drug induced bradycardia case study, drugs causing decrease in heart rate.

1. Drug induced Bradycardia
Name: Dr Anjum Ahamadi
Pharm. D

2. Definition
• Bradycardia or bradyarrhythmia is the heart rate, i.e.
ventricular rate less than 60 bpm in the setting of sinus
rhythm, a variety of atrial rhythms, atrial fibrillation/flutter,
junctional, or idioventricular rhythm and advanced
atrioventricular (AV) block.
• Drug-induced bradycardia in adults is frequently observed.[1]

3. Types of Bradycardia
• Drug-induced bradycardia: In the heart with normal sinus and AV
node and normal infranodal conduction, drug-induced bradycardia
may be due to overdosage and toxic effect of medication, or to a
synergistic ‘brady effect’ of several medications.
• Drug-provoked bradycardia: In the heart with underlying latent
disease of the sinus and/or AV node, and/or infranodal conduction
system, bradycardia may be due to a trigger effect of even sub-
therapeutic doses of drugs inducing bradycardia. This kind of ‘drug-
induced’ bradycardia should be classified as drug-provoked
bradycardia. It is important to note that generally drugs inducing
bradycardia (β- and calcium channel blockers and most anti-
arrhythmic drugs) have no influence on infranodal conduction.

4. • Drug-associated bradycardia: In patients with underlying latent disease of
the sinus and/or AV node, and/or infranodal conduction, significant
bradycardia may be associated with drugs inducing bradycardia but not
due to a brady effect of these drugs.
• In patients with normal heart therapeutic doses of drugs inducing
bradycardia generally cannot cause clinically significant bradycardia,
especially due to AV block. This suggestion is logical extension of previous
three. All definitions based on level of evidence C.[2]

5. Drugs causing Bradycardia
• Clinically significant bradycardia can be induced by β-blockers, non-
dihydropyridine calcium channel antagonists, digitalis, and anti-arrhythmic
drugs.
• Other drugs include sympatholytic anti-hypertensives, tedisamil,
carbamazepine, cimetidine, anti-depressants, lithium, opioid blockers, and
cocaine.
• Severe symptomatic bradycardia has been observed after the eating of
honey (called mad honey) produced from the nectar of rhododendrons (of
the family Ericaceae). Grayanotoxins extracted from this honey and
injected to rats cause severe bradycardia.[8]
• There are case reports regarding a toxic effect of doxorubicin and
antismoking remedy (herbs) leading to symptomatic bradycardia due to
heart block.
• Bradyarrhythmia develops more commonly with amiodarone, sotalol and
other β-blockers, propafenone, or flecainide than with procainamide,
quinidine, or disopyramide; combined drug therapy increases the risk of
significant bradycardia.[1-7]

6. CASE STUDY

7. Subjective evidence
• Chief complains: A 74 years old female came
with complains of low heart rate while
monitoring at home.
• History of present illness: Was admitted for
arterial flutter 6 days ago and was discharged
within 4 days.
• Past medical history: HTN, DM,
Hypothyroidism, Arterial flutter.
• Surgical history: PTCA to CAD 10 years ago.

8. Drug Dose Frequency
T. Clopilet 75mg OD
T. Aztor 40mg OD[HS]
T. Eliquis 5mg BD
T. Lasilactone 20/50mg OD
T. Cordarone 200mg TID
T. Pan 40mg OD
T. Alprax 0.5mg OD
T. Oxra 10mg OD
T. Dilzem 30mg TID
T. Thyronorm 100mcg OD
Medical history:

9. Objective evidence
• Vitals: BP – 130/80, HR – 46, PR – 18, pallor.
• Lab values: Urea – 80mg/dl,
serum creatinine – 1.55mg/dl,
GRBS – 214mg/dl.
• ECG findings: P wave.

10. Assessment
• Drug induced Bradycardia.
• Significant Bradycardia.

11. Plan
• Hold Dilzem and Cardarone.
• IV NS 70ml/hr.
• Atropine 0.6mg should be administered as it is helpful
in treating symptomatic sinus bradycardia.
• Stop IV fluids at night.
• Don’t provide fruits, juices, soups, coconut water.
• The patient was stable and asymptomatic after one day
so, amiodarone 100mg od and dilzem regular dose was
started and patient was shifted to room.
• Concomitant administration of amidarone and dilzem
should be avoided.

12. Drug chart:
Si. No. Drug Dose Frequency Indication
1. T. Clopilet 75mg OD CAD
2. T. Aztor 40mg HS CAD
3. T. Eliquis 5mg BD CAD
4 T. Lasilactone 20/80mg OD HTN
5. T. Dilzem 30mg TID Arterial flutter
6. T. Thyronorm 100mcg OD Hypothyroidism
7. T. Pan 40mg OD Gastric
disturbance
8. T. Oxra 10mg OD DM
9. T. Amiodarone 100mg OD Arterial flutter
10. Inj. Insuline SC 6U [12U of
GRBS - >336]
SOS DM

13. Referance
1. Ovsyshcher IE, Barold SS (2004) Drug-induced bradycardia: to pace or not to pace?
Pacing Clin Electrophysiol 27:1144–1147
2. I.E. OVSYSHCHER Drug-Induced, Drug-Provoked and Drug-Associated Bradycardia.
3. Friedman PL, Stevenson WG (1998) Proarrhythmia. Am J Cardiol 82:50N-58N 5.
4. Zipes DP (1987) Proarrhythmic effect of antiarrhythmic drugs. Am J Cardiol 59:26E-
31E
5. Hofman R, Leisch F (1995) Symptomatic bradycardia with amiodarone in patients
with pre-existing conduction disorders. Wien Klin Wochenschr 107:640–644 7.
6. Israel CW, Ehrlich JR, Barold SS et al (2002) Treatment of tachyarrhythmias with
pacing and antiarrhythmic drugs. In: Israel CW, Barold SS (eds) Advances in the
treatment of atrial tachyarrhythmias: pacing, cardioversion, and defibrillation. Futura,
Armonk, NY, pp 305–323 8.
7. Yusuf S, Camm AJ (2003) Sinus tachyarrhythmias and the specific bradycardia
agents: a marriage made in heaven? J Cardiovasc Pharmacol Ther 8:89–105
8. Onat F, Yegen BC, Lawrence R et al (1991) Site of action of grayanotoxins in mad
honey in rats. J Appl Toxicol 11(3):199–201