This article evaluates the suitability of low frequency (LF) heart rate variability (HRV) as an index of sympathetic cardiac control and the LF/high frequency (HF) ratio as an index of autonomic balance. It includes a comprehensive literature review and a reanalysis of some previous studies on autonomic cardiovascular regulation. The following sources of evidence are addressed: effects of manipulations affecting sympathetic and vagal activity on HRV, predictions of group differences in cardiac autonomic regulation from HRV, relationships between HRV and other cardiac parameters, and the theoretical and mathematical bases of the concept of autonomic balance. Available data challenge the interpretation of the LF and LF/HF ratio as indices of sympathetic cardiac control and autonomic balance, respectively, and suggest that the HRV power spectrum, including its LF component, is mainly determined by the parasympathetic system.

SUMMARY A method of determining baroreceptor reflex sensitivity is proposed that is based on spectral analysis of systolic pressure values and RR interval times, namely, the modulus (or gain) in the mid frequency band (0.07-0.14 Hz) between these two signals. Results using this method were highly correlated (0.94; n = 8) with results of the phenylephrine method. In addition, compared with the values for the preceding rest period, the modulus decreased during mental challenge, as might be expected from the literature. (Hypertension 10: 538-543, 1987) KEY WORDS modulus baroreceptor reflex sensitivity • spectral analysis • phenylephrine B ARORECEPTOR reflex sensitivity (BRS) is assessed by either the neck suction method 1 or the traditional pharmacological method.2 ' 3 In the latter technique a pressor agent (usually phenylephrine) that does not affect heart rate directly is administered as an intravenous bolus injection. The ensuing rise in blood pressure causes a baroreceptormediated slowing of heart rate. The successive systolic pressure values are correlated with the length of the next RR interval. The regression coefficient of the correlation diagram gives the BRS in milliseconds of interval prolongation per millimeter of mercury pressure rise (Figure 1).Variability of blood pressure and RR interval time can be expressed by its standard deviation. However, this measure does not give any information about the source of the fluctuations. In this respect, spectral analysis is more informative, as has been shown for the analysis of heart rate variability 4 ' 5 and for the relaFrom the Institute for Experimental Psychology (H.

The VR-CoDES CC may be used to help clinicians in recognizing or facilitating cues and concerns, thereby improving the recognition of patients' emotional distress, the therapeutic alliance and quality of care for these patients.

Research employing the VR-CoDES-P should be applied to develop research-based approaches to maximize appropriate responses to patients' indirect and overt expressions of emotional needs.

Patient-centered communication skills such as those presented in this intervention study can be taught. The ability to gain medical information and the readiness to communicate about aspects of medical treatment seem to improve with more professional experience; however, they also profit from the intervention.

Our data provide empirical evidence of separable peripheral and central sympathetic response components. The combined report of low-frequency BPV and PEP gives distinct information on both central SNS control and the level of sympathetic cardiac activation achieved.

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Coronary artery disease (CAD) as well as depression are both highly prevalent diseases. Both cause a significant decrease in quality of life for the patient and impose a significant economic burden on society. There are several factors that seem to link depression with the development of CAD and with a worse outcome in patients with established CAD: worse adherence to prescribed medication and life style modifications in depressive patients, as well as higher rates in abnormal platelet function, endothelial dysfunction and lowered heart rate variability. The evidence is growing that depression per se is an independent risk factor for cardiac events in a patient population without known CAD and also in patients with established diagnosis of CAD, particularly after myocardial infarction. Treatment of depression has been shown to improve patients' quality of life. However, it did not improve cardiovascular prognosis in depressed patients even though there is open discussion about the trend to better outcome in treated patients. Large scale clinical trials are needed to answer this question. Selective serotonin reuptake inhibitors seem to be preferable to tricyclic antidepressants for treatment of depressive patients with comorbid CAD because of their good tolerability and absence of significant cardiovascular side effects. Hypericum perforatum (St. John's wort), an increasingly used herbal antidepressant drug should be used with caution due to severe and possibly dangerous interaction with cardioactive drugs.