ECG NOTES

Conduction System

Heart Beat Graphic from Boston Scientific International. Start the Heart

ECG

ECG Parts P – Atrial depolarization (contraction) QRS – Ventricular depolarization (contraction – BP systole) T – Ventricular repolarization (rest – BP diastole) U – Atrial repolarization (rest – BP diastole)

Important “Times” 1 small square = 0.04 second 1 large square = 0.2 second Atrial contraction – P-R interval (PRI) = second Ventricular contraction – QRS complex = second Always use 6 second (30 large squares) strip to analyze an ECG waveform

Sinus Rhythms – always have P wave followed by QRS Normal Sinus Rhythm (NSR) rate is and rhythm is regular

Sinus arrhythmia – rate is and rhythm is irregular

Sinus bradycardia – rate is less than 60 and is usually regular

Sinus tachycardia – rate is more than 100 and less than 150 is usually regular

Atrial Rhythms – P wave and/or PRI are abnormal. QRS may be missing after some P waves. QRS is always normal, if it is present

Premature Atrial Contraction (PAC) Rate is usually normal and may be regular except when the PAC occurs. Some contractions have a shortened PRI or the P wave may not be identified because it is buried in the T wave.

Atrial tachycardia (A Tach) Rate is ) and usually regular. PRI is shorter than normal and the P wave may move up on the T wave or be buried in it (wet T). Each P wave is followed by a QRS complex.

Atrial Flutter (AF) Rate is P waves are usually 0.2 seconds each and occur in clusters of 2, 3, or 4 (look like saw teeth). Each cluster is followed by a QRS complex at regular intervals. Because of this, they are classified as being AF 2:1, 3:1, or 4:1.

Atrial fibrilliation (A-Fib) Atrial rate is too fast to count and individual P waves may be difficult to identify. Normal QRS complexes appear at irregular intervals. There will be many more P waves than QRS complexes. May cause blood clots to form and be sent to the brain, heart or lungs.

Atrial Fibrillation

Ventricular Rhythms – rate varies. No P wave in front of abnormally wide QRS complexes (they will be greater than 0.1 second). It may be difficult to identify parts as being QRST. There will be more QRS complexes than P waves in the strip.

Premature Ventricular Contraction Rate is usually normal and may be regular except when PVC occurs. PVC may occur alone at regular intervals (bigeminy, trigeminy) or in clusters (salvos). If 6 or more PVCs occur in 1 minute, the heart is becoming very irritable and ventricular tachycardia can begin at any time.

Ventricular tachycardia (V Tach) Rate is and regular (looks like ric rac). No P waves are seen. This is a continuous PVC run.

Ventricular fibrillation (V Fib) Rate is too irregular to count. Cannot identify any par of the waveform.

Asystole – Straight line No heart activity is seen. Clinical death is present. Will become biological death if lasts longer than 4-6 minutes.

Pathology of MI Plaque builds up slowly (frequently LAD) Sudden blockage occurs and muscle and nerve tissue distal begin to malfunction and then die Abnormal activity and contractions Leads to V Fib/Asystole Scar tissue may form during healing and cause disrhythmias.

Coronary Vessels

Plaque

Myocardial Infarction Heart Attack

MI Treatment Aimed at restoring coronary blood flow Angioplasty and stent placement Coronary artery by-pass graft (CABG) Anticoagulants: heparin and coumadin Aspirin (ASA): anticoagulant and anti- inflammatory agent

Pathology of CHF Congestive heart failure Damaged valves or ventricular muscle Heart cannot completely empty Right failure – blood backs up in legs (pitting edema, 1+ to 4+) Left failure – blood backs up in lungs (pulmonary edema) Cardiotonic – lanoxin, digoxin (not if pulse < 60) Diuretic - lasix

CHF Heart Failure

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