CHAPTER 26: The Stethoscope

COLOR FLOW DOPPLER AND HEART MURMURS

• The finding of mitral or aortic regurgitation on color flow should prompt a search for the corresponding murmur.

• An absent murmur when there is evidence of severe regurgitation on color flow needs an explanation.

• The echocardiographic explanation of a murmur may reside in the left ventricle: hypertrophy, outflow obstruction, chamber dilatation, mitral annulus dilatation.

• Color flow Doppler is highly capable of detecting valvular regurgitation.

• It is an instantaneous spatial display of mean blood flow velocities—different from an angiogram.

• Regurgitant murmurs are commonly found by color flow Doppler without being heard on auscultation.

• Connecting color flow with a murmur is not always straightforward, but correlation of the color flow Doppler exam with auscultation is extremely valuable clinically.

• Innocent flow murmurs may become audible in the recumbent position due to increased venous return. There is no color flow Doppler equivalent to a murmur caused by normal forward flow through the right cardiac chambers.

• Turbulent blood flow is displayed with a variance map on color flow, and by spectral broadening on pulsed-wave Doppler.

• Practical example: A sclerotic aortic valve may give rise to a prominent systolic ejection murmur, but there will be no significant gradient on pulsed- and continuous-wave Doppler.

• Color flow Doppler is useful during the assessment of the severity of aortic stenosis. Multiple transducer positions are used to align the continuous-wave Doppler beam with the stenotic jet. Color flow can help find the turbulent flow in the aorta in the right parasternal and suprasternal transducer positions during the “hunt” for the fastest aortic stenosis velocity.

• Bedside scanning tip: Palpate for the thrill of the aortic stenosis murmur first, and place the transducer directly over that spot on the chest.

Source

• Yoshida K, Yoshikawa J, Shakudo M, et al. Color Doppler evaluation of valvular regurgitation in normal subjects. Circulation. 1988;78:840–847.

SYSTOLIC EJECTION MURMURS

• The Doppler flow pattern can help sort out a systolic ejection murmur by providing the following parameters:

  • - Time of systolic peaking.

  • - Onset in relation to the isovolumic period.

  • - Ejection time.

• The peak of a systolic Doppler flow signal through the aortic valve can be correlated with the auscultatory impression of whether an aortic murmur peaks early or late in systole.

• Systolic ejection murmurs end before the second heart sound.

• There is an auscultation “caveat” that may help the listener decide whether the murmur stops before the second heart sound (making it an ejection-type murmur).

• This only works with loud murmurs where it is clear to the listener that the murmur is louder than the second heart sound.

• The caveat goes as follows: If the listener hears a second heart sound that is softer than the preceding systolic murmur, it means that the murmur stops before the second heart sound.

• This auscultatory impression can be confirmed by the Doppler flow pattern.

• Pulsed-wave Doppler can show the ...