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42 Cards in this Set
- Front
- Back
Which Artery supplies the SA node?
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Sinoatrial Br. from RCA (60%)
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Through what receptor is vagal tone supplied to heart?
Sympathetic? |
Vagal= muscarinic, cholinergic mAchR, (as opposed to nAchR, nicotinic cholinergic)
Symp: adrenergic, B1 receptors |
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Which 3 factors, released after an MI and retained locally, can cause bradycardia?
Mechanism |
glutamic acid,
aspartic acid, HYPERkalemia ---all have Negative chrontrophic effect |
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What 3 maneuvers might trigger bradycardia (BC)
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Valsalva (shutting mouth/nose and force exhale--sim to lifting heavy objects/straining bowels)
-Carotid Pressure -Ocular Pres. |
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With myxedema secondary to it, what is a metabolic cause of BradyCardia
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HYPOthyroidism
--hypothermia and Beta adrenergic blockage also causes BC |
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How does Heart rate change/cause sinus arrhythmias with respiration
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HR increases with inspiration
HR degreases with expiration |
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What is the most common cause of a pause in ECG, thus a BC segment?
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a non-conducted PAC.
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How does digitalis cause BC
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slows SA by increasing parasympathetic tone
--other drugs used for HTN cause BC (clonidine, beta blockers "olols") -quinidine, hyperkalemia |
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Which sort of MI often causes BC?
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Acute, Inferior MI
--ischemia to this region |
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inc BP, inc pCO2
dec. pO2, dec. pH --all cause what arrhythmia? |
Bradycardia
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What effect do Beta Blockers have on heart rate?
How? |
cause BC:
Inhibit SA conduction by suppressing sympathetic tone |
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What is characteristic of SSS in EKG?
When seen? |
tachy and brady and flatline
--seen in ischemic, scleotic or inflammatory changes in SA node |
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Under what conditions might you treat Sinus BC
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if HR < 45-50 with Hemodynamic Compormise or
unstable acute conditions |
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What is most common Tx of Sinus BC.
Special cautions? -2nd Line Tx to Atropine? |
Atropine: .3-->.5-->1mg or 2mg IV over 10mins
-caution in glaucoma--inc IOP -Use epinephrine (last is isoproterenol) --surgical PM implant |
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List 4 types of Bradycardia
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1. Sinus BC
2. Non-conducted Atrial Bigeminy (tri too) 3. SA Block--(look for Atrial/Junctional/Ventricular escape) 4. AV Block--incomplete/complete (complete when ventricular rate is very slow) |
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Which arrhythmia is associated with lung Dx like COPD, pneumonia etc?
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MAT
Multifocal Atrial Tachycardia |
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Syncope, Lightheadedness, Chest Pain, Palpitation, CHF are Sx/History of what arrhythmia
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Both Tachy AND Brady
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Which valvular Dx is assc w/ Tachycardia (TC)?
Which Heart Dxs? |
Mitral Valve (prolapse)
--stenosis -Ischemia to/causing CAD, MI ---or inc. BP |
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Which are aminophylline and thyrotox assc. w/, BC or TC?
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Tachy
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How are the majority of SVT caused?
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Supra Ventricular Tachs are mostly caused by reciprocating reentry tach; due to an ectopic circulating wave
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What is a common mechanism for a SVT initiation?
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the Conduction of a PAC (or Premature atrial Beat, PAB), P` come early and drop early beat,
as opposed to a blocked PAC (as would cause brady) |
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List the Six Classifications of SVTs of Atrial Tachycardia
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1. Sinus Tach
2. Sinus Node re-entry (rarer) 3. Atrial Fib 4. Atrial Flutter 5. Atrial Tach (1 ectopic automaticity focus) 6. MAT (several foci) |
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List the 3 Classifications of SVT of Junctional origins causing tachy?
---Sign for on EKG |
1. AV nodal reentry
2. AV reentry 3. Paroxysmal Junctional Tach ---look for P wave adjacent, in or after QRS |
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Name the 2 Pre-excitation syndromes for SVTs & their mechanism
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Bypass AV node/insulation straight to ventricle.
-WPW, has Kent down R. side. R. atrium -LPL-James tract over AV node ----look for blend/curving of P into QRS |
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What are physiologic causes of Sinus Tach in Thryoid and blood volume?
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HYPERthyroid
Hypovolemia |
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Shortened diastole in SVT causes what EKG feature?
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ST-T depression
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How might you treat PT with Sinus rhythm into Atrial Tachycardia
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Dig
BBlockers |
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If ekg shows tachycardia w/o identifiable P waves, what is likely classification of SVT?
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Junctional (nodal) Tach
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How might you treat a SVT due to Junctional/Nodal tach?
ie, how to slow nodal impulses |
Adenosine
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describe EKG for AVNRT
AV Nodal Reentrant Tach? |
P-waves may be obscured in/around QRS, due to retrograde depol starting in node)
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describe EKG for AVRT with BT?
Atrioventricular Reentrant Tach with Bypass tract |
Short PR intervals
sluring of Pwave into QRS Delta Wave (in WPW, retrograde depol to above tract)-- U-shaped before T wave |
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What is main distinguishing EKG feature for determining a Tachycardia is SVT instead of ventricular?
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narrow QRS
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which SVT is indicated by irregular undulation of baseline assc. w/ irregular ventricular rhythm.
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Atrial Fibrilation --- irregularly irregular
--coarse/ medium/ fine -----few to many impulses get to vents |
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this arrhythmia has no p-waves, normal QRS complexes that are irregular in time
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Atrial Fib
--p waves replaed by 'f' waves (or NO sign at all of atrial activity) |
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Mitral Stenosis is indicated by what on EKG (until proven otherwise)
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Combo of A. Fib and RAD
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Term for Atrial Fib with venricular beats (or average of vent beats) of 100 or less
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Controlled A-Fib
--Atrial Fib with Rapid Response is vent are tachy |
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What is difference b/w wandering pacemaker and MAT
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Both have changing P` due to multiple atrial foci, but it's MAT ONLY if the atria impulses conduct vents in tachycardia
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What are most salient features of Atrial Flutter?
View in V1 Which leads best identify |
Sawtooth/Undulating 'f' waves in inferior leads (2,3, AVF)
-Sharp, P-like Wave in V1 -250-350 beats Inferior LEads best for A.Flutter |
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What are QRSs like in Atrial Flutter?
Most common ratios |
QRS normal (ie, not widened)
2:1 and 4:1 flutters to dropped beat (AV conducted) range is to 8:1 though, and 3:1 is uncommon |
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Can an Atrial Flutter be Irregularly Regular
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Yes, it can be an irregular heart beat, but have a regular/repeating ration of flutter waves to dropped beats
--ie, will note 2:1 or 4:1 sawtooths to QRS in Inferior Leads (II, III & AVF) and spiked p-like waves in V1 |
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Remember!!!
When counting beats for SVTs, to determine flutter vs fib. your counting the??? |
The atrial beats, while the vents may or may not be tachycardic (controlled or rapid response) the atrial will be
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Which SVT is assc. w/
varying PR-intervals Irregular Rhythm freq PACs ---theophylline, catechoalmines |
MATs: Lung/Pulmonary Dx
also HYPOKalemia & HypoMg ---treated with MgSulfate |