1 Introduction
2 Methods
2.1 Study population
Males (%) | 24 (75 %) | End diastolic volume | 154 ± 26.9 mL |
Age | 41.5 ± 12.5 years | End systolic volume | 58.1 ± 11.9 mL |
Weight | 83.3 ± 20.2 kg | Stroke volume | 96.1 ± 18.6 mL |
Body mass index | 26 ± 4.4 kg m−2
| Ejection fraction | 62.2 ± 4.6 % |
Body surface area | 2.02 ± 0.30 m2
| Cardiac output | 6.08 ± 1.3 L min−1
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Heart rate | 63.3 ± 7.6 beats min−1
| Cardiac index | 3.00 ± 0.41 L min−1 m−2
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2.2 Echocardiography protocol
2.3 MRI protocol
2.4 cMRI image analysis
2.5 Transbrachial electrical (bioimpedance) velocimetry (TBEV)
2.5.1 TBEV device
2.5.2 Assumptions of the method [15, 20, 21]
2.5.3 TBEV data collection protocol
2.5.4 TBEV signal processing
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VC = volume conductor (mL) = 32 × W1.02, where W = total body weight (kg)
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dZ/dtmax = peak time rate of change of the transbrachial impedance pulse variation (Ω s−2)
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Z0 = quasi-static transbrachial base impedance (Ω)
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TSF = systolic flow time (s) ≡ left ventricular ejection time (s)
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\(\sqrt {\frac{{dZ/dt_{\hbox{max} } }}{{Z_{0} }}}\) = ohmic mean velocity (s−1)
2.5.5 Statistical analysis
3 Results
3.1 Demographics and echocardiography
3.2 cMRI
3.3 TBEV
Pre-MRI session | Males (n = 21) | Females (n = 8) | ||
---|---|---|---|---|
Mean ± SD | Range | Mean ± SD | Range | |
Vc (mL) | 2929 ± 458 | 2144–4000 | 1914 ± 541 | 1571–3286 |
TSF (ms) | 321 ± 19.2 | 276–356 | 328.8 ± 25.3 | 296–388 |
dZ/dtmax (Ω s−2) | 0.97 ± 0.39 | 0.47–1.92 | 1.60 ± 0.41 | 1.03–2.46 |
Z0 (Ω) | 74.3 ± 11 | 49–96 | 86.6 ± 15.4 | 64.9–113.8 |
SV (mL) | 104.1 ± 16.3 | 75.9–143.8 | 83.8 ± 19.9 | 70.7–135.3 |
HR (BPM) | 67 ± 8 | 53–86 | 61 ± 7 | 55–71 |
CO (L min−1) | 6.9 ± 1.1 | 5.1–9.4 | 5.2 ± 1.7 | 3.9–9.7 |
Post-MRI session | Males (n = 22) | Females (n = 8) | ||
---|---|---|---|---|
Mean ± SD | Range | Mean ± SD | Range | |
Vc (mL) | 2935 ± 448 | 2144–4000 | 1914 ± 541 | 1571–3286 |
TSF (ms) | 318 ± 22.7 | 278–372 | 328 ± 32.3 | 288–384 |
dZ/dtmax (Ω s−2) | 0.89 ± 0.29 | 0.42–1.67 | 1.51 ± 0.52 | 0.86–2.65 |
Z0 (Ω) | 72.1 ± 14.2 | 41.8–100.0 | 90.0 ± 20.7 | 51.4–117.8 |
SV (mL) | 102.5 ± 18.4 | 55.8–138.2 | 80.0 ± 20.4 | 54.4–128.3 |
HR (BPM) | 67 ± 8 | 57–86 | 61 ± 7 | 50–72 |
CO (L min−1) | 6.8 ± 1.3 | 3.4–8.7 | 5.0 ± 1.7 | 3.6–8.9 |
3.4 Bland–Altman: mean bias, precision, and limits of agreement (LOA)
Mean bias (%) | Precision (%) | 95 % Limits of agreement | |||
---|---|---|---|---|---|
Upper (%) | Lower (%) | % Error | |||
TBEV SV-1 versus TBEV SV-2 | 2.87 | 13.59 | +29.51 | −23.77 | – |
TBEV SV versus cMRI SV | −1.56 | 13.47 | +24.85 | −27.97 | – |
TBEV CO versus cMRI CO | 5.01 | 12.85 | +30.20 | −20.17 | – |
Mean bias (mL) | Precision (mL) | 95 % Limits of agreement | |||
---|---|---|---|---|---|
Upper (mL) | Lower (mL) | % Error | |||
TBEV SV-1 versus TBEV SV-2 | 2.05 | 11.99 | +25.55 | −21.45 | – |
TBEV SV versus cMRI SV | −1.53 | 12.84 | +23.64 | −26.71 | 26.2 |
Mean bias (L min−1) | Precision (L min−1) | Upper (L min−1) | Lower (L min−1) | ||
---|---|---|---|---|---|
TBEV CO versus cMRI CO | 0.32 | 0.77 | +1.83 | −1.19 | 24.8 |
3.5 Linear regression analysis
TBEV and cMRI comparisons | Regression equation (y = mx + b) | Correlation coefficient (r2, r) |
---|---|---|
TBEV SV-1 versus TBEV SV-2 | y = 0.76x + 25.1 | r2 = 0.71, r = 0.84 |
Average TBEV SV versus cMRI SV | y = 0.82x + 19.1 | r2 = 0.61, r = 0.78 |
Average TBEV CO versus cMRI CO | y = 0.92x + 0.78 | r2 = 0.74, r = 0.86 |