Two-dimensional speckle-tracking echocardiographic assessment of left ventricular mechanical synchrony in clinically normal cats

Figures & data

Figure 1 Measurement of circumferential and radial strain and strain rate.

Notes: An example of six segments of the left ventricle for measurement of circumferential and radial strain and strain rate using two-dimensional speckle-tracking echocardiography obtained from the right parasternal short axis view at the level of the papillary muscle (A). The software algorithm semiautomatically divides the left ventricular short axis view into six myocardial segments within the inter-ventricular septum and the free wall (B): anteroseptal, anterior, lateral, posterior, inferior, and septal (C).

Figure 2 Measurement of longitudinal strain and strain rate.

Notes: An example of six segments of the left ventricle for measurement of longitudinal strain and strain rate using two-dimensional speckle-tracking echocardiography obtained from the left parasternal apical four-chamber view (A). The software algorithm semiautomatically divides the left ventricular long-axis view into six myocardial segments within the inter-ventricular septum and the free wall (B). basal septal, mid septal, apical septal, apical lateral, mid lateral, and basal lateral (C).

Figure 3 An example of six segments of the left ventricle for measurement of segmental heterogeneity in the circumferential direction using two-dimensional speckle-tracking echocardiography obtained from the right parasternal short-axis view at the level of the papillary muscle.

Notes: The software algorithm semiautomatically divides the left ventricular short axis view into six myocardial segments within the inter-ventricular septum and the free wall: anteroseptal, anterior, lateral, posterior, inferior, and septal. For this cardiac cycle, the range for these six segments to reach the peak strain was 9.09%.

Figure 4 An example of six segments of the left ventricle for measurement of intra-ventricular mechanical synchrony in the longitudinal direction using two-dimensional speckle-tracking echocardiography obtained from the left parasternal apical four-chamber view.

Notes: The software algorithm semiautomatically divides the left ventricular long-axis view into six myocardial segments within the inter-ventricular septum and the free wall: basal septal, mid septal, apical septal, apical lateral, mid lateral, and basal lateral. For this cardiac cycle, the range of time for all of these six segments to reach peak strain was 24 ms. The standard deviation for all six segments to reach peak strain can be calculated accordingly for the intra-ventricular mechanical synchrony in the longitudinal direction.

Table 1 The descriptive statistics of two-dimensional and M-mode echocardiographic parameters of 34 clinically healthy cats

Parameter	Value, mean ± SD
Two-dimensional indices
IVSd (mm)	4.08±0.61
LVFWd (mm)	4.17±0.65
LVDd (mm)	14.98±1.63
LVDs (mm)	6.81±1.58
LA/Ao	1.35±0.16
M-mode indices
EPSS (mm)	0.43±0.25
IVS% (%)	69.66±17.84
LVFW% (%)	63.19±15.24
FS (%)	54.74±8.01
Pulse-wave Doppler indices
MEVp (m/s)	0.82±0.14
MAVp (m/s)	0.68±0.16
ME/A	1.25±0.27
TEVp (m/s)	0.65±0.15
TAVp (m/s)	0.52±0.14
TE/A	1.29±0.27
IVRT (ms)	44.17±7.42
Tei index	0.51±0.09
QP-Ao (ms)	−3.90±13.22

Abbreviations: EF_M, ejection fraction derived from M-mode; EPSS, E point to septal separation; ESVI, end systolic volume index; FS, fractional shortening; IVRT, isovolumic relaxation time; IVS%, percentage thickening of the inter-ventricular septum; IVSd, inter-ventricular septum thickness in end-diastole; LA/Ao, the ratio of left atrium and aortic diameter; LVDd, left ventricular dimension in end-diastole; LVDs, left ventricular dimension in end-systole; LVFW%, percentage thickening of the left ventricular free wall; LVFWd, left ventricular free wall thickness in end-diastole; M_E/A, early and late mitral inflow ratio; MAVp, peak late mitral inflow velocity; MEVp, peak early mitral inflow velocity; Q_P-Ao, difference between pulmonary pre-ejection time and aortic pre-ejection time; T_E/A, early and late tricuspid inflow ratio; TAVp, peak late tricuspid inflow velocity; Tei index, myocardial performance index; TEVp, peak early tricuspid inflow velocity.

