the clinical evaluation of left ventricular ( lv ) diastolic function has been a difficult challenge .
lv filling and pulmonary venous doppler patterns have been utilized to estimate lv diastolic function , comprising variables as such stiffness , relaxation and even lv filling pressures .
doppler echocardiography has been utilized not only as a diagnostic tool but also as a monitoring tool , permitting follow - up of the effects of therapeutic interventions . in the previous issue of critical care , vignon and
colleagues demonstrated the value of tissue doppler imaging ( tdi ) to estimate lv diastolic function in a setting where acute alterations of preloading conditions may interfere .
they also clearly show some weak points with respect to the correct use of these function variables .
a typical transmitral doppler pattern consists of a larger early filling velocity wave ( e wave ) followed by an atrial contraction flow velocity wave .
reduced lv relaxation ( present in patients with advanced age , ischaemic heart disease or arterial hypertension ) will induce a reduction of the e wave in comparison with the atrial contraction flow velocity wave . increasing filling
pressures will increase the e wave velocity and will shorten the deceleration time of the e wave , with a transition from pseudonormalization to a restrictive pattern .
the phase of diastolic dysfunction for an individual patient remains difficult because of the interplay between relaxation and preload , which makes the routine pulsed wave doppler indices useless  particularly in a setting where preloading conditions may change constantly and abruptly , as in many critically ill patients .
this doppler mode facilitates the assessment of the movement of the myocardial tissue , which typically reflects low velocity with very high amplitude doppler signals .
tdi can therefore be utilized to estimate myocardial velocities at the mitral annulus to obtain an impression of both systolic and diastolic myocardial motion .
the spectral doppler pattern is characterized by a systolic wave , an early diastolic wave ( e ' wave ) and an atrial velocity wave .
the technique is hampered by shortcomings related to the doppler technology ( angle misalignment , translation and rotation of the myocardial tissue ) and by intrinsic characteristics of myocardial function ( for example , the presence of regional wall motion abnormalities ) .
nevertheless , regional lv systolic function and lv diastolic function assessment is possible provided the sample volume is placed at the level of the mitral annulus and no ischaemia / infarction in the annulus region is present .
whereas the systolic component of this doppler pattern has been shown to be clearly preload dependent , less transparency exists on the load dependency of the diastolic myocardial velocities . with the initial description of this variable
, the index appeared to be load independent in settings of rapid infusion or preload alteration .
jacques and colleagues , however , reported both afterload independency and preload dependency of the e ' wave in situations where a normal lv function was present .
in contrast to the present study of vignon and colleagues , jacques and colleagues did not report the sample volume location .
comparison between the septal and lateral mitral annulus signals suggests that the septal signals are apparently more sensitive to preload alterations .
the reader , however , should bear in mind that the stability of the signals obtained at the septal side can be questioned , particularly in mechanically ventilated patients with ventilation - induced , right - sided , afterload shifts .
nevertheless , several authors have already reported differences in e ' wave velocities between the septal and lateral walls , without the ability to indicate a clear cause for this difference .
vignon and colleagues show no changes of the e ' wave in a rather small subset of intensive care unit patients , and again several issues have to be kept in mind .
the effects of drugs such as epinephrine , however , have not been described ; one should expect an increase of the e ' wave , at least when considering a similar effect to that with dobutamine .
it can thus be questioned whether an ultrafiltration ( and thus load diminishing ) effect is not concurring , keeping the e ' wave constant .
second , the influence of ultrafiltration itself on lv systolic function and lv diastolic function during septic shock is largely unknown .
the combination of lower preload ( by ultrafiltration ) and decreased lv function would render a less preload - dependent e ' wave , as suggested by jacques and colleagues   the number of intensive care unit patients included in this subset is again far too small to conclude in a proper manner . from all these studies , it is unclear whether the discussed concepts apply to all haemodynamic states . the fact that the e wave / e ' wave relates to pulmonary capillary wedge pressure   suggests that increased intrathoracic pressures could impede this relationship strongly .
apart from the fact that the e ' wave ( in conjunction with traditional doppler parameters ) is useful in determining lv diastolic function more accurately , tdi in the critically ill patient keeps more questions open than are answered .
e wave = early filling velocity wave ; e ' = early diastolic wave ; lv = left ventricular ; tdi = tissue doppler imaging .
this work was supported by an unrestricted grant from the international research centre of ghent university .
 assessment of left ventricular diastolic function in the critically ill patient remains a difficult issue in clinical practice . combined use of routine transmitral and pulmonary venous doppler patterns in conjunction with tissue doppler imaging 
 have been claimed to allow bedside diagnosis of diastolic dysfunction . 
 although in the previous issue of critical care it was clearly demonstrated there might be a difference in load dependency of the early myocardial tissue doppler velocity between lateral and septal placed sample volume , there remain still several unanswered questions , particularly with respect to the preload dependency of these indices . 
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