Module 3: ECGs

What is the primary purpose of monitoring ECGs?

To evaluate the effects of disease or injury on heart function, monitor heart rate, evaluate pacemaker function, and assess response to medications.

What are the two types of myocardial cells?

Electrical (pacemaker) cells and mechanical cells.

What is the intrinsic rate of the SA node?

60 - 100 beats per minute.

What is the function of the AV node?

To slow down conduction from the atria to the ventricles to allow for atrial contraction.

What is depolarization in cardiac cells?

The process of stimulation where sodium ions diffuse into the cell, causing a positive charge.

What does a tall, peaked T-wave indicate?

Hyperkalemia (high potassium levels).

What is the normal duration of a P wave?

0.08-0.12 seconds.

What is the significance of the QTc interval?

It is a corrected QT interval, with a normal value of less than 0.41 seconds.

What does the PR interval measure?

The time it takes for the electrical impulse to travel from the atria to the ventricles.

What is the normal duration of a QRS complex?

Less than 0.12 seconds.

What does the ST segment represent?

It should be neutral, indicating no ischemia or injury.

What is the 9-step method to ECG analysis?

1. P wave presence

2. P-P regularity

3. P-P rate

4. PR interval

5. R-R regularity

6. R-R rate

7. QRS complex

8. QTc interval

9. ST segment

How do you calculate heart rate using the 6-second method?

Count the number of R waves in a 6-second strip.

What is the role of electrolytes in cardiac cells?

They help develop electrical activity necessary for heart function.

What does repolarization refer to in cardiac cells?

The resting phase where the cell membrane returns to a negative charge.

What happens during phase 2 of the cardiac action potential?

Calcium moves into the cell and potassium diffusion slows, prolonging the action potential.

What is the significance of the R-R interval?

It is used to determine the heart rate.

What does a wide QRS complex indicate?

It may suggest a ventricular origin of the impulse or a conduction delay.

What is the function of Bachman's bundle?

To transmit the pacing impulse from the SA node to the left atrium.

What is the normal range for the intrinsic rate of the AV node?

40 - 60 beats per minute.

What does the presence of inverted P-waves indicate?

It may suggest a junctional rhythm.

What is the purpose of the sodium-potassium pump during repolarization?

To remove sodium from the cell and restore the negative charge.

What is the duration of a full ECG strip?

10 seconds.

What does the term 'electric potential' refer to?

The difference between charges inside and outside the cell.

What does a regular P wave indicate?

A normal atrial depolarization.

What is the normal P-P rate range?

60-100 beats per minute (bpm).

What does a prolonged PR interval indicate?

It may suggest a delay in atrial depolarization, potentially affecting cardiac output (CO).

What is the normal PR interval duration?

0.12-0.20 seconds.

How is the R-R interval assessed?

By counting the number of R waves in 6 seconds or using the formula 1500 divided by the number of small boxes between R waves.

What does the QRS complex represent?

The time it takes for ventricular depolarization.

What might a wide QRS complex indicate?

It may suggest a bundle branch block or other conduction abnormalities.

What does the QTc interval represent?

The time during which the heart cells are 'busy' and is adjusted for heart rate.

What is the normal QTc interval duration?

Less than 0.41 seconds.

What does significant deviation in the ST segment indicate?

It may indicate ischemia or infarction.

What are the characteristics of Normal Sinus Rhythm (NSR)?

Rate: 60-100 bpm; Rhythm: regular; P waves: present and consistent; PR interval: 0.12-0.2 seconds; QRS duration: 0.06-0.1 seconds.

What is Sinus Bradycardia?

A heart rate of less than 60 bpm with a regular rhythm.

What is Sinus Tachycardia?

A heart rate greater than 100 bpm but less than 180 bpm with a regular rhythm.

What is a Premature Atrial Contraction (PAC)?

An ectopic focus in the atria fires an impulse before the next sinus impulse is due.

What are the characteristics of Atrial Flutter?

Regular or irregular ventricular rate with saw-toothed/flutter waves.

What defines Atrial Fibrillation?

An irregular rhythm with multiple P waves and a rapid atrial rate, often leading to inadequate ventricular filling.

What is Supraventricular Tachycardia (SVT)?

