Hypoperfusion of the left ventricle in the absence of changes in segmental contractility as observed through echocardiography by using microbubbles during dobutamine infusion

Abstract

time. With the recent development of intermittent harmonic imaging, it is possible to emit an ultrasound pulse every 1, 3, 5, 7 or more heartbeats, greatly decreasing the destruction of microbubbles and thus allowing evaluation of perfusion [2][3][4] . Case ReportThis is the report of a 46-year-old businessman with a 3-month history of short term precordial burning at rest and occasionally at moderate exertion, without irradiation, and no other accompanying symptoms. He had a history of dislipidemia, had stopped smoking seven years prior, and had a brother who had died of acute myocardial infarct one month before the exam.He had a normal physical examination; his total serum cholesterol level was 295mg/dl, with an LDL of 198mg/dl, HDL of 38mg/dl and triglycerides of 293mg/dl. His resting electrocardiogram showed an upper left anterior divisional block ( fig. 1). Left ventricular function was normal at rest, and his treadmill test was negative for myocardial ischemia.Due to the persistence of his symptoms, the patient underwent a dobutamine-atropine stress echocardiogram associated with the use of PESDA (perfluorocarbon-exposed sonicated dextrose and albumin) contrast echocardiography, after having signed an informed consent. This examination is included in a multi-center trial approved by UNIFESP's commission on medical ethics in research and CONEP (the National Ethics and Research Commission).The PESDA contrast agent was continously administered intravenously with an infusion pump at rest and at peak dobutamine infusion, at which point, real-time and intermittent harmonic images were obtained in five different acoustic windows Total doses of 40µg/kg/min of dobutamine and 0.5mg of atropine were infused, and a peak heart rate of 150bpmMale patient with chest pain and dislipidemia, an exsmoker with a family history of coronary artery disease (CAD), whose electrocardiogram and ergometric test were both negative for CAD. Due to persistent symptoms, he was submitted to a dobutamine-atropine stress echocardiogram with contrast agent for study of myocardial perfusion, which showed a hyperdynamic response of the left ventricle at peak stress, but clear perfusion defects of the anterior, lateral and apical walls. Cineangiocoronariography revealed multivessel coronary lesions.Echocardiography with the use of microbubbles is a recent diagnostic advance in cardiology that allows better evaluation of left ventricular function (ventriculography with microbubbles) and myocardial perfusion, since the microbubbles reach coronary microcirculation. One of the most important potential applications of this method is the investigation of coronary artery disease (CAD) through echocardiographic studies based on induction of ischemia. Temporary changes in the segmental contractility of the left ventricle (LV) are signs of myocardial ischemia easily detected by echocardiography. Dobutamine stress echocardiography is one of the most frequently used methods in medical practice and has shown good accuracy for the diagnosis of significant co...