Ventricular Arrhythmias

Question 1

What are the ventricular arrhythmias?

Answer 1

1. Premature Ventricular Beats
2. Ventricular Tachycardia
3. Torsades de Pointes
4. Ventricular Fibrillation

Question 2

What are the characteristics of ventricular arrhythmias?

Answer 2

1. Originate in ventricles below Bundle of HIS
2. Occur when electrical impulses depolarize myocardium using a different pathway from normal impulses
3. Can lead to significant decrease in cardiac output

Question 3

What are the EKG findings for ventricular arrhythmias?

Answer 3

1. P wave absent
2. QRS wider than normal
3. T wave deflection is opposite QRS deflection

Question 4

Describe PVCs

Answer 4

1. Ectopic beats originating in ventricles
2. May occur alone or in clusters of two or more (couplets, triplets)
3. May occur in a repeated pattern (bigeminy, trigeminy, quadrigeminy) ≥ 3 PVC’s = V Tach
4. Caused by electrical irritability in ventricle
5. Multiform (mutifocal) PVC’s
6. Can lead to ventricular tachycardia in cardiac disease patients
7. Can ↓ CO if frequent

Question 5

What are the EKG findings for PVCs?

Answer 5

1. Occur earlier than expected
2. Appear wide & bizarre
3. P wave absent
4. T wave has deflection opposite that of QRS
5. Followed by compensatory pause allowing SA node to resume normal conduction

Question 6

What is R on T phenomenon? When does it occur?

Answer 6

PVCs may trigger more serious rhythm disturbances when PVC occurs on downslope of preceding normal T wave (R on T phenomenon)

Question 7

What can the R on T phenomenon lead to?

Answer 7

V tach, torsades de pointe

Question 8

What are the general characteristics of v tach?

Answer 8

1. Ventricular tachycardia (VT) is defined as 3 or more consecutive PVC’s
2. May originate from working ventricular myocardium and/or from the distal conduction system

Question 9

What can cause v tach?

Answer 9

1. Frequent complication of:
A. MI 
B. Dilated cardiomyopathy 
C. Hypertrophic cardiomyopathy 
D. Electrolyte disturbances
E. Often asst with hemodynamic compromise

Question 10

What is non sustained VT?

Answer 10

Runs of 3 or more PVC’s lasting < 30 sec and terminating spontaneously

Question 11

What is sustained VT?

Answer 11

Lasts > 30 sec and does not terminate spontaneously

Question 12

What is the rate of VT?

Answer 12

Ventricular rate 100-250 beats/min

Often unstable rhythm

Question 13

What can VT lead to?

Answer 13

1. May preceed V Fib

2. Due to increased myocardial irritability

Question 14

What are the EKG changes in VT?

Answer 14

1. P wave usually absent

2. QRS wide (> 0.12 sec) & bizarre

Question 15

What is monomorphic VT?

Answer 15

1. Monomorphic: ventricular activation sequence is constant, resulting in QRS complex that remains the same
   A. Seen commonly with structural heart diseases

Question 16

What is polymorphic VT?

Answer 16

1. Polymorphic: QRS complex varies from beat to beat
   A. Torsades de Pointes
   B. Bidirectional V Tach (rare)

Question 17

What is an impetus of torsades de pointes?

Answer 17

Starts w/long QT interval & PVC trigger

Question 18

What are the EKG findings for torsades de pointes/

Answer 18

1. Rate 150-250 beats/min
2. Rhythm irregular
3. QRS wide w/ changing amplitude
4. QRS complexes that rotate about baseline

Question 19

What can torsades de pointes turn into?

Answer 19

V fib

Question 20

What meds can cause torsades de pointes?

Answer 20

Drugs that lengthen QT interval
1. Antiarrhythmic drugs
A. Procainamide, quinidine, disopyramide (Norpace)
B. Tricyclic antidepressants
C. Haloperidol (Haldol)
D. Some antibiotics and antifungals
-Erythromycin, ketoconazole (Nizoral), trimethoprim sulfa (Bactrim)
E. Phenothiazines
-Prochlorperazine (Compazine), chlorpromazine (Thorazine), promethazine (Phenergan)

Question 21

What are non-med causes of torsades de pointes?

Answer 21

1. MI
2. Electrolyte abnormalities
3. High dose methadone
4. Cocaine

Question 22

What is bidirectional V tach?

Answer 22

Rare - characterized by a beat-to-beat alternation of the frontal QRS axis

Question 23

What can cause bidirectional V tach?

Answer 23

Digitalis toxicity

Question 24

What are the sxs of V tach?

Answer 24

1. Asymptomatic → sudden death
2. Syncope
3. Palpitations
4. Lightheadeness
5. Tachycardia
6. Hypotension
7. Tachypnea
8. Pallor
9. ↓ level of consciousness

Question 25

What are the dx studies for V tach?

Answer 25

1. EKG 2. Labs A. CMP B. Hypokalemia C. Hypomagnesemia D. Hypocalcemia E. Dig level F. Troponin G. CK MB H. Drug screen I. CBC

Question 26

How is treatment of VT determined?

Answer 26

Determined by degree hemodynamic compromise & duration of arrhythmia

Question 27

How is a hemodynamically unstable pt with VT treated?

Answer 27

Cardioversion | 100 – 360 J

Question 28

How is a stable pt with VT treated?

