Wednesday, July 30, 2014

Variation Analysis of Sphygmogram to Assess Cardiovascular System Under Meditation

Chuan-Yi Liu, Ching-Chuan Wei, Pei-Chen Lo

Evid Based Complement Alternat Med. 2009;6(1):107-112.

http://www.medscape.com/viewarticle/704717

Abstract and Introduction

Abstract

In this article, we studied how meditation affects the characteristicsof the cardiovascular system, mainly based on blood pressurewaveforms (BPW). Four parameters derived from BPW include therising slope (h 1/t 1), normalized height of T wave (h 3/h 1), normalizedheight of V 3 valley (h 4/h 1) and normalized height of D wave(h 5/h 1), where t 1 and hi , i = 1, ... ,5 are quantitative featuresof the BPW waveform pattern. A larger value of h 1/t 1 reflectsbetter heart ejection ability and aorta compliance. A largervalue of h 3/h 1 may infer an arterial system with good elasticity.The decrease (increase) of h 4/h 1 parameter indicates the decrease(increase) of peripheral resistance of vessels. A larger valueof h 5/h 1 indicates better artery elasticity and aortic valvefunction. In comparison with the control group, Zen-meditationpractitioners have more after-meditation h 1/t 1, h 3/h 1 and h 5/h 1increase, with more h 4/h 1 decrease, with statistical significance(P < 0.05). The observation allows us to infer that Zen meditationmay effectively improve relevant characteristics of the cardiovascularsystem.

Introduction

The blood pressure waveform (BPW) of the systemic arterial treeis an important determinative of cardiovascular system performance.This signal originates in the systole and diastole of the heartand conveys such information as blood ejection ability of theheart, elasticity of the artery wall and peripheral resistance,etc.[1]. In examinations of the clinical value of BPW, Hanexplored possible biophysical and pathologic mechanisms of BPWfrom the viewpoint of hemodynamics[2]. Research showed thatBPW analysis is a highly reproducible method and easy to applyto clinical studies. This measure provides important informationabout arterial stiffness and cardio-vascular interactions[3-4].Abnormality in the BPW is linked to various physiologic or pathologicstates such as aging and hypertension[5-6]. Actually, the BPWof the radial artery detected at the wrist is the sphygmographicsignal used in Traditional Chinese Medicine (TCM)[7]. Accordingto theory of the sphygmographic signal, the TCM clinician canidentify the status of the human body and treat the patient.
As more clinical evidence supported the benefits of meditationfor health, about fifty years ago researchers began investigatingthe physiologic phenomena of the human body under meditation.Dillbeck et al. [8] compared the physiologic differences intwo groups of subjects, one under transcendental meditationand the other at rest. Some research found that the training of transcendental meditation could significantly lower the systolic and diastolic blood pressure of hypertensive persons[9-12].Meditation hereafter became a feasible method to improve hypertension.Hankey,[13] compared Tibetan Buddhist meditation with Transcendental Meditation. He summarized how practicing different meditation techniques influenced hypertension and other physiologic changes.Barnes et al. [14] found that, under meditation, total peripheral resistance decreased and they suggested that was why meditation could decrease or control hypertension. To assess how meditation affects the cardiovascular system, this paper presents a quantitative approach to evaluate variations in BPW before and after meditation sessions.
We measured the blood pressure waveforms of twenty Zen-meditation participants and twenty normal, healthy subjects in the same age range as the participants. According to the clinical experience of TCM professionals, we designed a set of parameters that quantify the waveform patterns of BPW.
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... More details at http://www.medscape.com/viewarticle/704717
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Discussion

Why does meditation improve the cardiovascular system? It is possible that in meditation, the meditator devotes attention to breathing, thus reducing dispersive thoughts, brain activity,muscle stress and the influence of the sympathetic system on blood vessels. Consequently, the artery wall becomes more relaxed and elastic. In other words, the blood flow encounters less peripheral resistance and can be more easily transported into organ, tissue, cell, etc. With such a high-efficiency blood transporting system, human health improves.
Recently, complementary and alternative medicine has sparked researchers to investigate their scientific evidence. No doubt,meditation plays an important role in these corresponding fields.Here we report the immediate effect of Zen meditation on cardiovascular characteristics, with a control group containing the same number of normal, healthy subjects of a similar age range. We analyzed the immediate variations because of the difficulty of controlling open-system experimental conditions for human subjects.
In modern society, cardiovascular related diseases have become a dominant cause of death for a long time. Meditation provides an alternative mode of health care for conditions that are challenging conventional treatment. At the same time, scientists are urged to develop a scientific approach to the underlying mechanism and how it affects the human life system. More scientific and clinical evidence may inject innovative ideas into mainstream medicine and popular health care practices. According to preliminary results analyzing BPWs, Zen meditation is more effective in improving cardiovascular characteristics than normal relaxation.

References

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Acknowledgments
The invaluable assistance of the Taiwan Zen-Buddhist Associationis greatly appreciated. This work has been supported in partby the National Science Council of Taiwan (grant NSC 94-2213-E009-136).
Reprint Address Pei-Chen Lo, Department of Electrical and Control Engineering, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan, R.O.C. Tel: 886-3-573-1667; Fax: 886-3-571-5998; E-mail: pclo@faculty.nctu.edu.tw
Evid Based Complement Alternat Med. 2009;6(1):107-112. © 2009  Oxford University Press
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