The transthoracic echocardiographic examination compromises of three standard windows. Traditionally the examination starts with the parasternal, followed by the apical and lastly the subcostal window. However in cases of haemodynamic shock the subcostal window is often imaged first, in particular to outrule cardiac tamponade. Images are obtained by angulation and rotation of the transducer. Two orthogonal planes, the short and long axis, are recorded in the parasternal and subcostal windows. Two dimensional (2D) imaging supplemented by doppler (colour, pulsed and continuous wave) are the mainstay of the echocardiographic exam. In the intensive care patients are imaged in the supine position and the examiner may be positioned on either side of the patient. One should note that the transducer locations on the precordium are approximate as there is considerable variation amongst patients. This is particularly applicable to critically ill patients where pulmonary oedema, pleural effusions and chronic lung disease may be a feature.
Parasternal Long Axis
Parasternal long axis; the transducer is applied to the third intercostal space on the left parasternal border with the transducer marker pointing to the patient’s right shoulder. The scanning plane runs along an imaginary line from the right shoulder to the left flank. This is parallel to the major axis of the left ventricle. Further refinement can be achieved through minor rotation of the transducer to reveal the true “major axis” and lateral to medial angulation to reveal the maximal diameter of the left ventricle. It may be necessary to move up or down one space. This window is best obtained with the patient in the left lateral decubitus position.
Parasternal short axis; view the transducer is applied to a similar position on the precordium as used for the long axis view. However, the transducer marker points between the 12 o’clock position and the patient’s left shoulder. This corresponds to approximately 90 degrees of rotation.
Parasternal Short Axis
Four imaging planes are described for the parasternal short axis. These are the basal, mitral, mid papillary and apical plane. Movement across several intercostal spaces may be necessary. This is usually up or down one space. This window is best obtained with the patient in the left lateral decubitus position.
Parasternal Short Axis Transition
As a general rule of thumb the parasternal short axis (PSAX) mitral view is captured with the transducer perpendicular to the chest wall. Sweeping the transducer medially and superiorly will capture the basal view. Conversely, sweeping the transducer laterally and inferiorly will capture the mid-papillary and apical views.
Apical 4 Chamber
The position is found by palpating the apex beat and then moving laterally and inferiorly (this is particularly relevant in cases of cardiac enlargement). This window is best obtained with the patient in the supine position. The transducer marker is directed at the right shoulder. This places the left ventricle on the right side of the image with the apex seen at the top.
Apical 4 to 5 Chamber Transition
For the apical 5 and 4 chamber view, the transducer is placed in an identical physical location on the chest wall. The 5 chamber view is acquired by anterior tilting of the transducer.
Apical 4 to 2 Chamber Transition
Apical 2 chamber is acquired by anti-clockwise rotation (from the apical 4 chamber). The transducer marker is placed at the twelve o’clock position.
Apical 2 Chamber
The transducer is placed at the same physical location on the chest was as the Apical 4 and 5 chamber views. The position is found by palpating the apex beat and then moving laterally and inferiorly (This is particularly relevant in cases of cardiac enlargement). This window is best obtained with the patient in the supine position.
Apical 2 to 3 Chamber Transition
The transducer beam rotated further anti-clockwise (from the apical 2 chamber postion). This brings both the aortic and mitral valves into the same imaging plane.
Apical 3 Chamber
The transducer is placed at the same physical location on the chest was as the Apical 2 chamber view. The position is found by palpating the apex beat and then moving laterally and inferiorly (This is particularly relevant in cases of cardiac enlargement). This window is best obtained with the patient in the supine position.
A particularly important view in ICU echocardiography as it may be the only available acoustic window. The transducer is placed just inferior to the xiphisternum with the transducer marker pointing to the left flank.
Subcostal IVC Transition
For the Subcostal IVC view the transducer is rotated 90 degrees anti-clockwise. The beam is then directed to the patient's right mid-clavicular line and angled slightly posteriorly.
Caution should be taken in correctly identifying the IVC (vs. abdoinal aorta). IVC measurements are taken here.