Mrs. K is exhibiting the signs and symptoms of heart failure.  Heart failure can be caused by left ventricular dysfunction or right ventricular dysfunction.  According to Ramani & Weber (2017), the S3 sound is the commonly known as the third heart sound.  The S3 sound commonly occurs when there is a volume overload in the circulatory system or when there is a ventricular dysfunction.  The S3 sound occurs when the rapid filling of the ventricle ends abruptly.  However, it is unclear as to where the sound originates from.  There are thoughts that the sound may be related to vibrations in the valve cusps or related to tautening of the cardiac muscles.  Auscultation of an S3 heart sound is difficult to hear and often goes unnoticed if heart failure is not being assessed as a possibility.  Auscultation of the heart sound will be heard best in different locations dependent on where the S3 sound originates from.  Ramani & Weber (2017) point out that an S3 sound in the left ventricle would be best heard with the patient in the left lateral decubitus position, in held end expiration, and with the bell of the stethoscope.  When an S3 sound is originating in the right ventricle, the sound would be best heard along the left lower sternal border and the sound would be louder during inspiration.  Some causes of ventricular dysfunction may include ischemia, cardiomyopathy, myocarditis, and cor pulmonale.  The S3 sound is a key factor in the diagnosis of congestive heart failure (Ramani & Weber, 2017).  
            In addition to the S3 heart sound, Mrs. K is exhibiting many other symptoms that are common findings in the assessment of a patient with heart failure.  Symptoms of heart failure may include pulmonary rales, extremity edema, dyspnea, orthopnea, and systemic edema.  According to Long et al. (2019), the most common symptoms associated with acute heart failure include paroxysmal nocturnal dyspnea, orthopnea, and edema.  This is caused from elevated filling pressures of the left ventricle of the heart.  In addition, Mrs. K is exhibiting inspiratory crackles due to the likelihood of pulmonary edema secondary to congestive heart failure.  Because of Mrs. Ks history of myocardial infarction and coronary artery bypass surgery, this may present as a major reason of her congestive heart failure that may have been steadily progressing.  Risk factors for heart failure include uncontrolled hypertension, renal disease, heart disease, diabetes, dysrhythmias, and cardiac ischemia.  Long et al. (2019) outlined the proper diagnostic techniques of heart failure in an emergency room setting.  This includes the auscultation of clients cardiac rhythm and pulmonary assessment.  It also includes laboratory testing to include a complete blood count, basic metabolic panel, a BNP level, troponin, renal function testing, and liver function testing.  A decreased glomerular filtration rate was associated with increased length in hospital stay and mortality rates.  An electrocardiogram and x-ray imaging was also recommended in the diagnosis of heart failure (Long et al., 2019).
References
Long, B., Koyfman, A., & Gottlieb, M. (2019). Diagnosis of acute heart failure in the emergency 
            department: An evidence-based review. The Western Journal of Emergency Medicine,
            20(6), 875-884. https://doi.org/10.5811/westjem.2019.9.43732
Ramani, S., & Weber, B.N. (2017). Detecting the gallop: the third heart sound and its
            significance. Medical Journal of Australia, 206(5), 198-199. 
            https://doi-org.wilkes.idm.oclc.org/10.5694/mja16.00613