RV systolic function

Measurement of tricuspid annular plane systolic excursion (TAPSE)

To obtain the systolic excursion of the right ventricular (RV) annular segment along its longitudinal plane, start from the standard apical four-chamber view. Place an M-mode cursor at the tricuspid lateral annulus and measure the peak excursion of the annulus's longitudinal motion during systole.

A TAPSE measurement of less than 17 mm indicates right ventricular (RV) systolic dysfunction.

It shows a good correlation with Right Ventricular Ejection Fraction (RVEF) assessed by radionuclide angiography.
The method is simple, widely available, and reproducible.

However, there are some limitations to consider:
The function is angle-dependent.
It does not capture the complex motion of the entire right ventricle (RV).
It ignores the contribution of outlet and septal motion to overall RV ejection function.
Additionally, it is load-dependent, making it less accurate for representing RV systolic function in cases of tricuspid regurgitation.

Right Ventricular Fractional Area Change

Right ventricular fractional area change (RVFAC) is defined as follows: (RV end-diastolic area - RV end-systolic area) / RV end-diastolic area.

An RVFAC of less than 35% indicates RV systolic dysfunction.

RVFAC is independent of the geometric assumptions used to assess right ventricular function. It has demonstrated prognostic significance in patients with myocardial infarction, pulmonary embolism, and pulmonary hypertension (PH).

To obtain RVFAC, one must use the apical four-chamber view and trace the endocardium of the right ventricle (RV) during both systole and diastole, starting from the annulus. It is crucial to ensure that the entire RV, including the apex and the RV free wall, is visible in the imaging during both phases. Care should be taken to accurately trace the free wall beneath any trabeculations.

RVFAC is best correlated with ejection fraction (EF) derived from cardiac magnetic resonance (CMR) imaging. Accurately tracing the endocardial borders of the RV during systole and diastole is essential for measuring RVFAC correctly.

Myocardial systolic velocity (S')

Tissue Doppler Imaging (TDI) enables the quantitative assessment of right ventricular (RV) systolic and diastolic function by measuring myocardial velocities.

Myocardial systolic velocity (S'), obtained via pulsed TDI, is a reliable indicator of RV function, with a cut-off value of less than 9.5 cm/s indicating abnormal function. The pulsed TDI sample is positioned at the tricuspid lateral annulus or the basal segment of the RV free wall in the apical four-chamber view.

An S' value below 9.5 cm/s has demonstrated high sensitivity and specificity for detecting RV dysfunction, particularly in patients with pulmonary arterial hypertension (PAH). This assessment method is also relevant in conditions like chronic obstructive pulmonary disease, scleroderma, obstructive sleep apnea syndrome, and RV myocardial infarction.

While pulsed tissue Doppler is simple and reproducible, it is angle-dependent and can be affected by overall cardiac motion and the tethering of adjacent segments, assuming that the function of a single segment reflects the entire RV function.

TEI index

Pulsed Doppler method

TCO

TCO time is measured using either pulsed Doppler of the tricuspid inflow or continuous Doppler of the tricuspid regurgitation (TR) jet.

The ejection time is the duration from the onset to the cessation of the S' wave.

Tissue Doppler method

TCO

IVCT

IVRT

pulsed TDI sample is positioned at the tricuspid lateral annulus

The Myocardial Performance Index (MPI), also known as the RIMP or Tei index, is defined as the ratio of the sum of isovolumic contraction time (IVCT) and isovolumic relaxation time (IVRT) divided by ejection time (ET). This can be expressed with the formula: [(IVRT + IVCT) / ET] or [(TCO - ET) / ET]. There are two methods to obtain the MPI.

The abnormality thresholds for MPI are as follows:

- More than 0.43 when using the pulsed Doppler method (normal value: 0.26 ± 0.085).

- More than 0.54 when using the tissue Doppler method (normal value: 0.38 ± 0.08).

Pulsed Doppler Method:

- The ejection time is derived from the pulsed Doppler of the right ventricular (RV) outflow, while the isovolumic intervals are determined based on tricuspid flow.

- The tricuspid closure-opening (TCO) time is measured using either pulsed Doppler of the tricuspid inflow or continuous Doppler of the tricuspid regurgitation (TR) jet.

Tissue Doppler Method:

- The MPI can be measured from a single beat by pulsing the tricuspid annulus.

- The ejection time is the duration from the onset to the cessation of the S' wave.

- The TCO time is measured from the end of the A' wave to the beginning of the E' wave.

The MPI has been shown to be a predictor of poor prognosis in conditions associated with pulmonary arterial hypertension (PAH). One significant advantage of the MPI is that it is independent of loading conditions, heart rate, and geometric assumptions, making it a reproducible parameter of right ventricular global performance. However, the MPI may be unreliable in patients with varying R-R intervals, such as in atrial fibrillation.

RIMP = (IVRT + IVCT)/ET = (TCO-ET)/ET

TCO

Result

References

Anastasiadis, Kyriakos; Westaby, Stephen; Antonitsis, Polychronis. The Failing Right Heart (p. 130). Springer International Publishing. Kindle Edition.