SVT with Left Bundle Branch Block Following Gastrectomy

Archana

First Year DNB Resident, Emergency Medicine, Kauvery Hospitals, Trichy

Case Presentation

A 55-year-old man was recently diagnosed with carcinoma of the stomach and underwent gastrectomy.

Clinical History

The patient’s medical history was significant for poorly controlled diabetes, CAD, Left bundle branch block, ischemic cardiomyopathy, and moderate to severe LV dysfunction, with low normal ejection fraction 55%. His gastrectomy, performed to excise the gastric carcinoma, was uneventful, and he was recovering well during the initial postoperative days.

Postoperative Day 5

On the fifth day after surgery he experienced sudden onset palpitations, and heart rate of more than 160 beats per minute was noted. He was promptly shifted to the MICU for further management. On receiving him in the MICU, patient was conscious, oriented with a BP of 120/70mm Hg, heart rate 168/min, SpO2 98% with 4 liters of oxygen.

An immediate electrocardiogram (ECG) revealed supraventricular tachycardia (SVT) with aberrant conduction, due to the left bundle branch block (LBBB)

The POCUS study revealed the following findings:

  1. Heart- moderate to severe LV dysfunction/ global hypokinesia/concentric LVH/no RA, RV dilatation/no pericardial effusion/ no evidence of clot or PTE.
  2. Lungs- Bilateral basal collapse with congestion.
  3. No evidence of DVT.

Diagnostic Assessment:

  1. ECG Findings: The ECG confirmed SVT with a heart rate exceeding 160 beats per minute and showed LBBB morphology, indicating a disruption in the heart’s electrical conduction system.
Diagnostic-Assessment-1

Fig. 1. ECG, showing SVT with aberrant conduction. Note Left axis deviation, QS in V1-2-3 and wide QRS with slurred S wave in V6.

2. Cardiac Enzymes: Cardiac enzyme levels were within normal limits, ruling out acute myocardial infarction.

Management and Interventions

  1. Vagal maneuvers: Carotid massage was performed for nearly 10 seconds on this patient after carefully ruling out the presence of any bruit.
  2. Adenosine administration: Resuscitation defibrillator was on standby as we administered 6mg of intravenous adenosine as a rapid bolus injection followed by a flush of 10ml normal saline and lifting the arm to ensure that the medicine reaches the heart within its short period of action (less than 10 seconds, due to rapid uptake in RBC and endothelial cells).
  3. Continuous cardiac monitoring was done to assess the heart rate, rhythm and any adverse reactions.

Outcome and Follow-up:

Following IV Adenosine administration, the patient’s heart rate stabilized, and he remained free of SVT.

Diagnostic-Assessment-2

Fig. 2. Stable ECG showing LAD and pre-exisiting LBBB.

  1. Vitals after stabilization:
  2. BP:120/70mmHG
  3. HR-100/min
  4. SpO2- 98% with 4 liters of oxygen.

Cardiology Consultation

A cardiology consultation was sought. History of pre-existing ischemic heart disease was likely to be the cause for his tachyarrhythmia. Despite the persistence of LBBB, the patient’s overall condition improved, and he was discharged with a carefully crafted medication regimen and a plan for close follow-up with both the cardiology and oncology teams.

Conclusion

This case highlights the challenges in managing complex arrhythmias in patients with multiple comorbidities. The presence of SVT with LBBB in a postoperative setting necessitates swift intervention, multidisciplinary collaboration, and long-term management to ensure optimal outcomes. Careful monitoring and individualized treatment strategies are essential in such cases to address both acute arrhythmia and the underlying cardiac pathology.

Supra Ventricular Tachycardia

Supra ventricular tachycardias originate from a focus within or above the AV node and most often present with a narrow QRS complex, thus termed as narrow complex tachycardias. A supra ventricular rhythm can also present with a widened QRS complex due to aberrant ventricular conduction, the widened QRs complex resulting from a fixed (preexisting) bundle branch block, rate related conduction block, ventricular pre excitation syndrome (i.e. Wolff Parkinson White syndrome) or toxic metabolic condition.

ECG features of SVT

Diagnostic-Assessment-3

1.Ventricular rate usually 170-180 beats/min; the rate can range from as low as 130 beats/min to as high as 300 beats/min.

2.Absence of normal P waves ( p waves are buried within the QRS complex ) with normal PR interval.

3. Rare retrograde P wave (immediately adjacent to QRS complex before or after)

4.Narrow QRS complex, usually <100ms in duration.

ECG features of LBBB

Diagnostic-Assessment-4

Management

Vagal maneuvers heighten the parasympathetic tone and may slow the electrical conduction in the heart to a degree that abolishes sustained re-entry. If applied early, they can convert many patients presenting with reentrant tachycardias , such as Paroxysmal supraventricular tachycardia and narrow complex tachycardia associated with WPW syndrome.

Adenosine is a very short acting agent that blocks conduction through the AV node and can interrupt sustained reentry when AV node is part of the circuit. AV nodal blocking of adenosine is very transient, although quite profound, so a brief period of AV nodal blockade with near immediate recurrence of the reentrant SVT is not a treatment failure but a consequence of the medication’s short duration of effect. In such cases, repeat adenosine with a higher dose 12mg is given.

Second line drugs include Beta blockers and Calcium channel blockers.

Synchronized electrical cardioversion can be used in narrow complex tachycardias when patients are unstable or do not respond to pharmacologic measures.

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