Arrhythmias 239 - 251 Flashcards
(113 cards)
1
Q
Mechanism of tachyarrhythmias
A
- Enhanced automaticity
- Triggered arrhythmias (afterdepolarization occuring during phase 3 or 4 or immediately after the action potentials)
- Reentry - most common
2
Q
Acetylcholine
A
- activates potassium current IkAch the decrease slope of phase 4
3
Q
Sympathetic
A
- activates IcaL and If to decrease slope of phase 4
4
Q
Na channel imp domains
A
- 3rd and 4th domain: critical to inactivation
- 6th membrane spanning repeat in the 4th domain: binding site of local anesthetic antiarrhythmics
- *ca channel drug binding site: alpha 1 subunit
5
Q
Triggered automaticity 2 types of afterdepolarizations
A
- early afterdepolarization: occur during the action potential - due to prolonged action potential (hypomagnesemia, hypokalemia, bradycardia, drugs - class 1b/III antiarrhythmics, nonsedating antihistamines)
- late after depolarizations: after the ap - due to calcium loading (ischemia, digitalis, catecholamines)
6
Q
Ead associated arrhythmia
A
Torsades des pointes
7
Q
Sustained reentry requirement
A
Tachycardia wavelength (conduction velocity x refractory period) must fit within the path length (total anatomic length of the circuit)
8
Q
Region between the head of the activatiom wavefront and the refractory tail
A
Excitable gap
9
Q
Reentrant arrhythmias with no excitable gap
A
Leading circle reentry
10
Q
Myocardial gap junctions
A
Connexin 43
11
Q
Ecg signatures
Wpw syndrome
Arrhythmogenic rv dysplasia
Brugada syndrome
A
Wpw syndrome - delta wave
Arrhythmogenic rv dysplasia - epsilon wave
Brugada syndrome - right precordial st segment abnormality
12
Q
Relative c/i to head up tilt test
A
- cad with prox coronary stenosis
- severe ms
- lv outflow obstruction
- severe ms
13
Q
Vaughan-Williams Classificationnof antiarrhythmics
A
Class I - Na channel inhibitor
1a (open na channels and k channels) (increase action potential duration) - quinidine, disopyramide, procainamide
1b (open and inactivated) (decrease action potential duration) - lidocaine (mi), phenytoin (doc for digoxin toxicity), tocainide, mexiletine
1c (open na channels but dissociate slowly) (no effect action potential duration, prologn qrs) - flecainide, propafenone
Class II - Beta blocker
Class III - K Channel blocker (amiodarone, dofetilide, ibutilide, sotalol)
Class IV - Ca channel blocker (verap, diltiaz)
14
Q
Cryoablation temp
A
<32degrees
15
Q
Sa node vs av node
A
Sa: epicardial, Sulcus terminalis, ra-svc junction
Resting membrane potential -40 to -60
Av: subendocardial, apex of the triangle koch (coronary sinus ostia, tendon of todaro, tricuspid annulus)
16
Q
Sa node dysfunction
A
- sinus pause
- sinus bradycardia
- Tachy- brady variant of sss are at increased risk for thromboembolism and need anticoag
- Chronotropic incompetence
- inability to increase the heart rate to 85% of max predicted for age with max exercise
- failure to achieve hr >100bpm
17
Q
SSS1
A
- AR, SCN5A chromosome 3
- atrial inexcitability syndrome, no p on ecg
18
Q
SSS2
A
- AD, HCN4 Gene chromosome 15 (funny channels)
- Tachycardia-bradycardia sick sinus syndrome
19
Q
SSS3
A
- associated with variations in MYH6 (myosin heavy chain 6)
20
Q
Neuromuscular disease + SSS
A
- Kearns- Sayre syndrome: ophthalmoplegia, pigmentary degeneration of retina, cardiomyopathy
- myotonic dystrophy
21
Q
Carotid Sinus hypersensitivity
A
- pauses >3s in autonomic nervous system testing
22
Q
Sa node assessment
A
- Intrinsic heart rate
- propanolol 0.2mg/kg and atropine 0.04mg/kg
- 117.2 - (0.53x age)
- low ihr =sa node disease - Sinus node recovery time
- longest pause after overdrive pacing
- normal <1500ms; corrected for cycle length <500ms - Sinoatrial conduction time
- 1/2 the difference between instrinsic sinus cycle length and a noncompensatory pause after premature atrial stimulus
- <125ms
23
Q
Sa node dysfunction is not associated with increased mortality
A
Sa node dysfunction is not associated with increased mortality
24
Q
Pacemakers modes and function
A
