JH IM Board Review - Arrhythmias II

Question 1

What is the QRS morphology of VT?

Answer 1

Wide QRS complex.

Question 2

What is the origin of the majority of wide-complex tachycardias?

Answer 2

85% ==> Ventricular.

***remainder are supraventricular w/ aberrant conduction.

Question 3

What are the 4 types of VT?

Answer 3

1. Non sustained (3 beats to 30sec).
2. Sustained (>30sec).
3. Monomorphic.
4. Polymorphic.

Question 4

What is the determinant of prognosis and Tx in VTs?

Answer 4

Dependent on presence of underlying structural heart disease.

Question 5

What is the VT which may occur in otherwise healthy pts with structurally normal hearts?

Answer 5

Benign idiopathic VT.

Question 6

What is the MC form of benign idiopathic VT?

Answer 6

RVOT VT.

Question 7

What is the clinical presentation of nonsustained VT?

Answer 7

May be asx or cause occasional palpitations.

Question 8

What is the clinical presentation of sustained VT?

Answer 8

More likely to cause palpitations, lightheadedness, near-syncope, syncope, cardiac arrest.

Question 9

What is the 1st step in the diagnosis of VT?

Answer 9

Evaluation for structural heart disease.

==> Do echo.

Question 10

What are the additional studies for the evaluation of structural heart disease besides echo in pts with VTs?

(3)

Answer 10

1. Stress testing with imaging.
2. CT or conventional coronary angio.
3. Cardiac MRI.

Question 11

What is the monitoring for a pt with VT?

Answer 11

Depending on sx frequency — May include 24-48h Holter monitor.

Or 30-day event monitor.

Or long-term implantable loop recorder (ILR).

Question 12

What is the form of VT in which EPS is most useful?

Answer 12

In the evaluation of monomorphic VT.

Question 13

What is the tx in an hemodynamically unstable pt with VT?

Answer 13

Emergent cardioversion/defibrillation.

Question 14

What is the major determinant of chronic tx of most VTs?

Answer 14

The underlying presence of ischemic heart disease.

Question 15

What is the prognosis in pts with monomorphic VT and no underlying structural heart disease (ie idiopathic VT)?

Answer 15

Good prognosis.

80-90% cure rates w/ ablation.

Question 16

What are the target groups in which we should consider placing an ICD (shown to improve survival)?

(2)

Answer 16

1. IHD w/ previous MI and LVEF 30% or less measured more than 3mo after revascularization + medical tx.
2. Ischemic or non ischemic cardiomyopathy (LVEF <35%) and NYHA II or III despite at least 3mo of guideline-directed medical tx w/ beta-blockers and afterload-reducing agents.

Question 17

What is the role of EP study in some pts w/ milder forms of cardiomyopathy who have non sustained VT or sx possibly related to VT (palpitations, syncope)?

Answer 17

May be useful for risk stratification.

Question 18

What is a useful adjunctive therapy for recurrent VT in pts w/ ICDs that can help prevent sx and recurrent ICD shocks?

Answer 18

Catheter ablation.

Question 19

What is torsades?

Answer 19

A form of polymorphic VT a/w prolonged V-repolarization, manifesting on ECG as a prolonged QT interval.

Question 20

What are the main syndromes with which Torsades is a/w?

Answer 20

Both congenital + acquired long QT syndromes.

Question 21

What is the usual cause of congenital LQT syndrome?

Answer 21

Mutations in cardiac ion channels affecting ventricular repolarization (MC K or Na channels).

Question 22

What is the percentage of pts with congenital LQT syndrome in which a genetic mutation can be identified?

Answer 22

60-70%.

Question 23

What are the 2 MC associations of acquired LQTS?

Answer 23

1. Drugs.

2. Electrolyte disturbances (ie hypokalemia, hypomagnesemia).

Question 24

What is the usual precipitant of torsades (Polymorphic VT)?

Answer 24

Premature ventricular contraction occurring on the preceding T wave (R-on-T wave).

Question 25

What is the acute management of torsades? | 4

Answer 25

1. IV Mg (2g IV push, repeat as necessary). 2. Correct underlying metabolic abnormality or stop offending meds. 3. Consider IB antiarrhythmics (IV lidocaine 1-1.5 mg/kg over 2min). 4. Increase HR to decrease QT duration.

Question 26

What are the 2 ways by which you can increase HR therapeutically in order to decrease QT duration?

Answer 26

1. IV isoproterenol. | 2. Temporary pacer and overdrive pace to 90-100 beats/min.

Question 27

What is the chronic management of torsades?

Answer 27

1. Avoid QT prolonging drugs. 2. Avoid hypokalemia and hypomagnesemia. 3. Beta blockers in pts with congenital LQTS. 4. Consider ICD placement in selected pts.

Question 28

What are the high risk pts w/ congenital LQTS that may be helped by ICD placement?

Answer 28

1. Pts w/ recurrent syncope. 2. Torsades on beta blockers. 3. Personal/FHx of cardiac arrest. 4. Other high risk markers.

Question 29

What is the definition of syncope?

Answer 29

Transient + involuntary LOC and postural tone (lasting seconds to minutes) caused by cerebral hypoperfusion, followed by full spontaneous recovery.

Question 30

What is the percentage of syncopes in which the cause remains unknown?

Answer 30

25-40%.

Question 31

What is NOT included in the definition of syncope?

Answer 31

LOC caused by seizure, hypoglycemia, cataplexy etc.

Question 32

What is essential in all pts with syncope?

Answer 32

ECG.

Question 33

What is the management in a pt with a vasovagal syncope? | 5

Answer 33

1. Incr. Fluid intake + salt intake. 2. Advise pts to stand slowly from a seated position. 3. Eliminate offending meds. 4. Consider midodrine or SSRIs in refractory cases. 5. Consider pacemaker placement in exceptional cases a/w prolonged asystole.

Question 34

What is the definition of SCD?

Answer 34

Sudden, unexpected death that occurs within 1h of sx b/c of documented or presumed cardiac cause.

Question 35

What is the percentage of SCDs for which V-fib or pulseless VT is responsible?

Answer 35

30-60%.

Question 36

What is often the 1st manifestation of IHD?

Answer 36

SCD.

Question 37

What is the use of ECG in the evaluation of SCD? | 4

Answer 37

1. Evidence of MI or ischemia. 2. WPW syndrome. 3. Prolonged QT. 4. Brugada.

Question 38

What are the indications for ICD implantation?

Answer 38

1. Documented VT/VF cardiac arrest not caused by transient or reversible causes (ie MI, intoxication). 2. Documented familial or inherited conditions w/ high risk of life-threatening arrhythmia, such as LQTS, HCM. 3. Documented previous MI (>40 days), LVEF <40%, inducible sustained VT or VF at EPS (MADIT-1 criteria). 4. Documented previous MI, LVEF<30% either 40 days following medically managed MI or 3mo following revascularization (PCI or bypass surgery). 5. Pts w/ ischemic or nonischemic DCM, measured LVEF <35%, and NYHA II or III despite at least 3mo of guideline-directed medical tx. 6. Pts w/ NYHA IV who meet other requirements for cardiac resync therapy.