Cardiac Electrophysiology and ECG Interpretation for Healthcare Students

What is the primary function of cardiac cells in relation to electrical impulses?

Cardiac cells have an electrical charge, and stimulation of one cell initiates stimulation of adjacent cells, leading to contraction.

What are the properties of electrical/pacemaker cardiac cells?

They form the conduction system of the heart and possess automaticity, allowing them to spontaneously initiate electrical impulses.

Define excitability in the context of cardiac cells.

Excitability is the ability of a cardiac cell to respond to an electrical impulse.

What does conductivity refer to in cardiac cells?

Conductivity is the ability of a cardiac cell to transmit an electrical impulse to another cell.

What is contractility in myocardial cardiac cells?

Contractility is the ability of myocardial cells to contract after receiving an electrical impulse.

What is the role of the SA node in cardiac function?

The SA node is the main pacemaker of the heart, generating electrical impulses that regulate heart rate.

How does sympathetic stimulation affect cardiac function?

Sympathetic stimulation increases automaticity, heart rate (chronotropy), force of contraction (inotropy), and speed of conduction (dromotropy).

What is the impact of parasympathetic stimulation on the heart?

Parasympathetic stimulation decreases automaticity, heart rate, force of contraction, and speed of conduction.

Why is ECG monitoring important?

ECG monitoring visualizes electrical changes in the heart, allowing for the detection of rhythm and conduction disturbances.

List some indications for performing an ECG.

Chest pain, shortness of breath, tachycardia, bradycardia, dizziness, hypotension, electrolyte abnormalities, and drug therapy monitoring.

What is the purpose of a 3 Lead ECG?

A 3 Lead ECG is used for transport monitoring and interventions like transcutaneous pacing and cardioversion.

What distinguishes a 5 Lead ECG from a 3 Lead ECG?

A 5 Lead ECG includes telemetry monitoring and displays leads I, II, III, and a V lead.

What is the significance of a 12 Lead ECG?

A 12 Lead ECG provides a detailed view of the heart and is necessary for suspected acute coronary syndrome (ACS) symptoms.

What should be considered if a 12 Lead ECG shows ST elevation in inferior leads?

Consider right-sided lead placement to assess for right ventricular involvement.

What are the signs of a suspected posterior myocardial infarction (MI)?

Signs include ST depression in V1-V3, tall broad R waves, and upright T waves, confirmed with a 15 Lead ECG.

What are the main components of an ECG?

The main components are waves (P wave, QRS complex, T wave), intervals, and segments.

What is the isoelectric line in an ECG?

The isoelectric line is the reference point in an ECG tracing where no waveform occurs, used to assess abnormalities.

How is heart rate calculated from an ECG?

Heart rate can be calculated by counting QRS complexes and multiplying by 10, or by measuring the distance between R waves.

What does a normal P wave represent?

A normal P wave indicates atrial depolarization and should be present, upright, rounded, regular, and precede every QRS complex.

What is the normal range for the PR interval?

The normal PR interval is 0.12 to 0.20 seconds (3 to 5 small boxes).

What does the QRS complex represent?

The QRS complex represents ventricular depolarization and should be narrow (0.08-0.10 seconds) with all three waves present.

How is the ST segment assessed?

The ST segment is measured for its position relative to the isoelectric line, with normal being within 1mm above or below.

What does the QT interval represent?

The QT interval represents the time from the start of depolarization to repolarization and should be less than half the RR interval.

What does a normal T wave indicate?

A normal T wave indicates ventricular repolarization and should be present, upright, and rounded.

What is Sinus Bradycardia?

A heart rate of less than 60 bpm, commonly caused by older age, athleticism, vagal stimulation, or certain medications.

What is Sinus Tachycardia?

A heart rate greater than 100 bpm, often due to pain, dehydration, anxiety, or stimulant medications.

What is Sinus Arrhythmia?

A variable heart rate with an irregular rhythm, usually due to respiratory variation, more common in children and young adults.

What is the typical management for asymptomatic sinus rhythms?

No intervention is typically required; treatment focuses on addressing underlying causes in bradycardia or tachycardia.

What are common underlying causes of dysrhythmias?

Cardiac conduction issues, electrolyte imbalances, drug effects, hypoxia, shock, and metabolic conditions.

How does abnormal ECG affect cardiac output?

Disordered electrical stimulation can reduce the effectiveness of heart contractions, leading to decreased cardiac output.

What characterizes stable vs. unstable dysrhythmias?

Stable dysrhythmias are asymptomatic or have minimal symptoms; unstable dysrhythmias present severe symptoms like hypotension or altered LOC.

