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Chapter 68 Flashcards

1
Q

A disorder of impulse formation causing slowing or cessation of spontaneous sinus node automaticity

A

Sinus arrest
Difficult to differentiate from SA Exit Block

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2
Q

Indication for permanent pacing in sinus bradycardia

A

Only in symptomatic patients

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3
Q

Most frequent form of arrhythmia that is physiologically normal

A

Sinus arrhythmia

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4
Q

Pause in the sinus rhythm and the P-P interval is not a multiple of the basic P-P interval

A

Sinus pause

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5
Q

A conduction disturbance resulting to a pause from the absence of the normally expected P wave

A

Sinoatrial exit block
- duration of the pause is a multiple of the basic P-P interval

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6
Q

A disorder of impulse formation causing slowing or cessation of spontaneous sinus node automaticity

A

Sinus arrest

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7
Q

Differentiation of respiratory form of sinus arrhythmia from non-respiratory form

A

P-P interval shortens

-inhibition of vagal tone
In non-respiratory form, P-P interval is unrelated to respiration

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8
Q

Cause of non-respiratory form of sinus arrhythmia

A

Digitalis

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9
Q

Treatment for sinus arrhythmia

A

None
If symptomatic: sedatives, tranquilizers, atropine, ephedrine or isoproterenol

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10
Q

ECG of first degree Sinoatrial Exit Block

A

None

cannot be diagnosed on surface ECG

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11
Q

Causes of SA exit block (5)

A

Excessive vagal
Acute myocarditis
MI
Fibrosis of the atrium
Drugs (quinidine, procainamide, flecainide, digitalis)

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12
Q

True of type I Wenckebach 2nd degree SA Exit block:
A. P-P interval progressively shortens
B. P-P interval progressively lengthens
C. Duration of the pause is less than 2 P-P cycles
D. A and C
E. B and C

A

D

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13
Q

Types of sick sinus syndrome (4)

A

(1) persistent spontaneous sinus bradycardia inappropriate for the physiologic circumstance (chronotropic incompetence)
(2) sinus arrest or exit block
(3) combinations of SA and AV conduction disturbances,
(4) alternation of paroxysms of rapid regular or irregular atrial tachyarrhythmias and periods of slow atrial and ventricular rates (bradycardia- tachycardia syndrome

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14
Q

Anatomic basis of sick sinus syndrome (6)

A

> total or sub-total destruction of the sinus node
areas of nodal- atrial discontinuity
inflammatory or degenerative changes in the nerves and ganglia surrounding the node, and >pathologic changes in the atrial wall.
Fibrosis and fatty infiltration occur, and sclerodegenerative processes generally involve the sinus node and the AV node or the bundle of His and its branches or distal subdivisions
Occlusion of the sinus node artery

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15
Q

Definition of chronotropic incompetence

A

failure to increase 80% or 85% of either maximal expected heart rate or of inadequate HR reserve (Resting HR-age predicted maximal HR)

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16
Q

Principal determinant of rate of Oxygen consumption (VO2) and exercise capacity

A

Increase in HR due to physiologic demand
(4x increase in VO2 = 2.2x increase in HR)

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17
Q

Causes of Chronotropic incompetence (5)

A

Aging
SA node disease, AF, CAD, HF

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18
Q

TRUE/FALSE
Heart rate recovery and increase with exercise is heritable

A

TRUE

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19
Q

TRUE/FALSE
Beta blocker does not cause chronotropic incompetence

20
Q

Rate less than 50 beats/min

A

Sinus bradycardia

21
Q

P waves in sinus bradycardia:

A
  • Normal contour
    • Upright in leads I, II, and aVF
    • Occur before each QRS complex
    • Constant PR interval longer than 120msec
    • Sinus arrhythmia often exists
22
Q

Definition of phasic variation in sinus arrhythmia (2)

A

max SCL - min SCL >120msec
max SCL - min SCL/minSCL >10%

23
Q

True of sinus arrythmia:
A. Increases with age
B. Bimodal occurrence
C. Most frequent form of arrhtyhmia
D. Pathologic

A

C

-Most frequent form of arrhythmia and is physiologically normal
- Usually occurs in the young, especially those with slower heart rates or with enhanced vagal tone
- Decreases with age or with autonomic dysfunction, such as in diabetic neuropathy

24
Q

It is recognized electrocardiographically by a pause resulting from absence of the normally expected P wave

