Lecture 13: Poisoning due to Cardiovascular Drugs

Question 1

What is the therapeutic role of Beta-blockers (3)

Answer 1

• Competitively inhibits catecholamines at Beta1 receptors on heart
• Slows heart rate
• Reduces myocardial contractility

Question 2

What is a negative chronotropic effect

Answer 2

slowing of heart rate

Question 3

What is a negative ionotropic effect

Answer 3

reduction of myocardial contractility

Question 4

What are Beta-blockers used in the treatment of (3)

Answer 4

• hypertension
• angina
• tachyarrhythmias

Question 5

What is a tachyarrythmia?

Answer 5

abnormal fast heart rate due to electrical problems with the heart

Question 6

Beta-blocker poisoning features (3)

Answer 6

• bradycardia
• hypotension
• cardiorespiratory arrest

Question 7

What is bradycardia

Answer 7

slow heart rate with pulse less than 50 beats per minute

Question 8

What is hypotension

Answer 8

systolic pressure below 100mmHg

Question 9

What effects whether Beta-blockers can cross the BBB and cause CNS effects

Answer 9

how lipophillic the drug is

Question 10

CNS effects due to Beta-blockers (4)

Answer 10

• drowsiness
• coma
• convulsions and seizures
• delirium and hallucinations

Question 11

Beta-blocker poisoning management (3)

Answer 11

• symptomatic and supportive care
• reducing absorption
• glucagon

Question 12

What is symptomatic and supportive care for Beta-blocker poisoning (3)

Answer 12

• A-B-C
• monitor pulse, BP and cardiac rhythm
• treat convulsions with diazepam

Question 13

How do you reduce absorption of Beta-blockers

Answer 13

• AC if patient presents within 1 hour of potentially life-threatening OD

Question 14

How is glucagon used as a specific treatment for Beta-blocker poisoning

Answer 14

• increases intracellular cAMP which mediates a beta-stimulant effect on the heart
• glucagon to the heart bypasses the blocked Beta-receptor
• gets around negative ionotropic and chronotropic effect

Question 15

What 3 types of cells do calcium channel blockers block the inward passage of calcium through voltage gated channels

Answer 15

• Myocardial cells
• Cardia conducting cells
• Vascular smooth muscle cells in arteries

Question 16

What 3 effects do calcium channel blockers have

Answer 16

• Reduction in contraction
• Reduction in heart rate
• Vasodilation

Question 17

Features of calcium channel blocker poisoning (4)

Answer 17

• negative inotropic effect
• negative chronotropic effect
• vasodilation
• confusion

Question 18

Specific measures for calcium channel blocker poisoning

Answer 18

• IV calcium salts
• Beta-stimulating inotropes
• glucagon
• high does insulin/ dextrose
• IV lipid solution

Question 19

How does IV lipid solution overcome calcium channel blocker poisoning

Answer 19

• calcium channel blockers are lipophilic
• adding large amount of lipid solution to patient will pull lipophilic calcium channel blocker away from target calcium cells

Question 20

What does digoxin do

Answer 20

• causes hyperkalaemia by inhibiting Na+/K+ ATPase

Question 21

Therapeutic effects of digoxin (2)

Answer 21

• positive inotropic effect
• negative chronotropic effect

Question 22

What is digoxin used in treatment of (2)

Answer 22

• Atrial arrhythmia
• heart failure

Question 23

Cardiac features of digoxin poisoning (4)

Answer 23

• sinus bradycardia
• Atrio-ventricular block
• Atrial/ ventricular arrhythmias
• cardiac arrest