Table 2 Segmental and global circumferential, radial, and longitudinal strain and strain rate values determined using two-dimensional speckle-tracking echocardiography of the left ventricle in 34 clinically healthy cats

CS (%)		CSR (s^−1)		CSR−E (s^−1)		CSR−A (s^−1)
CS1	−21.87±6.69	CSR1	−2.60±0.78	CSR−E1	2.71±1.33	CSR−A1	0.99±0.38
CS2	−21.83±6.40	CSR	−2.73±0.97	CSR−E2	2.33±1.09	CSR−A2	0.99±0.23
CS3	−21.82±5.97	CSR3	−2.77±0.95	CSR−E3	2.35±1.00	CSR−A3	1.13±0.51
CS4	−21.98±7.81	CSR4	−2.75±1.21	CSR−E4	2.22±1.41	CSR−A4	1.15±0.74
CS5	−21.90±8.52	CSR5	−2.73±1.17	CSR−E5	2.33±1.39	CSR−A5	1.33±0.63
CS6	−23.03±7.15	CSR6	−2.61±0.87	CSR−E6	2.53±0.91	CSR−A6	1.21±0.48
CSg	−22.26±5.01	CSR	−2.7±0.72	CSR−Eg	2.39±0.81	CSR−Ag	1.16±0.32
	P=0.997		P=0.996		P=0.920		P=0.536
RS (%)		RSR (s^−1)		RSR−E (s^−1)		RSR−A (s^−1)
RS1	26.32±11.64	RSR1	2.40±0.82	RSR−E1	−2.18±1.59	RSR−A1	−1.62±0.93
RS2	25.50±13.58	RSR2	2.38±1.02	RSR−E2	−2.09±1.20	RSR−A2	−1.55±0.82
RS3	27.12±12.76	RSR3	2.46±0.95	RSR−E3	−2.28±1.06	RSR−A3	−1.69±0.93
2RS4	27.38±10.36	RSR4	2.43±0.84	RSR−E4	−1.89±1.01	RSR−A4	−1.70±0.90
RS5	28.68±10.04	RSR5	2.67±1.00	RSR−E5	−1.92±1.26	RSR−A5	−1.80±0.88
RS6	29.46±12.71	RSR6	2.74±1.00	RSR−E6	−2.06±1.56	RSR−A6	−1.92±1.10
RSg	26.08±8.18	RSRg	2.51±0.71	RSR−Eg	−1.99±1.12	RSR−Ag	−1.82±0.85
	P=0.913		P=0.793		P=0.980		P=0.930
LS (%)		LSR (s^−1)		LSR−E (s^−1)		LSR−A (s^−1)
LS1	−18.69±4.92	LSR1	−2.23±0.70	LSR−E1	1.88±0.81	LSR−A1	1.55±0.98
LS2	−18.85±4.46	LSR2	−2.33±0.59	LSR−E2	1.89±0.65	LSR−A2	1.45±0.45
LS3	−15.36±6.30	LSR3	−1.87±0.84**	LSR−E3	1.55±0.81	LSR−A3	0.92±0.52
LS4	−13.67±5.37*	LSR4	−1.63±0.66*	LSR−E4	1.29±0.82	LSR−A4	0.93±0.55
LS5	−19.84±8.00	LSR5	−2.42±1.00	LSR−E5	1.78±1.12	LSR−A5	1.28±0.94
LS6	−22.93±10.80	LSR6	−2.80±1.24	LSR−E6	1.80±1.37	LSR−A6	1.42±1.16
LSg	−18.22±4.78	LSRg	−2.21±0.58	LSR−Eg	1.52±0.73	LSR−Ag	1.21±0.57
	P<0.001		P<0.001		P=0.664		P=0.393

Notes: Data presented as mean ± SD.

