Cardio 1 Arrhythmias

Question 1

What is the normal rate of QRS complexes?

Answer 1

Normal rate is 60-100 bpm.

Question 2

How is the regularity of the QRS complex assessed?

Answer 2

The regularity is assessed by checking if the R-R interval is the same.

Question 3

What is the difference between normal and wide QRS complexes?

Answer 3

A wide QRS complex suggests ventricular tachycardia.

Question 4

What is considered a normal P-wave in a sinus rhythm?

Answer 4

A normal P-wave is upright in lead II, biphasic in V1, and occurs before every QRS complex.

Question 5

What are the normal intervals for PR and QT?

Answer 5

PR interval: 0.12-0.21 seconds.
QT interval: less than 0.4 seconds.

Question 6

What characterizes sinus tachycardia?

Answer 6

A heart rate greater than 100 bpm, normal P-wave followed by QRS, regular R-R intervals, narrow QRS complex, and camel hump where the P-wave merges with the T-wave.

Question 7

What causes sinus tachycardia?

Answer 7

Causes include increased sympathetic tone (exercise, anxiety, pain), alcohol, caffeinated beverages, drugs (e.g., β-adrenergic agonists, anticholinergic drugs), and systemic etiologies like fever, hypotension, hypovolemia, anemia, thyrotoxicosis, CHF, MI, shock, and pulmonary embolism.

Question 8

How is sinus tachycardia treated?

Answer 8

Treatment involves addressing the underlying cause and considering beta-blockers for symptomatic cases (if beta-blockers are contraindicated, use CCB).

Question 9

What is respiratory sinus arrhythmia?

Answer 9

It is a change in sinus rhythm during respiration, where the heart rate increases during inspiration and decreases during expiration.

Question 10

What are the characteristics of supraventricular tachycardias (SVT)?

Answer 10

SVTs arise above the Bundle of His with narrow QRS complexes. They are characterized by rapid rates, regular rhythms, and can involve re-entry mechanisms like AVRT (Atrioventricular Reentry Tachycardia) or AVNRT (AV Nodal Reentry Tachycardia).

Question 11

What is paroxysmal supraventricular tachycardia (PSVT)?

Answer 11

PSVT is an abrupt onset and offset of tachycardia, often seen in young patients with no structural heart disease. It is commonly due to re-entry tachycardia.

Question 12

What are the two types of PSVT?

Answer 12

The two types are:
AVRT (Atrioventricular Reentry Tachycardia): Anatomical reentry, often associated with an accessory pathway like in Wolff-Parkinson-White (WPW) syndrome.
AVNRT (Atrioventricular Nodal Reentry Tachycardia): Functional reentry within the AV node, involving fast and slow pathways.

Question 13

What is the ECG characteristic of PSVT?

Answer 13

The ECG shows regular rhythm, a heart rate around 250 bpm, narrow QRS complexes, and the P-wave is sometimes hidden due to the rapid rate. There may also be ST depression.

Question 14

How is PSVT treated?

Answer 14

First line: Vagal maneuvers like carotid massage. If unsuccessful, IV adenosine is used.
Second line: IV beta-blockers, diltiazem, or verapamil.
Cure: Ablation of the accessory pathway.
Unstable patients: Emergency cardioversion.

Question 15

What are the characteristics of atrial fibrillation (A. fib)?

Answer 15

Atrial fibrillation is irregularly irregular, lacks distinct P-waves (only fine oscillations), and has a narrow QRS complex. It can have a fast or slow ventricular response.

Question 16

What are the common complications of atrial fibrillation?

Answer 16

The most feared complications are ventricular fibrillation and embolism, leading to stroke.

Question 17

What are the common causes of atrial fibrillation?

Answer 17

Cardiac causes: Myocardial infarction, mitral stenosis, hypertension.
Non-cardiac causes: Thyrotoxicosis, pulmonary embolism, alcohol, and hypokalemia.

Question 18

How is atrial fibrillation diagnosed?

Answer 18

Diagnosis is confirmed with an ECG showing the irregularly irregular rhythm and absence of P-waves. An echo is required to assess cardiac function and rule out structural heart disease.

Question 19

What is the treatment for atrial fibrillation?