- Chamber paced - 0 none, a atrium, v ventricle, d dual
- Chamber sensed - 0 none, a atrium, v ventricle, d dual
- Response - 0 none, I inhibition, T triggered, D both
- Rate monitoring - r rate responsive (rate sensor: movement, minute ventilation, qt interval)
- Antitachycardia function - O none, P antitachycardia pacing, S shock, D pace + shock
- most common dual: DDDR
- most common single: VVIR
25
Twiddler syndrome
- rotation of pacemaker pulse generator
| - failure to sense or pace
26
Pacemaker syndrome
- pacemaker fails to restore av synchrony
- neck pulsation, fatigue, palpitations, cough, confusion, exertional dyspnea, dizziness, syncope, elevatoon in jugular venous pressure, canon a waves, chf
- prevention: minimize vetricilular pacing, biventricular pacing
27
Class I indication for pacemaker in SA node dysfunction
1. Symptomatic sinus brady or sinus pause
2. Meds with no alternative
3. Symptomatic chronotropic incompetence
4. Af in svr and sinus pause >5s
28
Class IIa indication for pacemaker in SA node dysfunction
1. Hr <40 without clear and consistent association between symptoms and bradycardia
2. Hr <40 on meds with no alternative with no clear and consistent association between symptoms and bradycardia
3. Syncope of unknown origin but with sa node dysfunction on provocation testin
29
Class IIb indication for pacemaker in SA node dysfunction
1. Mildly symptomatic with hr <40
30
Class III
1. Asymptomatic or symptoms not related to brady (evem if hr <40)
2. Brady sec to nonessential meds
31
Types of pacemaker
Sa node dysfunction: dual chamber pacing
| Carotid sinus hypersensitivity: single chamber pacing
32
Av blocks anterior vs inferior mi
Inferior - more common, av node, stable narrow
| Anterior - distal av nodal complex, wide unstable, poorer prognosis
33
Ah interval
- time from the most rapid deflection of the atrial electrogram in the his bundle recording to the his electrogram
- represents av node conduction
- normal <130ms
34
Hv interval
- time from the his electrogram to earliest onset of qrs
- conduction thru his purkinje
- normal <55ms
35
Class I pacemaker indications in av block
1. 3rd degree - symptomatic, essential drug tx, asystole >3s, escape rhythm <40bpm, post op, catheter ablation associated, neuromuscular d/o associated
2. Symptomatic 2nd degree
3. T2 2nd degree wide qrs
4. Exercised induced 2nd/3rd
5. Af in svr with pause >5s
36
Class IIa pacemaker indications in av block
1. Asymptomatic 3rd degree
2. Asymptomatic t2 2nd degree narrow qrs
3. Asymptomatic t2 2nd degree within or below His on EPS
4. first or second degree av block with symptoms
37
Class IIb pacemaker indications in av block
1. Av block with use of drugs but expect block to recur despite discontinuation
2. Neuromuscular disease
38
Class III pacemaker indications in av block
1. Asymptomatic 1st degree
2. Type 1 2nd degree at av level
3. Expected to resolve (lyme, drug)
39
Class I pacemaker indications in ami
1. Persistent and symptomatic 2nd/3rd degree block
2. Transient 2nd/3rd degree block infranodal with associated bundle branch block (if site uncertain may require electrophysiologic studies)
3. Persistent second degree with bilateral bundle branch block or 3rd degree within or below the his
40
Class IIb pacemaker indications in ami
1. Persistent 2nd/3rd degree av block at av node level
41
Class III pacemaker indications in ami
1. Transient av block without ivcd
2. Transient av block with isolated left anterior fascicular block
3. Acquired left anterior fascicular block without av block
4. Persistent first degree av block in the presence of bundle branch block which is old or age indeterminate
42
Class I pacemaker indications in trifascicular/bifascicular blocks
1. Intermittent 3rd degree av block
2. T2 2nd degree av block
3. Alternating bundle branch block
43
Class IIa pacemaker indications in trifascicular/bifascicular blocks
1. Syncope not demonstrated due to the block but other cause excluded
2. Prolomged hv interval >100ms on electrophysiologic studies in asymptomatic
