Bradycardia

1. Bradycardia Under the guidance of Dr Murali Mohan NT PROF & HOD, EMD By Dr. Soumya Nath Maiti (IMO)

2. Overview

3. Definition Bradycardia – Bradycardia from the Greek  ( bradys  "slow", and  kardia , "heart "), is the resting heart rate of under 60 beats per minute (BPM), although it is seldom symptomatic until the rate drops below 50 BPM.

4. Bradycardia - causes Bradycardia may have multiple causes . Physiological - A well trained athlete may have a heart rare in the range of 40- 50 beats / min. This are called as functional or relative bradycardia . It occurs as a sport adaptation and helps prevent tachycardia during training.

5. Bradycardia - causes Pathological – Divided into cardiac and non-cardiac causes Non-cardiac causes are usually secondary R ecreational drug use  or  abuse.   M etabolic  or endocrine  disorders, especially   thyroid disorders. An  electrolyte  imbalance.   Neurological   factors S ituational factors such as prolonged bed rest A utoimmunity . 

6. Bradycardia - causes Cardiac causes A cute or chronic ischemic heart disease V ascular  heart disease, V alvular heart disease, D egenerative primary electrical disease. Ultimately , the causes act by three mechanisms: Depressed automaticity of the heart, Conduction block & escape pacemakers and rhythms.

7. Bradycardia - causes In general, two types of problems result in bradycardias : disorders of   SA node, and disorders of the  AV node. With sinus node dysfunction (sometimes called sick sinus syndrome), there may be disordered automaticity or impaired conduction of the impulse from the sinus node into the surrounding atrial tissue

8. Bradycardia - causes Atrioventricular conduction disturbances may result from impaired conduction in the AV node, or anywhere below it, such as in the Bundle of His. The clinical relevance pertaining to AV blocks is greater than that of sinoatrial blocks

9. Relative Bradycardia The term  relative bradycardia  is used in explaining a heart rate that, although not actually below 60 BPM, is still considered too slow for the individual's current medical condition. For example A heart rate of 70 beats/min is too slow for a patient in cardiogenic or septic shock

10. Criteria for symptomatic bradycardia A symptomatic bradycardia exists only when three criteria are present The hart rate is slow. The patient has symptoms. The symptoms are due to slow heart rate.

11. S ymptoms Chest Discomfort Shortness of breath Decreased level of consciousness, Weakness & fatigue Light headedness & dizziness Presyncope or syncope

12. Signs Hypotension, orthostatic hypotension Pulmonary congestion on Xray & auscultation Features of Frank congestive heart failure Features of pulmonary oedema

13. The Bradycardia Algorithm The bradycardia algorithm outlines the steps for assessment and management of a patient presenting with symptomatic bradycardia The primary point in the bradycardia algorithm is determination of adequate perfusion.

14. Identification of B radycardia Present by definition ie Heart rate < 50/ min Inadequate for the patients condition

15. BLS and ACLS Survey Maintain patent airway Assist breathing as needed. Monitor vitals, obtain and review a 12 lead ECG. Establish IV access Conduct a problem focused history and physical examination . Search for contributing factors.

16. Are sings & symptoms caused by B radycardia ? Look for adverse signs and symptoms of bradycardia . Sometimes the symptom is not due to bradycardia . Ex – Hypotension associated with Bradycardia may be due to myocardial dysfunction rather than braycardia .

17. Adequate Perfusion Decision should be taken if the patient has adequate or poor perfusion If the patient has adequate perfusion, observe and monitor (Box 4). If the Patient has poor perfusion Proceed to T reatment sequence. (Box 5 )

18. Treatment Sequence

19. Treatment sequence: Atropine In the absence of immediately reversible causes, atropine remains the first-line drug for acute symptomatic Bradycardia . For bradycardia , give atropine 0.5 mg IV every 3 to 5 mins to a total dose of 0.04mg/kg.

20. Treatment sequence: Atropine Atropine should be used cautiously in the presence of MI. An atropine induced increase in heart rate may worsen ischemia or increase infract size. Atropine can not be relied upon in case of Mobitz type II 2 nd or 3 rd degree AV block or in patients with 3 rd degree AV block with a new wide QRS complex.

21. Treatment sequence: Pacing Immediate pacing should be considered in critical patients when IV access is unavailable or patient is unresponsive to Atropine. Following initiation of pacing, confirm electrical and mechanical capture. Reassess the patient for symptom improvement and Haemodynamic stability.

22. Pacing Technique

23. Treatment sequence: Epinephrine & Dopamine Both epinephrine and dopamine are vasoconstrictors as well as chronotropes , patients intravascular volume status must be assessed to avoid hypovolemia. Begin epinephrine infusion at a dose of 2-10mcg/min and titrate to response. Begin dopamine infusion at 2-10mcg/min and titrate to response . Lower dose of dopamine has a more selective effect on inotropy and heart rate.

24. Next actions

25. Referances AHA SELS manual 2013 Harrison’s principal of internal medicine 17 th episode