1.6 PERIPHERAL AND CENTRAL AMBULATORY BLOOD PRESSURE IN RELATION TO ECG VOLTAGE

Abstract

Background: The heart ejects in the central elastic arteries. No previous study addressed the question whether ECG voltages are more closely associated with central than with peripheral blood pressure (BP). Methods: Using the oscillometric Mobil-O-Graph 24 h PWA monitor, we measured brachial, central BP and central hemodynamics over 24 hours in 177 men (mean age, 29.1 years), and linked to ECG voltages. Results: From wakefulness to sleep, as documented by diaries, systolic/diastolic BP decreased by 11.7/13.1 mmHg peripherally and by 9.3/13.6 mmHg centrally, whereas pulse pressure (PP) increased by 4.3 mmHg. Over 24 hours and the awake and asleep periods, the peripheral-minus-central differences in systolic/diastolic BPs and pulse pressure averaged 11.8/–1.6, 12.7/–1.8 and 10.3/–1.2 mmHg and 13.4, 14.4 and 11.5 mmHg, respectively (P < 0.0001). Cornel voltage and index averaged 1.18 mV and 114.8 mV×ms. The Cornell voltages were 0.104/0.086 and 0.082/0.105 mV higher in relation to brachial 24-h and asleep systolic/diastolic BP (per 1-SD), respectively, and 0.088/0.90 mV and 0.087/0.107 mV higher in relation to central BP. The corresponding estimates for the Cornel indexes were 9.6/8.6 and 8.2/105 mV×ms peripherally and 8.6/8.9 and 8.8/10.7 mV×ms centrally. The regression slopes were similar for brachial and central BP (P≥0.054). Associations of the ECG measurements with awake BP, PP, the augmentation ratio and pressure amplification did not reach significance. Cornell voltage (SV3 + RaVL, mV) Cornell index (Cornell voltage × QRS duration, mV·ms) Peripheral BP Central BP Peripheral BP Central BP Estimate (95% CI) P Estimate (95% CI) P Estimate (95% CI) P Estimate (95% CI) P Systolic BP 24-h 0.104 (0.016 to 0.191) 0.021 0.088 (0.0003 to 0.177) 0.049 9.61 (0.65 to 18.57) 0.036 8.58 (−0.40 to 17.56) 0.061 Awake 0.086 (−0.001 to 0.175) 0.054 0.062 (−0.026 to 0.151) 0.17 7.69 (−1.30 to 16.69) 0.093 5.80 (−3.23 to 14.82) 0.21 Asleep 0.082 (−0.006 to 0.170) 0.068 0.087 (−0.001 to 0.175) 0.053 8.17 (−0.82 to 17.16) 0.075 8.76 (−0.217 to 17.74) 0.056 Diastolic BP 24-h 0.086 (−0.002 to 0.174) 0.056 0.090 (0.002 to 0.178) 0.045 8.57 (−0.41 to 17.55) 0.061 8.93 (−0.04 to 17.90) 0.051 Awake 0.056 (−0.032 to 0.145) 0.21 0.060 (−0.029 to 0.149) 0.18 5.62 (−3.42 to 14.65) 0.22 5.97 (−3.06 to 15.00) 0.19 Asleep BP 0.105 (0.017 to 0.192) 0.020 0.107 (0.019 to 0.194) 0.017 10.53 (1.60 to 19.47) 0.021 10.71 (1.78 to 19.64) 0.019 Pulse pressure 24-h 0.040 (−0.049 to 0.129) 0.38 0.016 (−0.073 to 0.105) 0.72 3.07 (−5.99 to 12.13) 0.50 1.31 (−7.76 to 10.38) 0.77 Awake 0.048 (−0.041 to 0.137) 0.29 0.012 (−0.077 to 0.101) 0.78 3.63 (−5.43 to 12.68) 0.43 0.68 (−8.40 to 9.74) 0.88 Asleep 0.001 (−0.091 to 0.088) 0.98 0.001 (−0.087 to 0.090) 0.98 −0.29 (−9.37 to 8.78) 0.95 0.21 (−8.86 to 9.28) 0.96 ECG refers to electrocardiography. BP stands for blood pressure. Cornell voltage is the voltage sum of S wave in precordial V3 lead (SV3) and R wave in limb aVL lead (ReVL), while Cornell index is the product of QRS duration multiplied by the Cornell voltage. The estimate (95% Confidence Interval, CI) of the association was unadjusted and expressed as 1-SD increase of BP. P value is for significance of the estimate. The association estimates of Cornell voltage (P ≥ 0.054) and index (P ≥ 0.079) with central BP were not significantly different from those estimates with peripheral measurements. TableAssociation of ECG Cornell voltage and indexes with peripheral and central BP. Conclusions: The diurnal rhythm of peripheral and central BP run in parallel. Central BP does not improve the association of Cornell voltage or index with peripheral BP.