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Cardiac Function

Analyze Heart Rhythm

The CardioSleeve stethoscope attachment records  High-Fidelity 3- Lead ECG tracings with a digital caliper to be viewed and analyzed on a connected device.

Identify Heart Failure

CardioSleeve's advanced cutting-edge technology detects heart failure at any point of care.

 

 

 

Acoustic Cardiography

CardioSleeve represents the most significant advancement in the development of the modern stethoscope to date. For the first time, the integration of an already proven exciting, new, easy-to-use, modernized cutting edge technology of Acoustic Cardiography has been added to the hallmark of the physician.

 

What is Acoustic Cardiography?   

 

The technique incorporates simultaneous acquisition and quantitative measurements of combined ECG and cardiac acoustical data. This permits acquisition of detailed information regarding systolic and diastolic left ventricular function and provides both a computerized interpretation and a visual display of the findings. 

 

The system identifies and quantifies normal and abnormal heart sounds, which are related to the left ventricle, and determines the timing of those heart sounds in every cardiac cycle versus the onset of the P wave and QRS complexes in the simultaneously recorded ECG. It produces a variety of measurements including the presence and strength of heart sounds (such as the S3 and S4) and the duration of systolic time intervals.

Relationship between ECG and heart sounds. The panel represents a schematic of the key landmarks of the ECG and heart sound recordings in the cardiac cycle and the main acoustic cardiographic parameters.

The panel represents a schematic of the relationships among the ECG, the aortic, left ventricular and left atrial pressures, the traditional systolic time intervals and several acoustic cardiographic parameters for a normal and systolic heart failure subject. A comparison of the right and left panels shows that with systolic heart failure, both the LVST (Left ventricular systolic time) and EMAT (Electromechanical activation time) are prolonged. (Paul Erne Division of Cardiology, Kantonsspital Luzern, Lucerne, Switzerland SWISS MED WKLY 20 08; 138(31–32):439–452)

The technology uses sophisticated signal processing techniques to evaluate the heart sound data. The raw sound data undergoes a time-frequency analysis, which allows not only the separation of heart sounds from murmurs and artifacts, but also the separation of left and right-sided events.

 

Time-Frequency Analysis of Heart Sounds

The figure presents a schematic of a single heart beat showing a simultaneous ECG and sound recording in the time domain (upper two traces) as well as the wavelet filter based time-frequency representation of the heart sound recording (scalogram). Abbreviations: P – ECG P wave; Q – ECG Q wave; T – ECG T wave; S1 – First heart sound; M – Mitral component; T – Tricuspid component; S2 – Second heart sound; A – Aortic component; P – Pulmonary component; S3 –Third heart sound; S4 – Fourth heart sound.

Acoustic cardiography records a variety of parameters that assess both systolic and diastolic left ventricular function.

Systolic Parameters:

  • Electromechanical Activation Time (EMAT) – the interval in milliseconds from the onset of the QRS to the point of peak intensity of S1. It measures the amount of time that the left ventricle requires to generate sufficient force to close the mitral valve. EMAT is prolonged in systolic heart failure.
  • LV systolic time (LVST) - the interval in milliseconds measured from S1 to S2. The interval is reduced in patients with LV dysfunction.

 

Diastolic Parameters:

  • S3 Strength – the S3 energy is expressed on a scale of intensity from 0 to 10. If the intensity is >5.0, an S3 is considered to be present. S4 Strength – the S4 energy is expressed on a scale of intensity from 0 to 10. If the intensity is >5.0, an S4 is considered to be present.
  • The S3 is often present in systolic dysfunction, especially when the left ventricular filling pressure is elevated. The S4 is often detected in patients with diminished left ventricular compliance (e.g. in acute myocardial infarction and ischemia).

 

The recorded measurements have been found comparable with both cardiac catheterization and echocardiographically determined hemodynamic parameters. In particular, the comparison of acoustic cardiography parameters obtained during left heart catheterization studies have shown that: 1) S3 strength correlates well with the absolute value of the LV end-diastolic pressure (LVDP); 2) a prolonged EMAT is associated with reduced LV maximum contractility; and 3) reduced LVST values correlate to reduced LV ejection fraction (LVEF) in patients with systolic dysfunction. The reliable detection of S3 and the ratio EMAT/LVST correlate with echocardiographic evidence of LV dysfunction.