Answer 19

Hemodynamically unstable: DC cardioversion.
Stable patients:
1. Rate control: Beta-blockers, calcium channel blockers, or digoxin.
2. Rhythm control: Electrical cardioversion or pharmacological options (amiodarone for structural heart disease, flecainide, or propafenone for non-heart disease).
3. Anticoagulation: Based on CHA2DS2-VASc score.
4. Underlying cause treatment.

Question 20

What is atrial flutter?

Answer 20

Atrial flutter is characterized by no distinct P-waves but sawtooth flutter waves. It always involves some degree of AV block (e.g., 2:1, 3:1, 4:1).

Question 21

What are the ECG findings in atrial flutter?

Answer 21

The ECG shows sawtooth flutter waves, especially in the inferior leads (II, III, aVF), and there is usually some degree of AV block (e.g., 2:1). After vagal maneuvers, the heart rate can drop to a regular rate, such as 75 bpm.

Question 22

What are the causes of atrial flutter?

Answer 22

Atrial flutter is often associated with underlying heart disease such as cardiomyopathy, chronic obstructive pulmonary disease (COPD), hyperthyroidism, and hypertension.

Question 23

How is atrial flutter treated?

Answer 23

Unstable patients: Electrical cardioversion.
Stable patients:
Rate control: Beta-blockers, diltiazem, verapamil, or digoxin.
Chemical cardioversion: Sotalol, amiodarone, or class I antiarrhythmics.
Anticoagulation (similar to atrial fibrillation).
Long-term management: Antiarrhythmic medications (amiodarone, flecainide, propafenone) or radiofrequency (RF) catheter ablation.

Question 24

What is multifocal atrial tachycardia (MAT)?

Answer 24

MAT is a rapid, irregular atrial rhythm arising from multiple ectopic foci within the atria. It is most commonly seen in patients with severe COPD or congestive heart failure.

Question 25

How is multifocal atrial tachycardia (MAT) distinguished from atrial fibrillation?

Answer 25

MAT involves an irregular rhythm with varying PP, PR, and RR intervals and at least three distinct P-wave morphologies in the same lead, unlike atrial fibrillation, which has no distinct P-waves.

Question 26

What is the prognosis of multifocal atrial tachycardia (MAT)?

Answer 26

MAT is considered a poor prognostic sign when it develops during acute illness, as it is associated with increased mortality due to the underlying condition.

Question 27

What is ventricular tachycardia (VT)?

Answer 27

VT is characterized by three or more consecutive premature ventricular beats, with a heart rate typically ranging from 140 to 200 bpm. It results in wide, bizarre-shaped QRS complexes.

Question 28

How is ventricular tachycardia classified?

Answer 28

VT is classified into: Monomorphic VT: More common, with a consistent QRS shape. Polymorphic VT: Includes Torsade de Pointes, where there is beat-to-beat variation in the QRS shape.

Question 29

What is the treatment for hemodynamically unstable ventricular tachycardia?

Answer 29

Hemodynamically unstable VT is treated with electrical cardioversion starting at 100 joules.

Question 30

What is the treatment for hemodynamically stable ventricular tachycardia?

Answer 30

If stable, the treatment includes electrical cardioversion, amiodarone, or type I antiarrhythmics (e.g., procainamide, quinidine). Reversible causes like hypokalemia, ischemia, heart failure, or hypotension should also be corrected.

Question 31

What is Torsade de Pointes?

Answer 31

Torsade de Pointes is a polymorphic ventricular tachycardia that involves twisting of the QRS axis, with beat-to-beat variation in the shape of the QRS complexes. It typically occurs in patients with a baseline QT prolongation.

Question 32

What are the causes of Torsade de Pointes?

Answer 32

Causes include congenital long QT syndrome, drugs (e.g., class IA antiarrhythmics like quinidine, class III like sotalol, phenothiazines, erythromycin, quinolones, antihistamines), and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia).

Question 33

What is the treatment for Torsade de Pointes?

Answer 33

The treatment for Torsade de Pointes is intravenous magnesium sulfate. The underlying cause of prolonged QT should also be corrected.

Question 34

What is ventricular fibrillation (VF)?

Answer 34

VF is a very rapid and irregular ventricular activation with no coordinated contraction, leading to no mechanical effect and no cardiac output. It results in cardiac arrest, where the patient is pulseless and rapidly loses consciousness.

Question 35

What is the treatment for ventricular fibrillation (VF)?

