21 Coronary artery disease and LV systolic function

Question 1

Why is the assessment of LV size and function challenging?

Answer 1

The volumetric measurements assume the LV shape is uniform and there are no RWMAs.

Question 2

When are end-systolic and end-diastolic measurements performed?

Answer 2

End-diastolic measurements are performed at the start of the QRS complex when the LV is biggest.

End-systolic measurements are performed at the end of the T wave when the LV is smallest.

Question 3

What are the BSE values for LV dimensions, volumes and masses?

Answer 3

…

Question 4

What are the BSE values for the assessment of LV hypertrophy?

Answer 4

…

Question 5

What are the 2 methods used to calculate LV volume?

Answer 5

The modified Simpson’s rule method and the area length method.

The modified Simpson’s rule method is based on dividing the LV into elliptical discs and adding the elliptical discs. For the modified Simpson’s rule method, in A4C and A2C, trace the LV endocardial border at end-diastole and end-systole.

The area length method uses the calculation: LV volume = (5 x area x length) / 6). For the area length method, in PSAX mid LV level, trace the LV endocardial border, and, in A4C, measure the LV length at end-diastole and end-systole.

Question 6

What is the calculation for LV mass?

Answer 6

Shell volume = total LV volume – LV cavity volume.

LV mass = myocardial shell volume x myocardial density (1.05g/ml).

LV mass (g) = {0.8 x [1.04 x ((LVIDd + LVPWd + IVSd)3 – (LVIDd)3)]} + 0.6

Question 7

What are the 2 methods used to calculate LV volume?

Answer 7

The modified Simpson’s rule method and the area length method.

The modified Simpson’s rule method: myocardial volume = total LV volume – LVEDV

Area length method: …

Question 8

What are the 7 methods used to assess LV systolic function?

Answer 8

Ejection fraction is the percentage of blood ejected from the LV with every beat.

Fractional shortening is the percentage change in the LV dimension between diastole and systole.

Cardiac output is the volume of blood the heart pumps in one minute.

Stroke distance is the average distance travelled by the blood during every beat.

Stroke volume is the volume of blood ejected into the aorta by the LV with every beat.

Rate of ventricular pressure rise during systole is fast.

The MV E point septal separation is the distance between the E point, or maximal anterior movement of the anterior MV leaflet, and the septum.

Question 9

What are the 7 calculations used to assess LV systolic function.

Answer 9

EF = ((LVEDV - LVESV) / LVEDV) x 100%.

FS= ((LVIDd - LVIDs) / LVIDd) x 100%.

CO = (SV x HR) / 100.

SD is measured.

SV = CSA LVOT x VTI LVOT.

dP/dt = 32 / dt.

EPSS is measured.

Question 10

What are the normal values for the 7 methods used to assess LV systolic function?

Answer 10

EF = >55%.

FS = 23-43%.

CO = 4-8L/min.

SD = 18-22cm.

SV = 60-100ml/beat.

dP/dt = >1200mmHg.

EPSS <6mm.

Question 11

What is the rate of ventricular pressure rise (dP/dt)?

Answer 11

The dP/dt is a measure of the speed at which the LV generates pressure during the isovolumic contraction phase of systole.

In LV systolic function, the dP/dt decreases because LV contractility decreases.

In A4C, use CWD to trace the MR. Use good alignment. Increase the sweep speed to max to make it easier to measure. Use the trace to mark the points where the velocity hits 1m/s and 3m/s. Measure the time (dt) between these two points in s. At 1m/s, the PG is 4mmHg, and, at 3m/s, the PG is 36mmHg. The change in pressure gradients (dP) is 32mmHg. Calculate the dP/dt in mmHg. dP/dt = 32 / dt. The longer the dt, the lower the dP/dt, the worse the LV systolic function.

Question 12

What is the MV E point separation (EPSS)?

Answer 12

The EPSS is the distance between the E point, or maximal anterior movement of the anterior MV leaflet, and the IVS. The EPSS is a measure of LV systolic function.

In LV systolic dysfunction, the EPSS increases because the LV dilates and the LV contractility decreases.

Question 13

What are the 3 methods used to assess LV longitudinal systolic function?

Answer 13

MAPSE is the movement of the mitral annulus towards the apex during systole.

The mitral annular TDI is the velocity of the myocardial tissue of the MV annulus. The S’ measures the velocity of the MV annulus moving towards the apex during systole.

