ECG

• What is the primary use of ECG in acute care settings?

  During cardiopulmonary resuscitation
• In which situations is ECG routinely used?

  In preoperative screening and diagnosis of unstable angina, myocardial infarction, and heart failure
• Why is ECG important for individuals in high-risk occupations and sports?

  It is part of their annual assessment
• What initiates each heartbeat in the heart?

  Specialized pacemaker cells
• What property do pacemaker cells of the heart have?

  Rhythmic, spontaneous electrical activity
• What occurs when cardiac muscle cells depolarize?

  Contraction of cardiac muscle occurs
• What is ECG used for?

  ECG is used in the acute care setting during cardiopulmonary resuscitation, for preoperative screening, and in the diagnosis and treatment of individuals with unstable angina, myocardial infarction, and heart failure. It is also routinely used as part of the annual assessment of individuals who are involved in high-risk occupations and in sports.
• What is the purpose of the cardiac muscle contraction?

  Contraction of cardiac muscle propels blood through the circulatory system.
• What initiates each heartbeat?

  Each heartbeat is initiated by specialized pacemaker cells of the heart.
• What property do the cardiac cells have that allows them to initiate each heartbeat?

  Cardiac cells have the property of rhythmic, spontaneous electrical activity.
• What happens when cardiac muscle cells depolarize?

  Contraction of cardiac muscle occurs when cells depolarize.
• What are the main reasons for performing an ECG?

  ECG is used to assess cardiac rate, cardiac rhythm, cardiac conduction abnormalities, myocardial ischemia, myocardial infarction, and other cardiac diseases such as valvular heart disease, cardiomyopathy, pericarditis, and hypertension. It is also used for monitoring and evaluating the response to therapy (drugs, ventilation, oxygenation).
• What are the three main types of cells in the heart?

  The three main types of cells in the heart are: pacemaker cells, electrical conducting cells, and myocardial cells.
• Where is the sinoatrial (SA) node located?

  The sinoatrial (SA) node is located in the right atrium and is the dominant pacemaker of the heart.
• What is the role of the SA node?

  The electrical signal from the SA node spreads across the right and left atrium, creating the depolarization and atrial contraction.
• What is the role of the atrioventricular (AV) node?

  The AV node gets the electrical signal from the SA node and then transmits it to the ventricles.
• What are the four parts of the ventricular conducting system?

  The ventricular conducting system consists of the AV node, the bundle of His, the right and left bundle branches, and the Purkinje fibers.
• What are the main components of an ECG?

  An ECG is made up of waves, signals, and intervals, including the P wave (atrial depolarization), the QRS wave (ventricular depolarization), and the T wave (ventricular repolarization).
• What is the duration of 1 small block on an ECG?

  1 small block on an ECG represents 0.04 seconds.
• What is the duration of 1 big box on an ECG?

  1 big box on an ECG represents 0.20 seconds.
• What is the duration of 1 second on an ECG?

  1 second on an ECG is represented by 25 small blocks or 5 big boxes.
• What is the duration of 1 minute on an ECG?

  1 minute on an ECG is represented by 1500 small blocks or 300 big boxes.
• What is the vertical scale on an ECG?

  Vertically, 1 small block on an ECG represents 0.01 mV, and 1 big block represents 0.5 mV.
• What are the three bipolar limb leads in an ECG?

  The three bipolar limb leads are: Lead I (right arm (-) to left arm (+)), Lead II (right arm (-) to left leg (+)), and Lead III (left arm (-) to left leg (+)).
• What is the normal heart rate range?

  The normal heart rate range is 60-100 beats per minute (bpm).
• What is tachycardia?

  Tachycardia is a heart rate greater than 100 bpm. Causes include hypoxia, anemia, blood loss, hypovolemia, hypotension, shock, heart disease, anxiety, uncontrolled pain, fever, and certain drugs.
• What is bradycardia?

  Bradycardia is a heart rate less than 60 bpm. Causes include severe hypoxia, vagal stimulation, severe acidosis, cardiac disease, arrhythmia (heart block), and administration of certain medications like beta-blockers. Well-trained athletes may have a resting heart rate of 40-50 bpm.
• What is asystole?

  Asystole is the absence of real waveforms, intervals, or QRS complexes on an ECG.
• What is pulseless electrical activity (PEA)?

  Pulseless electrical activity (PEA) reveals organized or semi-organized electrical activity in the absence of a palpable pulse, indicating the need for CPR.
• What is left-sided heart failure?

  Left-sided heart failure, also known as LVF, pump failure, or CHF, occurs when the heart fails to maintain adequate blood circulation. This causes blood to back up into the lungs, leading to pulmonary congestion and increased vascular pressures. This can then lead to right-sided heart failure (cor pulmonale).
• What is right-sided heart failure (cor pulmonale)?

  Right-sided heart failure, or cor pulmonale, is caused by lung disease. Chronic hypoxia due to lung disease causes increased pulmonary vascular resistance (hypoxemic vasoconstriction) and pulmonary hypertension, leading to right ventricular failure. Common causes include COPD, bronchiectasis, cystic fibrosis, interstitial lung disease, chronic restrictive pulmonary diseases, sickle cell anemia, and diseases that occlude the pulmonary vasculature.
• What is the purpose of a 12-lead ECG?

  The 12-lead ECG is used to identify cardiac waveforms and determine if any abnormalities are caused by arrhythmias, electrolyte imbalances, toxicities, or diseases. The patient needs to be resting in a supine or semi-Fowler position for the non-invasive procedure.
• Where are the electrodes placed for a 12-lead ECG?

  The electrodes are placed as follows: RA on the right forearm or wrist, LA on the left forearm or wrist, LL on the left lower leg, RL (ground lead) on the right lower leg. The precordial leads are placed as: V1 in the 4th intercostal space, right sternal border; V2 in the 4th intercostal space, left sternal border; V3 between V2 and V4; V4 in the 5th intercostal space, midclavicular line; and V5 in the anterior axillary line, straight in line with V4.
• What are the key steps for interpreting an ECG rhythm strip?

  Key steps for interpreting an ECG rhythm strip:

  1. Calculate and evaluate the heart rate
  2. Evaluate the cardiac rhythm
  3. Assess the P waves, PR interval, and relationship of P waves to QRS complexes
  4. Assess the QRS complex
  5. Inspect the ST segment
  6. Determine the QRS axis
  7. Overall assessment of the ECG