Non-invasive Measurement of Cardiovascular Response

The title of this chapter is wide-ranging and to cover all aspects implicit in the title would require a book of its own. Consequently, this chapter needs to be restrictive—in particular, when it comes to interpreting the words ‘cardiovascular response’. Just one area of the cardiovascular system will be considered, namely cardiac function (i.e. assessments of the heart function). Response will be restricted to the effects of drugs on this cardiovascular parameter at rest and during the stress of exercise. Further, the term ‘non-invasive technique’, while clearly understood by research workers, particularly those involved with assessing the effects of drugs on cardiac function, does lack a clear definition, which is needed when writing a chapter such as this. A working definition could be: non-invasive techniques, when applied to studies involving measurements of cardiac function (invariably left ventricular function), are those which do not employ methods of direct entry into the circulation such as occurs when measuring cardiovascular parameters from cardiac catheterisation. Such techniques, therefore, will be made from the ‘surface’ of the body and will not involve the breaking of the skin (other than perhaps to inject a marker into the circulation for subsequent noninvasive measurements, e.g. as radionuclide methods for assessing cardiac output).