ECG Analysis - Cobra (Naja naja) Envenomation

Patient & Context

• Patient: Female, 43 years old
• Date/Time: 4 Aug 2025, 19:12:17
• Machine: MAC800 1.02, 4×2.5s format
• Speed: 25 mm/s | Gain: 10 mm/mV
• Clinical context: The papers visible beside the ECG reference Naja naja (Indian Cobra) and Bungarus carinatus (Common Krait) - this patient has been bitten by one of these elapids. The notes in the background show the ABCDE assessment: Airway, Breathing, Circulation, monitoring TPR/BP, GCS/SCOM.

ECG Measurements (machine-reported)

Systematic Interpretation

• Heart rate ~80 bpm - normal sinus rate
• Regular rhythm consistent with normal sinus rhythm

• QRS axis ~97° - right axis borderline (normal up to 90-100°), mildly rightward
• T-wave axis 30° - normal

• P waves visible and upright in lead I, II - normal sinus P morphology
• PR interval 144 ms - normal

• Duration 94 ms - narrow, normal (no bundle branch block)
• Morphology: leads appear to show normal R-wave progression in precordial leads

• QTc = 459 ms - mildly prolonged (upper limit of normal for females is 460 ms by some guidelines, borderline abnormal by others using 440 ms cutoff)
• This is the most significant finding in the context of cobra envenomation

• The precordial leads (V1-V6) show some nonspecific changes
• No obvious acute ST elevation/depression to suggest ischemia
• T-wave flattening may be present in some leads

Clinical Significance in Elapid Envenomation

• QTc prolongation - the most common ECG abnormality (as seen here)
• Sinus tachycardia or bradycardia
• ST-T changes (myocarditis pattern)
• Ventricular arrhythmias in severe cases (VPCs, VT)
• Complete heart block (rare, severe)

Summary of Findings

Immediate Recommendations

1. Serial ECGs - repeat every 4-6 hours to watch for progression of QTc prolongation or new arrhythmias
2. Cardiac monitoring - continuous telemetry given risk of arrhythmia
3. Avoid QT-prolonging drugs - do not administer medications that further prolong QTc (certain antibiotics, antiemetics like ondansetron, etc.)
4. Troponin & CK-MB - check cardiac enzymes to assess myocardial injury
5. Electrolytes - correct any hypokalemia/hypomagnesemia, which worsen QTc
6. Anti-snake venom (ASV) - polyvalent ASV should be administered promptly if not already done; it is the mainstay treatment for elapid envenomation
7. Neostigmine - may be used for neurotoxic features (ptosis, respiratory paralysis) in Naja bites which are post-synaptic blockers

The QTc of 459 ms is at the borderline threshold. In the context of active snake envenomation, this should be treated as clinically significant and warrants close cardiac monitoring regardless of whether it technically crosses a specific cutoff, as it may worsen over the next few hours.