Disordered left ventricular contraction associated with abnormalities of conduction: an echocardiographic study

A PATIENT withcardiomyopathy often presents with evidence ofheart failure intheabsence ofapparent underlying cause. Thisclinical picture usually results fromdisease oftheheart muscle itself, butthepossibility exists thatitmight alsobeduetoimpairment oftheaction ofstructurally andfunctionally normal myocardium byinco-ordinated ventricular contraction. Thedevelopment ofechocardiography has provided a non-invasive methodofstudying left ventricular contraction, allowing frequent records to bemaderapidly andpainlessly without hazard tothe patient. Thepattern ofcontraction ischaracterized fromrecords showing echoes fromtheinterventricular septum andposterior wallinaregion just belowthemitral valve. Thenormalposition and movement ofthese twostructures areshowninFig. 1. During ventricular systole thedominant movement oftheinterventricular septum isina posterior direction, while theposterior wall movesforwards as thetransverse diameter ofthecavity isreduced. During diastole, thetwoechoes moveinthereverse direction, rapidly atfirst andthenmoreslowly inthe period ofdiastasis. Thispattern ofmovementhas beentaken torepresent aco-ordinated ventricular contraction andisthatcommonly seen, eveninthe presence ofconsiderable cavity dilatation orventricularhypertrophy. Abnormalities ofseptal movement havepreviously beendescribed inassociation withatrial septal defect andareprobably related totheincrease inright ventricular stroke volumethatoccurs inthis condition (Diamond etal., 1971). Inthemajority of thesepatients septal movementisthereverse of normal, being inananterior direction during systole whileintheremainder itundergoes a series of movements oflowamplitude, withno dominant displacement ineither direction. Similar abnormalities ofseptal movementmayoccurinassociation withacquired pulmonary hypertension ortricuspid regurgitation due, forexample, torheumatic mitral valvedisease, whentherelative loads ontheright andleft ventricles arealtered. Inthepresent study, echocardiography wasused todefine theeffects ofabnormalities ofventricular activation on thepattern ofcontraction. Eight patients withclassical left bundle branch block were studied, inwhomtheduration oftheQRScomplex -w'-~