Question of the Week:  September 17, 1999

How can I differentiate a right ventricular waveform from a pulmonary artery waveform?

Right Ventricle Waveform (RV) Pulmonary Artery Waveform (PA)
  • there is no dicrotic notch
  • the RVsystolic pressure equals the PA systolic pressure (during systole, the open pulmonary valve makes the two chambers "one")
  • the RV has a very low diastolic pressure, which is equal to the diastolic pressure of the right atrium (RA) (the RA and RV are one chamber during diastole when the tricuspid valve is open)
  • the rise in the RV waveform is simultaneous with the QRS and preceeds the mechanical systole (depolarization causes the pressure to rise; once the pressure in the RV exceeds the PA, the pulmonary valve opens and systole begins)
  • a small pressure wave may be visible prior to the main pressure rise, if a sinus rhythm is present (in late diastole, atrial kick produces a small rise in the ventricular volume)
  • ventricular arrhythmias may occur if the tip of the catheter is in the RV



    In a direct RV measurement, the rise in the RV pressure occurs simultaneous with the QRS.  This rise in pressure will appear farther away from the QRS in an RV pressure wave obtained from a pulmonary artery catheter because of the prolonged transmission distance between the catheter and the transducer.

  • there is a dicrotic notch
  • the PAsystolicpressure equalsthe RV systolic pressure (during systole, the open pulmonary valve makes the two chambers "one")
  • the PAdiastolic pressure is higher than the RV diastolicpressure (since both RV and PA systolic pressures are equal, the lower RV diastolic pressure makes the RV waveform taller than the PA)
  • the rise in the PA pressure occurs after systole begins, as a result of blood entering the pulmonary artery (thus the rise in the PA waveform is always later in the cycle than the rise in the RV, when compared to the QRS in the same patient)
  • there is no visible evidence of atrial contraction on the PA waveform



Example of RV Waveform
Example of PA Waveform
I think that the tip of my pulmonary artery catheter is displaying a Right Ventricular waveform.  What clues would help validate a right ventricular tracing?

TIP:  Obtain a pulmonary artery tracing at the beginning of each shift, to use as a reference for comparison of any future waveform changes.

  • A right ventricle waveform will appear taller than the previous pulmonary artery tracing (if measured on the same scale).
  • If the new waveform has a systolicpressure that is the same as previous pulmonary artery systolic recordings, but now has a much lower diastolic pressure, the new waveform is most likely right ventricle.
  • If the new waveform has a systolic pressure that is the same as the previous pulmonary arterysystolic readings, but the diastolic pressure on the new waveform is similar to the right atrial diastolic pressure, the catheter tip is likely in the right ventricle.
  • Compare the new waveform to the baseline pulmonary artery waveform.....if the rise in the new waveform is closer to the QRS than the rise in the pulmonary artery waveform, the new waveform is probably right ventricle.
  • A waveform change accompanied by new ventricular ectopic beats suggests that the tip of the catheter might be in the right ventricle.