We appreciate the comments of Dr. Feigenbaum, which allow us to discuss some aspects of the deliberations of the writing group that did not make it into print. As with most guidelines documents, it was not possible in the final product to detail all the issues that were discussed or the content of that discussion. The committee’s greatest concern was for establishing a contemporary minimum level of performance for echocardiography laboratories. As part of this discussion, we reviewed many aspects of echocardiography, including M-mode echocardiography. We can assure the readers of the journal that M-mode echocardiography was discussed and appreciated as an important component of echocardiography in the quality echocardiography lab. However, it is important to remember that the goal of the document was to highlight the components of echocardiography laboratory operation that should be performed to achieve the minimum quality standards: a level of quality that can be achieved by all. It is our hope that this document serves as a modern “blueprint” that all laboratories can use to elevate their level of service.

As Dr. Feigenbaum points out in his letter and his prior writings, M-mode echocardiography has an important role in echocardiography laboratories because of the superior temporal resolution of this modality. In fact, on page 3 of our guidelines document, when describing the imaging process, it is stated that before performing a cardiac ultrasound exam, laboratory personnel must determine the correct components of that study on the basis of the indication for the test and the characteristics of the patient. We specifically mentioned M-mode echocardiography in that section, recognizing that there are unique situations in which the timing of cardiac events, such as valve leaflet motion among others, is important and can best be graphically depicted on the M-mode display. This is also particularly true for the evaluation of abnormal motion of the interventricular septum and, in combination with color Doppler, for the timing of some abnormal flows in tachycardic states. However, to focus on process and how to improve quality, and for the sake of brevity, the use of various echocardiographic techniques in distinct clinical or physiologic entities was not detailed in this document.

From a practical standpoint, the writing committee also recognized that in today’s echocardiography laboratory, where operators have the ability to perform many modes of ultrasound imaging (including M-mode, two-dimensional, three-dimensional, spectral Doppler, continuous-wave Doppler, color Doppler, contrast echocardiography, tissue Doppler, and speckle tracing), there is a need to tailor exams to ensure that the key information is obtained within an efficient period of time. Consequently, although M-mode echocardiography is important in many exams, it is not a prerequisite for performance in every exam at the minimal quality level prescribed by this committee. This is one of the reasons that our discipline requires careful thought by sonographers and physicians before and during every exam.