ECG & Heart Sounds Practical Flashcards

Vocabulary flashcards generated from the ECG & Heart Sounds Practical Study summary notes.

Autorhythmicity

The ability of cardiac muscle to contract on its own without needing external nerve stimulation, unlike skeletal muscle.

Cardiac Conduction Signal Path

The intrinsic pathway of electrical impulses through the heart: SA node → AV node → Bundle of His → bundle branches → Purkinje fibers.

Depolarization

The process in which cardiac cells become more positive electrically, triggering muscle contraction.

Repolarization

The process in which cardiac cells become more negative again, resetting their electrical state.

Electrocardiogram (ECG)

The sum of all electrical impulses in the heart detected via electrodes placed on the skin.

ECG Lead

A specific viewpoint or angle from which electrodes observe the electrical activity of the heart.

Wilhelm Einthoven

The Dutch scientist and Nobel Prize winner who developed the electrocardiogram (ECG).

P wave

The waveform on an ECG that represents atrial depolarization.

QRS complex

The waveform on an ECG that represents ventricular depolarization.

T wave

The waveform on an ECG that represents ventricular repolarization.

PR interval

The duration from the start of the P wave to the start of the QRS complex, representing atrial depolarization plus the delay at the AV node.

QRS interval

The duration of ventricular depolarization.

QT interval

The duration from the start of the QRS complex to the end of the T wave, representing full ventricular electrical activity.

Bipolar Limb Leads

Einthoven leads I, II, and III, which form a triangle across both arms and the left leg.

Augmented Leads

bipolar limb leads observing the heart: aVR (right arm), aVL (left arm), and aVF (left foot).

Precordial (Wilson) Leads

Chest electrodes V1–V6 that record heart electrical activity in the horizontal plane.

Electrode Colour Setup

Standard ECG lead placement colours: Red on right arm (R), Yellow on left arm (L), Green on left leg (F), and Black on right leg (N — neutral/ground).

ECG Amplitude Standard

International recording standard where $10\,mm$ on paper corresponds to $1\,mV$ of voltage.

ECG Speed Standard

International recording standard where paper speed is $25\,mm/s$ ($10\,mm$ per $0.4\,s$).

RR interval

The time duration between successive R waves on an ECG, which reflects heart rate.

QTc (Corrected QT Interval)

A rate-corrected QT interval calculated as $\text{QTc (ms)} = \frac{\text{QT-interval (ms)}}{\sqrt{\text{RR-interval (s)}}}$ to allow standard comparison across different heart rates and individuals.

Phonocardiography

The recording of heart sounds and murmurs using a microphone placed on the chest wall or esophagus.

Phonocardiography Frequency Requirement

The required minimum frequency detection capability of at least $500\,Hz$ necessary to catch heart murmurs.

Erb's point

The anatomical location at the 3rd intercostal space on the left side where phonocardiography recordings are made.

1st Heart Sound

Acoustic sound caused by the closing of the AV valves (mitral and tricuspid), occurring around or after the QRS complex.

2nd Heart Sound

Acoustic sound caused by the closing of the semilunar valves (aortic and pulmonary), occurring around or after the T wave.