A

Sinoatrial exit block

-duration of the pause is a multiple of the basic P- P interval

25
Type of arrhythmia when P-P cycles that contain a QRS complex are shorter than P-P cycles without a QRS complex
Ventriculophasic Sinus Arrhythmia ## Footnote >occurs during complete AV block and a slow ventricular rate >Similar lengthening can be present in the P-P cycle that follows a PVC with a compensatory pause
26
In 2nd degree AV Block: Type I or Type II? 1. Antedates Adams-Stokes syncope 2. Antedates Complete AV block 3. Accompanied inferior MI 4. Accompanies anterior MI 5. The block is almost always at the level of the AV node 6. Associated with high mortality if complicates MI 7. Transient and does not require pacing when complicates MI
1. Antedates Adams-Stokes syncope- II 2. Antedates Complete AV block- II 3. Accompanied inferior MI - I 4. Accompanies anterior MI- II 5. The block is almost always at the level of the AV node- I 6. Associated with high mortality if complicates MI- II 7. Transient and does not require pacing when complicates MI - I
27
Which of the following worsens AV nodal conduction in His-Purkinje block? A. Atropine B. Carotid sinus massage C. Isoproterenol D. Exercise
C ## Footnote The rest improves AV nodal conduction. >atropine can minimally improve conduction in the AV node and greatly increase the sinus rate, which results in an increase in AV nodal conduction time and the degree of AV block as a result of the faster atrial rate. >Conversely, if an increase in vagal tone minimally prolongs AV conduction time but greatly slows the heart rate, the net effect on type I AV block may be to improve conduction. >In general, however, carotid sinus massage improves and atropine worsens AV conduction in patients with His-Purkinje block, whereas the opposite results are to be expected in patients with AV nodal block.
28
Which of the following is true? A. Ventricular rate in congenital complete heart block is < 40 beats/min B. Ventricular rate in acquired complete AV block is variable C. Congenital AV block result from a block at the level of the AV node D. all of the above
C ## Footnote > >ventricular rate in acquired complete heart block is < 40 beats/min but can be faster with congenital complete AV block.
29
Hereditary form of conduction block caused by degeneration of the His bundle and bundle branches has been linked to the ___ gene.
SCN5A ## Footnote Also responsible for LQT3
30
A normal phenomenon that is a disturbance of impulse conduction caused by physiologic refractoriness resulting from inexcitability secondary to a preceding impulse.
Interference
31
Type of AV block Level of Block Etiology
Complete AV block AV node Congenital ## Footnote No P wave is followed by His bundle potential, but each ventricular depolarization is preceded by a His bundle potential
32
Type of AV block Level of Block Etiology
Complete AV block distal to His Bundle Acquired ## Footnote >Complete anterograde atrioventricular (AV) block with retrograde VA conduction. >All the sinus P waves are blocked distal to the His bundle >Ventricles escape at a cycle length of approximately 1800 msec (33 beats/min) and are not preceded by His bundle activation >Ventricular escape rhythm produces a QRS contour with left axis deviation and a right bundle branch block, possibly caused by impulse origin in the posterior fascicle of the left bundle branch
33
A phenomenon characterized by PR intervals as long as 1.0 second and can at times exceed the P-P interval.
skipped P waves ## Footnote 1st degree AV block
34
Locate the level of the block in 1st degree AV block: 1. normal contour and duration of QRS 2. BBB QRS pattern
1. AV node (rarely His) 2. AV node or His-Purkinje ## Footnote causes of PR prolongation: conduction delay in the AV node, His-Purkinje, both sites, equally delayed conduction over both bundle branches, intra-atrial conduction delay
35
TRUE/FALSE Type I second-degree AV nodal block can revert to a first-degree block with deceleration of the sinus rate.
TRUE ## Footnote Acceleration of the atrial rate or enhancement of vagal tone by carotid massage can cause first-degree AV nodal block to progress to type I second-degree AV block. Conversely, type I second-degree AV nodal block can revert to a first-degree block with deceleration of the sinus rate.
36
The site of Wenckebach block most commonly occurs in the ___.
AV node
37
Two features serve to establish the characteristics of classic Wenckebach group beats
>the increment in conduction time is greatest in the second beat of the Wenckebach group >the absolute increase in conduction time decreases progressively over subsequent beats ## Footnote (1) the interval between successive beats progressively decreases, although the conduction time increases (but by a decreasing function); (2) the duration of the pause produced by the nonconducted impulse is less than twice the interval preceding the blocked impulse (which is usually the shortest interval); and (3) the cycle that follows the nonconducted beat (beginning the Wenckebach group) is longer than the cycle preceding the blocked impulse.
38
TRUE/FALSE First-degree is normal in children, while type I second-degree AV block is pathologic.
FALSE ## Footnote First-degree and type I second-degree AV block can occur in normal healthy children >chronic second-degree AV nodal block (proximal to the His bundle) without structural heart disease- benign prognosis
39
TRUE/FALSE Wenckebach AV block can be a normal phenomenon in well-trained athletes
TRUE ## Footnote related to increase in vagal tone
40
locate the block in the AP (phase): 1. tachycardia-dependent AV block 2. pause-dependent paroxysmal AV block
1. Phase 3 2. Phase 4 ## Footnote Phase 3: >>incomplete action potential recovery, postrepolarization refractoriness, and concealed conduction in the AV node Phase 4: spontaneous depolarizations during the resting phase of the action potential result in an inability to depolarize
41
PE findings: 1st degree; 2nd degree: type1, type 2; 3rd degree 1. long a to c wave interval in the jugular venous pulse 2. diminished intensity of the first heart sound (S1) 3. increase in HR, decreasing S1 4. widening of the a to c interval, terminated by a pause 5. a wave not followed by a v wave 6. Intermittent ventricular pauses and a waves in the neck not followed by v waves 7. large (cannon) a waves 8. bruit de canon 9.
1. 1st degree 2. 1st degree 3. type I 4. type I 5. type I 6. type II (S1 is constant) 7. 3rd degree 8. 3rd degree
42
Symptoms that would suggest an intermittent infrahisian block?
syncope, presyncope ## Footnote in those with BBB or intraventricular delay
43
Short-term treatment for evanescent block:
isoproterenol atropine ## Footnote isoproterenol- caution with MI; use pacing instead
44
When to use biventricular pacing?
AV block + LV dysfunction
45
Type of neutrally mediated response defined as ventricular asystole exceeding 3 seconds
Cardioinhibitory response ## Footnote treatment: Atropine, pacemaker
46
Type of neutrally mediated response defined as a decrease in systolic blood pressure (SBP) of 50 mm Hg or more without associated cardiac slowing or a decrease in SBP exceeding 30 mm Hg when the patient’s symptoms are reproduced
Vasodepressor response ## Footnote Elastic support hose and sodium-retaining drugs not responsive to atropine or pacemaker
47
Medications that can enhance neurally mediated bradyarrhythmias and be responsible for symptoms in some patients (4)
digitalis, methyldopa, clonidine, and propranolol

Braunwalds (34 decks)

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