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NSG 478 > Cardiac Conduction Problems Part 1 > Flashcards

Cardiac Conduction Problems Part 1 Flashcards

1
Q

Arrhythmias

A
  • Disorders of Electrical impulses or conduction within the heart
  • Can cause disturbances of the HR, heart rhythms or both
  • Can cause changes in hemodynamics due to changes in pumping action
  • Diagnosed by ECG
  • Treatment is based on the frequency and severity of symptoms produced
  • Named according to site of origin of the electrical impulse and mechanism of conduction involved.
    • For example if impulse originates in SA (Sinoatrial node) node, and the rate is above 100 its Sinus Tachycardia
    • Conduction should start in the SA node but heart blocks and arrythmias can interupt that
    • If the conduction starts in SA node its sinus
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2
Q

Normal electrical flow through the heart

A
  • SA
  • AV
  • Bundle of his
  • Bundle branch
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3
Q

Main pacemaker of the heart

A

SA node,with a normal electrical stimulus of 60-100 impulses per min

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4
Q

Stimulation of the sympathetic nervous system results in

A
  • Positive Chronotropy
  • Positive dromotropy
  • Positive inotropy
  • Constriction of peripheral blood vessels which increase BP
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5
Q

Stimulation of the parasympathetic nervous system

A
  • reduces HR, AV conduction, and force of atrial contraction
  • Reduction of BP
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6
Q

Diagnostic workup of cardiac arrhythmias, to identify cause vs problems with the heart itself

A
  • ECG and echo
  • Labs with chemistries (K, Mg, Ca, Na) and BNP (HF), thyroid function test, CBC
  • Dig levels if appropriate
  • Cardiac enzymes if MI (Troponin)
  • CT and MRI and D-dimer if PE suspected
  • Chest X-ray
  • Exercise testing; holter monitoring
  • Electrophysiology studies
  • Cardiac cath
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7
Q

Electrophysiology studies

A

Setting the pt into the rhythm to see how they act or see cause

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8
Q

Why echo for arrythmias

A

Echo can see EF and reduced EF can lead to arrhythmias

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9
Q

P wave

A

Atrial depolarization

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10
Q

PR interval

A
  • Start of P wave (Atrial depolarization) to the start of ventricular depolarization (Start of Q wave)
  • the PR segment is the end of the P wave to the start of the Q wave

Normal is 0.12-0.2 sec 3-5 boxes

Find a p wave that starts on a line

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11
Q

QRS complex

A

Ventricular depolarization

Normal is 0.8-0.12 seconds, 2-3 boxes

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12
Q

T wave

A

Ventricular relaxation (repolarization)

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13
Q

QT interval

A
  • Start of Q wave to end of T wave
  • Drugs can prolong this (antidepressants and such)
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14
Q

How long is one small box, ECG (1mm)

A

0.04 seconds

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15
Q

How long is a large box, ECG (5mm)

A

0.2 seconds

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16
Q

How do you calculate the HR using an ECG

A
  • Count the QRS complex (Only regular rhythms)
  • Most strips are a standard 6 seconds, so multiple the number by 10
  • Easy but not accurate

Normal is 60-100

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17
Q

Calculating the rhythm

A
  • Determine if it is regular or irregular
  • Measure from R wave to R wave
  • If irregular is there any pattern to irregularity
  • Is there a P wave for each QRS (Very important for heart blocks and arrythmias)
  • For heart blocks check the pr ratio
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18
Q

Calculating the rhythm: P wave

A
  • There should be one P wave for each QRS (Is there more than one)
  • Are the P waves rounded?, are they notched or peaked? (Each P wave should look the same)
  • All P waves should look essentially the same in size shape and direction to be considered normal
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19
Q

Sinus bradycardia

A
  • Same as normal sinus but HR is under 60 bpm
  • Normal when sleeping or athletes
  • Persistent brady can cause decreased CO
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20
Q

Causes of sinus brady

A
  • Valsalva maneuver
  • Vagal stimulation
  • Sleep apnea
  • Hyperkalemia
  • Hypoglycemia
  • Increased intracranial pressure
  • Disease of SA node
  • Admin of drugs (Dig, CCB, BB)
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21
Q

Treatment of sinus brady

A
  • None
  • If symptomatic however you give Atropine, temp or perm pacemaker, Treat the cause
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22
Q

Sinus Tachycardia

A
  • Same as Normal sinus but over 100 bpm
  • Normal after exercise
  • Can lead to decreased CO and decreased BP due to there not being enough time for the heart to fill with blood
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23
Q

Causes of sinus tachy

A
  • Fever
  • Pain
  • Hypoxia
  • PE
  • HF
  • Hypovolemia/hypotension
  • Stress
  • Anxiety
  • Drugs that increase sympathetic tone (Epi, NE, DA, Dobutamine, isoprotenrenol, nitroprusside
24
Q

