Novel techniques of coronary artery imaging

Intraoperative assessment of coronary grafts by novel digital epivascular imaging

OBJECTIVE

We sought to validate and evaluate 2 novel intraoperative ultrasound probes for epicoronary and epiaortic imaging.

BACKGROUND

The noninvasive intraoperative assessment of successful coronary artery bypass grafting remains a challenge.

METHODS

A total of 19 consecutive patients (4 female, 15 male; mean age 60.5 +/- 13.8 years SD, range 34-84) underwent coronary artery bypass grafting. The epivascular probes (GE Ultrasound) were validated in vitro and intraoperatively. Coronary arteries, grafts, and ascending aorta were imaged and quantified.

RESULTS

Mean adjusted flow measured by flowmeter was 3.25 L, SE 0.47 (range: 1-5.5 L) and was 3.15 L, SE 0.46 (range: 1-5.0 L) by ultrasound, with r = 0.97, P <.0001. Intraoperatively, 56 native coronary vessels were bypassed using 15 left internal mammary artery grafts, 25 vein grafts, and 16 venous jump grafts. A total of 15 left internal mammary artery grafts (100%), 12 left internal mammary artery anastomoses (80%), 20 vein grafts (15 left anterior descending coronary arteries, left circumflex artery grafts, 5 right coronary artery grafts) (80%), 4 jump grafts (25%), and 15 ascending aortas (78%) were successfully imaged by inexperienced surgeons. Doppler flow measurements were possible in 50 vessels (89%). Mean lumen diameter for graft arteries (veins) was 2 mm (2.87 mm), maximal velocity was 72 cm/s (46 cm/s), and mean velocity was 29 cm/s (21 cm/s) with a mean flow rate of 70 mL/m (55 mL/m).

CONCLUSIONS

We conclude that: (1) the novel intraoperative probes measure validated flow; (2) intraoperative hemodynamic assessment of graft patency is feasible without a learning curve; and (3) these findings should encourage the routine use of these intraoperative epivascular digital ultrasound probes.

New developments in ultrasound systems for contrast echocardiography

Contrast echocardiography (CE) has evolved significantly in the past decade. Contrast agents and the hardware and software used to detect them and display optimal images have developed in tandem. Not only are hardware and contrast agents available that allow left ventricular cavity enhancement, but recent research points to the usefulness of CE for the evaluation of myocardial perfusion in the cardiac catheterization laboratory and operating room. Advances in ultrasound technology, such as transient harmonic imaging and integrated backscatter, coupled with the development of newer contrast agents that contain smaller, more stable microbubbles capable of transpulmonary passage for intravenous injection, promise a vast increase in the applications of CE in clinical practice.

The emerging role of contrast agents in echocardiography

Because of an outstanding track record for diagnostic accuracy, noninvasive properties, ease of use, and relatively low expense, echocardiography has become a leading technique in the evaluation of cardiac disorders. In the three decades since echocardiography entered the ranks of standard cardiac diagnostic tools, refinements and technological advances have progressively increased its usefulness. One of the most noteworthy advancements has been the development of ultrasound contrast agents, which investigators are avidly seeking to apply to a broad spectrum of clinical settings and issues.

Ultrasound contrast media and their use in obstetrics and gynecology

Contrast media have gained acceptance to enhance ultrasonography in many fields of medicine; in particular, cardiology. Several agents have been described and many more are being manufactured and tested. By increasing the number of strong sound scatterers, these agents improve images by increasing the amount of echoes. This is true both for grey-scale and color or Doppler imaging. Their use in obstetrics is very limited at the moment because of safety issues. In a laboratory setup, they have been shown to markedly enhance placental imaging. In gynecology, imaging of the uterine cavity and Fallopian tubes is greatly improved. A potential area where ultrasound contrast may find a role is gynecological oncology. Vascularity is increased in many tumors, but usually vessel diameter is small and velocity low. One can therefore expect future use of the ultrasound contrast agents in ovarian or other gynecological neoplasms.