Small birth size linked to changes in the cardiovascular system that predispose to later disease

July 23, 2008

Researchers have found the first evidence that smaller size at birth is associated with specific alterations in the functioning of the heart and circulation in children and that these changes differ between boys and girls.

The research by Dr Alexander Jones and colleagues, published online in Europe's leading cardiology journal, the European Heart Journal [1] today (Wednesday 23 July), adds to the evidence that adverse environments experienced by the baby before birth and indicated by low birth weight, can cause long-term changes in the heart and blood vessels, leading to heart and blood vessel disease in later life. So far, the mechanisms involved have been poorly understood, and there has been little research into the alterations that might occur during childhood.

Dr Jones, who was a clinical research fellow at the Medical Research Council's Epidemiology Resource Centre at the University of Southampton and Southampton General Hospital, UK, at the time of the research (he is now a Clinician Scientist at the UCL Institute of Child Health, London), studied 140 children aged between eight and nine, while they underwent a psychosocial stress test. Growing evidence suggests that measures of the way the heart and blood vessels function during stress reveal individual characteristics associated with a greater risk of hypertension (high blood pressure) and disease of the heart and blood vessels.

The children had been healthy babies, born in a maternity hospital in Southampton, and were within the normal birth weight range (with an average of 3.56 kg for boys and 3.41 kg for girls). They were asked to perform a public-speaking task involving storytelling followed by mental arithmetic while the performance of their heart and circulation was recorded using electrical sensors.

Dr Jones said: "In boys, we found that the lower their birth weight was, within the normal range, the more likely they were to have a higher vascular resistance - the resistance to flow that has to be overcome to push blood around the circulatory system - and higher blood pressure, particularly 25-30 minutes after the start of the stress test. This probably represents a prolongation of the vascular stress response in these boys.

"In contrast, girls who were smaller at birth did not demonstrate a specific response to stress. They consistently (whether under stress or at rest) showed evidence of greater activity in the sympathetic nervous system - the part of the nervous system that controls involuntary actions and becomes more active during stress, contributing to the 'fight or flight' response.

"This is the first evidence in children of relationships between size at birth and the later function of the heart and blood vessels. The sex differences in these relationships were striking and may eventually lead to a better understanding of why men and women tend to develop high blood pressure and heart or vascular disease at different times in their lives. It suggests that different underlying mechanisms for developing the same disorder may exist in the two sexes but have the same eventual result."

While the changes in the children's responses to stress did not show that they had any early indications of disease, Dr Jones said: "We have strong reasons to believe that children with more exaggerated stress responses are more likely to become adults who develop hypertension and go on to develop heart or vascular disease earlier in life than those who do not demonstrate these greater responses."

A strength of the study was that it was carried out in young children before puberty when it was unlikely that any disease processes would have started that might alter the results - unlike the situation in adults. "Thus, we can be more confident that the differences we are finding represent the very early indicators of processes that underlie later disease," said Dr Jones.

"By highlighting these specific heart and circulatory changes in the developing child, we may, in the future, be able to develop interventions that target the origins of heart and circulatory diseases. These diseases are the world's biggest killers but their causes are still poorly understood and the vast majority of medical attention is given to their palliation once they have already occurred. I believe my studies and future studies will focus more on childhood in an effort to better understand the processes that lead to disease and to seek to reverse them before it is too late to do anything about it."

[1] Sex-specific programming of cardiovascular physiology in children. European Heart Journal. doi:10.1093/eurheartj/ehn292.

European Society of Cardiology

The Cardiovascular System at a Glance
by Philip I. Aaronson (Author), Jeremy P. T. Ward (Author)

This concise and accessible systems-based text provides an integrated overview which considers both the basic sciences and clinical applications of the cardiovascular system. A general introduction to the cardiovascular system is followed by anatomy and histology, blood and body fluids, biochemistry and excitation–contraction coupling, form and function, integration and regulation, and pathology and therapeutics. The Cardiovascular System at a Glance is a perfect introduction and revision aid to understanding the heart and circulation and now also features:

An extended section of self-assessment clinical cases to aid revision and illustrate clinical relevance
Up-to-date information on pharmacology of the cardiovascular system
Expanded material on history and examination...