3. Pacing induced infra his bloch which is not physiologic on electrophys studies
44
Class IIb pacemaker indications in trifascicular/bifascicular blocks
1. Neuromuscular disease
45
Class III pacemaker indications in trifascicular/bifascicular blocks
1. Fascicular but no av nor symptoms
| 2. Fascicular with 1st degree av block and no symptoms
46
- Most common supraventricular tachycardia
- Most common sustained arrhythmia in older adults
- Most common paroxysmal sustained tachycardia in young healthy adults
- Most common supraventricular tachycardia : Sinus tachycardia
- Most common sustained arrhythmia in older adults: atrial fibrillation
- Most common paroxysmal sustained tachycardia in young healthy adults: AVNRT
47
Svt with 1:1 conduction, p wave relationships
1. Avnrt: no discernible, synchronous with qrs
| 2. Ort (orthodromic av reentry): p waves following the qrs; rp pr interval
48
Svt response to av nodal blockade
1. Avnrt: terminate
2. Ort: terminate
3. At: continuation/terminate
4. Aflutter: exposes underlying flutter waves
49
Postural orthostatic hypotension syndrome
- increase hf by >30bpm or >120bpm within 10 minutes of standing but no hypotension
- if due to viral illness autonomic dysfunction returns to normal in 3-12 mos
- tx: volume expansion, salt, compression stockings, fludrocortisone, midodrine
50
Focal atrial tachycardia not dependent on av nodal conduction, will not terminate/change its rate with av block
Vs avnrt/avrt - node dependent
Tx: adenosine - higher doses maybe needed (triggered activity)
Cardioversion (if recurs suggests automaticity)
Correct precipitants
Beta blocker or calcium channel blockers
Catheter ablation
51
FAT distinguished from sinus tachycardia because impulse originates elsewhere, p wave morphology different
Abrupt onset and offset
- origins: crista terminalis, valve annuli, atrial septum, atrial muscle, cardiac thoracic veins (coronary sinus, svc, pulmo veins)
1. Atrial septum: narrower
2. Left atrium: monophasic positive p wave in lead v1 and negative p waves in I and avl
3. Superiorly (svc, pulmo veins): + p in II, III, AVF
4. Inferiorly (coronary sinus/ostia): - p in II, III, AVF
52
Most common location of accessory pathways
- left atrium and left ventricular free wall
Followed by posteroseptal, right free wall, anteroseptal
-Right: lbbb pattern
- left: rbbb pattern
53
Accessory pathways
- wpw syndrome: atrioventricular, kent bundle
- mahaim fibers: atriofascicular
- lown ganong levigne syndrome: bundle of james: atria to bundle of his
54
Most common tachycardia caused by an accessory pathway
Orthodromic av reentry tachycardia
55
Nearly incessant tachycardia due to reentry facilitated by slow ap conduction
Permanent junctional reciprocating tachycardia
56
Preexcited tachycardia
Ventricles activated by anterograde pathway. Most common antidromic av reentry. Wide qrs.
57
Bystander ap conduction
Preexcited tachycardia which occurs with ap allows antegrade conduction of afib, flutter, avnrt
58
Treatment of preexcited af and ci
CI - Amiodarone, adenosine, beta blockers, CCB (verapamil, diltiazem)
Tx - cardioversion, iv PROCAINAMIDE/IBUTILIDE
59
Risk of cardiac arrest in accessory pathway with symptoms
2/1000 patients
60
Risk of cardiac arrest in accessory pathway with no symptoms
1/1000 patients years
61
Treatment for concealed ap/low risk ap with orthodromic av reentry
Beta blocker, verapamil, diltiazem, flecainide
62
Treatment for very irregular wide complex tachycardia
Likely preexcited af or flutter: cardioversion, iv procainamide/ibutilide
63
Treatment stable paroxysmal svt
Vagal maneuvers/iv adenosine/iv verapamil/diltiazem -> AV nodal blocking agent + iv procainamide/ibutilide or cardioversion
64
Common/typical ra flutter
- cavotricuspid isthmus (sub eustachian) dependent
- counterclockwise: negative p in II, III, AVF, Positive p in V1
- clockwise: opposite
- 240-300 atrial beats/min, 2:1 conduction, 150bpm ventricles
- flutter waves revealed by maneuvers which increase av nodal block
