Feasibility of Real-Time Myocardial Contrast Echocardiography to Detect Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is an important adverse prognostic factor for pediatric heart transplant (HT) recipients. Invasive coronary angiography (ICA) is the gold standard for CAV detection but lacks sensitivity for early microvascular changes and cumulative radiation exposure is of concern. Real-time myocardial contrast echocardiography (RTMCE) using ultrasound enhancing (contrast) agents performed during dobutamine stress echocardiography (DSE) can assess myocardial function, perfusion, and microvascular integrity. The objective of this study was to determine the safety and feasibility of RTMCE during DSE to detect CAV in a pediatric HT population. METHODS: HT patients 10-21 years of age were recruited to undergo DSE with RTMCE to determine technical feasibility, test tolerability and adverse event rate, and detection of perfusion defects compared with ICA-detected CAV. Thirty-six patients from two centers were enrolled, with a mean age 13.5 ± 4.3 years; 21 (58%) were male. Wall motion and myocardial perfusion were qualitatively assessed and compared with ICA findings of CAV. Myocardial blood flow (MBF) at rest and peak stress was quantified, and myocardial blood flow reserve (MBFR) was defined as the ratio of peak to rest MBF. RESULTS: Five (14%) patients had CAV by ICA, two with obstructive disease and three with mild CAV. Real-time myocardial contrast echocardiography was feasible in 32 (89%) patients. Three patients had wall motion defects, including one with a mixed defect and two with fixed defects. A perfusion abnormality was present in five patients, two of whom had obstructive CAV and one with mild CAV. Sensitivity and specificity of RTMCE for CAV detection were 60% and 94%, respectively, and diagnostic accuracy was 89%. MBFR assessment was feasible in 20 (63%) patients. The mean MBFR was 3.4 ± 0.7. Patients with CAV had lower MBFR than those without (2.0 ± 0.2 vs 3.7 ± 0.8; P < .01). There were no serious adverse events related to RTMCE. CONCLUSIONS: Dobutamine stress RTMCE appears to be safe and feasible for the assessment of CAV in pediatric HT recipients. Further assessment is warranted to determine whether this noninvasive technique could provide a reliable alternative to ICA.

Safety of stress echocardiography supervised by registered nurses: results of a 2-year audit of 15,404 patients.

BACKGROUND: Stress echocardiography has traditionally been performed under the supervision of physicians. In the last decade, at some institutions, specially trained registered nurses have taken on the task of directly supervising and conducting these stress tests with appropriate physician involvement and assistance. METHODS: The safety of 15,404 stress echocardiograms that were performed under the direct supervision of registered nurses during a recent 2-year period was evaluated. RESULTS: The stress modality was treadmill exercise in 8592 (56%), dobutamine in 6755 (44%), and transesophageal atrial pacing in 57 (0.04%) patients. The mean age was 65 +/- 13 years, and 54% were male. A total of 55 patients (0.36%) had complications related to stress echocardiography, including 26 patients (0.18%) who were subsequently transferred to hospital. Complications included atrial fibrillation (n = 28, 0.18%), other supraventricular tachycardias (n = 9, 0.06%), sustained ventricular tachycardia (n = 4, 0.03%), and ventricular fibrillation (n = 2, 0.01%). Eight patients (0.05%) were hospitalized for markedly positive tests or prolonged chest pain and 4 patients (0.03%) for symptomatic hypotension. No patient had cardiac rupture or died. Complications were more common with dobutamine stress echocardiography (DSE) (47/6755; 0.7%) compared with exercise echocardiography (8/8592; 0.09%) or transesophageal atrial pacing stress echocardiography (0/57) (P < .0001). Arrhythmias were more commonly associated with DSE (39/6755, 0.58%) than exercise echocardiography (4/8592, 0.05%). Potentially life-threatening ventricular arrhythmias occurred in 6 of 6755 patients who underwent DSE (0.09%) and in none of the patients who underwent exercise echocardiography. Patients who underwent DSE were, on average, older, and had more comorbidities compared with those who underwent exercise echocardiography. CONCLUSIONS: Stress echocardiography, when supervised directly by specially trained registered nurses, can be performed safely; complications are uncommon (1/280 stress tests) and these complication rates are comparable with previously reported studies evaluating the safety of stress echocardiography supervised by physicians.