Echocardiographic Evaluation of Left Ventricular Diastolic Function in Post-Myocardial Infarction Patients

INTRODUCTION : From a physiological point of view the heart is a muscle – pump system. The term diastole is interpreted as a division, notch, or separation between two contraction – relaxation cycles. (Brutsaert 1984). In this interpretation its meaning is restricted to the passive properties of the heart (Gillebert 1994). Diastole of the left ventricle starts when active relaxations have been completed and include the diastasis and the trial contraction phase. In the English medical literature diastole has however come to mean “the dilatation or period of dilatation of the heart, especially that of the ventricles, coinciding with the interval between the second and first heart sounds” (Brutsaert 1984). In this interpretation it is part of the cardiac cycle which starts with the isovolumetric relaxation phase and ends with cessation of mitral inflow (Arrighi 1995). In the present thesis the latter, clinical definition of diastole will be used. Heart failure cab be defined as “the pathophysiological state in which an abnormality of cardiac function is responsible for failure of the heart to pump blood at a rate commensurate with the requirements of the metabolizing tissues, or to do so only from an elevated filling pressure” (Braunwald 1992). As a consequence, in diastolic failure increased resistance to ventricular filling leads to elevated ventricular filling pressures or inadequate cardiac output. Accordingly, an increase in pulmonary wedge pressure may lead to symptoms of congestion. It is clear that within this definition many cardiac diseases may result eventually in diastolic failure, including reduced systolic performance, pericardial and valvular disease. The main causes of diastolic failure can be divided into relaxation abnormalities, decreased compliance and inappropriately high heart rates (Brutseart 1993). All three causes can contribute separately to diastolic failure, but in many conditions they act together. AIM OF THE STUDY : The aim of the study was to observe the prevalence of diastolic dysfunction in post myocardial infarction patients. And frequent identification of the diastolic elements in myocardial dysfunction may prove helpful in directing therapy and gauging its benefits. MATERIALS AND METHODS : 2D Targeted Doppler ultrasound recording were obtained with an Irex meridian echo Doppler system. HEWLETT PACKARD 77020A Equipped with 3.5 MHz and 5 MHz phased array transducer. This system has a pulsed Doppler capacity with a movable cursor and adjustable sample depth. It was examined in left lateral portion using standard parasternal short axis and bus chamber apical view. Pulsed Doppler echocardiogram was obtained from the standard apical four chamber view. Mitral in flow velocity were recorded with the sample volume at the submitted annular level. The transducer was then manipulated to obtain the minimum how signed as assessed by the auditor and spectral output Doppler measurement were made on at least 3 cardiac cycles using the darkest part of spectral recording and was then averaged. DISCUSSION : In this study seventy five patients were enrolled and only forty eight patients are taken for study. Remaining twenty seven patients are left out since they had diabetes, hypertension and excess age group i.e. more than fifty five years. Among forty eight patients, thirty four are male (70.8% of study) and fourteen are female (29.2%) of study age group included was forty to fifty five. Anterior wall myocardial infarction (AMI) occurred in twenty two patients (45.8% of study), Inferior wall myocardial infarction in thirteen (27% of study). Anterior wall myocardial infarction (IWMI) and inferior wall myocardial infarction (AMI+IWMI) together in eight patients (16.6% of study), anterior wall myocardial infarction and lateral wall myocardial infarction (AMI+LWMI) in five patients (10.4%) of study. Twenty two patients were smokers, hypercholestermia occurred in fourteen patients. Among forty eight patients eleven patients (22.91% had on E/A ratio less than I and four patients (8.33%) has Pseudonormalisation pattern. All the other patients had E/A ratio more than one upto 2.86. CONCLUSION : From our study we conclude that diastolic dysfunction is present in 22.91% of patient of MI after excluding HT, DM and elderly. It is also noted that diastolic dysfunction correlate with size of infarction. Despite the limitations discussed above the results of this study indicate that left ventricular diastolic filling analyzed by pulsed wave Doppler mitral inflow is an important prognostic tool in patients who have MI. And presence of left ventricular diastolic dysfunction may alter treatment in a better way with ACEI, CCB and BB