A novel phonetic approach to continuous flow left ventricular assist device auscultation

The dominant sound generated by continuous flow left ventricular assist devices (cf-LVADs) has generically been referred to as a "hum". This term, however, implies that despite distinct engineering designs, all cf-LVADs generate the same quality of sound. Furthermore, no structured method for auscultation of cf-LVADs exists. We hereby report a novel and simple phonetic approach to device auscultation, the aims of which are to improve recognition, understanding, and teaching of sound produced by normally functioning cf-LVADs. We sought to evaluate whether clinically relevant pump or person related events can produce changes in the expected audio fingerprint of a particular cf-LVAD, and whether these changes in sound can be identified by auscultation and translated phonetically.

Sound recordings were made on 7 people implanted with one of 3 U.S. Food and Drug Administration (FDA) approved cf-LVADs. Of the 7, 3 were considered to have normal device function and stable condition. The remaining 4 people had a clinically relevant pump or person related event. Recordings were made with a stethoscope attachment that allows digital recording of sound and provides a real time phonocardiogram.

The main findings were the following: 1.) each cf-LVAD generates a unique audio fingerprint 2.) the audio fingerprint can be phonetically translated in a simple manner. 3.) pump or patient related events result in changes in device sound, that can be appreciated phonetically.

Phonetics offer a novel and easily reproducible method for evaluation and teaching normal cf-LVAD sounds by auscultation. Additionally, clinically relevant pump or person related events can produce changes in the expected audio fingerprint of a particular cf-LVAD. These changes in sound can be identified by auscultation and translated phonetically. Auscultation is an important component of the physical examination of people supported with cf-LVADs.