Encuestas aplicadas a los estudiantes modalidad presencial de la UTPL

Baseline trans-thoracic echocardiography was carried out on the same day that blood sample was drawn. Standard M-mode and 2D echocardiography were performed with patients in the left decubitus position using GE Healthcare Vivid q cardiovascular ultrasound system⁹⁵. A variable frequency phased-array transducer (3.5 – 5.0 MHz) was used. Two dimensional imaging examinations were performed in the standard fashion in parasternal long- and short-axis and apical four- and two-chamber views. Measurements were obtained according to the recommendations on M-mode standardization of the American Society of Echocardiography (ASE)⁹⁶. Measurements were taken in three cardiac cycles and the mean calculated.

DESCRIPTION OF THE VARIOUS ECHOCARDIOGRAPHIC MEASUREMENTS

Parasternal long axis view was obtained by placing the transducer in the third left intercostal space with the transducer mark turned towards the right shoulder. The transducer was moved up or down across one or two intercostal spaces and the angulation slightly adjusted to obtain a good view showing the two leaflets of the mitral valve, two of the aortic valve cusps and posterior border of the left ventricle. This view depicted the right ventricle (RV), interventricular septum (IVS), left ventricle (LV), left atrium (LA), left ventricular outflow tract (LVOT), mitral valve (MV), aortic valve (AV) and ascending aorta. The picture was frozen on the screen and Mmode measurements were done with the in-built calipers of the echocardiography machine.

M- mode at the level of mitral valve leaflet in the parasternal long axis view.

M-mode cursor was placed at the tip of the mitral leaflet, the beam passing through RV, IVS, and Left Ventricle. Using the leading edge to leading edge method according to recommendations of American Society of Echocardiographer (ASE) ⁹⁶ the following measurements were taken from the M-mode image-

1. Interventricular septal thickness at end diastole (IVSTd): measurement was done between the anterior-most edges of the right side and left side of the septum.

2. LV internal dimensions at end diastole (LVIDd): measurement was done between the anterior-most edges of the left side of septum and the posterior wall of left ventricle.

3. Posterior wall thickness at end diastole (LVPWTd): measurement was done between anterior-most edges of posterior wall of left ventricle and the pericardium.

4. Measurements were taken at the peak of posterior wall motion or nadir of septal wall motion using the leading edge method to obtain LV internal dimension at end systole (LVIDs), interventricular septal thickness at end systole, (IVSTs) and posterior wall thickness at end systole (LVPWTs).

The section of the M- mode in which the ventricle is largest, shortly before the walls began to move in was used to measure end- diastolic diameter. The left ventricular end-systolic dimension was measured from the peak downward motion of IVS to the leading edge of LVPW.

M- mode at the level of aortic valve leaflet in the parasternal long axis view.

M-mode cursor was positioned at the tip of the aortic valve through aorta and LA to obtain the following measurements:

1. Aortic Root Diameter (AOd): was measured at end-diastole, shortly before the aortic valve opens between the leading edges of the anterior and posterior aortic wall.

2. Left atrial size at end systole (LAD): was measured at end-ventricular systole when the aortic valve closes between the leading edges of the anterior and posterior atrial walls.

CALCULATION OF DERIVED VARIABLES

3.12.1 EVALUATION OF LEFT VENTRICULAR STRUCTURE

1. Relative wall thickness (RWT) was calculated using the formula⁹⁹.

RWT = 2 x LV end -diastolic posterior wall thickness Left ventricular diameter in diastole

Increased relative wall thickness was taken as RWT >0.42⁹⁹.

2. Left ventricular (LV) mass was calculated using the formula that has been shown to yield values closely related to autopsy LV weight, and which also has good inter study

reproducibility¹⁰⁰.

LVM = 0.8 [1.04 (IVSd + LVIDd + PWT d) ³ – LVIDd³)] + 0.6g

(Where LVM = Left Ventricular Mass; LVID = Left ventricular internal diameter; IVS = interventricular septum in diastole; PWT d = diastolic left ventricular posterior wall thickness).

