A 51-year-old woman was admitted to our hospital complaining of chest tightness, palpitations and dyspnoea after activity. On admission, physical examination revealed a normal state of consciousness, an average heart rate of 76 beats per minute (bpm), and a blood pressure of 111/70 mmHg. Cardiac auscultation revealed variable first heart sound intensity and a diastolic murmur in the mitral stethoscope area. The other findings were unremarkable. The electrocardiogram showed atrial fibrillation. The echocardiogram performed by our hospital also showed rheumatic heart disease (severe mitral stenosis and regurgitation) with normal cardiac function and wall motion.
After the completion of the preoperative examination, the patient was sent to the operating room for mitral valve replacement. The operation was successful. After the aorta was reopened, ventricular fibrillation occurred. Sinus rhythm was not restored until 5 rounds of electrical defibrillation had been performed. Not long after returning to the intensive care unit (ICU), this patient developed heart failure with low blood pressure (70~85/45~50 mmHg) and tachycardia (125–135 bpm). Blood gas analysis showed progressive lactic acidosis, and blood lactate increased from 2.4 mmol/L to 15.3 mmol/L. Troponin T was slightly elevated compared to the preoperative level (1.960 ng/mL vs 0.019 ng/mL). N-terminal pro-brain natriuretic peptide levels increased markedly from 821.7 pg/mL to 21,025 pg/mL. Electrocardiogram (ECG) (Fig. 1) showed that the V5–6 ST-segment depression was 0.1 mV. The bedside chest film showed a small amount of fluid in the left chest. Urgent bedside echocardiography demonstrated akinesis in the middle and apical segments of the left ventricle with depressed LV function (EF 36%),while basal segments’ movement were generally normal.
To determine the blood flow in the myocardium, myocardial contrast echocardiography (MCE) was performed immediately (Figs. 2a, b, and 3a). For the MCE examination, the ultrasound system was switched to the contrast mode, with a mechanical index of 0.1–0.5. MCE was performed using intravenous administration of 2.0 mL of SonoVue (Bracco, Milan, Italy). To achieve a balance among ultrasound intensity, penetration, and the duration of myocardial opacification, the contrast-specific imaging mode needed to be adjusted. Similar enhancement intensity was observed in the basal, middle and apical segments. Quantitative analysis also showed approximately equivalent maximum intensity values in these regions.
The diagnosis was considered TCM instead of myocardial infarction. The treatment mainly involved maintaining effective circulation and reducing the postcardiac load. After the administration of epinephrine and norepinephrine, the patient’s blood pressure was still low. Considered the patient’s condition as heart failure, an intra-aortic balloon pump was inserted. Although myocardial enzyme levels were elevated, the doctors did not perform treatment for coronary heart disease, considering the reason of tissue injury after heart surgery. The therapeutic regimen for this patient included ventilator-assisted ventilation, postoperative anticoagulation therapy, anti-infection treatment and other conservative treatments.
A week later, the patient underwent coronary angiography, and the results showed no significant narrowing of the coronary artery. This patient was extubated 13 days after surgery and was later weaned from epinephrine. Myocardial contrast echocardiography performed 2 weeks later (Figs. 2c, d, and 3b) showed that apical movement was significantly improved, with a slight decrease in interventricular septal motion. In addition, the perfusion of the myocardium was normal, with an EF (Simpson) of 52%.
The clinical evolution was favourable, and the patient was discharged 3 weeks later. Before discharge, echocardiography showed that the artificial mitral valve function and the segmental wall movement were normal, with an EF of 72%. One year later, the patient remained asymptomatic and showed normalization of ventricular wall motion in the apical segment.