• Ventricular Pacing
• Sgarbossa Criteria
• ECG and Acute STEMI with Ventricular Pacing
• Ventricular Pacing and Ventricular Pacing + STEMI
• Ventricular Pacing and Old Anteroseptal STEMI
• Cabrera Sign and Old Anterior STEMI

Ventricular Pacing

• It is the ability of a pacemaker to stimulate the ventricular myocardium through an electrode
• The electrode stimulates the myocardium with an electrical impulse (similar to the SA node)
• The ventricular electrode of the pacemaker is placed in the right ventricle
• Thus, the ventricles are depolarized from the right ventricle
• Exactly like in a left bundle branch block (LBBB)
• Pacing on the ECG is seen as a pacing artifact (a vertical line, also known as a spike)
• Ventricular pacing creates a LBBB pattern on the ECG
• And LBBB masks the ECG signs of infarction

ECG and Acute STEMI with Ventricular Pacing

• 1. Concordant ST elevation > 1mm (V4-V6, aVL, I)
• In leads with a positive QRS complex
• 5 points
• 2. Disconcordant ST elevation ≥ 5mm (V1-V3)
• Or ST elevation > 25% of the depth of the S wave
• In leads with a negative QRS complex
• 2 points
• 3. Concordant ST depression > 1mm (V1-V3)
• In leads with a negative QRS complex
• 3 points
• If the total score is ≥ 3 (Sgarbossa criteria are met)
• Then the patient has STEMI in the context of
• Ventricular pacing
• or LBBB
• Ventricular pacing on ECG is recognized by
• stimulus artifact before the QRS complex

• ST elevation = 3.2mm
• Depth of S wave = 10mm
• 3.2/10 = 0.32 (32%)
• ST elevation is 32% of the S wave
• Criterion 2 is positive
• (2 points)

Ventricular Pacing and Old Anteroseptal STEMI

• Septal Q wave arises from septal activation in lateral leads (V5-V6, I, aVL)
• The septum is activated from left to right (towards the lateral leads)
• Ventricular pacing without infarction does not create a Q wave in the lateral leads
• Because the septum is activated from right to left (towards the lateral leads)
• The septum is activated by the electrode in the right ventricle
• If a Q wave is present in the lateral leads (V5-V6, I, aVL) in the context of ventricular pacing
• Then this Q wave arose due to the electrical window following a septal infarction
• Infarct-related Q wave appears approximately 9 hours after STEMI

Cabrera Sign and Old Anterior STEMI

• Old anterior STEMI creates a scar in the myocardium
• During the spread of impulses around the scar, the impulse "stutters"
• And a notch forms during ventricular depolarization
  
  
• Cabrera Sign
• Is a notch on the ascending part of the S wave
• In precordial leads (V1-V6)
• Most commonly V3-V4
• In ventricular pacing
• Indicates old anterior STEMI

Acute STEMI and Ventricular Pacing

• Ventricular pacing with LBBB pattern
• Concordant ST elevation > 1mm (V4-V6, aVL, I)
• No
• Disconcordant ST elevation ≥ 5mm (V1-V3)
• No
• Concordant ST depression > 1mm (V1-V3)
• Yes (3 points)
• The patient has acute STEMI in the territory of ventricular pacing
• The patient had on coronary angiography
• Occlusion of a branch of the right coronary artery for the posterior wall
• Had acute posterior wall STEMI