[Pulsus alternans: alternation of relaxation parameters]

Pulsus alternans was observed during transluminal coronary angioplasty of the left anterior descending artery in a 48 year old man. Analysis of left ventricular pressures (Millar catheter) showed alternation of the parameters of relaxation. After the strong beats there was a lengthening of the relaxation constant T (78.8 +/- 3.9 ms compared to 72.9 +/- 4.4 ms, p less than 0.001), a widening of the negative deflection of dp/dt without a significant variation in amplitude and the point of minimal diastolic pressure was delayed. The first weak beat occurred after the longest constant of relaxation T and the lowest negative deflection of dp/dt. Regression of pulsus alternans was accompanied by a progressive decrease of T and an increase in amplitude and narrowing of the negative deflection of dp/dt. The increase in the constant of relaxation T and widening of the negative dp/dt, more apparent after the weak beats, could be signs of left ventricular asynchronism.