65
Atypical ra flutter
Not dependent on cavotricuspid isthmus
66
Atrial flutter tx
- catheter ablation of cavotricuspid isthmus effective >90%
- anticoagulation: same risk for embo as af
- antiarrhythmic: amio, sotalol, dofetilide, disopyramide
67
% of avnrt which converts to af in 5 yrs
50%
68
Warfarin target inr 2-3:
Risk of major bleeding per yr
Risk of intracranial bleeding per yr
Warfarin target inr 2-3
Risk of major bleeding per yr 1%
Risk of intracranial bleeding per yr 0.1-0.6%
69
Multifocal atrial tachycardia
3 diff p wave morph
100-150bpm
Tx: treat underlying (pulmo ds), amiodarone
**cardioversion not effective
70
Atrial fibrillation prevalance in older than 80
- 10%
| More common in men
71
Risk of stroke with af
5 fold
| Cause 25%of strokes overall
72
Types of af and causes
1. Paroxysmal af (<7d) - ectopic foci (commonly pulmo veins)
2. Persistenr af (>7d) - electrophysiologic remodelling
3. Permanent af (>1yr) - chronic substrate fibrosis
73
Tachycardia associated cardiomyopathy is reversible
Tachycardia associated cardiomyopathy is reversible
74
Drug used in unstable af to reduce energy requirement for defibrillation
- ibutilide: c/i - long qt or severe lv dysfunction at risk for torsades des pointes
- baseline need 200kj synchronized cardioversion
75
Duration for anticoagulation for af
- <48hrs: may cardiovert
- >48hrs: 3wks prior to cardiovert then at least 4 weeks post cardioversion to allow for tome for recovery of atrial mechanical fxn
* * consider indefinite extention if high chads vasc
76
Major source of af thrombus
Left atrial apoendage
77
Af goal of rate control
Acute: Hr <100bpm
Chronic at rest: Hr <80
Chronic with exertion: hr <100bpm but may increase to 110bpm if asymptomatic
78
Warfarin reduction of stroke
- 64% vs placebo
| - 37% vs antiplatelet
79
Risk of stroke persistent = paroxysmal af
Anticoagulation required for paroxysmal af: ms, hocm, previous hx of stroke
Warfarin required if ms/rhd/mechanical valves
Risk of stroke persistent = paroxysmal af
Anticoagulation required for paroxysmal af: ms, hocm, previous hx of stroke
Warfarin required if ms/rhd/mechanical valves
80
Valvular af definition
With mitral stenodid
81
Factor xa inhibitor reversal agent
Andexanet
| Ciraparantag
82
Af tx
Rate control: beta blocker/ccb/digoxin
Rhythm control: class 1 (flecainide, propafenone, disopyramide) and class 3 (amiodarone - 3% torsades, dofetilide)
Anticoagulation
83
Ventricular tachycardia nomenclature
Vtach - 3 pvc >100bpm
Idioventricular rhythm - 3 pvc <100bpm
Nonsustained vtach - terminate within 30s
Sustained vtach - persists >30s
84
Sinusoidal vts causes
- HYPERkalemia, drugs which block the na channel, ischemia
85
Most frequent site of origin of idiopathic ventricular arrhythmia
Rv outflow tract
86
Treatment of idiopathic pvc and nonsustained vt
```
Asymptomatic + no structural heart disease
- no tx
- avoid stimulants
- beta blockers, ccb
Acute coronary syndrome
- harbinger of sustained vt and vfib
- amiodarone: reduce suddentl death but does not increase mortality
- beta blocker: reduce sudden death
- icd
```
87
Icd indications acs
- survivors if mi >40d and lvef <30%
- lvef <35% with hf nyha II/III
- survivors >5d, lvef <30% and inducible vt/vf om eps
88
Nonsustained vt in hf tx
- markers of disease severity
- tx: class I antiarrhythmics c/i (proarrhythmics, negative inotropy, increase mortality)
Amiodarone: decrease sudden death but no effect on mortality
Icd: decrease mortality 36% -> 29% over 5yrs
89
Pvc induced ventricular dysfunction most common source and tx
- lv outflow tract or papillary muscles
| - tx: amiodarone, catheter ablation
90
Differentials for uniform wide complex qrs tachycardia
- monomorphic ventricular tachycardia
- svt with bbb aberrant conduction
- svt with accessory pathway
- rapid cardiac pacing pacemaker
91
Criteria for vtach
- av dissociation
- monophasic r or rs in avr
- concordance from v1-v6 of monophasic r or s wave
92
Vtach management
- acute: acls - stable trial of adenosine, amiodarone (DOC)
