SINUS BRADYCARDIA TIPS and TRAPS

Dr Rajesh Badani

MD,DNB,FCPS,DNB(Card),FESC

Fellowship in EP

Senior Consultant-Cardiology and Electrophysiology

Aditya Birla Memorial Hospital

Pune

Definition

• Heart rate below 60 beats per minute(particularly in awake state) in adults above 18 yrs.

Causes

Physiological • Sleep • Drugs(BB/CCB(Diltiazem/verapamil/Amiodarone/Digoxi

n ) • Athletes heart(Excess vagotonia)

Pathological • Sinus node dysfunction • SAH with raised ICP • Hypothermia • Systemic illness(Obstructive Jaundice)

Classification

• 1.Intermittent Only during standing position(postural) Occuring during exercise - particularly in HCM pts -chronotropic incompetence During procedure---Syncope diagnosis 1. HUTT ---Cardioinhibitory response 2. Carotid sinus hypersensitivity 2. Continuous Physiological Pathological

TIPS

• Identify diagnosis.

• R/o structural heart disease

• R/o treatable causes of bradycardia

• R/o vasovagal syncope

• R/o sinus node dysfunction

• ECG markers

Sinus node dysfunction

• Degenerative disorder of the conduction system

• Generally occurs in elderly.

• Can present predominantly with sinus bradycardia.

• Rarely AT/AF

• Previously named a “Tachy-Brady” syndrome

Symptoms

• Easy fatiguability

• Effort intolerance

• Presyncope

• Syncope

• Dyspnoea on exertion(Uphill travel)

65/F,recurrent syncope BASELINE ECG

Sinus Arrest Transient lack of impulses from the SA node

Pauses not multiple of SCL

SA Exit Block

1080 1080

2160 (2 x 1080)

Sinus arrest or exit block ?

A type I sinoatrial (SA)

• SAnodal exit block has the following features: The P-P interval shortens from the first to the second cycle in each grouping, followed by a pause. The duration of the pause is less than twice the shortest cycle length, and the cycle after the pause exceeds the cycle before the pause. The PR interval is normal and constant.

Type II SA blk

• The P-P interval varies slightly because of sinus arrhythmia. The two pauses in sinus nodal activity equal twice the basic P-P interval and are consistent with a type II 2:1 SA nodal exit block. The PR interval is normal and constant.

Indication of EP study in SND

• To confirm diagnosis

• To confirm severity

• Calculating

• SACT(sinoatrial conduction time)

• cSNRT(corrected sinus node recovery time)

Sinus Node Dysfunction – Indications for Pacemaker Implantation

Class I Indications • Sinus node dysfunction with documented symptomatic sinus

bradycardia • Symptomatic chronotropic incompetence Class II Indications • Class IIa: Symptomatic patients with sinus node dysfunction

and with no clear association between symptoms and bradycardia

• Class IIb: Chronic heart rate < 30 bpm in minimally symptomatic patients while awake

Class III Indications • Asymptomatic sinus node dysfunction

JACC Vol. 31, no. 5 April 1998, 1175-1209

Bradycardia during sleep Role of sinus pauses

• Physiological to have sinus pauses of >3 sec during sleep.

• Hence evaluate the holter and the time of pause before deciding for permanent pacing.

What is the abnormality

• What is the incidence of sinus bradycardia in the setting of ac. M I ?

Sinus Bradycardia

• Most common arrhythmia occurring during the early hours after MI and may occur in up to 40% of inferior and posterior infarcts.

• May be related to autonomic imbalance or to atrial and sinus node ischemia or both.

• Are we excessively concerned about this rhythm. If so, why?

•

• Profound bradycardia may predispose the patient to ventricular ectopy.

• Usually resolves spontaneously, treatment is reserved for hemodynamically symptomatic arrhythmias and those with bradycardia dependent vent. Arrhythmias.

• Name the treatment modality

Sinus bradycardia- treatment

• Atropine usually successful for symptomatic bradycardia. Temporary pacing is rarely required.

46 Yrs/f, RHD on Amiodarone for AF

Presents With Syncope – HR 46/min

What is the Cause of Syncope ?

ECG Monitoring Strips

TRAPS

• When is sinus bradycardia spurious?

• Always look at the ECG carefully

• Analyse the rhythm strip and PP and RR intervals.

• Decide whether treatment is required or not

• Falsely diagnosed as 2:1 AV block .

• Differentiating features

• Morphology of ectopic P waves different

• Physiological

• No treatment reqd.

• Metabolic cause to be ruled out.

What is the rhythm? Would you treat this rhythm?

• Interesting rhythm strip

• VPCs not included and alarm gives a heart rate exactly half of the heart rate.

• Plan:

• Identify the cause

• Generally physiological

• Increased physical activity

Diagnosis

What is the abnormality ?

Conclusion

• Very common in clinical practice

• Needs thorough history taking to identify the cause

• Investigate completely

• Remove offending drugs

• Evaluate for sinus node dysfunction