA-node depolarisation to ventricular activation.

Cardiac Cycle Duration

≈0.8 s (Systole ≈ 0.27 s, Diastole ≈ 0.53 s) at a normal heart rate.

SA Node Location

Superior posterolateral wall of the right atrium, just inferior to the SVC opening.

AV Node Location

Posterior-inferior interatrial septum beneath endocardium, near the tricuspid valve and coronary sinus.

RCA Supply to Conduction System

Right coronary artery perfuses the SA node, AV node and proximal AV bundle in most hearts.

Left Coronary Supply to Bundles

Branches of the LCA (especially LAD) supply right and left bundle branches and Purkinje fibres.

Stenotic Valve Strategy (“Slow & Tight”)

For lesions like AS or MS: keep heart rate slow and systemic vascular resistance normal-high.

Regurgitant Valve Strategy (“Fast & Loose”)

For lesions such as MR, AR, TR, PR: maintain a rapid heart rate and low systemic vascular resistance.

Diastolic Murmurs

Mitral stenosis, tricuspid stenosis, aortic regurgitation and pulmonary regurgitation occur during diastole.

Systolic Murmurs

Aortic stenosis, pulmonary stenosis, mitral regurgitation and tricuspid regurgitation occur during systole.

Aortic Regurgitation Pulse

Water-hammer (Corrigan) pulse due to rapid runoff of blood back into the ventricle.

Aortic Stenosis Murmur

Crescendo–decrescendo systolic murmur accompanied by a slow-rising pulse.

Mitral Regurgitation Murmur

Pansystolic (holosystolic) blowing murmur best heard at the apex radiating to the axilla.

Atrial Fibrillation

Irregularly irregular rhythm with absent P waves, commonly produced by multiple re-entry circuits.

Hypertrophic Cardiomyopathy Management

Maintain or increase preload and afterload and keep heart rate slow to reduce LV outflow obstruction.