- recurs: antiarrhythmic or icd
* *more commonly, occurs as isolated episode
93
Sustained monomorphic vtach associated specific diseases
- coronary artery disease
- nonischemic dilated cardiomyopathy
- Arrhythmogenic right ventricular cardiomyopathy
- tof repair
- idiopathic
94
Cad in monomorphic vt
- scars from previous mi
- 70% risk of recurremce over 2yrs
- tx: icd (reduce annual mortality 12.3 to 8.8% and lower arrhythmic deaths by 50%), amiodarone if not a candidate
Cad
- scars from previous mi
- 70% risk of recurremce over 2yrs
- tx: icd (reduce annual mortality 12.3 to 8.8% and lower arrhythmic deaths by 50%), amiodarone if not a candidate
95
Arvc in monomorphic vt ecg findings and treatment
- t wave inversion v1-v3 and epsilon wave (s wave slurring)
| - icd + beta blocker (if exercise triggered)/amiodarone/sotalol
96
Cardiocutaneous syndromes with arvc
- desmosomal protein mutation, ad inheritance; but in cardiocutaneous syndrome, ar inheritance
- naxos disease
- carvajal syndrome
97
Risk factors for vt risk in tof repair
- repair after 5 y/o
- high grade vemtricular ectopy
- inducible vt in eps
- abnormal hemodynamics
- sinus rhythm qrs >180ms
98
Idiopathic monomorphic vtach tx
sudden death is rare
treatment if with symptoms or lv dysfunction
- bb, ccb, catheter ablation if meds not effective
99
Polymorphic vtach in mi greatest risk during
- 1st hr
Occurs in 10% of mi
**within 48hrs of mi = does not increase risk for subsequent arrhythmia
100
Polymorphic vtach mi tx
Acute - acls
| Chronic - determined by lvef (<0.35)
101
Acquired long qt characteristic initial sequence for polymorphic vtach
Pause dependent: pvc -> sinus pause -> prolonged qt ecg complex -> pvc which interrupts the t wave is the first beat of the polymorphic vtach
102
Acquired long qt polymorphic vtach treatment
- mgso4 1-2mg
- isoproterenol infusion of cardiac pacing to increase hr 100-120bpm
- correct underlying (hypokalemia, hypocalcemia, bradycardia, drugs)
103
Congenital long qt types which account for 90% of congenital lqts
Type I - kcnq1 gene, trigger exertion and swimming
Type II - kcnh2 gene, trigger auditory and emotional
Type III - scn5a gene, trigger sleep
104
Congenital lqts tx
Lqts 1/2: nonselective betablocker (preferred propanolol and nadolol)
High risk: icds
- female, qt >0.5s, syncope/cardiac arrest, recurrent symptoms despite bb
105
Short qt definition, associated channel dysfunction and associated arrythmia
- <0.36
- gain of function k channel
- af, polymorphic vtach, sudden death
106
Brugada syndrome types
Type 1: coved
- >0.2 mV ST segment elevation, t wave inversion
Type 2: saddle
- >0.2 mV ST segment elevation, isoelectric st segment, t wave upright
Type 3: neither 1 or 2
- give ajmaline, procainamide, flecainide to reveal st elevation
107
Brugada syndrome tx and channel dysfxn
- hcn5a (na channel)
- provoked by febrile illness
- tx: QUINIDINE, catheter ablation, icd
108
Catecholaminergic polymorphic vtach mutation, ecg findings, tx
- cardiac ryanodine receptor, calsequestrin
- bidirectional vtach: alternating qrs morphology
- tx: bb, flecainide, verapamil, icd, left ventricular sympathetic denervation
109
Most common inherited genetic cardiovascular disorder
Hocm - 1/500
110
Hocm tx
- bb, verapamil, disopyramide
- icd
- surgical myomectomy:1% risk of scd/yr
- ethanol septal ablation: 1-5% risk of scd/yr
111
Electrical storm and incessant vt definition
- electrical storm: 3 or more vt/vf in 24hrs
| - incessant vt: recurrence after conversion to sinus
112
Treatment Electrical storm and incessant vt
- correct underlying
- torsades des pointes: mgso4
- possible brugada: quinidine/isoproterenol
- not working: general anesthesia, left stellate ganglion block, thoracial spinal epidural, hook to mech vent, icd
113
Icd shock management
- check if shock was appropriately delivered for arrhythmia
- workup for ischemia, infection, decline in cardiac function
- consider antiarrhythmics: amiodarone, sotalol, beta blocker, amio+ bb(more effective)
- catheter ablation
