An Einthoven ECG trace shows

PHYSICS · Multi-part · Fermi University Physics · Biophysics & Medical Physics · Bioelectricity, the senses and the physics of the body · Bioelectricity, the senses and the physics of the body

Forces, Machines and Signals, Ch Muscle, heart and the fields outside the body

Problem

An Einthoven ECG trace shows, at the peak of the R wave, an amplitude of 0.80 mV0.80\,\mathrm{mV} in lead I and 0.20 mV0.20\,\mathrm{mV} in lead III. ((a)) Use Einthoven's law to find the amplitude in lead II. ((b)) Use the axis relation tan⁡θ=2(II/I)−13\tan\theta = \dfrac{2(\mathrm{II}/\mathrm{I}) - 1}{\sqrt3} (with θ\theta measured from lead I) to find the mean electrical axis. ((c)) State whether this axis lies within the normal range of about −30∘-30^\circ to +90∘+90^\circ.

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