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Acoustic cardiography utilizes 3 inputs: a single electrocardiogram (EKG) lead from 2 standard electrodes, and 2 audio sensors placed at the usual V3 and V4 positions on the chest.  These 3 channels synchronously record electrical and audio information. The audio information is processed using wavelet signal processing techniques and a diagnostic algorithm that filters out extraneous noise and uses time-frequency analysis to objectively define the heart sounds and the intervals between sounds. An analogue visual display of the audio data is then displayed and paired with the electrical data from the EKG recording.  Output from acoustic cardiography can generate numerous parameters, some of which may have clinical applicability. Three of these measures are: 

1. S3 strength—a quantitative measure of the intensity of the S3 heart sound, which is an abnormal sound that is associated with systolic dysfunction; 
2. Electromechanical activation time (EMAT), defined as the interval between the onset of the QRS complex and the closure of the mitral valve. EMAT is the main parameter that is used to optimize CRT therapy by choosing the interval that optimizes cardiac output; 
3. Left ventricular systolic time (LVST)—the interval between mitral valve closure and aortic valve closure. This length of the LVST has been correlated with changes in ejection fraction.

Auscultation for an S3 is part of the physical exam when evaluating for presence of heart failure. The presence of an S3 indicates systolic dysfunction and is a specific physical exam finding supporting systolic heart failure. The S3 is an indistinct sound that can be difficult to hear and is not present in all patients with systolic dysfunction. Other components of the diagnostic evaluation for heart failure include a variety of clinical symptoms and physical exam findings such as dyspnea, orthopnea, pulmonary rales, increased jugular venous pressure, and peripheral edema. Routine diagnostic evaluation for heart failure also includes measurement of brain natriuretic peptide (BNP) and other common laboratory measures, and a chest x-ray. A direct measure of ejection fraction by echocardiography, nuclear medicine imaging, or other imaging modalities is a crucial component of clinical evaluation for heart failure. Systolic dysfunction can be confirmed by echocardiography and/or other imaging modalities.

Optimization of CRT therapy is usually done using Doppler echocardiography. Optimization involves manipulation of the atrio-ventricular (AV) and interventricular (VV) pacer settings in order to maximize left ventricular (LV) filling and stroke volume. Some evidence has reported that optimization improves overall clinical benefit, but these data are not uniform. Also, the question of whether re-optimization should be performed following initial optimization is controversial, as is the timing of re-optimization if it is performed.

The Audicor™ system and electrodes received 510(k) marketing clearances from the U.S. Food and Drug Administration (FDA) for “use in acquiring, analyzing and reporting EGG and heart sounds (phonocardiograph) data and to provide interpretation of the data for consideration by physicians.”

A related medical policy is Biventricular Pacemakers for the Treatment of Heart Failure. 

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

07/17/2012: Policy reviewed; no changes.

Non-Covered Codes

This is not an all-inclusive list of non-covered procedure codes.

All codes billed for this procedure are considered investigational and not eligible for coverage. 

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