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critical care test 3
| Question | Answer |
|---|---|
| count the numbers of QRS complexes on a 6-second rhythm strip and multiply by 10. the least accurate of all the methods | 6-second strip method |
| there are 300 big blocks every minute, so count the number of big blocks between consecutive QRS complexes an divide that number into 300. the fastest method | the memory method |
| count the number of little blocks between QRS complexes and divide into 1,500, since there are 1,500 little blocks in one minute | the little block method |
| is concerned with the spacing of the QRS complexes | rhythm regularity |
| this in which the R-R intervals vary by only one or two little blocks. the QRS complexes usually look alike | regular |
| regular rhythm that is interrupted by either premature beats or pause | regular but interrupted |
| are those that arrive early, before the next normal beat is due | premature beats |
| this is which the R-R intervals vary, not just because of premature beats or pauses, but because the rhythm is intrinsically chaotic | irregular |
| calculate the heart rate by choosing any two successive QRS complexes and using the little block or memory method | to calculate HR for regular rhythms |
| calculate the mean rate by using the 6-second strip method, and then calculate the heart rate range using the little block or memory method | to calculate HR for irregular rhythms |
| ignore the premature beats and calculate the heart rate, using the little block or memory method, on an interrupted part of the strip | to calculate HR for rhythms that are regular but interrupted by premature beats |
| calculate the heart rate range slowest to fastest, along with the mean rate | to calculate HR for rhythms that are regular but interrupted by pause |
| the normal rhythm originating from he sinus node is called | normal sinus |
| heart rate for normal sinus | 60-100 |
| in normal sinus p waves should be | upright, rounded and "married" to the QRS complexes |
| PR interval in normal sinus | 0.12-0.20 seconds |
| ORS interval in normal sinus | <0.12 seconds |
| heart rates that are too slow or too fast can cause symptoms of | decreased cardiac output |
| the criteria that must be met for the rhythm to be sinus in origin | 1) upright matching P waves followed by a QRS 2) PR intervals constant 3) heart rate less than or equal to 160 at rest |
| the width and deflection of the QRS complex is | irrelevant in determining whether a rhythm originates in the sinus node |
| sinus rhythm is the | normal rhythm |
| heart rate of sinus rhythm | 60-100 |
| regularity of sinus rhythm | regular |
| p waves of sinus rhythm | upright in most leads, on P to each QRS, same shape, P-P interval in regular |
| PR interval in sinus rhythm | 0.12-0.20 seconds |
| QRS interval in sinus rhythm | <0.12 seconds |
| slower than normal rhythm from the sinus node | sinus bradycardia |
| heart rate in sinus brady | <60 |
| regularity in sinus brady | regular |
| p waves in sinus brady | upright in most leads, one P to each QRS, same shape, P-P interval regular |
| PR interval in sinus brady | 0.12-0.20 seconds |
| QRS interval in sinus brady | <0.12 seconds |
| causes of sinus brady | vagal stimulation, MI, hypoxia, digitalis toxicity, other med side effects |
| is sinus brady common in athletes | yes |
| adverse effect of sinus brady | decreased cardiac output |
| treatment for sinus brady | none unless patient is symptomatic. atropine, pacemaker, epinephrine, dopamine, O2 |
| the sinus node fires at a heart rate faster than normal | sinus tachycardia |
| heart rate in sinus tach | 101-160 |
| regularity of sinus tach | regular |
| p waves in sinus tach | upright in most leads, one P to each QRS, same shape, P-P interval regular |
| PR interval in sinus tach | 0.12-0.20 seconds |
| QRS interval in sinus tach | <0.12 seconds |
| causes of sinus tach | atropine or bronchodilators, emotional upset, PE, MI, CHF, fever, inhibition of vagus nerve, hypoxia, thyrotoxicosis |
| adverse effects of sinus tach | decreased cardiac output |
| treatment for sinus tach | treat the cause, beta-blockers, O2 |
| the criteria that must be met for it to be atrial in origin | 1) matching upright Ps, atrial rate >160 2) No Ps at all 3) P waves of > or = 3 different shapes 4) premature abnormal P wave 5) Heart rate > or = 130, rhythm regular, P waves not discernible |
