ECG Voltage in Relation to Peripheral and Central Ambulatory Blood Pressure

Abstract

Background: The heart ejects in the central elastic arteries. No previous study in workers described the diurnal profile of central blood pressure (BP) or addressed the question whether electrocardiogram (ECG) indexes are more closely associated with central than peripheral BP.

Methods: In 177 men (mean age, 29.1 years), we compared the associations of ECG indexes with brachial and central ambulatory BP, measured over 24 hours by the validated oscillometric Mobil-O-Graph 24h PWA monitor.

Results: From wakefulness to sleep, as documented by diaries, systolic/diastolic BP decreased by 11.7/13.1 mm Hg peripherally and 9.3/13.6 mm Hg centrally, whereas central pulse pressure (PP) increased by 4.3 mm Hg (P < 0.0001). Over 24 hours and the awake and asleep periods, the peripheral-minus-central differences in systolic/diastolic BPs averaged 11.8/-1.6, 12.7/-1.8, and 10.3/-1.2 mm Hg, respectively (P < 0.0001). Cornell voltage and index averaged 1.18 mV and 114.8 mV·ms. Per 1-SD increment in systolic/diastolic BP, the Cornell voltages were 0.104/0.086 mV and 0.082/0.105 mV higher in relation to brachial 24-hour and asleep BP and 0.088/0.90 mV and 0.087/0.107 mV higher in relation to central BP. The corresponding estimates for the Cornell indexes were 9.6/8.6 and 8.2/10.5 mV·ms peripherally and 8.6/8.9 and 8.8/10.7 mV·ms centrally. The regression slopes (P ≥ 0.067) and correlation coefficients (P ≥ 0.088) were similar for brachial and central BP. Associations of ECG measurements with awake BP and PP were not significant.

Conclusions: Peripheral and central BPs run in parallel throughout the day and are similarly associated with the Cornell voltage and index.

Keywords: ECG voltage; ambulatory blood pressure; blood pressure; blood pressure monitoring; central blood pressure; clinical science; hypertension.

Figure 1.

Diurnal profiles in 177 study participants of central systolic pressure (a), central diastolic pressure (b), central pulse pressure (c), and heart rate (d). Plotted values are 2 hourly mean with 95% confidence interval. P values are for the comparison between awake and asleep averages.

Figure 2.

The Cornell voltage (a) and index (b) plotted against peripheral and central systolic 24-hour blood pressure (SBP). The data markers are averages by sixths of the distributions of ECG indexes. The lines are the slopes of the ECG indexes on peripheral and central SBP averaged by sixths of the distributions of the ECG indexes. P_peripheral and P_central indicate the corresponding significance levels. P_difference is the significance of the difference between the slopes for peripheral and central SBP. Abbreviation: BP, blood pressure; ECG, electrocardiogram; SBP, systolic blood pressure.

Figure 3.

Correlations of Cornell voltage (a) and index (b) with 24-hour and asleep systolic and diastolic pressures. Data markers and whiskers represent the point estimates of the correlation coefficients and their 95% confidence interval, respectively. P values derived by the Hotelling–William test denote the significance of the pairwise comparison of peripheral (open symbols) vs. central (closed symbols) blood pressure. Abbreviation: BP, blood pressure.