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CET-EKG prep
| Question | Answer |
|---|---|
| first heart sound is due to the closure of the mitral and tricuspid valves | S1 or lubb |
| second heart sound is due to the closure of the aortic and pulmonic valves | S2 or dupp |
| arteries are the right and left coronary from the aorta; veins accompany the arteries and terminate in the right atrium | vessels of the heart |
| heart is influenced by the autonomic nervous system (ANS) which is divided into the sympathetic and parasympathetic nervous systems | neural influences of the heart |
| affectys both the atria and ventricles by increasing heart rate, conduction, and irritability | sympathetic nervous system |
| affects the atria only by decreasing heart rate, conduction, and irritability | parasympathetic nervous system |
| primary characteristics of cardiac cells | automaticity, excitability, conductivity, and contractility |
| ability of the cardiac pacemaker cells to spontaneously initiate their own electrical impulse without being stimulated from another source | automaticity |
| sites that possess automaticity | SAn node, AV junction, Pukinje fibers |
| also referred to as irritability; shared by all cardiac cells; ability to respond to external stimuli; electrical, chemical, and mechanical | excitability |
| ability of all cardiac cells to receive an electrical stimulus and transmit the stimulus to other cardiac cells | conductivity |
| ability of cardiac cells to shorten and cause cardiac muscle contraction in response to an electrical stimulus; can be enhanced by medications such as digitalis, dopamine, and epinephrine | contractility |
| charge of resting cardiac cells inside as compared to outside | negative |
| when a cardiac cell is stimulated and sodium ions rush into the cell and potassium leaks out changing the charge within the cell to positive; results in contraction; flows from the endocardium to the myocardium to the epicardium | depolarization |
| ions shift back to their original places and the cell recovers the negative charge inside; results in myocardial relaxation; flows from the epicardium towards the endocardium | repolarization |
| SA node to AV node to Bundle of His to right and left bundle branches to Purkinje fibers | conduction system of the heart |
| found in the upper posterior portion of the right atrial wall just below the opening of the superior vena cava; primary pacemaker of the heart with a normal firing rate of 60-100 beats per minute | SA node |
| AV node and Bundle of His | AV junction |
| located at the posterior septal wall of the right atrium just above the tricuspid valve; one tenth of a second delay of electrical activity to allow blood to flow from the atria to the ventricles | AV node |
| found at the superior portion of the interventricular septum; pathway that leads out of the SA node; able to initiate electrical impulses with an intrinsic firing rate of 40-60 beats per minute | Bundle of His |
| located at the interventricular septum; divides in the the right and left bundle branches; functions to conduct the electrical impulse to the Purkinje fibers | Bundle branches |
| found within the ventricular endocardium; consists of a network of small conduction fibers that delivers the electrical impulse to the ventricular myocardium; able to initiate electrical impulses and act as a pacemaker at a rate of 20-40 beats per minute | Purkinje fibers |
| Consist of three bipolar leads and three augmented leads. These leads record electrical potentials in the frontal plane. | Limb Leads |
| Electrodes are applied to the left arm (LA), the right arm (RA) and the left leg (LL). Electrode and lead are also applied to the right leg which acts as a ground (or reference lead) and has no role in production of the electrocardiogram | Bipolar Standard Leads |
| the left arm is positive and the right arm is negative. (LA - RA) | Lead I |
| the left leg is positive and the right arm is negative.(LL-RA) | Lead II |
| the left leg is positive and the left arm is negative.(LL-LA) | Lead III |
| They are designated as aVR, aVL, and aVF. These leads are unipolar and they require only one electrode from one limb to make a lead. The EKG machine uses a midpoint between the two other limbs as a negative reference point | Augmented Unipolar Lead |
| the right arm is positive and the other limbs are negative | Lead aVR |
| the left arm is positive and the other limbs are negative | Lead aVL |
| the left leg (or foot) is positive and the other limbs are negative | Lead aVF |
| Six positive electrodes are placed on the chest to create Leads VI through V6 | Unipolar Precordial Leads |
| Fourth intercostal space, right sternal border | V1 |
| Fourth intercostal space, left sternal border | V2 |
| Equidistant between V2 and V4 | V3 |
