Cardiology Essentials ECG Quiz

Study Notes

Heart assessment involves evaluating rate, intervals, axis, rhythm, conduction blocks, and signs of coronary artery disease (CAD) or acute coronary syndromes (ACS).
Normal heart rate is 60-100 beats per minute; rhythm can be regular or irregular.

Intervals: Normal duration is 0.06 - 0.10 seconds; amplitude ranges from 0.5 - 2.5 mm.
Heart Rate Measurement: Use a 3-step method with large squares on the ECG grid; calculations include:
- 1 large square = 0.2 seconds, equating to HR = 300 bpm if one large square between R waves.
- Alternatively, for tachy rhythms, count small squares between R waves and divide by 1500.

Right Axis Deviation can indicate right ventricular hypertrophy (RVH), conduction disturbances, myocardial infarction (MI), and various diseases such as valvular or pulmonary hypertension.
Left Axis Deviation can signify left ventricular hypertrophy (LVH), conduction disturbances, MI, and systemic hypertension.

Normal Heart Rate: 60-100 bpm; abnormal is >100 bpm.
P Waves: Should be sinus; non-sinus indicates abnormality.
PR Interval: Normal between 0.12-0.20 seconds; prolonged indicates issues.
QRS Duration: Normal <0.12 seconds; wide indicates potential pathology (e.g., bundle branch block).
ST Segment: Should be flat; elevation or depression indicates ischemia or infarction.
T Wave: Normal is upright; abnormalities may indicate ischemia or electrolyte disturbances.

Sinus Bradycardia: Heart rate <60 bpm; may require treatment if symptomatic (e.g., pacemaker).
Sinus Tachycardia: Heart rate >100 bpm; treat underlying causes such as fever or dehydration.

Include supraventricular tachycardia (SVT), premature ventricular contractions (PVC), and ventricular tachycardia (V-tach).
SVT Treatment: Vagal maneuvers, adenosine administration, or electrical cardioversion.
V-tach Management: CPR and fix electrolytes, with advanced treatment required in pulseless cases.

Atrial Fibrillation and Flutter: Caused by underlying arrhythmias and electrolyte imbalances; management includes rate control and anticoagulation.
Premature Atrial Contractions: Generally benign unless there's significant cardiomyopathy.

2nd Degree AVR Block: Mobitz 1 and 2, differing in treatment and causes related to MI, electrolyte imbalance.
3rd Degree Block: No correlation between atrial and ventricular rates; requires urgent treatment for underlying conditions.

Left and right bundle branch blocks characterized by QRS duration >0.12 seconds; treatment involves addressing underlying issues.

Hypertrophy: Thickening of ventricular walls due to pressure overload; identified via QRS changes.
Enlargement: Occurs from volume overload; P wave changes indicate atrial enlargement.

Ischemia: Lack of blood flow leading to ST segment depression; angina is a symptom.
Injury: Prolonged ischemia causes ST segment elevation.
Infarction: Tissue death may present as abnormal Q waves; could lead to acute coronary syndromes.

LVH Causes: Hypertension, cardiomyopathy, aortic stenosis; manage with blood pressure control and valve surgery.
RVH Causes: Chronic lung disease and pulmonary hypertension; treatment focuses on the underlying condition.