Cardiac monitoring Egan’s Ch. 17, CARC Ch. 11

Objectives (1 of 2) To gain an understanding of basic terminology and techniques of cardiac monitoring. To give you the knowledge and tools you need to assist the advanced provider with the use and implementation of an ECG. To better understand the basic anatomy and physiology of the heart.

Objectives (2 of 2) Identify the components of basic cardiac arrhythmias (because many times the RTs are with the patient during the onset of the initial event). Evaluate the rate and rhythm of a patient’s cardiovascular system, and become familiar with the normal ECG. Familiarize yourself with and apply 4-lead electrodes and identify placements for the 12-lead systems.

Cardiac Monitoring Use of 12-lead ECGs in the hospital is essential for cardiac patients. Early identification of AMIs allows hospitals to be prepared. The RT should know how to place electrodes and leads.

Electrical Conduction System (1 of 2) A network of specialized cells in the heart Conducts electrical current throughout the heart The flow of electrical current causes contractions that produce pumping of blood. VIDEO

The Process of Electrical Conduction Electrical conduction occurs through a pathway of special cells. Automaticity Ability of heart cells to generate a spontaneous electrical impulse Sinoatrial (SA) node: the heart’s main pacemaker Paces at a ventricular rate of 60–100 beats/min **Any beat that originates outside the SA node is called “ectopic”**

The Process of Electrical conduction Atrioventricular Junction- electrical bridge between atria and ventricles, comprised of: (AV) node Bundle of His AV node Acts as secondary (backup) pacemaker Paces at a ventricular rate of 40-60 beats/min Impulse is temporarily delayed here to allow better filling of the ventricles Protects ventricles from excessively fast rates

The Process of Electrical conduction Bundle branches Purkinje fibers Fingerlike projections that pass electrical impulses throughout myocardium to create a coordinated contraction of the ventricles

Electrical Conduction System (2 of 2) VIDEO

Formation of the ECG (1 of 4)

Formation of the ECG (2 of 4)

Formation of the ECG (3 of 4)

Formation of the ECG (4 of 4)

Electrodes and Waves Electrodes pick up electrical activity of the heart.

The ECG Complex One complex represents one beat in the heart. Complex consists of P, QRS, and T waves.

ECG Paper Each small box on the paper represents 0.04 seconds. Five small boxes in larger box represents 0.20 seconds. Five large boxes equal 1 second. © Steve Cole/Photodisc/Getty Images

Normal Sinus Rhythm Consistent P waves Consistent P-R interval (0.12-0.20 seconds) 60–100 beats/min QRS < 0.12 seconds

Sinus Bradycardia Consistent P waves Consistent P-R interval Less than 60 beats/min Potential causes are: Hypoxia, hypothermia, heart disease, electrolyte imbalances(hyperkalemia), parasympathetic stimulation, hypothyroidism Cause: Stimulation of vagus nerve (during suctioning) Hypothermia Increased ICP *Sinus bradycardia may be normal in well-conditioned athletes. Treatment: If accompanied by shortness of breath, hypotension, or abnormal beats, atropine is used A pacemaker may also be indicated in symptomatic bradycardia. Unsymptomatic – treat the cause.

Sinus Tachycardia Consistent P waves Consistent P-R interval 100 – 160 beats/min Potential causes are: Fever, pain, hyperthermia, anxiety, medications, hypoxia, sympathetic stimulation Cause: Hypoxemia Increased sympathetic nervous system stimulation (fear, anxiety) Medication Treatment: Treat underlying cause Administration of digitalis or beta blockers.

First Degree Block Impulse delayed at AV node Prolonged PR interval There is always concern that the patient will progress to the next worse rhythm Cause: Complication of digoxin or beta blockers Ischemia of the AV node Treatment: Atropine Isoproterenol

2nd Degree Type I (Wenckebach) PR progressively longer until a QRS is dropped. Cause: Myocardial ischemia May be a progression from 1st degree block. Treatment: None needed if CO is stable

2nd Degree Type II (Mobitz) Nonconducted P waves followed by conducted P waves. Cause: Myocardial ischemia Treatment: Isoproterenol Atropine Pacemaker Can lead to 3rd degree block, so pacemaker needed even if patient is asymptomatic.