| Fifth intercostal space, left midclavicular line | V4 |
| Fifth intercostal space, anterior axillary line | V5 |
| Fifth intercostal space, midaxillary line | V6 |
| consists of placing 10 electrodes on the patient producing 12 Leads: I, II, III, aVR, aVF, aVL; VI-V6 | routine EKG |
| graph paper with horizontal and vertical lines at 1-mm intervals. A heavy line appears every 5mm. Running speed is 25mm/sec. Machine must be calibrate so 1mV produces a deflection of 10mm. | EKG grid |
| represents time: 1mm = 0.04 seconds; 5mm = 0.2 seconds. | horizontal axis |
| represents amplitude measured in millivolts but expressed in millimeters: O.1 mV = 1mm | vertical axis |
| refers to movement away from the isoelectric line either upward (positive) deflection or downward (negative) deflection | waveform |
| line between two waveforms | segment |
| waveform plus a segment | interval |
| several waveforms | complex |
| atrial activation, ventricular activation, and ventricular repolarization | normal electrocardiogram complexes |
| deflection produced by atrial depolarization; does not exceed 0.1 Is in duration or 2.5mm in height in standard, limb, and precordial leads | P wave |
| atrial activation | P wave |
| ventricular activation | QRS complex, Q wave, R wave, and S wave |
| ventricular repolarization | T wave and U wave |
| represents ventricular depolarization (activation). The ventricle is depolarized from the endocardium to the myocardium, to the epicardium. | QRS complex |
| the initial negative deflection produced by ventricular depolarization | Q wave |
| the first positive deflection produced by ventricular depolarization | R wave |
| the first negative deflection produced by the ventricular depolarization that follows the first positive deflection, (R) wave | S wave |
| the deflection produced by ventricular repolarization | T wave |
| the deflection seen following the T wave but preceding the next P wave. A prominent is due to hypokalemia (low potassium blood level) | U wave |
| interval between two R waves | RR interval |
| P wave plus the PR segment. The normal interval is 0.12 - 0.2 sec | PR interval |
| represents ventricular depolarization time. It should be no more than 0.1 sec. in the limb leads and 0.11 sec. in the precordial leads | QRS interval (or duration) |
| line from the end of the P wave to the onset of the QRS complex | PR segment |
| point at which QRS complex ends and ST segment begins | J (RST) junction |
| from J point to the onset of the T wave | ST segment |
| somatic tremors, wandering baseline, 60-cycle interference, broken recording | artifacts |
| patient's tremors or shaking the wires can produce jittery patterns on the EKG tracing. | Somatic tremors |
| sweat or lotion on the patient's skin or tension on the electrode wires can interfere with the signal going to the EKG apparatus causing the baseline of the tracing to move up and down on the EKG paper | Wandering baseline |
| can produce deflections occurring at a rapid rate that may mimic atrial flutter. This is caused by electrical appliances or apparatus being used nearby while the tracing is taken. | 60-cycle interference |
| the stylus goes up and down trying to find the signal. This can be caused by loose electrode or cables or by frayed or broken wires | Broken recording |
| How are artifacts prevented? | patient should be lying on a comfortable bed or table large enough to support the entire body;good contact between the skin and the electrode; EKG machine must be properly standardized; proper grounding; no patient contact with electronic equipment |
| A noninvasive diagnostic procedure to determine the presence and severity of coronary artery disease | stress testing |
| What are some indications for stress testing? | • Evaluation of chest pain in patient with normal EKG. • Evaluation of patient who has recently had a myocardial infarction. • Diagnosis and treatment of arrhythmias. |
| What are some indications for terminating a stress test? | • Patient develops chest pain, shortness of breath, or dizziness. • Blood pressure abnormalities |
| exercise stress test | performed until at least 85% of the target heart rate is reached or symptoms or EKG changes develop which requires the test to be terminated. Target heart rate is: 220 minus patient's age. |
| pharmocologic stress test | appropriate for patients with physical limitations; Medications (adenosine, dipyridamole, or dobutamine)are given IV to increase heart rate to the target level; concluded after 85% of the target heart rate is achieved. |
| Cardiac arrhythmias are due to what mechanisms? | Arrhythmias of sinus origin,Ectopic rhythms, Conduction blocks, Preexcitation syndromes |
