LESSON 2 o Location: right atrial wall near
ASSESSMENT OF THE CARDIOVASCULAR tricuspid valve.
SYSTEM o Delays to allow atrial
contraction/ventricular filling.
TOPICS • BUNDLE OF HIS:
1. ECG reading and interpretation o Splits into left/right bundle
2. Cardiac Rhythm and ECG Characteristics branches.
3. Management of Cardiac Arrhythmias o Left bundle divides into
4. ACLS with Pulseless arrest algorithm anterior/posterior branches.
5. ACLS Bradycardia and Tachycardia PURKINJE FIBERS:
algorithm • Terminal conduction network in
ventricular myocardium.
ECG READING AND INTERPRETATION • Rapid impulse transmission via Purkinje
cells.
WHAT IS ECG? HIERARCHY OF PACEMAKER SITES
• The electrocardiogram (ECG) is a medical Rate Dominance: Fastest firing rate controls
test for recording and interpreting heart rhythm.
cardiac activity through repeated cardiac • SA Node (60-100 bpm): default node fails.
cycles. The ECG is commonly used in • AV Node (40 – 60 bpm): backup if SA
many healthcare settings, including node fails
routine physical exams, emergency care, • Ventricular Sites (30-40 bpm): activated
and cardiac monitoring during surgery. if SA/VA nodes fail.
• It’s a non-invasive procedure, where small
electrode patches are attached to the skin CARDIAC ACTION POTENTIAL
of the chest, arms, and legs. These PROCESS:
electrodes detect the electrical impulses • DEPOLARIZATION:
generated by the heart as it beats, which o Ions (NA+/CA+) enter cell →
are then transmitted to an ECG machine. intracellular positive charge.
• This machine translates the electrical o Stimulates contraction.
activity into line tracings on paper or • REPOLARIZATION:
screens, which provide information about o K+ exits the cell → restores resting
the heart’s rhythm and rate and help negative charge.
diagnose heart conditions. PHASES:
• PHASE 0: Rapid depolarization
CARDIAC CONDUCTION SYSTEM o Atrial/ventricular myocytes: Na+
influx (fast response).
o SA/AV nodes: CA2+ influx (slow
FUNCTION response).
• Generates/transmits electrical impulses • PHASE 1: Early repolarization (K+ exit).
to stimulate myocardial contraction. • PHASE 2: Plateau (CA2+ influx).
• Synchronizes atrial → ventricular filling • PHASE 3: Repolarization (K+ exit).
and cardiac output. • PHASE 4: Resting state.
CARDIAC CONDUCTION SYSTEM
KEY COMPONENTS: WHAT IS A NORMAL ECG READING?
• SA NODE (Sinoatrial Node): • A normal ECG (electrocardiogram)
o Primary pacemaker (60-100 bpm). reading features a consistent heart
o Location: junction of superior vena rhythm and characteristic wave patterns
cava/right atrium. corresponding to each phase of the
o Responds to metabolic demands. heartbeat.
• AV NODE (Atrioventricular Node): • The normal sinus rhythm (NSR) is the
o Secondary pacemaker (40-60 default. Healthy cardiac rhythm.
bpm).
BALANO|1
, o QRS Complex should last 0.04 –
0.44 seconds.
o ST Segment follows the QRS
complex and should be on the
baseline.
Note: o QT Interval varies based on heart
6. 12-lead ECG: Gold standard for detecting rate but is generally up to 0.44
arrhythmias, ischemia, infarction, seconds.
electrolyte imbalances, and drug effects. o T Wave should be positive
(upright) in most leads and less
than 5 mm in height.
WHAT IS AN ABNORMAL ECG READING?
• Common variations from NSR (Normal
Sinus Rhythm)
o SINUS BRADYCARDIA: all
features of a normal cardiac
rhythm are present, but the rate is
slower than 60 bpm.
o SINUS TACHYCARDIA: all
• The electrical impulse originates from the features of a normal cardiac
sinoatrial (SA) node, and the ECG strip will rhythm are present, but the rate is
demonstrate the following characteristics. greater than 100 bpm. T wave may
o Normal resting heart rate from be “buried” or absent, at increased
60-100 bpm. HR.
o Regular rhythm with consistent
intervals between each heartbeat.
o P wave should be upright in most
leads, consistent in size and shape,
and present before each QRS
complex.
o Normal PR interval: 0.12 – 0.20
seconds.