3rd Degree Heart Block Ventricles and atria beat independently of one another. There is no relationship between the P waves and QRS complexes The patient will need a pacemaker Usually a temporary pacer (TCP) until a permanent one can be inserted Cause: Myocardial ischemia AV node damage Treatment: Pacemaker

Atrial Flutter Rapidly firing ectopic site in atria Characteristic “sawtooth” pattern At risk for thrombi Rate: 180-400 beats/min May progress to atrial fibrillation Cause: Hypoxia Arteriosclerotic heart disease MI Treatment: Cardioversion Carotid artery massage Procainamide Digitalis

Atrial Fibrillation Multiple ectopic sites within atria Atrial rate > 350 beats/min Decrease in ventricular filling Cause: Hypoxia Arteriosclerotic heart disease Mitral stenosis Valvular heart disease Treatment: Cardioversion Propranolol Digitalis

PVC’s Occasional PVC is ok but > 6/min is a sign of irritability Wide and bizarre QRS complex is the most distinguishing feature No P wave prior to PVC Bigeminyand trigeminy Unifocal and Multifocal Multifocal is more concerning because there are multiple irritated areas in the ventricles Occasional PVC is ok but > 6/min is a sign of irritability May progress to ventricular tachycardia Treatment Lidocaine (decreases ventricular irritability) Find the problem and fix it!

PVC’s Cause: Ventricular irritability caused by hypoxia Acid-base disturbances Electrolyte abnormalities CHF Coronary artery disease Treatment: Lidocaine IV Lido decreases ventricular irritability

Supraventricular Tachycardia (SVT) Impulse moves from atria – ventricles – atria (circular) Rate: 160-220 beats/min P waves may be unidentifiable, normal QRS Treatment If stable and narrow complex can try adenosine or vagal maneuvers If unstable, then immediate cardioversion Treatment: Immediate cardioversion (unstable) Carotid artery massage (stable) Valsalva maneuver

Ventricular Tachycardia Three or more PVC’s in a row Rate: 100-250 beats/min No distinguishable P waves Precedes or follows V-fib Treatment If stable, treat with amiodarone If unstable with a pulse, then cardioversion Pulseless VT is treated with CPR and defibrillation just like VF Cause: Arteriosclerotic heart disease Coronary artery disease Myocardial ischemia Mitral valve prolapse Hypertensive heart disease Treatment: Lidocaine Amiodarone (stable) If unstable….Defibrillation if pulseless, otherwise cardioversion

Ventricular Fibrillation Rapid, completely disorganized rhythm Deadly arrhythmia that requires immediate treatment A new onset is coarse and will progress to fine VF which is harder to defibrillate Fine VF can be confused with asystole Treatment is CPR and immediate defibrillation No effective CO. If not reversed death with ensue. If fine v-fib is present (harder to defib), epinephrine can increase the force of contractions and convert the rhythm into coarse v-fib. Cause: Coronary artery disease Hypertensive heart disease Acute MI Treatment: Defibrillation CPR

Pulseless Electrical Activity (PEA) Pattern does not generate a pulse. May show normal QRS complexes Can be any kind of a pattern from NSR to one or two complexes Treatment is CPR and identify the cause (H’s and T’s) PEA is not common but is associated with cardiac trauma, tension pneumothorax, severe electrolyte disturbances, and severe acid-base imbalances. Treatment: CPR

Asystole Complete absence of electrical cardiac activity Patient is clinically dead. Decision to terminate resuscitation efforts depends on local protocol.

Cardiac Monitors May be 3-, 4-, or 12-lead system Compact, light, portable Many monitors now combine functions beyond ECG.

4-Lead Placement Four leads are called limb leads. Leads must be placed at least 10 cm from heart.

12-Lead ECG Used to identify possible myocardial ischemia Studies show 12-lead acquisition takes little extra time. Early identification of acute ischemia and accurate identification of arrhythmias

12-Lead Placement Limbs leads placed at least 10 cm from heart. Chest leads must be placed exactly. Lead Location View V1 4th intercostal space, right sternal border Ventricular septum V2 4th intercostal space, left sternal border V3 Between V2 and V4 Anterior wall of left ventricle V4 5th intercostal space, midclavicular line V5 Lateral to V4 at anterior axillary line Lateral wall of left ventricle V6 Lateral to V5 at midaxillary line

Holter monitoring Portable, battery powered recording device Done over 24 hours Useful in patients experiencing irregular heart beats on an inconsistent basis.

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