EKG (test 5; S2)
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Created by:
Kholloway1119 on April 17, 2012
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129 terms
Terms | Definitions |
|---|---|
 the force the heart has to push against; it's volume related and related to the size of the blood vessels the heart has to push against | afterload |
| pointy part of the heart | apex |
| top chambers of the heart | atria |
| two heart valves that are between the atria and the ventricles | atrioventricular valves |
| heart valve on the right side | tricuspid |
| heart valve on the left side | mitral |
| broad part of the heart | base |
| amount of blood the heart pumps in one minute | cardiac output |
| part of the heart that keeps the valves in place so that they don't float back; they are basically anchors | chordae tendineae |
| something that is going to change the heart rate | chronotropic effect |
| positive chronotropic effect | increases the heart rate |
| negative chronotropic effect | decreases the heart rate |
| resting phase of the heart | diastole |
| the inner most layer of the heart | endocardium |
| outer layer of the heart | epicardium |
| effects the strength of the heart | inotropic effect |
| positive inotropic effect | increases the strength of the contraction |
| negative inotropic effect | decreases the strength of the contraction |
| middle muscle layer of the heart | myocardium |
| outer covering of the heart | pericardium |
| -stretching of the heart -also related to volume -measured best in the vena cava | preload |
| amount of blood pumped in one contraction | stroke volume |
| contraction phase of the heart | systole |
| anything that stimulates the vagal response and drops the heart rate | vagal maneuver |
| bearing down on a closed glottis which stimulates the vagal reflex and drops the heart rate | valsalva maneuver |
| comes back through the vena cava and can be decreased from positive intrathoracic pressure | venous return |
| 4 chambers of the heart | -right atria -right ventricles -left atria -left ventricles |
| 4 valves of the heart | -aortic semilunar valve -tricuspid valve -pulmonary semilunar valve -bicuspid valve |
| four major vessels of the heart | -superior and inferior vena cava -pulmonary trunk and left and right branches -pulmonary veins -ascending aorta |
| a decreased preload decreases _______ | cardiac output |
| increased afterload increases _______ | the work put on the left heart |
| supplies the right atrium, the inferior wall of the right ventricle, and half of the anterior surface of the left ventricle | right coronary artery |
| supplies the anterior surface of the left ventricle, the left atrium, the lateral wall of the left ventricle and part of the right ventricle | left coronary artery |
| returns to the heart through the coronary sinus into the right atrium | venous blood flow |
| stimulation increases the force of the contraction, heart rate, blood pressure, and cardiac output | sympathetic system |
| stimulation decreases the heart rate (example: vagal nerve) | parasympathetic system |
| located on the internal carotid arteries and the aortic arch | baroreceptors |
| baroreceptors detect changes in | blood pressure (a decrease in blood pressure will increase the heart rate) |
| -located in the medulla -responds to CO2 | central chemoreceptors |
| -located in aortic and carotid bodies -responds to O2 < 60 | peripheral chemoreceptors |
| chronotropic drugs | effect heart rate |
| dromotropic drugs | effects the speed of conduction through the A-V junction |
| inotropic drugs | change contractility (how strongly the heart contracts) |
| corresponds with the onset of the QRS complex to approximately the peak of the T wave | absolute refractory period |
| a reflection of the difference in the concentration of ions across a cell membrane at any given time | action potential |
| absence of a normal rhythm | arrhythmia |
| the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source (such as a nerve) | automaticity |
| the AV node and the Bundle of His | AV junction |
| -specialized cells located in the lower portion of the right atrium -delays the electrical impulse in order to allow the atria to contract and complete filling of the ventricles | AV node |
| -cardiac muscle fibers located in the upper portion of the interventricular septum -connects the AV node with the two bundle branches | Bundle of His |
| several waveforms | complex |
| the ability of a cardiac cell to receive an electrical stimulus and conduct that impulse to an adjacent cardiac cell | conductivity |
| the ability of cardiac cells to shorten, causing cardiac muscle contraction in response to an electrical stimulus | contractility |
