M-MODE ECHOCARDIOGRAPHY OF THE HEART

M-mode recording of the fetal heart cannot identify electrical events in the heart, but does depict the mechanical events that succeed them.

Information obtained from real time M-mode echocardiography include:

• Cardiac rate (both atrial and ventricular rates). Each atrial contraction is followed by a ventricular contraction.
• Ventricular cavity motion.
• Cardiac wall thickness and motion.
• Motion of the atrioventricular and semilunar valves.
• Cardiac arrhythmias.
• Small pericardial effusions (separation of parietal and visceral pericardium)

M-mode recordings can be obtained from any plane:

1. Plane through the left and right atrial chambers.
• Size and contraction of the atrial chambers only.
• Movement of foramen ovale.
2. Plane through the left and right ventricles.
• One can recognize the anterior wall of the near field ventricle, the atrioventicular valves, the interventricular septum, the distal ventricle and its posterior wall.
• The ventricular rate can be determined but one would not know the atrial rate nor could one ascertain whether atrial contractions are transmitted to the ventricles.
3. Plane through the left/right atrium, semilunar valve, left/right ventricle or through the right atrium, semilunar valve and left ventricle.
• This is the most informative view and allows one to analyze both the rate of atrial and ventricular contractions as well as the transmission of an impulse from the atrium to the ventricle.
• Different dysrhythmias can be more easily differentiated.
4. Motion of the aortic and pulmonary valves.
5. Motion of the semilunar valves.

Video clip of M-mode echocardiography