Mayer wave activity in vasodepressor carotid sinus hypersensitivity

Mayer waves are low frequency blood pressure waves, whose modulation involves central/peripheral baroreflex pathways. Although vasodepressor carotid sinus hypersensitivity (VDCSH) is a common hypotensive disorder in ageing, the mechanism of VDCSH is unknown. We hypothesize that VDCSH is due to impaired baroreflex function and that Mayer wave amplitude and oscillation frequency are therefore altered.

Ten minutes ECG and continuous beat-to-beat blood pressure (TNO Finapres(c)) recordings were taken in supine position. Blood pressure variance, spectral power (0.04-0.15 Hz) and centre of frequency was examined across a number of frequency bands. Vasodepressor carotid sinus hypersensitivity was defined as 50 mmHg drop in systolic blood pressure (SBP) during carotid sinus massage. Syncope facility was used in this study. Twelve patients with VDCSH median age 72 range (50-92) were compared with 36 case-controls median age 78 range (48-88). Diastolic blood pressure variability (median SD) was significantly higher in the VDCSH 6.6 (1.9-12.9) mmHg compared with controls 4.0 (1.7-9.5) mmHg; P < 0.05. Mean arterial blood pressure (MAP) variability (median SD) was significantly higher in the VDCSH 6.6 (2.9-10.1) mmHg compared with controls 4.6 (2.5-9.1) mmHg; P < 0.05. Low frequency Mayer wave activity in MAP in VDCSH compared with controls was increased at 0.06 Hz [controls -21.7 mmHg(2)/Hz (IQR: 30.8); VDCSH -31.5 mmHg(2)/Hz (IQR: 72.0) P < 0.05] and at 0.1 Hz [controls -4.9 mmHg(2)/Hz (IQR: 9.4); VDCSH -11.5 mmHg(2)/Hz (IQR: 12.9) P < 0.1]. High frequency blood pressure fluctuations were significantly increased at 0.3 Hz in VDCSH group in SBP [controls -4.1 mmHg(2)/Hz (IQR: 10.4); VDCSH -17.4 mmHg(2)/Hz (IQR: 47.9) P < 0.05] and MAP records [controls -32.5 mmHg(2)/Hz (IQR: 76.9); VDCSH -64.6 mmHg(2)/Hz (IQR: 59.8) P < 0.01].

Blood pressure variability in particular activity at Mayer wave frequencies was higher in VDCSH. Future work will investigate this approach as a basis for diagnosis of VDCSH, with implications for syncope and falls management.