| are premature beats that are fired out by irritable atrial tissue before the next sinus beat is due | premature atrial complexes (PAC) |
| heart rate with a PAC | can occur at any rate |
| regularity with a PAC | regular but interrupted (by the PAC) |
| p waves with PAC | shaped differently from sinus P waves, premature P waves of PACs may be hidden in T wave on preceding beat. |
| PR interval with PAC | 0.12-0.20 seconds |
| QRS interval with PAC | <0.12 seconds. QRS will be absent after a nonconducted PAC |
| the most common cause of an unexplained pause is | a nonconducted PAC |
| causes of PAC | Medications ( stimulants, caffeine, bronchodilators), tobacco, hypoxia, heart disease |
| are occasional PACs normal | yes |
| adverse effects of PACs | frequent PACs can be an early sign of impending heart failure or impending a-tach or a-fib, usually no ill effects from occasional PACs |
| treatment for PACs | usually none needed. omit caffeine, tobacco, and other stimulants. can give digitalis, CCB, or beta blockers to treat if needed. treat HF if present. O2 |
| s rhythm that results when one irritable atrial focus fires out regular impulses at a rate so rapid that a fluttery pattern in produced instead of P waves | atrial flutter |
| heart rate of atrial flutter | atrial rate of 250-350, ventricular rate depends on the conduction ratio |
| regularity of atrial flutter | regular if the conduction ratio if constant; irregular is the conduction ratio varies; can look regular but interrupted at times |
| p waves in atrial flutter | no p waves present; flutter waves are present instead |
| PR interval in atrial flutter | PR is not measured, since there are no real P waves |
| QRS interval in atrial flutter | <0.12 seconds |
| cause of atrial flutter | almost always implies heart disease; PE, valvular heart disease, thyrotoxicosis, or lung disease |
| adverse effects of atrial flutter | can be well tolerated at normal heart rates; decreased cardiac output |
| treatment of atrial flutter | digitalis, CCB, beta blockers, adenosine, and carotid sinus massage. electrical cardioversion can be done if meds are ineffective or the patient is unstable |
| hundreds of atrial impluses from different locations all fire at the same time | atrial fibrillation |
| heart rate with a-fib | atrial rate is 350-700; ventricular rate varies |
| regularity of a-fib | irregularly irregular; completely unpredictable |
| p waves with a-fib | no p waves are present; fibrillatory waves are present instead |
| PR interval with a-fib | since there are no p waves, there is no PR interval |
| QRS interval with a-fib | <0.12 seconds |
| causes of a-fib | MI, lung disease, valvular heart disease, hyperthyroidism |
| adverse effects of a-fib | decreased cardiac output; blood clots which can result in MI, strokes, or blood clots in the lung |
| treatment for a-fib | depends on duration of a-fib; if < 48 hrs the goal is to convert back to sinus. digitalis, CCB, beta blockers amiodorone, or electrical cardioversion; >48 hrs goal is to control heart rate. anticoagulants, cardioversion is delayed, heparin IV, TEE, O2 |
| is a catchall tern given to tachycardias that are superventricular; that is they originate above the ventricles in either sinus node, the atrium, or the AV junction, but whose exact origin cannot be identified because P waves are not discernible | supraventricular tachycardia (SVT) |
| heart rate in SVT | about 130 or higher (usually >150) |
| regularity in SVT | regular |
| p waves in SVT | not discernible |
| PR interval in SVT | PR cannot be measured since P waves cannot be positively identified |
| QRS interval in SVT | <0.12 seconds |
| causes of SVT | the atria becomes hyper; medications (stimulants, caffeine, bronchodilators), tobacco, hypoxia, heart disease |
| adverse effects with SVT | decreased cardiac output |
| treatment for SVT | adenosine, digitalis, ibutilide, CCB, beta blockers, O2, elective cardioversion can also be done if the patient is unstable |
| premature beats that originate in irritable ventricular tissue before the next sinus beat is due | premature ventricular complexes (PVC) |
| heart rate in PVC | can occur at any rate |
| regularity in PVC | regular but interrupted |
