Noninvasive assessment of ejection intraventricular pressure gradients.
OBJECTIVE
The study was designed to validate in vivo a new method to measure ejection intraventricular pressure gradients (IVPGs) by processing color M-mode Doppler data and to assess the effects of inotropic interventions on IVPGs in the clinical setting.


BACKGROUND
In the absence of obstruction, ejection IVPGs cannot be estimated by Doppler using the simplified Bernoulli equation.


METHODS
High-fidelity micromanometers were placed in the left ventricle of eight minipigs, and synchronic Doppler images and pressure signals were obtained during different hemodynamic conditions. Twenty healthy volunteers and 20 dilated cardiomyopathy patients were studied at baseline and during esmolol, dobutamine, and atropine infusion (only dobutamine in patients).


RESULTS
Excellent agreement was observed between micromanometer and Doppler methods for measuring instantaneous pressure differences among the apex, the mid-cavity, and the outflow tract (R(intraclass) = 0.98, 0.81, 0.76, and 0.98 for the peak, time-to-peak, peak reverse, and time-to-peak reverse values, respectively; n = 810 beats). Error of the noninvasive method was -0.05 +/- 0.25 mm Hg for the peak pressure difference. Parametrical images demonstrated that IVPGs originate mainly in the mid-ventricle and then propagate to the outflow tract. Both the magnitude and the temporal course of IVPGs were different among volunteers and patients. Inotropic interventions induced significant changes in the apex-outflow tract pressure differences in both populations, whereas atropine had no effect on IVPGs.


CONCLUSIONS
For the first time, ejection IVPGs can be accurately visualized and measured by Doppler-echocardiography. Important aspects of the dynamic interaction among myocardial performance, load mechanics, and ejection dynamics can be assessed in the clinical setting using this method.
Yotti
Raquel
R
Department of Cardiology, Hospital General Universitario Gregorio Marañon, Madrid, Spain.
Bermejo
Javier
J
Antoranz
J Carlos
JC
Rojo-Alvarez
José Luis
JL
Allue
Carmen
C
Silva
Jacobo
J
Desco
M Mar
MM
Moreno
Mar
M
García-Fernández
Miguel A
MA
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002311:Cardiomyopathy, Dilated / Q000453:epidemiology / Q000503:physiopathology; D004452:Echocardiography / Q000379:methods*; D018618:Echocardiography, Doppler, Color; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008955:Models, Cardiovascular; D015588:Observer Variation; D013223:Statistics as Topic; D013318:Stroke Volume / Q000502:physiology*; D013552:Swine; D017725:Ventricular Pressure / Q000502:physiology*