Pioneer of the Doppler Effect

Pradeep Rangappa¹ https://orcid.org/0000-0002-2187-8950, Ipe Jacob²

^1,2Department of Critical Care, Manipal Hospital, Bengaluru, Karnataka, India

Corresponding Author: Ipe Jacob, Department of Critical Care, Manipal Hospital, Bengaluru, Karnataka, India, Phone: +91 9844208268, e-mail: ipe.jacob@gmail.com

How to cite this article: Rangappa P, Jacob I. Pioneer of the Doppler Effect. J Acute Care 2023;2(3):168–169.

Source of support: Nil

Conflict of interest: Dr Pradeep Rangappa is associated as the Editorial Board member of this journal and this manuscript was subjected to this journal’s standard review procedures, with this peer review handled independently of this editorial board member and his research group.

Christian Andreas Doppler (Fig. 1) was a mathematician and physicist born in November 1803 in Salzburg, Austria. Due to his apparently frail health, he could not join the family stonemasonry business. After schooling in Salzburg, he trained and worked at the University of Vienna and later became a professor at the Polytechnic School in Prague. During his professorship, he authored >50 articles in mathematics, physics, and astronomy, including the landmark publication, ”Über das farbige Licht der Doppelsterne” (”Concerning the Colored Light of Double Stars”). He returned to Vienna, where in 1850, he took charge as the Director of the newly founded Institute of Physics at the University of Vienna. However, this phase of his life was beleaguered by recurrent health problems, including tuberculosis, for which he moved to Venice. He died in March 1853 surrounded by his family.

Fig. 1: Austria, 1992

Christian Doppler (Fig. 2) described a phenomenon in which the frequency or wavelength of a wave emitted by an object appears to change as it moves away from or toward the observer. This frequency appears higher than the actual frequency emitted by the object as it moves toward the observer and lower as it moves away. This perceived change in the frequency of sound is referred to as the Doppler effect or Doppler shift and is applicable to all forms of sound waves.

Fig. 2: Mali, 2011

The Doppler effect has been utilized in the development of audio equipment, velocity profile measurement, radar, medical equipment, military, aerospace navigation, astronomy, and automobile speed measurement.

The use of Doppler in ultrasonography has revolutionized echocardiography. There are two major modes used here, namely pulsed wave Doppler (PW) and continuous wave Doppler (CW). In the PW mode, the same piezo-electric crystals alternately send short bursts of ultrasound and then analyze the reflected sound waves. In this mode, the echocardiogram analyses signals reflected from a fixed depth, for instance, the left ventricular outflow or inflow tract. This precise location is set by moving the sample volume along the line of the Doppler beam. Multiple reflected signals are simultaneously analyzed to generate a two-dimensional image of intracardiac flow. This mode is useful for assessing areas of low-velocity blood flow such as mitral or tricuspid inflow, pulmonary venous flow, and left or right ventricular outflow. Color Doppler imaging is also based on the principles of PW and is used to visualize abnormal blood flow velocities in color in comparison to the greyscale images of PW. Blood flow is depicted as a colored dot within the image and is used to diagnose shunts and valvular disease.

Continuous wave Doppler (CW), in comparison, uses two dedicated crystals, allowing for simultaneous transmission and continuous reception of signals. This permits the measurement of high-frequency Doppler shifts and is used to measure higher velocities, such as in pulmonary hypertension, valvular regurgitation, and aortic stenosis. Thus, PW and CW are complementary to each other and are necessary for a complete examination of heart function.

Tissue Doppler imaging is another Doppler modality used to detect abnormal myocardial motion, as in coronary artery disease and cardiomyopathies. Here, instead of calculating the velocity of blood flow, the velocities of tissue movements are calculated by aligning a 3–5 mm sample in the septal wall, lateral left ventricular wall, or right ventricular free wall. In this mode, the echocardiograph measures the low-velocity and high-amplitude signals from myocardial motion. This model is also used to measure left ventricular filling pressures and for early detection of infiltrative cardiomyopathies, including Fabry’s disease, sarcoidosis, and amyloidosis.

Christian Doppler’s mid-19th century research thus continues to revolutionize the field of science and medicine in the 21st century.

ORCID

Pradeep Rangappa https://orcid.org/0000-0002-2187-8950

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