6 Rhythms Flashcards
Anterior, middle, and posterior intermodal tracts
Bachman, wenkebach, and thorel
Slow, intermediate, and fast conductions in cardiac pathway
SA+AV (slow), myocardial muscle (intermediate), HIS/BB/purkinje (fast)
Conduction velocity is a func of: 3
RMP, AP amplitude, rate of change in potential in phase 0
Accessory pathway connection: James fiber, atrio hisian fiber
Atria to AV, atria to his
Accessory pathway connection: Kent’s bundle, mahaim bundle
Atrium to ventricle, AV node to ventricle
Ventricle: phase 0-4 with electrical event
0-depolarization, 1-initial repol, 2-plateau/ST, 3-final repol, 4-resting
Ventricle: ion movement phase 0-4
0-Na in, 1- cl in and K out, 2- ca in k out, 3- k out, 4- na out
Event that leads to: pr depression, ST elev
Pericarditis. High k or endocarditis
Q wave abn that may make you think MI: 3
Amp grater than 1/3 of R wave, lasts > 0.04 sec, Depth >1 mm
T wave pts opposite direction of QRS if what: 2
Myo ischemia or BBB
T wave may be peaked with: 3
Myo ischemia, high K, IC bleed
U wave >1.5 mm when what
Low K
K too high can lead to what changes 7 (early to late)
Narrow/peaked T, short QT, wide QRS, low p amplitude, wide PR, nodal block, fusion of QRS-T—> VF/asystole
Low K leads to: 4
U wave, ST dep, flat T, long QT interval
High hi or low ca affects ekg
Hi- short QT, low- long QT
How hi or low mg affects ekg
Only if very hi —> heart block/arrest. Only if very low —> long QT
Vector of depolarization in heart
Base to apex and endo to epicardium
Vector of repolarization
Apex to base and epi to endocardium
Lateral leads and coronary artery
I, avl, V5-6. Circumflex
Inferior leads and artery
II, III, avf, RCA
Septal leads and artery
V1-2, LAD
Anterior leads and artery
V3-4, LAD
Right axis deviation
Leads reaching towards each other (I down Avf up)
Left axis deviation
Leads leaving each other (I up avf down)
Extreme right axis deviation
I and avf point down
Normal I and avf axis
Both point up
Normal axis between __ and __. L axis dev more neg than __, R axis dev more pos than
-30 to 90. -30, 90.
Causes of r axis dev: 5
COPD, acute bronchospasm, cor pulmonale, pulm htn, PE
Causes of L axis deviation: 6
Chronic htn, L BBB, AS, AI, mitral regurg
Sinus arrythmia
Inhalation —> dec intra p —> inc venous ret —> inc hr. Exhale —> inc intra p —> dec venous return —> dec hr
Brugada syndrome
Na ion channelopathy. Can cause sudden nocturnal death d/t v tach or fib
Second degree type I block
Wenkebach, longer longer drop. In AV node
Second degree type 2 block
Some ps dont conduct to ventricle. His or bundle branches
Third degree HB
AV dissociation. In av node rate 45-55, below av node 30-40.
IA, IB, IC where they work/how
A- dep phase 0, prolong phase 3. B- weak dep phase 0, shortens phase 3. C- strong 0 dep, little phase 3 fx
Where class II blockers work
Slows phase 4 depol in SA node
Where phase III blockers work
K channels, prolongs phase 3 repol, inc QT, inc refractory period
How phase IV blockers work
Dec velocity through AV node
When adenosine works and doesnt work
Works in SVT or WPW w narrow QRS. Doesn’t work in a fib, a flutter, or v tach.
How wpw works
No delay between atria and ventricle impulse, shorter refractory period
Orthodromic anvrt: incidence, pathway
More common, a—>av—>ventricle—>accessory path—>atrium
Orthodromic anvrt: QRS, tx
Narrow. Inc av node refractory period: vagal, amio, adenosine, bb, verapamil, cardiovert
Antidromic anvrt: incidence, pathway
Less common. Atrium, accessory, ventricle, av node, atrium
Antidromic anvrt: QRS morphology, tx
Wide. His purkinje bypassed. Block conduc pathway: procainamide, amio, cardiovert. DONT give agents that inc the refractory period of av node
Drugs to avoid in antidromic anvrt: 5
Adenosine, dig, ccb, bb, lidocaine
DOC in afib w wpw. Consid in radiofreq ablation
Procainamide. Monitor esophageal temp
Drugs that prolong QTc
Methadone, droperidol, haldol, zofran, halogenated IAs, amio, quinidine
Syndromes that prolong qtc, misc causes of inc qtc 3.
Romano ward and Timothy syndromes. HOCM, SAH, bradycardia
Pacers: positions 1, 2, 3, 4, 5
Chamber paced, chamber sensed, response, programmability, pacer can program multiple sites
how cautery affects pacer: which mode causes more Emi
Coag more than cutting
Conditions that make myo more resistant to repolarization
Low/hi k, low co2 (k into cell), low temp, mi, fibrosis around leads, antiarrythmic meds
Pacer/icd: ___ contraindicated but __ not
MRI. Lithotripsy
Reflex that mediates sinus arrythmia
Bainbridge
Glucagon initial dose and drip rate for bradycardia
50-70 mcg/kg q5 min then 2-10 mg/hr
Bipolar lead that is always positive, one that is always negative
I/right arm always negative, II left leg always positive
Part of ekg that is absolute vs relative refractory period
Absolute= first 1/3 t. Relative= last 2/3.
Causes of first degree hb 5
Aging, posterior wall mi, pns stim, amio, dig
Best lead to visualize the p wave
Lead II
Adenosine is best tx for
SVT