* LS₄/LSR₄ was significantly different from LS/LSR_1,2,5,6,g (P<0.05).

** LSR₃ was significantly different from LS₆ (P<0.05) in post hoc pairwise comparison by Games–Howell.

Abbreviations: C₁, anterio-septal; C₂, anterior; C₃, lateral; C₄, posterior; C₅, inferior; C₆, septal; C_g, global; CS, peak circumferential strain; CSR, peak circumferential strain rate; CSR_−A, peak circumferential late diastolic strain rate; CSR_−E, peak circumferential early diastolic strain rate; L₁, basal septa; L₂, mid septal; L₃, apical septal; L₄, apical lateral; L₅, mid lateral; L₆, basal lateral; L_g, global; LS, peak longitudinal strain; LSR, peak longitudinal strain rate; LSR_−A, peak longitudinal late diastolic strain rate; LSR_−E, peak longitudinal early diastolic strain rate; R₁, anterio-septal; R₂, anterior; R₃, lateral; R₄, posterior; R₅, inferior; R₆, septal; R_g, global; RS, peak radial strain; RSR, peak radial strain rate; RSR_−A, peak radial late diastolic strain rate; RSR_−E, peak radial early diastolic strain rate.

Table 3 Echocardiographic parameters of left ventricular heterogeneity and synchrony in 34 clinically healthy cats

Segmental heterogeneity (%)
Circumference		Radiation		Longitude
SH-cε	13.05±5.86	SH-rε	19.06±10.34	SH-lε	15.38±6.81
Transmural heterogeneity (%)
TH-cε	−14.28±4.60
Intra-ventricular synchrony (ms)
Circumference		Radiation		Longitude
RT-cε	32.49±9.32	RT-rε	40.21±28.72	RT-lε	44.24±22.62
SDT-cε	11.74±4.16	SDT-rε	16.48±13.41	SDT-lε	19.38±8.52
Inter-ventricular synchrony (ms)
QP-Ao	−3.9±13.22

Note: Data presented as mean ± SD.

Abbreviations: Q_P-Ao, difference between pulmonary pre-ejection time and aortic pre-ejection time; RT-cε, range of the six segment time to peak circumferential strain; RT-lε, range of the six segment time to peak longitudinal strain; RT-rε, range of the six segment time to peak radial strain; SDT-cε, standard deviation of the six segment time to peak circumferential strain; SDT-lε, standard deviation of the six segment time to peak longitudinal strain; SDT-rε, standard deviation of the six segment time to peak radial strain; SH-cε, circumferential segmental heterogeneity; SH-lε, longitudinal segmental heterogeneity; SH-rε, radial segmental heterogeneity; TH-cε, circumferential transmural heterogeneity.

Table 4 The intra-observer CV values derived from the parameters measured using two-dimensional speckle-tracking echocardiography

	Intra-observer CV (%)		Intra-observer CV (%)		Intra-observer CV (%)
CSg	6.43	RSg	10.24	LSg	4.56
CSRg	5.92	RSRg	14.91	LSRg	9.16
CSR−Eg	12.37	RSR−Eg	9.55	LSR−Eg	18.08
CSR−Ag	18.58	RSR−Ag	25.39	LSR−Ag	12.26

Abbreviations: CSg, global peak circumferential strain; CSR_−Ag, global peak circumferential late diastolic strain rate; CSR_−Eg, global peak circumferential early diastolic strain rate; CSRg, global peak circumferential systolic strain rate; CV, coefficient of variance; LSg, global peak longitudinal strain; LSR_−Ag, global peak longitudinal late diastolic strain rate; LSR_−Eg, global peak longitudinal early diastolic strain rate; LSRg, global peak longitudinal systolic strain rate; RSg, global peak radial strain; RSR_−Ag, global peak radial late diastolic strain rate; RSR_−Eg, global peak radial early diastolic strain rate; RSRg, global peak radial systolic strain rate.