Basic Measurements
Wave representing atrial depolarization
What is the P wave?
Regular rhythm originating from SA node w/ HR 60-100 bpm.
What is normal sinus rhythm?
Lethal rhythm. Chaotic, disorganized electrical activity. No discernible P, QRS, or T. Leads to immediate cardiac arrest.
What is ventricular fibrillation (VF)?
Heart block characterized by consistently prolonged PR interval (>0.20 sec) but every P is followed by QRS.
What is a 1st-deg AV block?
Often seen with ischemia. Downward shift of ST segment below isoelectric line.
What is ST depression?
Beginning of P to beginning of QRS. Nl duration is 0.12-0.20 sec.
What is the PR interval?
Irregularly irregular ventricular rate, no discernible P waves, & narrow QRS.
What is atrial fibrillation?
Rapid, regular rhythm. Wide QRS, originating from ventricles. HR 100-250 bpm.
What is ventricular tachycardia (VT)?
Heart block. Progressively lengthening PR interval until a QRS complex is dropped, then cycle repeats.
What is a 2nd-deg AV block, Mobitz Type I (Wenckebach)?
Hallmark of acute MI. Upward shift of ST segment above isoelectric line.
What is ST elevation?
Represents ventricular depolarization. Nl <0.12 sec.
What is the QRS complex?
"Sawtooth" pattern of atrial activity, typically at 250-350 bpm, w/ a variable ventricular response.
What is atrial flutter?
Complete absence of electrical activity. Requires immediate CPR.
What is asystole?
P waves march through regularly & QRS march through regularly, but no relationship between the 2.
What is a 3rd-degree AV block (complete heart block)?
T wave abnormality. Often seen in ischemia. Indicates a lack of O2 to heart muscle.
What is T-wave inversion?
Total measurement for ventricular depolarization & repolarization. Prolongation can indicate risk for Torsades.
What is the QT interval?
Rapid, regular narrow complex tachycardia originating above ventricles, often presenting w/ HR 150-250.
What is Supraventricular Tachycardia (SVT)?
Premature, wide, bizarre QRS. Originates from ectopic focus in ventricles. Not preceded by P wave. Often followed by compensatory pause.
What are Premature Ventricular Contractions (PVCs)?
Abnormality in ventricular conduction. Wide QRS complex w RSR' pattern in V1 & wide, slurred S in V6.
What is a Right Bundle Branch Block (RBBB)?
Pathological Q waves, wider/deeper than normal ones, indicate this type of myocardial injury.
What is a myocardial infarction (MI)?
Wave representing ventricular repolarization. Upright in most leads.
What is the T wave?
Premature, abnormal P waves that originate from ectopic focus in atria, often followed by normal QRS.
What are Premature Atrial Contractions (PACs)?
Clinical condition. Organized electrical activity on ECG monitor, but no palpable pulse. Requires immediate resuscitation.
What is Pulseless Electrical Activity (PEA)?
Abnormality in ventricular conduction. Causes wide QRS complex w/ a notched or slurred R in V6 & deep S in V1.
What is a Left Bundle Branch Block (LBBB)?
Syndrome encompassing spectrum of conditions: unstable angina, NSTEMI, & STEMI, all characterized by acute myocardial ischemia.
What is Acute Coronary Syndrome (ACS)?