Relation between apexcardiogram andchanges inleft ventricular pressureanddimension

wasstudied in12normal subjects and64patients with heart disease. In12patients, theapexcardiogram wasdelayed with respect tosimultaneous left ventricular pressure by17±18 ms during theupstroke and28±16msduring thedownstroke. Inthenormal subjects, changes inleft ventricular dimension during theupstroke anddownstroke oftheapexcardiogram weresmall, amounting to6±5and21± 7percenttotal excursion, respectively. In10patients with mitral regurgitation, there wassignificant inward wall movementduring theupstroke andin10patients with aortic regurgitation, significant outward movementduring thedownstroke, bothreflecting valvular regurgitation. In20patients withischaemic heart disease andsegmental abnormalities onleft ventricular angiography, apexcardiogramechodimension relations wereabnormal inall, because ofinward oroutward wall movementduring the upstroke, increased outward movementbefore the'O'point, orabnormal inward movementduring thedownstroke. These disturbances weredisplayed byconstructing apexcardiogram-echo dimension loops, which appeartobea sensitive meansofdetecting incoordinate left ventricular contraction, analogous tothose between pressure anddimension. A limitation intheuseofM-modeechocardiography instudying left ventricular function isthat wallmovementisrecorded fromonlyalocalized region ofcavity, sothatitisnotpossible totell whether achange indimension results fromfilling orejection ontheonehand, orfromanisovolumic shape change ontheother. Thevalue ofthetechnique would, therefore, beincreased ifinformation weresimultaneously available allowing this distinction tobemade,andincoordinate contraction and relaxation detected andquantified. We havepreviously shownthatthese abnormalities mayleadto characteristic alterations inthetimerelations between left ventricular dimensions measured by echocardiography andleftventricular pressure (Gibson andBrown,1976), particularly whena pressure-dimension loopisconstructed. In the present study, wehaveexplored thepossibility of substituting theapexcardiogram forthepressure pulse inorder toobtain thesameinformation noninvasively. We have,therefore, investigated the timerelations between thevarious phases ofthe Received forpublication 21July1976. 'Present address: Clinica MedicaII,Universitt diPavia, Pavia, Italy. apexcardiogram andthecorresponding phases of thehigh-fidelity left ventricular pressure pulse and oftheleftventricular dimension measured by echocardiography. Subjects