A rapid heart rate of 150-250 bpm with a regular rhythm and indistinguishable P waves.

What is the significance of a low heart rate?

It may lead to decreased cardiac output and symptoms of bradycardia.

What is the impact of Atrial Fibrillation on stroke volume?

It decreases stroke volume by approximately 25%.

What conditions are commonly associated with Atrial Fibrillation?

Hypertension (HTN), heart failure (HF), and coronary artery disease (CAD).

What is the treatment approach for Sinus Bradycardia?

Treatment may include medications or pacing, depending on symptoms.

What is the treatment approach for Atrial Fibrillation?

Management may include rate control, rhythm control, and anticoagulation.

What are Premature Ventricular Contractions (PVCs)?

Early ventricular complexes caused by increased irritability of ventricular cells, often followed by a compensatory pause.

What is Ventricular Tachycardia (VTach)?

A rapid heart rhythm defined as 3 or more consecutive PVCs, with a rate of 100-200 bpm and no discernable P-waves.

What is the difference between monomorphic and polymorphic VTach?

Monomorphic VTach has a consistent shape in the QRS complexes, while polymorphic VTach has varying shapes.

What is Ventricular Fibrillation (VF)?

A life-threatening condition characterized by chaotic electrical activity in the ventricles.

What does Asystole indicate?

A complete cessation of electrical impulses in the heart, resulting in no rate, rhythm, cardiac output, or pulse.

What is Pulseless Electrical Activity (PEA)?

A condition where there is organized electrical activity in the heart but no pulse is detected.

What are common signs and symptoms of decreased cardiac output due to arrhythmias?

Weakness, lightheadedness, chest pain, delayed capillary refill, respiratory distress, palpitations, and changes in level of consciousness.

What is the primary goal when treating arrhythmias?

To treat the underlying cause and improve cardiac output.

What are the actions/interventions to manage arrhythmias?

Decrease preload, decrease or increase heart rate, and use medications to improve contractility.

What is the role of defibrillation?

To deliver an electrical current across the heart muscle to terminate an abnormal heart rhythm.

What is the difference between STEMI and NSTEMI?

STEMI is caused by 100% occlusion of an artery, while NSTEMI involves ischemia without complete blockage.

What are common cues for Acute Coronary Syndrome (ACS)?

Pain or discomfort in the chest, nausea, vomiting, diaphoresis, shortness of breath, anxiety, and fatigue.

What is the significance of cardiac markers like Troponin?

Troponin levels indicate myocardial injury and are used to assess heart damage.

What is the initial management for ACS?

Heparin IV infusion and dual antiplatelet therapy (DAPT) including aspirin and a P2Y12 inhibitor.

What does the term 'ventricular standstill' refer to?

A condition where atrial activity is present but there is no ventricular activity.

What is the purpose of a 12-lead ECG?

To record the electrical activity of the heart and identify arrhythmias and ischemic changes.

What are the H's and T's in the context of cardiac arrest?

Common reversible causes of cardiac arrest, including hypovolemia, hypoxia, hydrogen ion (acidosis), hyper/hypokalemia, hypothermia, tension pneumothorax, cardiac tamponade, toxins, and thrombosis.

What is the significance of monitoring blood pressure and heart rate in arrhythmias?

To assess the adequacy of cardiac output and guide treatment decisions.

What is the difference between sustained and non-sustained VTach?

Sustained VTach lasts longer than 30 seconds, while non-sustained VTach lasts less than 30 seconds.

What is the treatment for symptomatic bradycardia?

Administer oxygen, IV fluids, and consider medications or pacing if the patient shows poor cardiac output.

What is the role of vagal maneuvers in tachycardia management?

To slow the heart rate in stable patients with tachycardia.

What does CPR stand for and when is it indicated?

Cardiopulmonary resuscitation, indicated in cases of cardiac arrest to maintain blood flow and oxygenation.

What is the purpose of the cardiac arrest algorithm?

To provide a systematic approach for managing cardiac arrest, including CPR and defibrillation.

What is the significance of assessing rhythm, rate, P-wave, PR interval, and QRS in ECG interpretation?

These parameters help determine the type of arrhythmia and guide treatment.