A text-book of physiology, for medical students and physicians . hould be borne in mind that the cardiograph curveis partly a pressure curve and partly a volume curve,—that is, thechanges in volume as well as the changes in pressure of the heartduring systole will affect the instrument. The Intraventricular Pressure During Systole.—The bestanalyses of the details of the systole of the ventricle have been madeby a study of the changes in pressure within the ventricle. Forthis purpose a tube filled with liquid is introduced into the cavity ofthe ventricle. A tube used for such a purpose is desig
A text-book of physiology, for medical students and physicians . hould be borne in mind that the cardiograph curveis partly a pressure curve and partly a volume curve,—that is, thechanges in volume as well as the changes in pressure of the heartduring systole will affect the instrument. The Intraventricular Pressure During Systole.—The bestanalyses of the details of the systole of the ventricle have been madeby a study of the changes in pressure within the ventricle. Forthis purpose a tube filled with liquid is introduced into the cavity ofthe ventricle. A tube used for such a purpose is designated as aheart-sound. For the right ventricle it is introduced through anopening in the jugular vein and pushed down until it lies in theventricle. For the left ventricle it is introduced by way of thecarotid or subclavian artery and in this case is forced through theopening guarded by the semilunar valves. The sound is thenconnected to a suitable recording apparatus by rigid tubing filledwith liquid. The changes in pressure in the ventricle are extensive. Fig. 221.—Two cardiograms from the same individual to show characteristic records: a,Beginning f systole; k-c, systolic plateau.—(AfterMarey.) and very rapid. To register them accurately the recording instru-ment must respond with great promptness and at the same timemust be free from inertia movements. A mercury manometer, forinstance, would be entirely useless For such a purpose, since theheavy mass of mercury could not follow accurately the quick changesin pressure. The recording manometer devised by Hurthle () seems to have met the requirements more satisfactorily than other of the numerous instruments described. A typical curveobtained by means of the Hurthle manometer is given in Fig. 222, V.(Consull also the classical curve obtained byChauveaii .and Mareyfrom the hear! of the horse [Tig. 217].) [twill be seen that the ure in the bearl rises suddenly with the beginning of the ven-tricular contraction and a
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