| Sumario: | In the future, automatic implantable cardioverter defibrillators (AICD) may incorporate sensors to differentiate hemodynamically stable from unstable ventricular tachycardias (VT). These sensors should also discriminate between ventricular and supraventricular tachycardias to avoid inappropriate responses from the device. Right ventricular pulse pressure (RVPP) and maximal systolic right ventricular dP/dt (dP/dt) were measured before, during and after 91 episodes of hemodynamically stable VT (VTs), hemodynamically unstable VT (VTus), supraventricular tachycardia (SVT) and sinus tachycardia (ST) induced in 49 male patients. The mean percent changes (mean ± S.E.M.) in RVPP from baseline (% [Delta] RVPP) during VTs and VTus were -35 ± 3% and -72 ± 3%, respectively (both P < 0.001). The % [Delta] RVPP during ST was +56 ±11% (P < 0.01) and % [Delta] RVPP was unchanged from baseline during SVT (+2 ± 9%; P > 0.01). Mean % change in RV dP/dt from baseline was -20 ± 3% during VTs (P < 0.001), -36 ± 5% during VTs, (P < 0.001), +15 ±13% during SVT (P < 0.01), and +85 ± 23% during ST (P > 0.01). The mean percent changes in RVPP were significantly different between each arrhythmia group (P < 0.01). The mean % changes in RV dP/dt were significantly different only between ST and VTs or VTus and between SVT and VTus. The range of values for % [Delta] RVPP during VTs overlapped considerably with the ranges of % [Delta] RVPP during VTus and SVT. The ranges of % [Delta] RVPP overlapped minimally between VTus and SVT. Percent change RVPP separated each episode of VTs and VTus from those of ST. The range of common values for % [Delta] dP/dt between all four groups was extensive. It is concluded that % [Delta] RVPP from baseline is significantly different between groups of patients during VTs, VTus, SVT, and ST, but that a large degree of overlap in the range of values for % [Delta] RVPP and RV dP/dt between different arrhythmias groups may limit the specificity of these hemodynamic variables in separating different arrhythmias.
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