All measurements were made at end- diastole.

LV hypertrophy was considered to be present when indexed LV mass exceeds 115g/m² in men and 95g/m² in women⁹⁷.

LV geometry was classified into the following⁹⁷:

Normal geometry: normal LVMI and RWT

Concentric remodeling: normal LVMI and RWT > 0.42

Eccentric LVH: increased LVMI and RWT ≤ 0.42

Concentric LVH: increased LVMI and RWT > 0.42

3.12.2 EVALUATION OF LEFT VENTRICULAR DIASTOLIC FUNCTION

Left ventricular diastolic function was assessed by pulsed-wave Doppler recording of the transmitral inflow. Two dimensional apical four-chamber view was obtained by placing the transducer at the 5^th intercostal space lateral and inferior to the apex, with the mark on the transducer pointing lateral. The apical four chamber view depicts the left ventricle, mitral valve, left atrium, right ventricle, tricuspid valve and right atrium⁵⁴. Transmitral peak velocities were recorded from the apical four chamber view during diastole by placing the cursor between the tips of the opened mitral valve leaflets, when they were maximally open. The cursor was placed as parallel as possible to the flow to obtain the maximum velocity during diastole.

The peak velocity of early rapid filling (E) was measured at the peak of the first waveform. The peak velocity of late filling caused by atrial contraction (A) was measured at the peak of second waveform. E/A ratio was calculated. Mitral deceleration time (DT) was measured as the time interval from the peak of the E-wave to the end of the E-wave. From apical four chamber view, the transducer at the apex was slightly rotated inward in order to get the apical five chamber view, showing all the four chambers, tricuspid valve, mitral valve and aortic valve. Isovolumic relaxation time (IVRT) was measured as the interval between the closure of aortic valve (end of left ventricular outflow) to the opening of mitral valve (beginning of transmitral blood flow) using the pulse wave mode with simultaneous visualization of both aortic and mitral flows¹⁰¹.

Diastolic function was categorized into grades using the table below:

Table 1: Grading of diastolic function¹⁰²

GRADE E/A DT(ms) IVRT(ms)

Normal 1 – 2 150 – 240 80 – 110

Impaired relaxation < 1 >240 >110 Pseudonormalization^* 1 – 2 150 – 240 80 – 110

Restrictive pattern >2 <150

*A reversal of pseudonormal to impaired relaxation pattern with valsava manoeuvre was used to differentiate normal diastolic function from pseudonormalised pattern of diastolic dysfunction.

E/A: ratio of mitral inflow early rapid peak velocity to late atrial peak velocity, DT: deceleration time; IVRT: isovolumic relaxation time.

Each parameter was measured in at least three cardiac cycles. The mean of the values were recorded for each parameter.

3.12.3 EVALUATION OF LEFT VENTRICULAR SYSTOLIC FUNCTION

Endocardial fractional shortening (FS) was calculated from LV internal dimensions in systole and diastole using the formula below⁹⁷:

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

LV ejection fraction (LVEF) was calculated using derived volumes by Teichholz formula⁹⁸ based on M- mode LV dimensions.

LV volume = 7/ (LVID + 2.4) X (LVID)³

This equation compensates for ventricles of abnormal size as against the cubed formula, but its accuracy is limited in patients with regional wall motion abnormality.

The criteria for depressed LV function was based upon FS < 29%, and EF < 50%⁶⁸

The patients being investigated are hypertensive patients therefore M- Mode is appropriate²⁹.

The grading for systolic function will be classified as follows⁶⁸. Systolic function EF (%)

Normal LV systolic function ≥ 50%

Mild LV systolic dysfunction 40 - 49% , Moderate LV systolic dysfunction 30 - 39%

Severe LV systolic dysfunction <30%