Heart failure is the fastest growing cardiovascular disorder in First World countries, and the only one increasing in incidence and prevalence1. Largely a disease of the elderly, heart failure is the leading cause of hospital admissions and readmission in Americans over 65 years of age¹.

Heart failure is characterised by ventricular dysfunction – the inability of the heart to pump blood to meet the requirements of the metabolising tissues or the ability to do so only in the presence of elevated end-diastolic volumes and/or pressures². There are two types of ventricular dysfunction: systolic and diastolic.
 

Systolic Heart Failure

Systolic dysfunction is characterised by impairment of myocardial contractility, leading to decreased stroke volume. In the case of systolic dysfunction, there is inadequate ventricular emptying and eventual ventricular dilation.

The principal abnormality of diastolic dysfunction is impaired relaxation of the ventricle and increased resistance to ventricular filling². Increased aortic stiffness is the likely cause of diastolic dysfunction, resulting in reduced exercise tolerance and diastolic heart failure⁵. Prevention of diastolic heart failure can be achieved through better control of hypertension and other cardiovascular risk factors³. Data from the Framingham study showed that 91% of patients that developed heart failure had previous hypertension, characterised by gross elevation in pulse pressure as a result of arterial stiffening¹.

The SphygmoCor System provides measures of aortic and systemic arterial stiffness, demonstrating the clinical impact of arterial stiffness on the heart. These measures allow effective management of hypertension, and early identification of diastolic dysfunction. This early identification enables intervention before progression to diastolic heart failure.
 

Diastolic Heart Failure

Diastolic heart failure refers to the clinical syndrome of heart failure with a preserved left ventricular ejection fraction (>0.50) in the absence of major valve disease³. Delayed relaxation and increased stiffness impair the ability of the heart to fill during diastole, especially when heart rate increases. This is worsened by any ischaemia¹.

Diastolic heart failure is an early event that is more common than previously thought, particularly in type 2 diabetes, accounting for about a third of heart failure patients^3,4.

As systolic and diastolic heart failure require different treatment strategies, it is necessary to distinguish between them². Clinical characteristics alone are unable to reliably do this³. The SphygmoCor System enables differentiation of these conditions through the analysis of the cardiac cycle timing. Diastolic dysfunction is typically characterised by delayed LV relaxation, but there is prolongation of systole as well, such that the total systolic time is usually increased⁵. This provides a practical measure to identify predominantly diastolic heart failure and separate this from systolic heart failure because in the latter, total systolic time is typically decreased⁵.

Mechanisms contributing to abnormal left ventricular diastolic properties include stiff large arteries, hypertension, ischaemia, diabetes, and intrinsic myocardial changes with or without associated hypertrophy³. Increased aortic stiffness leads to an increase in aortic and LV systolic pressure, increased myocardial oxygen demands and LV hypertrophy, and decreased aortic pressure throughout diastole with compromised coronary perfusion⁵. Analysis of the aortic waveform with the SphygmoCor System provides clinical measures of left ventricular load, coronary artery perfusion pressure, and central pressures. As treatment is typically aimed at the relief of acute symptoms, and enhancement of exercise tolerance^3,4, the SphygmoCor System now provides physician’s with hard clinical measurements to document the therapeutic regime implemented.
 

References

1. Macdonald PS, O’Rourke MF. Cardiovascular ageing and heart failure. Medical Journal of Australia (1998) 169:480-484.
2. Liew D, Krum H. Diastolic heart failure in the elderly. Medicine Today (2002) Vol 3, 11:44-50.
3. Vasan R. Diastolic heart failure. British Medical Journal (2003) 327: 1181-1182.
4. Brutsaert DL, Stanislas U. Diastolic dysfunction in heart failure. Journal of Cardiac Failure (1997) Vol 3, 3:225-243.
5. O’Rourke MF. Diastolic heart failure, diastolic left ventricular dysfunction and exercise intolerance. Journal of the American College of Cardiology (2001) Vol 38, 3:803-805.
6. Poirier P, Marois L, et al. Diastolic dysfunction in normotensive men with well-controlled type 2 diabetes. Diabetes Care (2001) Vol 24, 1:5-10.

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