What We Talk About When We Talk About the Wedge Pressure
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- heart failure
- pulmonary hypertension
- pulmonary wedge pressure
- vascular diseases
See Articles by Wright et al and Naeije et al
There is a joke that goes something like this: A mathematician, a statistician, and an economist all apply for the same job. The interviewer asks them all the same question: “What is two plus two?” The mathematician, without much thought, answers, “Four.” When the interviewer says, “Four exactly?” the mathematician, with a touch of incredulity replies, “Of course.” The statistician says, “Four, plus or minus ten percent. But on average, four.” When asked “What is two plus two?” the economist stands up, locks the door, closes the shades, and says “What do you want it to be?” As highlighted in a careful study by Wright et al,1 in this issue of Circulation: Heart Failure, we need to decide what we want the pulmonary arterial wedge pressure (PAWP) to be, or more precisely, how we want it to be measured and what we want it to tell us.
The current study takes a novel approach to investigate the controversial parameter of diastolic pressure difference, in particular focusing on how variations in measurement techniques affect hemodynamic assessment and disease classification.1 The diastolic pressure difference, more commonly referred to as the diastolic pulmonary gradient (DPG), has risen to prominence as a marker of pulmonary vascular disease in the setting of left heart failure through sound physiological reasoning. As first suggested by Naeije et al2 in 2013, the more traditional markers of pulmonary vascular disease “out-of-proportion” to left heart disease (transpulmonary gradient [TPG] and pulmonary vascular resistance) are fraught with physiological concerns. The TPG, defined as mean pulmonary artery pressure minus the PAWP, does not account for flow state or the …