| movement of ions across a cell membrane causing the inside of the cell to become more positive (an electrical event expected to result in contraction) | depolarization |
| abnormal rhythm | dysrhythmia |
| impulse(s) originating from a source other than the sinoatrial node | ectopic |
| period of time following repolarization of a myocardial cell (also called the "resting state") when the outside of the cell is positive and the interior of the cell is negative | polarized state |
| an elaborate web of fibers distributed throughout the ventricular myocardium | purkinje fibers |
| -corresponds with the downslope of the T wave -cardiac cells can be stimulated to depolarize if the stimulus is strong enough | relative refractory period |
| movement of ions across a cell membrane in which the inside of the cell is restored to its negative charge | repolarization |
| the normal pacemaker of the heart which discharges at a rhythmic rate of 60-100 bpm | sinoatrial node |
| originating from a site above the ventricles | supraventricular |
| primary function of myocardial cells is _______ | contraction and relaxation |
| primary property of myocardial cells is ________ | contractility |
| electrical cells (specialized cells) are responsible for _______ | -electrical conduction -generation and conduction of electrical impulses |
| electrical cells' (specialized cells) property is to ________ | conduct electrical impulses but they are automatic (have automaticity) |
| four characteristics of cell types | -excitability -automaticity -conductivity -contractility |
| makes cardiac cells irritable | excitability |
| can spontaneously generate an impulse at any time | automaticity |
| can conduct an impulse from one to the other (has domino effect) | conductivity |
| the ability of cardiac cells to shorten, causing cardiac muscle contraction in response to an electrical stimulus | contractility |
| -is in the upper portion of the right atrium -is our main pacemaker -fires at a rate of 60-100 | SA node |
| -in the lower portion of the right atrium, above the tricuspid valve -does not have any pacemaker cells -its main function is to delay the electrical impulse in order to allow the atria to contract and complete filling of the ventricles | AV node |
| -is in the upper portion of the interventricular septum and connects the AV node with the two bundle branches -these pacemaker cells will fire at a rate of 40-60 -escape pacemaker (number 2) | Bundle of His (AV junction) |
| the left bundle branch divides into two bundles to supply the _______ | left ventricle |
| -web of fibers about 1/3 of the way into the ventricular muscle -also an escape pacemaker that fires between 20-40 (number 3) | Purkinje fibers |
| major electrolytes | -sodium -potassium -calcium |
| when a cell membrane's charge becomes positive to generate an action potential. This is usually caused by positive sodium and calcium ions going into the cell | depolarization |
| when a cell membrane's charge returns to negative after depolarization. This is caused by positive potassium ions moving out of the cell | repolarization |
| -corresponds with the onset of the QRS to the peak of the T wave -the myocardial cells will not fire and the cells of the electrical conduction system cannot conduct an electrical impulse- no matter how strong | absolute refractory period |
| the downslope of the T wave | relative refractory period |
| an abnormal condition where cells that aren't normally pacemakers depolarize spontaneously | enhanced automaticity |
| causes of enhanced automaticity | -epinephrine -atropine sulfate -digitalis toxicity -acidosis -alkalosis -hypoxia -myocardial ischemia or infarction -hypokalemia -hypocalcemia |
| examples of rhythms that may occur if enhanced automaticity occurs | -atrial flutter -atrial fibrillation -supraventricular tachycardia (SVT) -premature atrial contraction (PAC) -junctional or ventricular complexes -ventricular tachycardia (VT) -ventricular fibrillation |
| an impulse returns to stimulate tissue that was previously depolarized | reentry |
| when the sinus node slows down or fails to initiate depolarization and a lower pacemaker site spontaneously produces electrical impulses | escape beats |
| escape beats are ________ | protective mechanisms |
| causes of dysrhythmias | -enhanced automaticity -reentry -escape beats -conduction disturbances |
| the QRS is the ________ contraction | ventricular |
| the P wave is the _______ contraction | atrial |
| usually identifies upright waveforms that are easily identified and shows the movement of the electrical impulse as it travels from the SA node through the AV junction, down the Bundle branches and across the ventricles towards the positive electrode | lead 2 |
