Computer system for four-dimensional transesophageal echocardiographic image reconstruction

The Use of Ultrasound to Guide Interventions: From Bench to Bedside and Back Again

The ultrasound machine was originally devised as a diagnostic tool to help evaluate heart structure and function. With recent advances in ultrasound, including live 3D ultrasound, its potential to guide interventions within the heart has increasingly been recognized. Cardiologists have adapted this technology and have now published guidelines on the use of ultrasound to guide interventional procedures. Anesthesiologists have also used ultrasound with much success in cardiac operating rooms (ORs) to guide cannula placement and, to a limited extent, interventions. The focus of this article is a review of the author’s work on ultrasound and virtual reality—guided cardiac interventions, both in the research laboratory and in the OR.

A novel operator-independent algorithm for cardiac output measurements based on three-dimensional transoesophageal colour Doppler echocardiography

AIMS

Cardiac output (CO) measurements from three-dimensional (3D) trans-mitral Doppler echocardiography are prone to error as manual selection of the region of interest (i.e. the site of measurement) is required. We newly developed an automated, user-independent algorithm to select the site of colour Doppler CO measurement. We aimed to validate this new method by benchmarking it against thermodilution, the current gold standard for CO measurements.

METHODS AND RESULTS

Transoesophageal colour 3D Doppler echocardiographic studies were obtained from 15 patients who also had received a pulmonary catheter for invasive CO measurements. Trans-mitral flow was determined using a novel operator-independent algorithm to automatically select the optimal site of measurement. The operator-independent CO measurements were referenced against thermodilution. A good correlation was found between operator-independent Doppler flow computations and thermodilution with a mean bias of 0.09 L/min, standard deviation of bias 1.3 L/min, and a 26% error (2 SD/mean CO). Mean CO was 4.94 L/min (range 3.10-7.10 L/min).

CONCLUSION

Our findings demonstrate that CO computation from transoesophageal colour 3D Doppler echo can be automated concerning the site of velocity measurement. Our operator-independent algorithm provides an objective and reproducible alternative to thermodilution.