Author + information
- Nils Johnson1,
- Jo Zelis2,
- Pim Tonino3,
- Patrick Houthuizen4,
- Frederik Zimmermann5,
- Arthur Bouwman2,
- Guus Brueren6,
- Daniel Johnson7,
- Jacques J. Koolen4,
- Erik Korsten2,
- Inge Wijnbergen4,
- Richard L. Kirkeeide1,
- Nico Pijls4 and
- K. Lance Gould8
- 1McGovern Medical School at UTHealth, Houston, Texas, United States
- 2Catharina Hospital Eindhoven, Eindhoven, Netherlands
- 3Catharina Hospital, Eindhoven, Netherlands, Eindhoven, Netherlands
- 4Catharina Hospital, Eindhoven, Netherlands
- 5Catharina Hospital Eindoven, Eindhoven, Netherlands
- 6Catharina ziekenhuis Eindhoven, Eindhoven, Netherlands
- 7McGovern Medical Schoola t UTHealth and Memorial Hermann Hospital, Houston, Texas, United States
- 8University of Texas Medical School, Houston, Texas, United States
Although symptoms from aortic stenosis (AS) arise during exertion, physiologic assessment almost always takes place at rest – a conceptual discordance.
The relationship between transvalvular pressure gradient (DP) and transvalvular flow (Q) fundamentally describes stenosis physiology. We developed a novel “FFR of the aortic valve”, the unitless aortic/LV average pressure ratio during systolic ejection at peak stress. We recruited patients undergoing routine TAVI and some with moderate AS. During graded dobutamine infusions before and after TAVI, 2 pressure wires continuously measured DP while a PA catheter regularly assessed thermodilution cardiac output.
20 subjects underwent assessment. DP versus Q did not display a consistent relationship. Neither linear (median R2 0.16) nor quadratic (median R2<0.01) models predicted stress observations, implying that a stenotic valve does not behave like a resistor or orifice. Dobutamine Ao/LV correlated best with the relative reduction in flow caused by the AS. After TAVI, a highly linear relationship (median R2 0.96) indicated a valid valve resistance, median 0.65 (IQR 0.41 to 1.15) Woods units.
Resting AS assessment cannot predict stress hemodynamics, implying that the Gorlin orifice model does not provide a proper physiologic description. Our novel focus on pressure loss versus flow relationships offers a more complete description. Because our results suggest that some valve-related exertional symptoms may be missed without routine provocative maneuvers, further study of moderate AS responses to stress appears justified.
STRUCTURAL: Valvular Disease: Aortic