Intracardiac echocardiographic imaging of the left ventricle from the right ventricle: quantitative experimental evaluation

Cardiac magnetic resonance, transthoracic and transoesophageal echocardiography: a comparison of in vivo assessment of ventricular function in rats

In vivo assessment of ventricular function in rodents has largely been restricted to transthoracic echocardiography (TTE). However 1.5 T cardiac magnetic resonance (CMR) and transoesophageal echocardiography (TOE) have emerged as possible alternatives. Yet, to date, no study has systematically assessed these three imaging modalities in determining ejection fraction (EF) in rats. Twenty rats underwent imaging four weeks after surgically-induced myocardial infarction. CMR was performed on a 1.5 T scanner, TTE was conducted using a 9.2 MHz transducer and TOE was performed with a 10 MHz intracardiac echo catheter. Correlation between the three techniques for EF determination and analysis reproducibility was assessed. Moderate-strong correlation was observed between the three modalities; the greatest between CMR and TOE (intraclass correlation coefficient (ICC) = 0.89), followed by TOE and TTE (ICC = 0.70) and CMR and TTE (ICC = 0.63). Intra- and inter-observer variations were excellent with CMR (ICC = 0.99 and 0.98 respectively), very good with TTE (0.90 and 0.89) and TOE (0.87 and 0.84). Each modality is a viable option for evaluating ventricular function in rats, however the high image quality and excellent reproducibility of CMR offers distinct advantages even at 1.5 T with conventional coils and software.

Phased-array intracardiac echocardiographic imaging of acute cardiovascular emergencies: Experimental studies in dogs

BACKGROUND

We evaluated a newly developed phased-array intracardiac echocardiographic catheter.

OBJECTIVE

Our aim was to evaluate the imaging capability of this new ICE catheter in an animal model simulating acute cardiovascular abnormalities.

METHODS

ICE images were obtained from the right atrium during (1) acute left ventricular dysfunction; (2) acute coronary occlusion; (3) pericardial effusion and tamponade; and (4) pulmonary embolism.

RESULTS

Left ventricular dysfunction, induced experimentally by halothane inhalation, resulted in a fall in echocardiography-calculated ejection fraction from 47% +/- 11% to 25% +/- 10%, P <.01. Regional contraction abnormalities after acute coronary occlusion were identified without and with the ultrasound contrast agent Optison. Pericardial effusion produced by saline infusion into the pericardium was detected in amounts as small as 15 mL. Right ventricular and atrial compression and respiratory variation in right ventricular inflow during tamponade were demonstrated. After injection of intravenous thrombin to create venous thromboembolism, we demonstrated right ventricular dilatation and dysfunction and thrombi attached to the tricuspid and pulmonary valves and in the pulmonary artery.

CONCLUSION

This new phased-array ICE catheter may be a useful clinical tool for the diagnosis of heart failure, ischemia, tamponade, and pulmonary embolism.

Anatomic and hemodynamic imaging using a new vector phased-array intracardiac catheter

BACKGROUND

We used a new vector, phased-array intracardiac catheter (AcuNav) with complete 2-dimensional imaging and Doppler capabilities to describe a systematic approach for a detailed anatomic and hemodynamic cardiac assessment.

METHODS

In 14 dogs, the intracardiac echocardiographic catheter was inserted through an 11F venous access and placed in the right side of the heart to perform a comprehensive ultrasound examination of the heart.

RESULTS

Imaging was successful in all dogs. All 4 cardiac chambers and valves were imaged clearly in multiple orientations. Additional structures seen included the vena cavae, coronary sinus, right and left appendages, interarterial septum, coronary arteries, and all 4 pulmonary veins. Intra-abdominal structures, such as the aorta, liver, and hepatic veins were also visualized. A complete Doppler examination of intracardiac and paracardiac flows was also possible.

CONCLUSION

AcuNav is a unique intracardiac imaging device, which allows comprehensive structural and functional cardiac assessment.

Coronary risk area measurement by intracardiac echocardiography and ultrasound contrast

The perfusion bed of an occluded coronary artery-the coronary risk area-determines infarct size. Our objective was to evaluate the combined techniques of intracardiac echocardiography (ICE) and ultrasound contrast echocardiography for real-time estimation of the coronary risk area in an experimental model. We studied 13 pigs and 2 dogs. The left anterior descending coronary was occluded by inflating coronary balloons. An ultrasound contrast agent was injected either through the dilation catheter (distal to the inflated balloon) directly into the occluded artery to opacify the "positive" risk area or into the aortic root during coronary balloon inflation to determine the nonopacified "negative" risk area. Evans blue dye was injected into the occluded artery to stain the risk area, allowing an independent measurement. The mean left anterior descending negative risk area was 26% +/- 10% of the left ventricular myocardial area, the mean positive risk area was 24% +/- 10%, and the Evans blue-stained risk area was 25% +/- 9%. By Bland-Altman analysis, the positive Optison-Evans blue mean +/- SD difference was 1.42% +/- 6.42%; the negative Optison-Evans blue mean +/- SD difference was 1.02% +/- 7.56%. Coronary risk area can be determined with intracardiac echocardiography and ultrasound contrast.