BALANO|2
ASSESSMENT OF THE CARDIOVASCULAR tricuspid valve.
SYSTEM o Delays to allow atrial
contraction/ventricular filling.
TOPICS • BUNDLE OF HIS:
1. ECG reading and interpretation o Splits into left/right bundle
2. Cardiac Rhythm and ECG Characteristics branches.
3. Management of Cardiac Arrhythmias o Left bundle divides into
4. ACLS with Pulseless arrest algorithm anterior/posterior branches.
5. ACLS Bradycardia and Tachycardia PURKINJE FIBERS:
algorithm • Terminal conduction network in
ventricular myocardium.
ECG READING AND INTERPRETATION • Rapid impulse transmission via Purkinje
cells.
WHAT IS ECG? HIERARCHY OF PACEMAKER SITES
• The electrocardiogram (ECG) is a medical Rate Dominance: Fastest firing rate controls
test for recording and interpreting heart rhythm.
cardiac activity through repeated cardiac • SA Node (60-100 bpm): default node fails.
cycles. The ECG is commonly used in • AV Node (40 – 60 bpm): backup if SA
many healthcare settings, including node fails
routine physical exams, emergency care, • Ventricular Sites (30-40 bpm): activated
and cardiac monitoring during surgery. if SA/VA nodes fail.
• It’s a non-invasive procedure, where small
electrode patches are attached to the skin CARDIAC ACTION POTENTIAL
of the chest, arms, and legs. These PROCESS:
electrodes detect the electrical impulses • DEPOLARIZATION:
generated by the heart as it beats, which o Ions (NA+/CA+) enter cell →
are then transmitted to an ECG machine. intracellular positive charge.
• This machine translates the electrical o Stimulates contraction.
activity into line tracings on paper or • REPOLARIZATION:
screens, which provide information about o K+ exits the cell → restores resting
the heart’s rhythm and rate and help negative charge.
diagnose heart conditions. PHASES:
• PHASE 0: Rapid depolarization
CARDIAC CONDUCTION SYSTEM o Atrial/ventricular myocytes: Na+
influx (fast response).
o SA/AV nodes: CA2+ influx (slow
FUNCTION response).
• Generates/transmits electrical impulses • PHASE 1: Early repolarization (K+ exit).
to stimulate myocardial contraction. • PHASE 2: Plateau (CA2+ influx).
• Synchronizes atrial → ventricular filling • PHASE 3: Repolarization (K+ exit).
and cardiac output. • PHASE 4: Resting state.
CARDIAC CONDUCTION SYSTEM
KEY COMPONENTS: WHAT IS A NORMAL ECG READING?
• SA NODE (Sinoatrial Node): • A normal ECG (electrocardiogram)
o Primary pacemaker (60-100 bpm). reading features a consistent heart
o Location: junction of superior vena rhythm and characteristic wave patterns
cava/right atrium. corresponding to each phase of the
o Responds to metabolic demands. heartbeat.
• AV NODE (Atrioventricular Node): • The normal sinus rhythm (NSR) is the
o Secondary pacemaker (40-60 default. Healthy cardiac rhythm.
bpm).
BALANO|1
, o QRS Complex should last 0.04 –
0.44 seconds.
o ST Segment follows the QRS
complex and should be on the
baseline.
Note: o QT Interval varies based on heart
6. 12-lead ECG: Gold standard for detecting rate but is generally up to 0.44
arrhythmias, ischemia, infarction, seconds.
electrolyte imbalances, and drug effects. o T Wave should be positive
(upright) in most leads and less
than 5 mm in height.
WHAT IS AN ABNORMAL ECG READING?
• Common variations from NSR (Normal
Sinus Rhythm)
o SINUS BRADYCARDIA: all
features of a normal cardiac
rhythm are present, but the rate is
slower than 60 bpm.
o SINUS TACHYCARDIA: all
• The electrical impulse originates from the features of a normal cardiac
sinoatrial (SA) node, and the ECG strip will rhythm are present, but the rate is
demonstrate the following characteristics. greater than 100 bpm. T wave may
o Normal resting heart rate from be “buried” or absent, at increased
60-100 bpm. HR.
o Regular rhythm with consistent
intervals between each heartbeat.
o P wave should be upright in most
leads, consistent in size and shape,
and present before each QRS
complex.
o Normal PR interval: 0.12 – 0.20
seconds.
BALANO|2