Answer 28

1. IV isoproterenol (Isuprel) A. Given to shorten QT interval & prevent recurrence 2. Lidocaine 1mg/kg IV bolus 3. Amiodarone 150 mg slow IV bolus over 10 min followed by slow infusion 1mg/min over 6 h 3. Mg sulfate of 1-2 g IV bolus empirically for Torsades de Pointes 4. Eliminate contributing factors

Question 29

When in an Implantable cardioverter-defibrillator (ICD) indicated for a VT pt?

Answer 29

1. Spontaneous sustained VT 2. Cardiac arrest not related to transient or reversible cause 3. Syncope of undetermined origin w/ sustained VT 4. If meds ineffective/intolerated 5. Nonsustained VT w/ CAD, prior MI, LV dysfunction, inducible VF or sustained VT during electrophysiologic study

Question 30

How is a VT pt with normal LV function treated?

Answer 30

Amiodarone + beta blocker

Question 31

Define v fib?

Answer 31

1. Chaotic pattern of electrical activity in ventricles in which electrical impulses arise from multiple foci 2. No effective cardiac contraction 3. No cardiac output 4. Fibrillation with no recognizable P wave, QRS, T waves

Question 32

What is the pneumonic for the underlying causes of v fib?

Answer 32

THINK H6 T5

Question 33

What are the H's for the underlying causes of v fib?

Answer 33

1. Hypovolemia 2. Hypoxia 3. Hydrogen ion (acidosis) A. Consider bicarbonate 4. Hyperkalemia/hypokalemia & metabolic disorders 5. Hypoglycemia (accucheck) 6. Hypothermia (check core temp-rectal)

Question 34

What are the T's for the underlying causes of v fib?

Answer 34

1. Toxins (toxicology, drug levels) 2. Tamponade, cardiac (cardiac ultrasound) 3. Tension pneumothorax (consider needle thoracostomy) 4. Thrombosis, coronary or pulmonary (consider thrombolytics) 5. Trauma

Question 35

What are the sxs of v fib?

Answer 35

1. Syncope 2. Unconsciousness 3. Cardiac death

Question 36

What is the clinical course of V fib?

Answer 36

1. Pulse disappears 2. Collapse, unconsciousness 3. Agonal breaths < 5 resp/min 4. Onset of reversible death

Question 37

What are the dx studies for V fib?

Answer 37

1. CMP 2. Cardiac enzymes 3. CBC 4. ABG 5. Toxicology screens 6. CXR

Question 38

Why is CMP checked for V fib?

Answer 38

Electrolyte abnormalities | K, Mg, Ca

Question 39

Why are cardiac enzymes checked for V fib?

Answer 39

Myocardial injury

Question 40

Why is CBC checked for V fib?

Answer 40

Contributing anemia

Question 41

Why are ABGs checked for V fib?

Answer 41

1. Acidosis | 2. Hypoxemia

Question 42

Why are toxicology screens and levels checked for V fib?

Answer 42

1. Illicit drugs | 2. Digoxin

Question 43

What are the CXR results in V fib?

Answer 43

1. Pulmonary edema 2. Cardiomegaly 3. Injury due to CPR

Question 44

How is V fib treated in the emergency setting?

Answer 44

1. CPR w/ early defibrillation (200-360 J) A. Endotracheal intubation/ventillation B. Defibrillation interferes w/ re-entrant arrhythmia, allowing intrinsic pacemakers to take over 2. Epinephrine or Vasopressin 3. Consider antiarrhythmic A. Amiodarone or Lidocaine B. Magnesium sulfate (Torsades de Pointes) 4. Defibrillation w/in 3 minutes →95% successful if underlying heart is functional (AED’s) A. Pre-existing pump failure → success rate 30% 5. Search for & Tx possible contributing factors (H6T5)

Question 45

How is chronic V fib treated?

Answer 45

1. Require ICD | 2. Most need antiarrhythmics drugs

Question 46

What is brugada syndrome?

Answer 46

1. Presence of an atypical RBBB w/ characteristic cove-shaped ST elevation in leads V1 to V3, & absence of obvious structural Dz A. Enhanced w/ procainamide & quinidine 2. Genetic disorder characterized by abnormal ECG findings & ↑ risk of sudden cardiac death 3. M > F (M = F in childhood)

Question 47

What is the most common cause of sudden death in young men of SE Asian descent (< 40 yr) w/out underlying cardiac Dz?

Answer 47

Brugada syndrome

Question 48

How does brugada syndrome present?

Answer 48

syncope due to polymorphic ventricular tachycardia (VT)

Question 49

What is the cause of death in brugada syndrome?

Answer 49

V fib

Question 50

What is type 1 EKG pattern in Brugada syndrome?

Answer 50

Coved type ST elevation w/ at least 2 mm J-point elevation (gradually descending ST segment followed by a negative T-wave)

Question 51

What is type 2 EKG pattern in Brugada syndrome?

Answer 51

Saddle back pattern w/ at least 2 mm J-point elevation & at least 1 mm ST elevation w/ a positive or biphasic T-wave

Question 52

What is type 3 EKG pattern in Brugada syndrome?

Answer 52

Has either type 1 or type 2 pattern w/ < 2 mm J-point elevation & < 1 mm ST elevation