What is Paroxysmal Supraventricular Tachycardia (SVT)?

A rapid heart rate that starts and stops abruptly, often requiring vagal maneuvers or IV Adenosine for management.

What is Atrial Flutter?

A sustained rhythm with a classic sawtooth flutter wave pattern, characterized by a variable atrial rate and conduction ratios affecting ventricular rates.

What is Atrial Fibrillation?

The most common dysrhythmia, characterized by an irregular rhythm and fibrillatory waves, with heart rates that can be controlled or rapid.

What is the role of Adenosine in managing SVT?

Adenosine acts as an anti-arrhythmic, slowing conduction through the AV node, and is administered as a rapid IV bolus.

What is synchronized cardioversion?

A treatment for unstable tachyarrhythmias that delivers energy synchronized with the heart's rhythm to restore normal rhythm.

What are Junctional Rhythms?

Rhythms originating from the area around the AV node, characterized by inverted, hidden, or absent P waves.

What defines Junctional Tachycardia?

A sustained heart rate greater than 100 bpm with regular rhythm and inverted or absent P waves.

What is the management approach for acute atrial dysrhythmias?

Assess for tachycardia, identify reversible causes, support vital functions, and perform a 12-lead ECG.

What are the symptoms of symptomatic unstable dysrhythmias?

Severe symptoms include hypotension, altered level of consciousness, signs of shock, and chest pain.

What is the significance of the conduction ratio in Atrial Flutter?

The conduction ratio (e.g., 4:1, 2:1) affects ventricular rate and patient stability, influencing symptom severity.

What is the heart rate range for Accelerated Junctional Rhythm?

A heart rate between 60-100 bpm with regular rhythm and inverted or absent P waves.

What is the typical heart rate for Junctional Rhythms?

A heart rate of 40-60 bpm with regular rhythm and narrow QRS complexes.

What are common symptoms of patients in SVT?

Patients may experience palpitations, shortness of breath, and hypotension.

What are the potential side effects of Adenosine?

Skin flushing, lightheadedness, nausea, sweating, nervousness, and a feeling of impending doom.

What is the significance of assessing hemodynamic stability in dysrhythmias?

It helps determine the urgency of intervention and the appropriate management pathway.

What is the heart rate for controlled Atrial Fibrillation?

A heart rate between 60-100 bpm.

What is the heart rate for rapid Atrial Fibrillation?

A heart rate greater than 100 bpm.

What is the heart rate for slow Atrial Fibrillation?

A heart rate less than 60 bpm.

What is the primary indication for intervention in junctional escape rhythm?

When the heart rate is less than 40 bpm.

What is the first-line therapy for symptomatic bradycardia?

Atropine.

What is the maximum dose of Atropine for treating bradycardia?

3 mg (1 mg IV every 3-5 minutes).

What are the indications for transcutaneous pacing?

Bradycardia unresponsive to drug therapy, 3rd degree heart block, and Mobitz type II second-degree heart block when hemodynamically unstable.

What characterizes ventricular rhythms?

They originate from an ectopic focus in the ventricle and result in a wide QRS complex.

What are isolated ventricular beats called?

Premature Ventricular Contractions (PVCs).

What is the difference between unifocal and multifocal PVCs?

Unifocal PVCs have the same morphology, while multifocal PVCs have different morphologies.

What is the heart rate range for idioventricular rhythms?

20-40 bpm.

What is the typical heart rate for accelerated idioventricular rhythms?

40-100 bpm.

What are the key steps in acute ventricular rhythm management?

Assess for bradycardia, identify reversible causes, support vital functions, obtain a 12-lead ECG, and assess for hemodynamic instability.

What is the characteristic finding in 1st degree AV block?

Prolonged PR interval greater than 0.20 seconds with one P wave for each QRS complex.

How does 2nd degree type I AV block present on an ECG?

PR interval progressively lengthens until a QRS complex is dropped.

What distinguishes 2nd degree type II AV block from type I?

Consistent PR interval with some dropped QRS complexes.

What is the defining feature of 3rd degree AV block?

No relationship between P waves and QRS complexes.

What is acute coronary syndrome (ACS)?

The acute manifestation of coronary artery disease.

What differentiates stable angina from unstable angina?

Stable angina has intermittent plaque restriction, while unstable angina involves plaque rupture and increased risk of myocardial infarction.

What does NSTEMI stand for and what does it indicate?

Non-ST Elevation Myocardial Infarction; it indicates a blockage causing injury to cardiac tissue without full thickness damage.

