Left Ventricular Aneurysm Vs Pseudoaneurysm

Both aneurysms and pseudoaneurysms occur post myocardial infarction. They can be differentiated from each other as follows - 

 

The neck is the junction between the normal part of the heart and the origin of with the aneurysm / pseudoaneurysm.

Evaluation of Mitral Stenosis - 2

The evaluation of mitral stenosis through echocardiography is not really very complicated. The primary view was that are involved in determining the mitral valve area and the severity of mitral stenosis of the parasternal long axis view, parasternal short axis view and through haemodynamic measurements.

In the parasternal long axis view, the anterior mitral valve leaflet assumes a hockey-stick shaped due to the thickening and restriction of the valve leaflets. This doming occurs because of elevated left atrial pressures in combination with a low diastolic pressure within the left ventricle. This appearance is quite classic and should never be missed.

In the parasternal short axis view, mitral valve planimetry can be performed at the level of the tips of the papillary muscles. The maximal area of mitral valve opening during diastole can be easily measured provided the views are clear. Excessive calcification can sometimes distort image quality.

The current recommendations suggest that a mitral valve area of < 1 cm² falls in the category of very severe mitral stenosis. This is often in combination with a diastolic pressure halftime of ≥ 220 ms. Associated with very severe mitral stenosis is left atrial enlargement and elevated pulmonary artery systolic pressure of >30 mmHg.

A mitral valve area of less than 1.5 cm² is severe mitral stenosis. Often, the diastolic pressure halftime would be >150 ms. There will be associated left atrial enlargement and elevated PASP as well.

Remember that you can also use the Wilkins classification when describing the mitral valve movement.

Doppler measurements are extremely useful when determining the mitral valve area. The pressure halftime is the most commonly used method that is derived from mitral valve haemodynamics. It basically describes the time that is required for the gradient between the left atrium and the left ventricle to reduced to one half of its initial value.

However, pressure halftime may not be accurate in the presence of conditions such aortic regurgitation where there is premature closure of the anterior mitral leaflet and alteration in the transmitral gradient.

Movement Of Mitral Valve On M-Mode

The mitral valve leaflets demonstrating a classic W and M pattern during atrial systole. The anterior mitral valve leaflet moves in and M shipped the manner while the posterior mitral leaflet moves in a W shipped the manner. The initial opening of the mitral valve occurs during left ventricular diastole and leads to the formation of the E point. 

Following this, there is a deceleration in velocity leading to the E-F slope. This is normally greater than 60 mm/second. 

At baseline, both the mitral valve leaflets almost reach a point of closure that coincides with the F point. This is followed closely by contraction of the atrium resulting in the A point.

At the time when the F point occurs, the left atrium passively allows blood to enter it through the pulmonary veins. This is called the conduit phase.

Flow Resistance

Flow resistance is calculated using the formula

Flow Resistance = 8 x length x viscosity / 𝚷 x Radius⁴. 

Given the inverse relationship to the radius, the flow resistance is most closely linked to the radius of the vessel.

Tissue Doppler Imaging Points

As the name suggests, tissue doppler imaging helps evaluate movement of tissues. It is useful in evaluating both systolic and diastolic function, though it is more often used to evaluate the latter. Optimal imaging is obtained at high frame rates.

As has been discussed in previous sections, E’ (or Ea) is a tissue doppler assessment of the early diastolic velocity of the mitral annulus is a good indicator of myocardial relaxation.

An E/e’ ratio of <10 is normal and is seen in impaired relaxation. However, an E/e’ ratio of >15 is indicative of a severe or fixed restriction. In addition, it is useful in assessing left ventricular filling pressures.

The main pointer that differentiates constrictive from restrictive physiology is mitral septal movement.

Mitral medial e' > 8cm/sec = Constrictive pericarditis
Mitral medial e' < 6cm/sec = Restrictive cardiomyopathy
Mitral medial e' between 6 - 8 cm = Mixed constriction and restriction

In athlete’s heart, the mitral valve annulus motion is normal as the myocardial function is normal, while this is not the case in the presence of heart disease (such as hypertrophic cardiomyopathy).

Uses of TDI

1. Assessing LV filling pressures
2. Differentiating constrictive pericarditis from restrictive cardiomyopathy
3. Differentiating athlete’s heart and hypertrophic cardiomyopathy
4. LV dyssynchrony assessment - measuring peak contraction times at different parts of the myocardium.
5. RV systolic assessment using Tricuspid Annular Plane Systolic Excursion (TAPSE) - Normal values >2cm.


References

1. Cardim N, Oliveira AG, Longo S, Ferreira T, Pereira A, Reis RP, Correia JM. Doppler tissue imaging: regional myocardial function in hypertrophic cardiomyopathy and in athlete’s heart. J Am Soc Echocardiogr. 2003; 16: 223–232.

2. Nagueh, Sherif F., et al. "Recommendations for the evaluation of left ventricular diastolic function by echocardiography: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging." European Journal of Echocardiography 17.12 (2016): 1321-1360.