Echocardiography is an effective means of assessing cardiac valve function. It is useful for a rapid qualitative assessment or a more comprehensive assessment for all forms of valve function using transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE). Doppler assessment allows an accurate quantitative measurement of the severity of stenotic and regurgitant lesions. The extent to which the critical care echocardiographer applies the sophisticated tools of the cardiologist to assess valvular heart disease is highly variable. By training, background, and interest, cardiologists often take the lead in this aspect of echocardiography. However, the intensivist who performs echocardiography should have competence in assessing valve function, as many patients in the intensive care unit (ICU) may have valve dysfunction that adversely impacts their cardiopulmonary status.
In general, the intensivist will be interested in the identification of catastrophic valve failure or valve dysfunction that is sufficiently severe to impact the hemodynamic functioning of the patient. Conversely, the identification of lesser degrees of valve disease or normal valve function are also of interest, as the intensivist may then determine that valve failure is not a contributing factor to the patient's critical illness. This chapter will review the echocardiographic assessment of valve function from the perspective of the bedside intensivist.
Intensivists who perform critical care echocardiography will either have competence in basic critical care echocardiography (several standard 2D views without comprehensive training in Doppler) or competence in advanced critical care echocardiography (see also Chapter 4). The latter is equivalent to level 2 training by standard cardiology criteria.1 Intensivists who have basic training in echocardiography have a limited ability to assess valve function. The standard 2D views of basic critical care echocardiography generally include the parasternal short- and long-axis, the apical four-chamber, and the subcostal views. Detailed examination of the tricuspid valve (TV) is not part of basic echocardiographic assessment, as the focus of the basic examination is to assess for left ventricular (LV) and right ventricular (RV) size and function, for pericardial effusion, and for evidence of preload sensitivity. It is not to perform a detailed valvular assessment. Without training in Doppler measurements, the basic-level examiner can identify obvious mechanical failure of the mitral valve (MV) (e.g., a flail leaflet, ruptured chordae, or ruptured papillary muscle) or obvious aortic valve (AV) disruption. Severe stenosis of these valves may also be apparent. By definition, intensivists with training in basic echocardiograpy do not have comprehensive Doppler training and often lack the ability to perform quantitative measurements of valve function.
Color Doppler may be used for a qualitative assessment of valve function. The basic-level critical care echocardiographer should be cautious in assuming to have the skills in the use of color Doppler. One of the problems with the technique is that it appears to be straightforward, when it is actually not. The pitfalls of color Doppler include gain settings, wall jet effects,2 angle effects, and shadowing by surrounding structures, such as prosthetic valve ...