Answer 35

The treatment for VF is immediate defibrillation. Survivors are at high risk for sudden death and require an Implantable Cardioverter-Defibrillator (ICD).

Question 36

What is the difference between cardioversion and defibrillation?

Answer 36

Cardioversion: Shock is delivered in synchrony with the QRS complex. It is used for patients who have a pulse but are hemodynamically unstable (e.g., atrial fibrillation, atrial flutter, SVT, VT with pulse). Defibrillation: Shock is delivered without synchronization with the QRS complex. It is used for patients who are pulseless (e.g., VF, VT without pulse).

Question 37

What is sinus bradycardia?

Answer 37

Sinus bradycardia is a heart rate of less than 60 bpm with a normal P-wave followed by a QRS complex. The R-R interval is regular.

Question 38

What are the causes of sinus bradycardia?

Answer 38

Sinus bradycardia can be normal during sleep or in athletes. Extrinsic causes include beta-blocker intake, hypothyroidism, and hypothermia. Intrinsic causes include acute ischemia and infarction of the sinus node (as a complication of MI) and degenerative changes such as fibrosis in the atrium and node (sick sinus syndrome).

Question 39

How is sinus bradycardia treated?

Answer 39

Treatment may not be necessary if it is normal or due to an offending agent. If symptomatic, atropine may be used. Persistent symptomatic bradycardia is treated with a permanent pacemaker.

Question 40

What is sick sinus syndrome?

Answer 40

Sick sinus syndrome is a condition where the sinus node fails to depolarize properly (sinus arrest) or fails to propagate the sinus impulse to the atria (sinoatrial block), leading to bradycardia and causing tachyarrhythmias due to ectopic pacemaker activity (tachy-brady syndrome).

Question 41

What are the ECG findings in sick sinus syndrome?

Answer 41

The ECG shows severe sinus bradycardia or intermittent long pauses between consecutive P-waves.

Question 42

How is sick sinus syndrome treated?

Answer 42

Treatment includes the insertion of a permanent pacemaker and anticoagulation if necessary.

Question 43

What are AV blocks?

Answer 43

AV blocks are abnormalities in the conduction of electrical impulses through the atrioventricular (AV) node. They are classified as: First Degree: AV conduction is excessively slowed but all impulses are conducted, resulting in a constant PR interval. Second Degree: Some impulses are blocked: Mobitz Type I: The PR interval progressively increases until a beat is dropped (Wenckebach). Mobitz Type II: The PR interval remains constant until a beat is suddenly dropped. Third Degree (Complete Heart Block): There is complete failure of AV conduction, with P-waves marching through without any correlation to the QRS complex.

Question 44

How are AV blocks treated?

Answer 44

Unstable patients: Atropine followed by percutaneous pacing. Mobitz Type II and third-degree blocks: Pacemaker insertion is required.

Question 45

What are bundle branch blocks (BBB)?

Answer 45

Bundle branch blocks are conduction defects in the left or right bundle branches, causing delayed conduction in the ventricles. Left Bundle Branch Block (LBBB): Features a wide QRS, broad R wave with a prolonged upstroke in the lateral leads (I, aVL, V5, V6), ST depression, and T-wave inversion. Right Bundle Branch Block (RBBB): Features a wide QRS, RSR’ pattern in V1 and V2 (“rabbit ears”), ST depression, and T-wave inversion with reciprocal changes in the lateral leads.

Question 46

What are the treatment options for bundle branch blocks?

Answer 46

Bundle branch blocks usually do not require treatment unless associated with other conditions like heart failure or arrhythmias.

Question 47

What is the mnemonic for antiarrhythmic drugs?

Answer 47

The mnemonic is “No Body Knows Cardiology,” which stands for: No: Na channel blockers (e.g., quinidine, procainamide, lidocaine, flecainide). Body: Beta blockers (e.g., propranolol, atenolol, bisoprolol). Knows: K channel blockers (e.g., amiodarone, sotalol). Cardiology: Ca channel blockers (e.g., verapamil, diltiazem).

Question 48

What are the general rules for treating arrhythmias?

Answer 48

Stable patients: Bradycardia: Atropine. Supraventricular tachycardia: Use ABCD (adenosine, beta blockers, calcium channel blockers, digoxin). Ventricular tachycardia: Use LAPS (lidocaine, amiodarone, procainamide, sotalol). Unstable patients: Bradycardia: Pacemaker. Tachycardia: DC shock.