| Arrhythmias of sinus origin | where electrical flow follows the usual conduction pathway but is too fast, too slow, or irregular. Normal is 60-100 bpm; >100 per minute, it is called sinus tachycardia; <60 per minute, it is referred to as sinus bradycardia. |
| Ectopic rhythms | electrical impulses originate from somewhere else other than the sinus node. |
| Conduction blocks | electrical impulses go down the usual pathway but encounter blocks and delays. |
| Preexcitation syndromes | the electrical impulses bypass the normal pathway and, instead, go down an accessory shortcut |
| What is myocardial ischemia? | occurs when there is a decrease in the amount of blood flow to a section of the heart. This is usually experienced as chest pain and discomfort and is called angina |
| What is myocardial infarction? | refers to the actual death of the myocardial cells |
| How does an MI present on an EKG? | abnormal Q waves (Q waves are >1 mm (0.04 second) wide and the height is greater than 25% of the height of the R wave in that lead) combined with changes in T waves and ST segments |
| What is the World Health Organization creiteria for the diagnosis of MI? | at least two of the following: Clinical history of ischemic-type of chest discomfort Changes on serial EKG tracings Rise and fall in serum cardiac markers |
| Ambulatory EKG monitoring | enables the evaluation of the patient's heart rate, rhythm, and QRST morphology during the usual daily activities |
| Holter monitor | an ambulatory EKG done to rule out intermittent arrhythmias or ischemia that could be missed on a routine EKG |
| What is the typical electrode placement for Holter monitoring? | Two exploring electrodes are placed over bone near the VI and V5; Two indifferent electrodes placed over the manubrium; One ground electrode placed over the 9th or 10th rib at the right midaxillary line |
| What indicates a positive Holter? | one that has recorded abnormalities that may explain the patient's symptoms which could include one or more of the following: • Tachycardias or bradycardias • ST segment elevation or depression • Pauses |
| What indicates a negative Holter? | A negative Holter will have no significant arrhythmias or ST changes |
| What are some artifacts of ambulatory EKG recording? | Incomplete tape erasure; Tape drag within the apparatus; Battery depletion; Loose connection; Movement of electrodes |
| can result in EKG tracings belonging to two different patients confounding both the scanner and the interpreter | Incomplete tape erasure |
| will result in recording of spuriously rapid cardiac rhythms. A narrowing of all EKG complexes and intervals should give clue to this situation. | Tape drag within the apparatus |
| may result in varying QRS amplitude | Battery depletion |
| can result in the absence of all EKG signals which may mimic bradycardia-tachycardia syndrome | Loose connection |
| may occur during scratching the chest near the electrodes and can produce tracings that look like malignant ventricular arrhythmias | Movement of electrodes |
| What is event monitoring (event recorder)? | a hand held device carried in the patient's pocket or purse which is switched only when the patient is actually experiencing the symptom. |
| What are some common pharmacological cardiovascular agents? | oxygen, epinephrine, isoproterenol (Isuprel), dopamine (Intropin), beta blockers (Propranolol, Metoprolol, Atenolol, and Esmolol), licodaine, verapamil, digitalis, morphine sulfate, and nitroglycerin |
| How is oxygen used as a pharmacological cardiovascular agent? | Oxygen should be given to all patients with acute chest pain that may be due to cardiac ischemia, suspected hypoxemia of any cause, and cardiopulmonary arrest. Prompt treatment of the hypoxemia may prevent cardiac arrest |
| How is epinephrine used as a pharmacological cardiovascular agent? | Epinephrine is indicated in the management of cardiac arrest. The chance of successful defibrillation is enhanced by administration of epinephrine and proper oxygenation |
| How is isoproterenol used as a pharmacological cardiovascular agent? | Isoproterenol produces an overall increase in heart rate and myocardial contractility, but newer agents have replaced it in most clinical settings. It is contraindicated in the routine treatment of cardiac arrest |
| How is dopamine used as a pharmacological cardiovascular agent? | indicated for significant hypotension in the absence of hypovolemia; significant hypotension =systolic blood pressure <90 mmHg, poor tissue perfusion, oliguria, or changes in mental status. |
| How are beta blockers used as a pharmacological cardiovascular agent? | reduce heart rate, blood pressure, myocardial contractility and oxygen consumption; effective in the treatment of angina pectoris and hypertension; useful in preventing atrial fibrillation, atrial flutter, and paroxysmal supra-ventricular tachycardia. |
Created by:
ericmichaelperkins