| p waves in PVC | usually not seen |
| PR interval with PVC | PR not applicable |
| QRS interval with pVC | >0.12 seconds; wide and bizarre in shape |
| t wave with PVC | slopes off in the opposite direction to the QRS |
| causes of PVCs | heart disease, hypokalemia, and hypoxia are the big three reasons; low blood mag levels, stimulants, caffeine, stress or aniexty |
| adverse effects with PVCs | occasional PVCs are of no concern; frequent PVCs can progress to lethal arrhythmias such as v-tach or v-fib |
| treatment for PVCs | occasional PVCs dont require treatment; frequent PVCs, treat the cause. O2, amiodarone, antiarrhythmias are used to treat both atrial and ventricular arrhythmias; frequent PVCs with bradycardia treat with atropine |
| PVCs that come from a single focus all look alike | unifocal PVCs |
| PVCs from different foci look different | multifocal PVCs |
| two consecutive PVCs are called a | couplet |
| if every other beat is a PVC, its called | ventricular bigeminy |
| if every third beat is a PVC, its called | ventricular trigeminy |
| if every fourth beat is a PVC, its called | ventricular quadrigeminy |
| an irregular rhythm in which the severely impaired heart is only able to "cough out" an occasional beat from its only remaining pacemaker, the ventricle | agonal rhythm |
| heart rate with agonal rhythm | <20; although a occasional beat might some in at a slightly higher rate |
| regularity of agonal rhythm | irregular |
| p waves of agonal rhythm | none |
| PR intervals with agonal rhythm | not applicable |
| QRS intervals with agonal rhythm | >0.12 seconds; wide and bizarre |
| t wave with agonal rhythm | slopes off in the opposite directions to the QRS |
| the cause of agonal rhythm | the patient is dying, usually from profound cardiac or other damage or from hypoxia |
| adverse effects of agonal rhythm | profound shock, unconsciousness, death is left untreated |
| treatment for agonal rhythm | CPR, epinephrine and/or vasopressin, atropine, O2 |
| an irritable ventricular focus has usurped the sinus node to become the pacemaker and is firing very rapidly | ventricular tachycardia |
| heart rate in v-tach | >100 |
| regularity in v-tach | usually regular but can be a little irregular at times |
| p waves in v-tach | usually none seen, but dissociated from the QRS if present |
| PR intervals in v-tach | variable PR if even present |
| QRS intervals in v-tach | >0.12 seconds; wide and bizarre |
| t wave in vtach | slopes off in the opposite direction to the QRS |
| causes of v tach | heart disease, hypokalemia, hypoxia, low blood mag levels, stimulants, caffeine, stress or anxiety |
| adverse effects of vtach | profound shock, unconsciousness, and death |
| treatment for vtach | amiodarone or lidocaine IV is pt is stable; electric shock to the heart is pt is unstable or pulseless; treat cause (low K, mag, or O2 levels); CPR is pulseless |
| a form of polymorphic ventricular tachycardia that is recognized primarily by its classic shape-it oscillates around an axis, with the QRS complexes pointing up, then becoming smaller, then rotating around until they point down | torsades de pointes |
| heart rate with torsades | >200 |
| regularity of torsades | regular or irregular |
| p waves of torsades | none seen |
| PR interval with torsades | not applicable |
| QRS interval with torsades | >0.12 seconds; wide and bizarre; before torsades QT will be prolonged |
| t wave with torsades | opposite the QRS, but may not be seen due to rapidity of the rhythm |
| causes of torsades | antiarrhythmic meds such as quinidine, procainamide, or amiodarone.. otherwise same causes as vtach |
| adverse effects of torsades | cardiac arrest |
| treatment for torsades | IV mag, electrical cardioversion or defilbrillation may be needed. O2 |
| hundreds of impulses in the ventricle are firing, each depolarizing its own little piece of territory; as a result the ventricles wiggle instead of contract | ventricular fibrillation |
| heart rate with v-fib | cannot be counted |
| regularity with vfib | none detectable |
| p waves with vfib | none |
| intervals with vfib | no PR or QRS |
| t wave with vfib | none |
| causes of vfib | drowning, drug overdoses, accidental electrical shock, and same as vtach |
| adverse effects of vfib | profound cardiovascular collapse |
