Comparison of the 10-minute supine-30-minute tilt test with 24-hour ambulatory blood pressure for the diagnosis of diastolic systemic hypertension

Cerebro- and cardiovascular reactivity and neuropsychological performance in hypertensive patients

BACKGROUND

Hypertensive (HT) patients are at higher risk of cognitive decline than normotensive individuals, because high blood pressure is a risk factor for mild cognitive deterioration. In this study cardio- and cerebrovascular reactivity along with cognitive performance was assessed on newly diagnosed HT patients.

METHODS

Diagnosis of hypertension was based on international recommendations. None of the patients had diabetes, and all of them had normal cerebral CT scan. Eighty-one patients (43.5±10.2 years, male/female ratio: 42/39) were compared with 94 healthy controls (44±9.4 years, male/female ratio: 50/44). In both groups continuous, non-invasive and simultaneous monitoring of cerebral and cardiac hemodynamical parameters were recorded during head-up tilt table testing (HUTT). Reaction time, attention and memory skills, anxiety and depression rate were determined by neuropsychological tests.

RESULTS

During HUTT significant differences were found in certain cardiovascular parameters (blood pressure, total peripheral resistance index, stroke index), but no differences were detected in cerebral blood flow velocity. While there was no significant difference in reaction time between the two groups, tests estimating short-term memory (Digit Span Test) differed significantly. Moreover, sum of standardized test scores was significantly lower, while anxiety level was significantly increased in HT patients compared to controls.

CONCLUSION

Decrease in neuropsychological performance along with alterations of cardiovascular parameters is an early manifestation of hypertension. Aim for an early intervention and accurate treatment is crucial for preventing further impairments.

Assessment of cardiovascular reactivity by fractal and recurrence quantification analysis of heart rate and pulse transit time

Methods used for the assessment of cardiovascular reactivity are flawed by nonlinear dynamics of the cardiovascular responses to stimuli. In an attempt to address this issue, we utilized a short postural challenge, recorded beat-to-beat heart rate (HR) and pulse transit time (PTT), assessed the data by fractal and recurrence quantification analysis, and processed the obtained variables by multivariate statistics. A 10-min supine phase of the head-up tilt test was followed by recording 600 cardiac cycles on tilt, that is, 5-10 min. Three groups of patients were studied, each including 20 subjects matched for age and gender--healthy subjects, patients with essential hypertension (HT), and patients with chronic fatigue syndrome (CFS). The latter group was studied on account of the well-known dysautonomia of CFS patients, which served as contrast against the cardiovascular reactivity of the healthy population. A total of 52 variables of the HR and PTT were determined in each subject. The multivariate model identified the best predictors for the assessment of reactivity of healthy subjects vs CFS. Based on these predictors, the "Fractal & Recurrence Analysis-based Score" (FRAS) was calculated: FRAS=76.2+0.04*HR-supine-DET -12.9*HR-tilt-R/L -0.31*HR-tilt-s.d. -19.27*PTT-tilt-R/L -9.42*PTT-tilt-WAVE. The median values and IQR of FRAS in the groups were: healthy=-1.85 (IQR 1.89), hypertensives=+0.52 (IQR 5.78), and CFS=-24.2 (5.34) (HT vs healthy subjects: P=0.0036; HT vs CFS: P<0.0001). Since the FRAS differed significantly between the three groups, it appears likely that the FRAS may recognize phenotypes of cardiovascular reactivity.

The capnography head-up tilt test for evaluation of chronic fatigue syndrome

OBJECTIVES

To compare the hemodynamic and ventilatory responses to autonomic challenge evoked by upright tilt table testing in patients with chronic fatigue syndrome (CFS) to healthy individuals.

METHODS

Thirty-two consecutive patients with CFS and 32 healthy volunteers were evaluated with the aid of the recently introduced capnography head-up tilt test (CHUTT). The main outcome measures were values of blood pressure (BP), heart rate (HR), respiratory rate (RR), and end-tidal pressure of co2 (ETPco2) recorded during recumbence and tilt. In addition, the end points of vasodepressor and cardioinhibitory reactions, hyperventilation (defined by ETPco2 <25 mm Hg) and the postural tachycardia syndrome, were recorded.

RESULTS

The BP, HR, RR, and ETPco2 recorded during recumbence were similar in both groups. During tilt, patients with CFS developed significantly lower systolic BP, diastolic BP, and ETPco2, and a significant rise in HR and RR (P<.01). In CFS patients, the postural tachycardia syndrome occurred in 44%, vasodepressor reaction in 41%, cardioinhibitory reaction in 13%, and hyperventilation in 31% of cases. One or more end points of the CHUTT were reached in 78% of patients with CFS but in none of the controls (P<.0001).

CONCLUSIONS

In most patients with CFS, a spectrum of abnormal homeostatic reactions is diagnosed with the aid of the CHUTT. Data provided by the CHUTT may reinforce the clinical diagnosis by adding objective and unbiased criteria to the subjective assessment of CFS.