Treatment of sinus tachy

A

Treat the cause

25
Overview of sinus arrhythmias
* All are regular * All have a P wave for a QRS complex * QRS with is the same for all * PR intervals are within normal limits * Rates are the main thing differing
26
Sinus arrhythmias (normal one)
* Time between beats can be slightly shorter or longer depending on whether youre breathing in or out * HR increases when breathing in * HR slows when exhaling Considered normal
27
How much does the Atria contribute to CO
25-30% with the atrial kick, with arrhythmias this will significantly decrease CO
28
Atrial arrhythmias
* Ectopic sites on the atrium, that generate an impulse, some are blocked at the AV node some are not * A-fib, a-flutter, SVT * SA to av node transmission is impaired
29
A-fib
* **Irregular Heart rhythm** originating from an ectopic site in the atria, usually rapid when it first occurs * Atrium depolarizing at a rate greater than **400 bpm**, with the majority of impulses being blocked at the AV node * AV node conducts impulses irregularly and randomly leading to an irregular ventricular rhythm * **As a result of 400 bpm the atria does not beat but quivers like a. bag of worms** * Very common * causes loss of atrial kick, decreasing CO * **Blood clots** are super common due to pooling of the blood in the atria
30
Causes of A-fib
* Strongly associated with diseases (HF, CAD, Valve disease, pulmonary disease, DM, HTN) Common after cardiac surgery as well * Sometimes previpitated by exertion, sleep, caffine and alc
31
Rapid ventricular rate A-fib
* HR exceeding 100 in a-fib * Increases myocardial oxygen demands, increases cardiac workload, decreases cardiac output
32
Treatment of afib: Control of clots
* Anticoagulants: Prevent clot formation due to high risk of stroke with A-fib * Dabigatran, Ravaro**xaban** Api**xaban** warfarin * Lovenox and heparin * Stroke risk assessment (CHA2DS2-VASc score) | Super duper important
33
Treatment of afib: Control of rate
* Beta blockers * Calcium channel blockers **diltiazem (Cardizem)** * Dig | Rapid afib is dangerous
34
Treatment of afib: Tachybrady syndrome
* HR flips between Tachycardia and bradycardia, so if you give a BB for example it might crash their HR * Needs a pacemaker to place a perm rhythm that prevents brady
35
Treatment of afib: Rhythm control
* Cardioversion (Electrical shock and conversion to sinus) * Meds (Flecainide, Propafenone, Dofetilide, Sotalol (First line agents)) Amiodarone * Ablation: Radiofrequency cath based, MAZE procedure during CABG
36
Ablation for A-fib
* Cath is inserted into the heart from femoral area, up onto where the arrhythmia is coming from, * Area of concern is identified and is burnt or frozen to damage the affected area * Once completed the cath is removed and incision is closed * Takes 4 hours
37
A-Fib and stroke
* Huge risk for a-fib, due to pooling of blood in the aria, left atrial appendage
38
A-fib on ECG
* Irregularly irregular * Atrial rate of 400-600, not measurable * PR, not able to determine (No P wave) * No P wave only fibrillary waves * QRS is normal (Its above the bundle of HIS) * Ventricular rate is normal or fast
39
Atrial flutter
* Similar to a fib, except its a sawtooth pattern except fib * A flutter originates in an ectopic site in the atria * Atrium depolarizes at a rate of 250-400 bpm * AV node blocks at least half the impulses to the ventricles | More of an electrical issue than a cardiac issue, unlike a-fib
40
A flutter: Conduction ratio stays the same
ventricular Rhythm will be regular
41
A flutter: conduction ratio varies
Ventricular rate will be irregular
42
T/F A flutter is a chronic condition
False, it is uncommon for it to be chronic but not impossible. Usually it converts to A fib or sinus (Spontaneously or following treatment)
43
Atrial flutter on ECG
* Atrial rate of 250-400 (can count if slow) * Abnormal P waves (Sawtooth/flutter waves) * PR unable to determine (Too many P waves) * Rhythm may be regular or irregular * Varying degree of flutter waves can be measured per QRS complex (2:1, 3:1 ...) * Treatment is the same as A-fib
44
How does A-fib differ from A-flutter: Cause
A-fib is caused more often from **cardiovascular issues** such as IHD, HTN, high cholesterol , nicotine, DM A flutter is less common and usually due secondary to an abhorrent **electrical** pathway in the atria
45
Paroxysmal A-fib
* A-fib that occurs intermittently and stops spontaneously within 7 days * Dangerous because of risk of shooting a clot to the brain when it resolves
46
Persistent A-fib
* Last longer than 7 days * May require cardioversion to restore sinus rhythm
47
Long standing A-fib
* Similar to persistent but last longer than a year
48
Paroxysmal or Supraventricular Tachycardia (PAT/SVT)
* Originates due to an ectopic pacemaker site in the atria * Atrial rate of 140-150 * May start and stop abruptly * Continuous rhythm or short burst of SVT * Rapid ventricular rate, decreased ventricular filling
49
Is SVT a ventricular or atrial arrythmia
Atrial
50
Clinical manifestations of SVT
* Palpitations * Fatigue * Exercise intolerance * mild dyspnea
51
Causes of SVT
* CAD or mitral valve disease * Nicotine * Stress/anxiety * Caffeine/alc * Fatigue * Lung disease (COPD) * Hyperthyroidism * Dig tox * More common in women
52
Mgmt of SVT
* **Vagal maneuvers:** (try and poop your pants), coughing, holding breath, carotid massage (not really) * **Adenosine IV** (Drug of choice) * Calcium channel blockers (Cardizem), BB * Pacemaker * Cardioversion * Ablation
53
SVT on an ECG
* HR is 150-250 bpm * Rhythm is usually regular * P waves are hidden in T waves, the TP wave is **distinguishing feature of this rhythm** * PR is non existent * QRS is narrow (fast)
54
Adenosine
* Given IV * 6mg dose followed by 20 mg saline slammed * Stops heart temp but it should start back up
55
Prolonged QT interval
* Delayed repolarization of the myocardium * Normal QT interval is <440 msec * Can progress to ventricular arrhythmias, (Torsades de pointes) * **mgmt is Mg**
56
Causes of prolonged QT interval
* Lots o drugs * Hypokalemia * Hypomag * Certain arrhythmias * Stroke * HF

NSG 478 (23 decks)

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