GLS assesses longitudinal systolic and diastolic function and measures the percentage of deformation/strain of the myocardium during the cardiac cycle. GLS uses speckle tracking echocardiography tmyocardium.

Question 14

What are the normal values for the 3 methods used to assess LV longitudinal systolic function?

Answer 14

MAPSE >1.2.

TDI
20-40 >6.4
40-60 >5.7
>60 >4.9

GLS < -18%.

Question 15

What is post-systolic contraction?

Answer 15

The secondary or tertiary regional myocardial contraction occurring after end-systole after AV closure due to accessory pathways or slow conduction.

It is present in healthy patients and patients with ischemia. It is an indicator of ischemia and early myocardial dysfunction.

Question 16

What is isovolumic acceleration by TDI?

Answer 16

Isovolumic acceleration is the ratio of TDI derived peak myocardial velocity during isovolumic contraction divided by the acceleration time.

IA = MV / AT.

Isovolumetric contraction, at the start of systole, is when the LV contracts, which increases the LV pressure, but the LV volume stays the same, because the valves are closed.

Question 17

What is LV torsion?

Answer 17

LV torsion is the twisting motion of the LV along its long axis.

During systole (ejection), the energy is stored, and during diastole (recoil), the energy is released which allows LV diastolic relaxation and filling.

Question 18

How are the cardiotoxic effects, of cancer treatment, on LV systolic function, assessed?

Answer 18

The BSE recommends performing 2D volumes, 2D LVEF, 3D volumes, 3D LVEF, GLS and LV/RV assessment (LV S’, RVD, TR Vmax, RV S’, TAPSE).

The BSE recommends performing a baseline echo. If normal, performing surveillance echos every 3 months, and, if abnormal, refer to cardio-oncology. If there is no cardiotoxicity, continue with surveillance, and, if there is cardiotoxicity, refer to cardio-oncology. 3-12 months after finishing cancer therapy, perform an echo.

Cardiotoxicity is a decrease in LVEF of >10% to <50%. Probable subclinical cardiotoxicity is a decrease in LVEF of >10% to >50% with a decrease in GLS of >15%. Possible subclinical cardiotoxicity is a decrease in LVEF of <10% to >50% or a decrease in GLS of >15%.

Question 19

What are the symptoms and signs of HF?

Answer 19

HFpEF >50%
HFmrEF 40-50%
HFrEF <40%

NT-proBNP >400ng/L. NT-proBNP >2000ng/L.

The symptoms are dyspnoea, fatigue and ankle oedema. The signs are tachycardia, gallop rhythm, tachypnoea, elevated JVP, cardiomegaly, pulmonary congestion/oedema, peripheral oedema, ascites and hepatomegaly.

Question 20

In patients with ischemic heart disease, how are TDI and STE used to assess regional LV function at rest and with stress?

Answer 20

TDI measures myocardial velocity to assess longitudinal LV systolic function. STE assesses myocardial deformation, by measuring strain, to assess longitudinal, radial and circumferential LV systolic function.

In patients with ischemia, LV systolic function is normal at rest but decreased with stress.

In patients with infarction and a viable myocardium, LV systolic function is decreased at rest and improved with stress.

Question 21

What is the myocardial performance index (MPI) and how is it calculated?

Answer 21

MPI assess global systolic and diastolic function.

MPI = (IVCT+IVRT) / ET

The isovolumic contraction time (IVCT) is the time between the closure of the MV and the opening of the AV is the time in which the LV contracts but not ejects (early systole). Perform PWD of the MV/LVOT and measure the distance between MV inflow and LV outflow.

The isovolumic relaxation time (IVRT) is the time between the closure of the AV and the opening of the MV in which the LV relaxes but not fills (early diastole). Perform PWD of the MV/LVOT and measure the distance between LV outflow and MV inflow.

The ejection time (ET) is the time between AV opening and AV closing in which the LV ejects blood. Perform PWD of the MV/LVOT and measure the duration of LV outflow.

Question 22

What is a normal myocardial performance index (MPI) value and why does it increase in disease?

Answer 22

Normal MPI <0.4.

In systolic HF, the IVCT is increased because contractility is impaired. In diastolic HF, the IVRT is increased because the relaxation is impaired. The increased IVCT and IVRT decrease the ET. This causes the MPI to increase.