The Cardiovascular System: Systems of the Body Series, 2e
by Alan Noble BSc PhD (Author), Robert Johnson BA BM MRCP (Author), Alan Thomas (Author), Paul Bass BSc MD FRCPath (Author)

This is an integrated textbook on the cardiovascular system, covering the anatomy, physiology and biochemistry of the system, all presented in a clinically relevant context appropriate for the first two years of the medical student course.One of the seven volumes in the Systems of the Body series.Concise text covers the core anatomy, physiology and biochemistry in an integrated manner as required by system- and problem-based medical courses.The basic science is presented in the clinical context in a way appropriate for the early part of the medical course.There is a linked website providing self-assessment material ideal for examination preparation.

Cardiovascular Physiology, Seventh Edition (LANGE Physiology Series)
by David Mohrman (Author), Lois Heller (Author)

The study guide that helps you to truly understand rather than merely memorize the essential principles of cardiovascular medicine The goal of this unique review is to give you a working understanding of the key concepts of cardiovascular physiology. Concise but thorough, Cardiovascular Physiology focuses on the facts you need to get a solid big picture overview of how the cardiovascular system operates under normal and abnormal situations. There is no faster or more effective way to learn how the key principles of cardiovascular function apply to common physiological and pathological challenges than this engagingly-written guide. Features:
Clarifies the details of physiologic mechanisms and their role in pathologic states Links cardiovascular physiology to...

The Amazing Circulatory System: How Does My Heart Work? (Slim Goodbody's Body Buddies)
by John Burstein (Author)

Cardiovascular Physiology Concepts
by Richard E Klabunde (Author)

Now in its second edition, this highly accessible monograph lays a foundation for understanding of the underlying concepts of normal cardiovascular function. Students of medicine and related disciplines welcome the book’s concise coverage as a practical partner or alternative to a more mechanistically oriented approach or an encyclopedic physiology text. A focus on well-established cardiovascular principles reflects recent, widely accepted research from the field.

The Body System Series: The Cardiovascular/Circulatory System and its Functions
by Alana Monet-Telfer

Body System Series: The Circulatory System and its Functions
Having Trouble with Biology? Need to find out information about the organ systems and how they work?
This book on the Cardiovascular/Circulatory system will help you to learn and understand about the organs of the Cardiovascular/Circulatory system and their functions. This book also provides the information on how the Cardiovascular/Circulatory system and Respiratory System work together to keep the body functioning. All of information in this eBook has been validated by my tutors; and has received the grade Distinction.

How the Circulatory System Works
by Robert E. Mehler (Author)

This book includes 10 lectures in a light, entertaining style, with each "lecture" building on the previous one - making it easy for the reader to comprehend the vastly complicated functions of the circulatory system. The length of the text has intentionally been kept short; it is neither exhaustively complete nor over-simplified. It is enriched by details about basic biologic mechanisms and clever ways nature has solved a problem or achieved a result.

Cardiovascular System (Crash Course)
by Paul Sutton (Author)

Part of the best-selling "Crash Course" series, this book focuses on the essential information students really need to know about the cardiovascular system. Comprehensive yet concise, it is more than just an exam crammer. Each component is considered in an integrated format, putting the basic sciences in clinical context. Highly illustrated with clear accessible text, it uses features such as hints and tips and clinical sketches to make the content easy to absorb and remember. An extensive self-assessment section allows the reader to test their knowledge and identify areas needing further study. Written by students for students, under faculty supervision, this new edition has been revised and updated throughout to reflect current curricula and exam formats.

First Aid for the Basic Sciences: Organ Systems, Second Edition (First Aid Series)
by Tao Le (Author), Kendall Krause (Author)

The essential companion for your first two years of medical school From Tao Le, author of First Aid for the USMLE Step 1 First Aid for the Basic Sciences: Organ Systems, 2e provides you with a solid understanding of the basic sciences relative to human organ systems with which all medical students must be familiar. The second edition has been completely revised to feature a more student-friendly and approachable text, an updated high-yield rapid review section, new images, and more. Delivers comprehensive single-source coverage of the entire second year of medical school Includes important background material most other reviews leave out Covers the high-yield topics and facts tested on the USMLE Offers full-color images, learning aids, tables, and concise text to streamline your study...

Epidemiology and Prevention of Cardiovascular Disease: A Global Challenge
by Darwin R. Labarthe (Author)

This book provides a comprehensive epidemiological perspective on cardiovascular diseases and analysis of measures for their prevention and control in community and clinical settings. Perfect for both students and practitioners, the second edition includes over 300 tables, figures, and exhibits; and has been thoroughly updated to reflect the most recent research in the field.