channelopathies

Question 1

definition

Answer 1

heterogeneous group of hereditary diseases of Na, K, Ca channels

Question 2

consequences

Answer 2

sudden death in infants, children, young adults without causing any grossly or microscopically visible abnormalities in heart

Question 3

How many types of congenital long QT syndrome?

Answer 3

13

Question 4

characteristic arrhythmia associated w/ QT syndrome

Answer 4

form of polymorphic ventricular tachycardia

–torsades de pointes (French for “twisting of the points”)

Question 5

most common type of congenital long QT syndrome (type 1)

Answer 5

caused by mutations in gene for subunit of the Iks potassium channel…impairs repolarization, prolonging QT, allowing early afterdepolarizations from mulltiple foci

Question 6

Brugada syndrome epidemiology

Answer 6

young adult Asian males

Question 7

Brugada syndrome pathogenesis

Answer 7

mutations in gene for subunit of cardiac Na channel…failure of expression of the channel,, or alterations in voltage and time dependence of activation, and accelerated or prolonged recovery from inactivation

duration of action potentials reduced

Question 8

Brugada syndrome consequences

Answer 8

persistently elevated ST segments descending w/ upward convexity to inverted T wave

V. fib

Question 9

persistently elevated ST segments descending w/ upward convexity to inverted T wave
in leads V1-V3

Answer 9

classic “coved type” Brugada pattern

Question 10

Ventricular arrhythmias may result from…

Answer 10

heterogeneity of myocardial refractory periods in right ventricle, arising from presence of both normal and abnormal sodium channels in same tissue and from differential impact of Na current in the three layers of myocardium