| -a modified chest lead with the positive electrode placed on the right mid chest at the 4th intercostal space -can help determine the origin of abnormal complexes | MCL1 lead |
| indicates atrial depolarization | P wave |
| indicated delay through the AV node | PR interval |
| indicates conduction through the ventricles | QRS |
| indicates ventricular repolarization | T wave |
| heart rate < 60 bpm | sinus bradycardia |
| heart rate 60-100 bpm | normal sinus |
| heart rate >100-150 bpm | sinus tachycardia |
| the most frequent cause of a PVC is ______ | hypoxia |
| *HR: 60-100 *rhythm: regular *P waves: present, identical, precede each QRS *PR interval: normal (0.12-0.20) *QRS: normal (<0.1 sec), identical | normal sinus rhythm |
| *HR: 60-100 but gradually increases and then slows *rhythm: regularly irregular because of increasing and then decreasing HR *P waves: present, identical, precede each QRS *PR interval: normal (0.12-0.20) *QRS - normal (< 0.1 sec) identical | sinus arrhythmia |
| clinical significance of sinus arrhythmia | if heart rate drops very low - dizziness, syncope... |
| *HR <60 *rhythm: regular *P waves: present, identical, precede each QRS *PR interval: normal (0.12-0.20) *QRS: normal (<0.1 sec) identical | sinus bradycardia |
| clinical significance of sinus bradycardia | hypotension, decreased CO, dizziness, lightheadedness, or syncope |
| *HR: >100 *rhythm: regular *P waves: present, identical, precede each QRS *QRS: normal (<0.1 sec) identical | sinus tachycardia |
| clinical significance of sinus tachycardia | increased work on the heart increases consumption of oxygen by the heart and increases the likelihood of angina |
| the HR at which CO drops out is going to be around _______ | 160-180 |
| causes of premature atrial contraction (PAC) | electrolyte imbalance, hypoxia, dig toxicity, cardiovascular disease, mitral stenosis, atrial septal defect |
| clinical significance of premature atrial contraction (PAC) occurs in | congestive heart failure, acute MI, more serious arrhythmias impending |
| ~HR: atrial 240-300 / ventricular about 150 ~rhythm: regular ~P waves: absent - activity called an f wave, is sawtoothed and regular with regular QRS waves ~FR interval: regular but vary in duration ~QRS: normal (0.1 sec) identical and regular | atrial flutter |
| causes of atrial flutter | rheumatic heart disease, mitral stenosis, preexcitation syndrome, cardiomyopathy, thyrotoxicosis, dig toxicity, hypoxia, acute or chronic corpulmonale, CHF |
| clinical significance of atrial flutter | atria do not empty completely decreasing cardiac output |
| ~HR: atrial 350-600/ ventricular 160-180 ~rhythm: irregular ~P waves: absent, activity called an f wave, irregularly shaped, rounded, pointed, and dissimilar ~fr interval: abnormal not measurable ~QRS: normal (<0.1 sec) | atrial fibrillation |
| causes of atrial fibrillation | advanced rheumatic heart disease, mitral stenosis, hypertensive or coronary heart disease, thyrotoxicosis |
| clinical significance of atrial fibrillation | atria do not empty causing decreased cardiac output |
| ~HR: 160-240 repeated episodes of fast heart beat lasting minutes to hours following a PAC ~rhythm: regular ~P waves: often absent or buried in the QRS. if present, identical precede each QRS ~PR interval: abnormal (< .12 sec) ~QRS: normal (< .1 sec) identical | PJT/SVT |
| ~rhythm: irregular ~P waves: present or absent, have no relation to the PVC which comes unexpectedly ~PR interval: normal (.12-.20) ~QRS: the QRS complex of the PVC appears prematurely without a P wave and before the next expected QRS > .12 sec followed by an abnormal ST segment and a large T wave | premature ventricular contraction (PVC) |
| two PVCs in a row | couplet |
| PVC every other beat | bigeminy |
| PVC every third beat | trigeminy |
| 3 or more PVCs | ventricular tachycardia (VT) |
| ~HR: 110-250 ~rhythm: usually reg but may be irregular ~P waves: may be present or absent, if present they have no relation to QRS ~PR interval: none - if P is present, it is independent of QRS QRS: > .1 sec usually distorted and bizarre often notched | ventricular tachycardia (VT) |
| ~HR: no coordinated beats with rate from 300-500 ~rhythm: grossly and totally irregular ~P waves: none ~PR interval: none ~QRS: none | ventricular fibrillation (VF) |
| ~long PRI > 0.2 sec ~the QRS does not follow some of the p waves ~progressive delay - PRI gets longer and longer and eventually drops QRS | AV blocks |
| normal QRS interval | 0.06-0.1 sec |
| normal PR interval | 0.12-0.20 sec |
| how many seconds is each little box | 0.04 sec |
| how many boxes do you count for a 6 sec strip | 30 |
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