"Hands-Free" continuous echocardiography during treadmill exercise using a novel ultrasound transducer.

BACKGROUND: Echocardiographic imaging using a handheld transducer in conjunction with treadmill exercise testing is commonly used for the diagnosis of coronary artery disease. Motion of the hand and the transducer during peak exercise preclude optimal imaging. To circumvent the limitations of handheld transducers, we developed a low profile transducer (CONTISON) which can be attached to the chest wall for continuous cardiac imaging. METHODS AND RESULTS: This feasibility study was performed in 10 normal male subjects (28 to 36 years). The ultrasound transducer was placed in the third or fourth intercostal space at the left sternal border to permit imaging of the left ventricle in its short axis. The transducer was interfaced with a commercially available ultrasound machine. The left ventricle was imaged at rest and while subjects exercised according to a standard Bruce protocol. All segments of the left ventricular short axis were seen at rest and peak exercise. Increased left ventricular wall thickening and wall motion were seen at peak exercise. There were no complications from the procedure. CONCLUSION: We demonstrated the feasibility of hands-free left ventricular imaging during treadmill exercise using the CONTISON transducer. Further evaluation of the technique to detect stress-induced wall motion abnormalities, as a means of diagnosing myocardial ischemia, appears warranted. (ECHOCARDIOGRAPHY 2010;27:563-566).

Use of a low profile ultrasound transducer for coronary sinus cannulation: a pilot study.

BACKGROUND: Cardiac resynchronization therapy with biventricular pacing has been shown to be beneficial in improving heart failure in patients with prolonged QRS duration (≥120 ms) and low ejection fraction (≤35%). Unsuccessful cannulation of the coronary sinus (CS) has been reported in up to 10% of cases. The feasibility of the transthoracic continuous cardiac imaging for coronary sinus cannulation has not been previously demonstrated. METHODS AND RESULTS: We developed a 2.5-MHz hemi-spherical continuous cardiac imaging transducer (CONTISON), mounted in an external housing, to permit steering in 360°. The transducer was attached to the chest wall using an adhesive ring. The CS was easily imaged by echocardiography by placing the transducer just medial to the apex and tilting it dorsally. The feasibility study was done in 11 patients. CS ostium and body were imaged in all patients. Cannulation was successfully achieved in nine patients with a mean cannulation time of 1 minute 16 seconds. In two patients, poor image quality precluded adequate visualization of CS. Fluoroscopy was not used for cannulation. CONCLUSION: We demonstrated the feasibility of using the CONTISON echography transducer for the guidance CS cannulation. This technique could expedite CS cannulation and reduce radiation exposure. Further studies comparing ultrasound versus fluoroscopy for CS cannulation appear warranted.