Dysrhythmias part 3

Question 1

what are Junctional Arrhythmias

Answer 1

• Rhythm originating from junction/AV node
• gradual or abrupt onset, with change in rate, followed by abrupt termination
• 70-120 bpm
• Retrograde P waves either immediately preceding QRS, immediately following QRS, or buried in the QRS and not visible

Question 2

causes of Junctional Arrhythmias

Answer 2

• Digoxin toxicity
• Electrolyte abnormalities
• Other AAD toxicities
• Ischemia, Myocarditis

Question 3

presentation of junctional arrhythmias

Answer 3

May be asymptomatic
Palpitations, dizziness, near syncope

Question 4

management for junctional arrhythmias

Answer 4

Treat underlying cause
Usually no need for pacemaker or other management

Question 5

2 mechanisms of Accelerated Idioventricular Rhythm

Answer 5

1. escape rhythm due to suppression of higher pacemakers resulting from sinoatrial and AV block or from depressed sinus node function
2. slow ventricular tachycardia due to increased automaticity

Question 6

causes of accelerated idioventricular rhythm

Answer 6

• In acute MI and following reperfusion with angioplasty or thrombolytics
• Also common with digoxin toxicity

Question 7

tx for accelerated idioventricular rhythm is not indicated unless ?

Answer 7

there is hemodynamic compromise or more serious arrhythmias.

Question 8

what is V tach?

Answer 8

1. Defined as 3+ consecutive ventricular premature beats
   - Nonsustained – < 30 s, terminates spontaneously
   - Sustained – > 30 s
2. 160–240 bpm

Question 9

causes of V tach

Answer 9

1. Acute MI, CAD
2. Cardiomyopathy, valvular disease, myocarditis
3. May occur in structurally normal hearts
   - Catecholaminergic Polymorphic VT
   - Long QT syndromes, Brugada
4. Torsades de pointes - severe hypokalemia, hypomagnesemia, or after administration of a drug that prolongs the QT interval

Question 10

what are Congenital Long QT Syndromes

Answer 10

• Rare in US – may be autosomal recessive or dominant, depending on underlying genetic disturbance
• Characterized by recurrent syncope, a long QT interval (0.5–0.7 s), documented ventricular arrhythmias, and sudden death.
• Specific genetic mutations affecting membrane potassium and sodium channels have been identified

Question 11

Congenital Long QT Syndromes may occur in the ____ or ___ of congenital deafness.
What are the official syndrome names?

Answer 11

presence (Jervell-Lange-Nielsen syndrome) or absence (Romano-Ward syndrome)

Question 12

Congenital Long QT Syndrome is mainly characterized by ____ that are often triggered by adrenergic stimulation, which can be brought about by physical exertion or mental or emotional stress.

Answer 12

episodes of torsades de pointes

Question 13

MC forms of congenital LQTS are caused by ?

Answer 13

ion channel defects

Question 14

which LQT is a Na channel mutation?

Answer 14

LQT 3

Question 15

which LQT are K+ channel abnormalities

Answer 15

LQT1 and LQT2

Question 16

Proposed as one of the causes of sudden infant death syndrome

Answer 16

Congenital Long QT Syndromes

Question 17

which type of congential LQT is MC

Answer 17

LQT1and LQT2account for 80% of the cases.
Exercise and sudden auditory stimuli are triggers

Question 18

which LQT is only seen in 10% of the cases, but it accounts for most of the lethal cases of LQTS.
Most of the events occur during sleep at slower heart rates

Answer 18

LQT 3

Question 19

Characterized by sudden death associated with one of several ECG patterns characterized by incomplete RBBB and ST-segment elevations in the anterior precordial leads

Answer 19

Brugada Syndrome

Question 20

Brugada Syndrome is MC in who?

Answer 20

The typical patient is young, male, and otherwise healthy, with normal general medical and CV PE.
Also more common in Asians (Philippines, Thailand, Japan)

Question 21

Brugada syndrome has been associated with alterations in what gene?

