Licence: In copyright
Credit: Arterial hypertonus, sclerosis and blood-pressure. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
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![trophy; but it has l.)een wisely insisted i;pon by Broadbent and others that the very existence of hypertrophy implies that part of the reserve has already been drawn upon, and therefore that the hypertrophied heart has less reserYe.than the non-hypertrophied one. In practical medicine we can go further than this, for it is equally well known that the reserve of power is often very small, and may be almost absent. In some instances the response to a call for even a little extra work may be followed by an exhaustion so extreme as to_be fetal. The left heart, in such myocardial degenerations as cloudy j swelling, fragmentation, fatty degeneration, acute and chronic i interstitial carditis, not only possesses a low driving powei’, but any reserve it lias is of tlie most flimsy character. This is shown by the embarrassment caused by the slightest movement, in extreme cases ; by the disturbances of the cirmdation which accompany gastric digestion, or miy burden thrown upon, or any disturbance of, the alimentary tract. In the right heart not only do the changes just mentioned occur, but it is in addition the special site of fatty infiltration. This lowers the normal reserve of the right ventricle, so that any pulmonary difficulty or physical effort may suddenly over- whelm it. In the normal sound animal, including man, increased strain calls out the reserve, and increased work is done. Every clinician, h(jwever, knows tliat the strain, to he suc- cessfully endured, depends upon the condition of the individual heart. It is common enough to see persons who have over- taxed their hearts, in whom the strain has exceeded the reserve, with tlie result that dilatation occurs, and the heart is promptly placed on a lower energy level than it previously occupied. In the first half or so of life, the period of greatest physical activity, this over-strain is rarely immediately fatal; hu^in the second half of life the risk is greater, and as life advances the daimer becomes more ursmut. This elfect of age u])on the circulation is universally recognised ; hut wliile this is so it is im])ortant to em])hasi.se the fact tliat the myocardium dilfers greatly in individuals of the same age from youth onwards, d'his means, of course, that in ylhlerent persons, at the same period of life, the heart reserve varies within wide limits, so that the general projiosition that the](https://iiif.wellcomecollection.org/image/b28036591_0028.jp2/full/800%2C/0/default.jpg)
