Significance of radiographic cardiomegaly in orthotopic heart transplant recipients.

Abstract

OBJECTIVE. The purposeof this studyis to evaluatethe clinical significanceof radio graphiccardiomegalyin orthotopichearttransplantrecipientsand to identify causativeana tomic and physiologic parameters. MATERIALS AND METHODS.We retrospectivelycomparedthe cardiothoracicratio (CTh) measured using standard posteroanterior chest radiography with left ventricular end diastolic diameter and left ventricular ejection fraction measured on two-dimensional echocardiography; right ventricularsystolicpressure; andsystolic,diastolic,and meanblood pressuremeasuredat biopsyin 46 hearttransplant recipients.RESULTS. Twenty-eight (61%)ofthe46patients hadradiographic cardiomegaly. When we comparedhearttransplant recipientswho had a CTR greaterthan0.5 with recipientswho had a CTR less than or equal to 0.5, we found no significant difference between their respec tive left ventricular end-diastolic diameters, left ventricular ejection fractions, right ventricu lar systolic pressures, systolic blood pressures, or mean blood pressures. A statistically significant difference existed between the mean values of diastolic blood pressure for trans plantrecipientswith andwithoutradiographiccardiomegaly. We foundno significantcorrela tion between CTR and left ventricular end-diastolic diameter, left ventricular ejection fraction, systolic blood pressure,diastolic blood pressure,or mean blood pressure.CONCLUSION. The statisticallysignificantdifferencebetweenthe meanvaluesof dias tolic blood pressureof transplantrecipientswith and without radiographiccardiomegalyis clinically insignificant and unlikely to account for the finding of radiographic cardiomegaly. We conclude that radiographic cardiomegaly, which occurs frequently in heart transplant re cipients, does not correlate with anatomic or physiologic parametersobtained under the same conditions.Radiographiccardiomegalyin heart transplantrecipientsdoes not connoteal lograft dysfunction or heart failure. R adiographic cardiomegaly,defined as a cardiothoracic ratio (CTR) greater than 50% as shown on a standardposteroanteriorchestradiograph,gen erally connotes organic heart disease. Radio graphic cardiomegaly resulting from cardiac chamberenlargement occursin patientswith id iopathic and ischemic dilated cardiomyopathy, left ventricular hypertrophy, and hypertrophic cardiomyopathy. Radiographiccardiomegaly can also occur as a result of causesother than cardiac chamberenlargement,such as pericar dial effusion, idiopathic enlargement of the right atrium with persistentsuperior vena cava [1], epicardialfat deposition [2], anomalousin ferior venacava [3], anddissectingaortic aneu rysm [4J. Heart size, however, can also be assessed by other means, such as radionuclide ventriculography, cineangiocardiography, and echocardiography.In our clinical experience, many orthotopic heart transplant recipients haveradiographic cardiomegaly withoutclini cal or hemodynamic evidenceof allograftdys function. We thereforeundertook this study to evaluate the clinical significanceof radio graphic cardiomegaly after o...