Exploring cardiac vector propagation in acute myocardial infarction: a spatial velocity perspective

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Acute myocardial infarction (AMI) significantly impacts cardiac function.
• Vectorcardiography (VCG) offers insights into cardiac electrical activity.
• Objective characterization of spatial-velocity dynamics in VCG is crucial for understanding AMI.

Purpose of the Study:

• To objectively characterize the spatial-velocity dynamics of the QRS-loop in the vectorcardiogram (VCG) of patients with acute myocardial infarction (AMI).
• To identify specific spatial-velocity alterations associated with different infarct locations.

Main Methods:

• Constructed VCG as a space curve using quasi-orthogonal leads (I, aVF, V2) from conventional ECG.
• Recorded spatial velocity (SV), spatial distance (SD), and spatial magnitude (SM) of the dynamic QRS loop.
• Analyzed axis-specific vector magnitude components (ΔX, ΔY, ΔZ) in 50 AMI patients and 25 healthy controls.

Main Results:

• AMI patients exhibited decreased SV (12-25%, p=0.02) and SD (10-26%, p=0.02) compared to controls.
• Altered spatial propagation patterns of ventricular vectors were observed in AMI.
• Significant vector changes were noted in the Y-Axis for inferior wall MI (IWMI, p=0.005) and X-Axis for anterior wall MI (AWMI, p=0.02).
• No significant alteration in SM was found in AMI patients.

Conclusions:

• Reduced SV and SD in AMI, without changes in SM, suggest approximation and clustering of ventricular vector tips.
• These findings may reflect early post-infarction ventricular remodeling, including dilation, thinning, and stress.
• Associated ischemia, tachycardia, and increased myocardial oxygen demand could contribute to these observed dynamics.