| treatment of vfib | immediate defibrillation, epinephrine, CPR, amiodarone, lidocaine, O2 |
| flat line EKG, every one of the heart's pacemakers has failed | asystole |
| heart rate with asystole | 0 |
| regularity with asystole | none |
| p waves with asystole | none |
| intervals with asystole | no PR or QRS |
| t wave with asystol | none |
| causes of asystole | profound cardiac or other body system damage, hypoxia |
| adverse effects | death |
| treatment for asystole | atropine, epinephrine and/or vasopressin, CPR, O2 |
| prolonged PR interval that results from a delay in the AV node's conduction of sinus impulses to the ventricle | first degree AV block |
| heart rate with first degree block | can occur at any rate |
| regularity with first degree block | depends on the underlying rhythm |
| p waves with first degree block | upright, matching; one P wave for each QRS |
| PR intervals with first degree block | prolonged >0.20, constant |
| QRS intervals with first degree block | <0.12 seconds |
| cause of first degree block | AV node ischemia, digitalis toxicity, SE of other meds (BB, CCB) |
| adverse effects of first degree block | causes no symptoms |
| treatment of first degree block | remove any meds causing it; treat the cause |
| occurs when the AV node becomes progressively weaker and less able to conduct the sinus impulses until finally it is unable to send the impulse down to the ventricle at all resulting in PR intervals grow progressively longer until there is a Pwave w/o QRS | second degree AV block (wenckebach) |
| heart rate with wenckebach | atrial rate usually 60-100; ventricular rate less than atrial rate due to nonconducted beats |
| regularity with wenckebach | usually irregular; can look regular but interrupted at times |
| p waves with wenckebach | normal sinus P waves. All Ps except the blocked P are followed by QRS, P-P interval regular |
| PR interval in wenckebach | PR gradually prolongs until a QRS is dropped |
| QRS interval in wenckebach | <0.12 seconds |
| cause of wenckebach | MI, digitalis toxicity, med SE |
| adverse effects of wenckebach | usually no ill effects, watch for worsening block |
| treatment for wenckebach | watch for transcutaneous pacing with signs of decreased cardiac output. atropine if pacemaker is not immediately available. cautious observation |
| a block caused by an intermittent block at the AV node or the bundle branches, preventing some sinus impulses from getting to the ventricles | Mobitz II second degree AV block |
| heart rate with mobitz II | atrial rate usually 60-100; ventricular rate is less than atrial rate due to dropped beats |
| regularity with mobitz II | may be regular, irregular, or regular but interrupted |
| P waves with mobitz II | normal sinus P wave, all Ps except the blocked Ps have a QRS behind them, P-P interval regular |
| PR interval with mobitz II | constant on the conducted beats |
| QRS interval with mobitz II | <0.12 seconds at AV node; >0.12 seconds at bundle branches |
| causes of mobitz II | MI, conduction system lesion, med side effect, hypoxia |
| adverse effects with mobitz II | decreased cardiac output, progress to third degree block |
| treatment for mobitz II | immediate transcutaneous pacing, O2, atropine or epinephrine (narrow QRS-atropine) (wide QRS-epinephrine) |
| the sinus node sends out its impulses as usual but none of them ever gets to the ventricles because there is a complete block at the AV node or the bundle branches | third degree AV block |
| heart rate with third degree block | atrial rate is usually 60-100; ventricular rate usually 20-60 |
| regularity of third degree block | regular |
| p waves with third degree block | normal sinus p waves, P-P interval is regular, may be hidden inside QRS complexes or T waves, not associated with QRS complexes |
| PR intervals with third degree block | varies |
| QRS intervals with third degree block | <0.12 seconds or >0.12 seconds depending on location of block |
| causes of third degree block | MI, conduction system lesion, med SE, hypoxia |
| adverse effects of third degree block | decreased cardiac output |
| treatment for third degree block | transcutaneous pacing is indicated is pt is symptomatic, atropine, epinephrine, or dopamine, O2 |
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