Diastolic Function Measurements in HFpEF
Heart failure with preserved ejection fraction (HFpEF) has no specific characteristic pattern of diastolic function. All the patterns described above apply to HFpEF, in particular the presence of LA enlargement. In addition, an E:A >1.5 in an elderly patient is highly suggestive of elevated filling pressures. The only difference is the disproportionately small volume of the LA with respect to the poor LV myocardial function in patients with amyloid heart disease, in whom the left atrium could be enlarged only to a small degree.
Diastolic Function in Fast Heart Rate
It is very important not to apply the absolute values of diastolic function parameters in patients with heart failure when presenting with tachycardia. Fast heart rate affects diastole before systole, hence all diastolic intervals and values are changed. Diastasis becomes minimal and the two filling components grow closer until they eventually merge and become one summation filling component. Therefore, the best way to assess diastolic function in this scenario is by correcting all time intervals to heart rate. An example of such a method is the assessment of total isovolumic time, which is the product of subtracting the sum of the filling time and ejection time from R-R interval and correcting it for heart rate. This gives a value in ms/s. It is simple and highly reproducible. It has also been shown to be very accurate in assessing the presence and severity of LV dyssynchrony in heart failure. Furthermore, the LV filling time can be measured and indexed to RR and normally it should not decrease by more than 40 % at peak exercise.
Diastolic Function and Ventricular Interaction
Ventricular interactions are known as a haemodynamic phenomenon from the studies by Bernheim.21 However, in primary RV disease, such as pressure overload (pre-capillary PH) or RV volume overload, the overload creates a septal shift as well as low LV filling volume. Commonly in both conditions a reduced LV E:A could be expected, and this has been shown to have a significant prognostic value.22