 

INTERPRETING ACOUSTIC CARDIOGRAPHY

 

Third Heart Sound

S3 Strength is expressed on a scale of intensity from 0 to 10. If the intensity is >5.0, an S3 is considered to be present. In conditions such as severe mitral regurgitation or pregnancy, an S3 is not necessarily linked to LV dysfunction.

S3 detected, (if S3 >=5.0) consider:

 
  • Indicates reduced systolic function with elevated Left Ventricular end-diastolic pressure (LVEDP)
  • Suggests acute heart failure in the presence of dyspnea
  • Risk marker in the presence of chest pain
  • Use of BNP plus S3 improves diagnostic accuracy for HF and LV dysfunction
  • Lowers patient prognosis

 

Fourth Heart Sound

S4 Strength is expressed on a scale of intensity from 0 to 10. If the intensity is >5.0, an S4 is considered to be present.

S4 detected, (if S4>=5.0) consider:

 
  • Indicates increased LV stiffness and elevated LVEDP
  • Reduced diastolic function
  • Risk marker in the presence of chest pain

 

EMAT

The electromechanical activation time (EMAT) is the time from the onset of the Q wave on the ECG to the closure of the mitral valve within the S1 heart sound. Percent EMAT (%EMAT) is computed as EMAT divided by the dominant RR interval, and it relates to the efficiency of the pump function.

EMAT (> 120ms) consider:

 
  • Indicates reduced systolic function
  • Correlates with LV dP/dt max (LV contractility)
  • %EMAT>15% predicts re-hospitalization for heart failure at and post discharge
  • Shortened EMAT correlates with improved LV function, increased contractility and short electro-mechanical delays

 

SDI

Systolic Dysfunction Index (SDI), a multiplicative combination of ECG and sound parameters has been shown to predict LV systolic dysfunction with high specificity. The multiplicative score SDI is derived from QRS duration, QR interval, %EMAT and S3 strength. SDI is reported as a value of 0-10.

SDI (> 5.0) consider:

 
  • Indicates degree of systolic function
  • SDI >=5 indicates systolic dysfunction (EF<50%)
  • SDI >7.5 indicates elevated filling pressure (EF<35%)
  • Diastolic and severe LV systolic function (if SDI >=7.5)
  • Chronic and acute thresholds at 5.0 and 7.5

 

Benefits of Acoustic Cardiography

The ease of use and low cost of Acoustic Cardiography makes it useful for the evaluation and monitoring of patients with known or suspected heart disease in a variety of clinical settings.

   

 

Heart Failure

The third heart sound S3 helps with the early identification of Heart Failure and its presence in these patients has significant prognostic and economic implications. Heart sounds captured by acoustic cardiograms have proven to assist clinicians in assessing dyspneic patients in the emergency department or office by utilizing strong specificity of an S3 for detecting acute decompensated heart failure. It gives instant results as compared to BNP laboratory analysis (which may take few hours) and also helps resolve a significant amount of the indeterminate BNP values.

   

 

Misdiagnosis Correction

Patients with sufficiently subtle or complicated heart failure are often misdiagnosed as Pneumonia and COPD. An S3 is highly specific and useful in diagnosing acute decompensated heart failure in subjects who had no prior history of heart failure, had a history of COPD, had a prior EF > 40% and an indeterminate BNP of <500 pg/ml.

   

 

Chemotherapy

Acoustic Cardiography can detect changes in hemodynamic status and follow patients who are receiving cardiotoxic chemotherapeutic agents such as doxorubicin and other anthracycline derivatives, which at present involve repetitive echocardiographic studies.

   

 

Mass Screening

The ease of use and low cost of acoustic cardiography makes it highly practical for mass screening large populations of patients i.e. screening for early detection of rheumatic heart disease in areas where the disease is endemic (e.g. Africa and Southeast Asia).

   

 

Sports Screening

In developed countries, idiopathic hypertrophic subaortic stenosis remains the most common cause of non-traumatic sudden death in young people. By readily providing simultaneous ECG and heart sound data, it is useful in screening young people for this disease (e.g. prior to their participation in strenuous sports).

   

 

Cardiac Arrhythmia

The ECG alone is sometimes unreliable in the differential diagnosis of wide complex tachycardia. The availability of heart sound data can be important. The low intensity and beat-to-beat variation of S1 in ventricular tachycardia helps distinguish it from supraventricular tachycardia with aberrant intra-ventricular conduction.

   

 

Cardiac Resynchronization Therapy

By using the EMAT parameter the AV delay setting of a biventricular pacemaker can be optimized. The method is faster, easy-to-use and far more cost-effective than echocardiographic evaluation.