Answer 21

SCN5Agene

Question 22

management of congenital LQT/brugada

Answer 22

1. Refer to Cardio or EP ASAP
2. Long-term tx - BB - Propranolol & Nadolol preferred
3. ICD implantation, esp Brugada
   - also recommended in recurrent syncope, sustained ventricular arrhythmias, or sudden cardiac death occurs despite medical therapy.
4. Avoid prolonging QT meds

Question 23

s/s of v tach

Answer 23

1. Patient may be asx, esp with nonsustained
2. Majority with sustained VT have sx
   - Palpitations, heart racing
   - Near syncope, syncope
   - Confusion, fatigue
   - Chest pain, SOB

PE findings and diagnostic study results depend on the underlying cause

Question 24

management for Acute Sustained VT

Answer 24

1. hemodynamically unstable - immediate synchronized direct current cardioversion
2. stable – IV amiodarone
   - IV Lidocaine if refractory
   - IV magnesium replacement
3. Manage any underlying causes

Question 25

long term therapy for v tach

Answer 25

ICD Beta blockers Amiodarone, Sotalol (Class III AAD) Catheter ablation

Question 26

management for nonsustained VT

Answer 26

If no heart disease – **BB** if _sx only_ If due to structural HD (low EF) - **BB**, even if no sx, d/t increased risk of sustained VT and sudden death

Question 27

Over 75% of VFib victims of sudden cardiac death have what underlying condition

Answer 27

severe CAD

Question 28

# ``` Other conditions besides Vfib that predispose to sudden death include:

Answer 28

* Severe LVH, hypertrophic cardiomyopathy, dilated cardiomyopathy * Severe AS * Primary pulmonary hypertension, cyanotic congenital heart disease * Hypoxia, electrolyte abnormalities * Long QT, Brugada syndrome, ARVD, catecholaminergic VT

Question 28

management for Vfib

Answer 28

* **IMMEDIATE unsynchronized defibrillation** * Follow ACLS protocol, CPR, etc. * Treat underlying condition * Consider ICD if indicated

Question 29

Intraventricular conduction defects are common in ?

Answer 29

individuals with otherwise normal hearts

Question 30

Intraventricular Conduction Delays can also occur in many disease processes, including:

Answer 30

* ischemic heart disease * inflammatory disease * infiltrative disease * cardiomyopathy * postcardiotomy

Question 31

LBBB most often occurs in patients with ?

Answer 31

* underlying heart disease and may be associated with progressive conducting system disease. * However, LBBB can also be seen in asx pts with a structurally normal heart

Question 32

which artery provides the primary blood supply for the LBB

Answer 32

left anterior descending artery

Question 33

causes of LBBB

Answer 33

1. **Structural Heart Disease** - not usually the result of a single clinical entity, except in acute MIs. - conditions that contribute to myocardial fibrosis (HTN, CAD, cardiomyopathies) can contribute to LBBB. - may result following acute myocardial insult = worse prognosis 2. **Functional LBBB** - Rate-related aberrancy

Question 34

Evaluation of a patient with LBBB:

Answer 34

1. In the setting of CP/ACS sx, MIs are difficult to determine with EKG alone - Assume MI until proven otherwise, unless old LBBB 2. Thorough H&P to assess for causes: HTN, CAD, CM, Valve disease, Myocarditis 3. Diagnostic testing should be based on H&P - Echo - Stress test or LHC

Question 35

management for LBBB

Answer 35

* _asx w/ isolated LBBB, no evidence of cardiac disease_ - **no therapy required** * Otherwise, **treat any underlying cause** * _Sx pts w/ LBBB and low EF_ - **CRT**

Question 36

The RBB receives most of its blood supply from ?

Answer 36

septal branches of L anterior descending coronary artery

Question 37

RBBB conduction can be compromised by?

Answer 37

both structural and functional factors: 1. Structural heart disease – - Processes that increase RV pressure, like COPD, PE, Pulm HTN - MI, HTN, CM, Myocarditis, Congenital heart defects 2. Rate-related aberrancy is possible

Question 38

T/F: Patients with isolated chronic RBBB are generally asymptomatic and do not require further diagnostic evaluation or tx

Answer 38

T

Question 39

presentation of bifascicular block

Answer 39

asymptomatic and fairly benign * asx - no further diagnostic evaluation or therapy is required * Pts should be screened carefully for s/s suggesting occult cardiac disease

Question 40

management for symptomatic bifascicular blocks

Answer 40

*present with presyncope or syncope and are noted to have bifascicular block on ECG* 1. _additional monitoring and eval are required_ - intermittent complete heart block may result occur - **Continuous ECG** monitoring x 24-48 h - inpatient - **Echo** - assess for underlying structural heart disease - CHB is identified - **PPM** Otherwise, _if no sx and no underlying ischemia, then no tx is necessary_