PURPOSE: Although simplified hand-carried ultrasound platforms enable quick-look screening for significant cardiac disease, few data exist on their image quality and the accuracy of subjective diagnosis. Therefore, we sought to examine the image quality and the diagnostic accuracy of subjective interpretation of left ventricular systolic dysfunction (lowEF) or left atrial enlargement (LAE) using a new pocket-sized ultrasound device.
METHODS: Parasternal left ventricular long-axis images (PLAX) obtained using a pocket-sized device (Acuson P10) and a fully-featured machine (Philips ie33) were compared in N=78 inpatients referred for standard echocardiography. Video-looped P10 images were subjectively reviewed by an expert for LAE, defined by the LA diameter appearing larger than the overlying aorta, and lowEF, defined when the anterior mitral leaflet did not encroach upon the LV outflow tract. Diagnostic confidence was reported with each interpretation. Corresponding ie33 studies were used to confirm the presence of an LA diameter >4cm or E point septal separation (EPSS) >1cm. All PLAX images were rated on a quality scale (0: no image, 1: motion detected; 2: grossly resolved; 3: endocardium seen, but incomplete, 4: >90% of endocardium and valved seen.). Technically-limited studies, score <2, were excluded from interpretation.
RESULTS: Of 78 inpatient studies (29% portable ICU studies), 19% of P10 and 13% of ie33 studies were technically-limited (p=NS). Of 61 technically-adequate studies, subjective interpretation of P10 images had sensitivity, specificity and accuracy for LA>4cm of 79%, 52%, and 64%; for EPSS>1cm of 47%, 98% and 82%; for either abnormality of 83%, 62% and 74%; and for either abnormality when interpretive confidence was high (n=23) of 92%, 82%, and 87%. P10 vs. ie33 quality score averaged 2.4 +1.1 vs. 2.8 +1.1 (p<0.01).
CONCLUSION: The pocket-sized device provided sufficient image quality for screening of two significant cardiac entities in a difficult patient population, but did not have the image quality of a state-of-the-art echocardiograph.
CLINICAL IMPLICATIONS: Subjective interpretation of a single parasternal view during bedside examination may quickly identify a potential cardiac source of dyspnea.
DISCLOSURE: Glynn Gilcrease, No Financial Disclosure Information; No Product/Research Disclosure Information