Parasternal Long Axis

Surface Anatomy

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.

3d

Normal 2d

parasternal long axis

The starting point of the standard transthoracic echocardiograpahic exam. Blood flow is perpendicular to ultrasound beam, which limits the utility of doppler studies in this view. Valvular motion is perpendicular to the ultrasound beam which provides excellent spatial resolution.

Cavities

parasternal long axis cavities

This view captures the long axis of the left ventricle with the apical portion placed on the left side of the screen and the left atrium on the right. The true apex is generally not visualised from this view. The mitral valve is placed between these two structures (roughly in the middle of the screen) allowing visualisation of both the anterior and posterior leaflets. The left ventricular outflow is located above the mitral valve. Following on, the aortic valve can be seen with the aortic outflow extending up over the left atrium. The right ventricle is the most anterior structure. The pericardium can be seen anteriorly and posteriorly with the descending aorta located “outside” the pericardium. This is an important anatomical feature used to distinguish pericardial from pleural effusion.

Walls

parasternal long axis walls

Basal, mid and apical segments of both the anteroseptal and inferolateral walls are visible (the apex is not visible). Quantification of left ventricular size may be possible here as long as the maximal diameter of the left ventricle is captured. The coronary sinus is visible in the posterior atrioventricular groove. This is near the base of the posterior mitral valve leaflet.

Mitral Valve

parasternal long axis mitral

The mitral valve apparatus is visible here. This consists of the annulus, leaflets, chordae and papillary muscles. The full excursion of the mitral valve leaflets should be visible. Integrity of the chordae and posteromedial papillary muscle can be assessed.

Aortic Valve

parasternal long axis aortic

Two (of three) aortic valve cusps are visible. These are the right and non coronary cusps. Assessment of valvular motion as well as structure may be done as the valvular motion is perpendicular to the ultrasound beam.

2d Video