What is the significance of ST elevation in STEMI?

It indicates complete occlusion of a blood vessel causing full thickness damage to cardiac tissue.

What symptoms might indicate unstable angina?

New or more intense chest pain, pressure, and possible non-specific ECG changes.

What is the role of cardiac enzymes in NSTEMI diagnosis?

They may be positive indicating ischemia, but in NSTEMI, they are often negative.

What should be done if a patient presents with new ECG changes?

Notify the physician and perform a focused assessment.

What is the bradycardia algorithm used for?

To manage symptomatic bradycardia and determine appropriate interventions.

What is the expected management for symptomatic 2nd degree type II and 3rd degree AV blocks?

Use atropine or transcutaneous pacing.

What is the relationship between heart rate and AV blocks?

AV blocks typically do not present with tachycardia as impulses are being slowed or blocked.

What should be assessed in patients with arrhythmias?

Determine if the arrhythmia is causing bradycardia and assess for hemodynamic instability.

What are common symptoms of ACS?

Chest pain, pressure, cool and clammy skin, shortness of breath, elevated BP and HR, nausea, vomiting, possible fever.

What ECG changes are possible in ACS?

ST depression, T-wave inversion, transient ST elevation, and development of pathological Q-waves.

What is ST Elevation Myocardial Infarction (STEMI)?

An acute myocardial infarction characterized by ST elevation on the ECG.

What ECG findings indicate STEMI?

New ST elevation in 2 or more contiguous leads, possible new pathological Q-waves, hyperacute T-waves.

What cardiac enzymes are typically elevated in ACS?

Troponin is commonly elevated in cases of ACS.

What are the nonmodifiable risk factors for ACS?

Increasing age, sex (men > women until age 65), ethnicity (Black > White), genetic predisposition, and family history of heart disease.

What are the modifiable risk factors for ACS?

Cholesterol levels, blood pressure > 140/90, tobacco use, physical inactivity, obesity, and elevated homocysteine levels.

What are contributing factors to ACS?

Diabetes mellitus, elevated fasting blood glucose level, and psychosocial risk factors (depression, anger, stress).

What is the significance of the J-point in ECG?

It is the junction between the end of the QRS complex and the beginning of the ST segment, used to measure ST elevation or depression.

What does T-wave inversion indicate?

It refers to the T-wave being deflected downwards from the isoelectric line, typically indicating ischemia.

What defines ST depression on an ECG?

ST segment is >0.5mm below the isoelectric line, measured at the J-point.

What are the criteria for pathological Q-waves?

Q-waves >0.04s wide, >2mm deep, and >25% of total depth of the QRS complex.

What is the first-line treatment for STEMI?

Percutaneous Coronary Intervention (PCI) is the first-line treatment.

What is the purpose of fibrinolysis in ACS?

To dissolve the thrombus and stop the infarction process when PCI is not available within the recommended timeframe.

What nursing assessments should be performed for suspected ACS?

Focused assessment including pain assessment using the PQRST acronym and obtaining a 12-lead ECG.

What does the acronym MONA stand for in ACS management?

Morphine, Oxygen, Nitrates, Aspirin.

What are the key nursing considerations for administering fibrinolytics?

Continuous monitoring for complications, establishing IV access, and following institutional guidelines for monitoring.

What is the recommended timeline for obtaining a 12-lead ECG in suspected STEMI?

Within 10 minutes of the presentation of symptoms.

What are the signs of re-occlusion after PCI?

Returning chest pain and ECG changes indicating re-occlusion.

What is the significance of reciprocal changes in STEMI?

Electrically opposite areas of the heart will show ST depression when ST elevation is present in one area.

What is the nursing care post-PCI for femoral access?

Bed rest for 2 hours post-sheath removal, keeping the head flat for 30 minutes, and avoiding hip and knee flexion.

What are the nursing assessments for brachial/radial PCI?

Keep the limb straight for 2 hours, assess for bleeding, and evaluate distal extremity for color, circulation, and motion.

What is the role of the nurse in the interprofessional management of STEMI?

Recognize signs and symptoms of ACS, perform assessments, and anticipate collaborative interventions.

What is the importance of understanding gender differences in ACS presentations?

Men are more likely to have blockages in coronary arteries, while women may have blockages in smaller vessels, leading to different symptom presentations.

What are the typical presentations of ACS symptoms in diabetic patients?

Symptoms can be mild or absent due to nerve damage, making them less recognizable.

What is the goal of treatment in ACS?

To achieve reperfusion and restore blood flow to the heart muscle.