At first I thought it was my heart — not because it was pounding harder, nor faster, nor with that urgency that precedes collapse, but because a pulse, muffled, flat, strangely regular, began to beat with an abnormal density, not in the rhythm itself, but in the placement, as if the tempo had shifted a few millimeters to the left, or downward, or elsewhere, and it now resonated off-axis, in an area I had never inhabited, a new cavity that should never have received a heartbeat, but nonetheless sheltered one — and it was this dissonance, this insidious misalignment between the regularity of the motion and the inadequacy of its source, that made me believe, at first, that it was my heart.
A beat too dense.
A poorly tuned rhythm.
A misaligned pulse.