Assessment of left ventricle preload by transthoracic echocardiography: an easy task?
© Blanco and Sasai; licensee BioMed Central. 2015
Received: 13 March 2015
Accepted: 4 May 2015
Published: 14 May 2015
In sicker hearts, right atrial pressure (an estimation of right ventricle preload) are not equivalent to left atrial pressure (an estimation of left ventricle preload). Both right and left atrial pressures are frequently estimated using invasive techniques and also transthoracic echocardiography. While right atrial pressure is easy to obtain with transthoracic echocardiography, the assessment of left ventricle preload or filling pressures is not simple. In relation to the study of Sasai et al. (J Intensive Care 2(1):58, 2014), this paper discusses in a succinct manner how to think and assess the left ventricle preload by transthoracic echocardiography.
KeywordsCentral venous pressure Left atrial pressure Left ventricle preload Transthoracic echocardiography Extravascular lung water
In failing hearts (septic and non-septic etiology), right atrial pressure (RAP) which infers right ventricle (RV) preload is commonly not equivalent to left atrial pressure (LAP), which infers the left ventricle (LV) preload or filling pressures.
As a daily example, it is not surprising to see patients presenting with cardiogenic pulmonary edema, which denotes a high LAP value, with normal inferior vena cava (IVC) analysis, which indicates a normal RAP.
RAP is commonly obtained by central venous pressure (CVP) measurement or through the analysis of the IVC by transthoracic echocardiography (TTE) in spontaneous breathing patients. LAP is estimated with the wedge pressure (pulmonary artery catheter) or commonly with a set of TTE two-dimensional and Doppler parameters.
At respect and as expected, the study carried out by Sasai et al.  shows no correlation between CVP and some selected TTE parameters of left chamber size and function for estimating the LV preload. Although the authors’ efforts to promote their findings are commendable, some points should be addressed.
The set of TTE parameters used for comparison with CVP, although simple and repeatable, are probably not accurate parameters of LV preload. For example, a patient with dilated cardiomyopathy and depressed LV systolic function could also present with hypovolemia. The simple inspection of the LV and LA suggests an elevated preload; however, other parameters like transmitral inflow and mitral annular velocities may aid in the correct distinction. Also, a patient with RV systolic failure and a low RV stroke volume, like in some cases of septic cardiomyopathy, also accompanied by several grades of tricuspid regurgitation, can have an elevated RAP, with normal or low LAP (again, the mitral inflow and annular parameters also aid in the correct diagnosis).
These are some examples that suggest that more reliable parameters of LV filling are necessary along with two-dimensional measurements.
We thank Dr. Blanco for his comments on our article.
In our study, we revealed that transthoracic echocardiography (TTE) findings are more informative marker for fluid management than CVP findings for assessing the left ventricular (LV) preload of patients with septic shock. LV preload is defined as a tension on the LV myocardium at the end of the diastolic phase (end-diastolic wall stress) and is clinically defined as LV end-diastolic volume (LVEDV) or LV end-diastolic pressure (LVEDP). In our study, we used LV end-diastolic diameter (LVEDD) as an index for LV preload. However, the authors have mentioned that LV preload cannot be easily evaluated with a single parameter, and a more detailed investigation is required. In daily practice, TTE findings, including LVEDD, may be used for estimating LV preload when actual LVEDV or LVEDP values cannot be easily obtained. Practically, in individual cases, we should treat patients with many indices instead of a single indicator. A complete evaluation of LV preload is difficult to perform and is complicated. However, a simple measurement may be sufficient to make the right decision in emergency or intensive care. Our aim was to assess whether CVP is a reliable marker of left ventricular preload; therefore, we used LVEDD, a relatively easier to measure standard indicator of LV preload, as a substitute for LVEDV.
Right atrial pressure
Left atrial pressure
Inferior vena cava
Central venous pressure
Pulmonary artery systolic pressure
Pulmonary vascular resistance
Right ventricle outflow tract
Pulmonary artery diastolic pressure
This work has not been presented at any conferences. This work has not been supported by any grants.
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