Intracardiac echocardiography identifies pericardial fluid and can monitor the success of pericardiocentesis: experimental studies

Percutaneous intrapericardial echocardiography during catheter ablation: a feasibility study

BACKGROUND

Percutaneous pericardial access, epicardial mapping, and ablation have been used successfully for catheter ablation procedures.

OBJECTIVES

The purpose of this study was to evaluate the safety and feasibility of closed-chest direct epicardial ultrasound imaging for aiding cardiac catheter ablation procedures.

METHODS

An intracardiac ultrasound catheter was used for closed-chest epicardial imaging of the heart in 10 patients undergoing percutaneous epicardial access for catheter ablation. All patients underwent concomitant intracardiac echocardiography and preprocedural transesophageal echocardiography. Using a double-wire technique, two sheaths were placed in the pericardium, and a phased-array ultrasound catheter was manipulated within the pericardial sinuses for imaging.

RESULTS

Multiple images from varying angles were obtained for catheter navigation. Notably, image stability was excellent, and structures such as the left atrial appendage were seen in great detail. No complications resulting from use of the ultrasound catheter in the pericardium occurred, and no restriction of movement due to the presence of the additional catheter in the pericardial space was observed. Wall motion was correlated to voltage maps in five patients and showed that areas of scars correlated with wall-motion abnormalities. Normal wall-motion score correlated to sensed signals of 4.2 +/- 0.3 mV (normal myocardium >1.5 mV), and scores >1 correlated to areas with signals <0.5 mV in that territory).

CONCLUSION

Intrapericardial imaging using an ultrasound catheter is feasible and safe and has the potential to provide additional valuable information for complex ablation procedures.

Pericarditis

Pericarditis is a common disorder that has multiple causes and presents in various primary-care and secondary-care settings. New diagnostic techniques have improved the sampling and analysis of pericardial fluid and allow comprehensive characterisation of cause. Despite this advance, pericarditis is most commonly idiopathic, and radiation therapy, cardiac surgery, and percutaneous procedures have become important causes. Pericarditis is frequently self-limiting, and non-steroidal anti-inflammatory agents remain the first-line treatment for uncomplicated cases. Integrated use of new imaging methods facilitates accurate detection and management of complications such as pericardial effusion or constriction. Differentiation of constrictive pericarditis from restrictive cardiomyopathy remains a clinical challenge but is facilitated by tissue doppler and colour M-mode echocardiography. Most pericardial effusions can be safely managed with an echo-guided percutaneous approach. Pericardiectomy remains the definitive treatment for constrictive pericarditis and provides symptomatic relief in most cases. In the future, the pericardial space might become a conduit for treatments directed at the pericardium and myocardium.

"Hands-Free" continuous transthoracic monitoring of pericardiocentesis using a novel ultrasound transducer

BACKGROUND

Pericardiocentesis can be monitored with a hand-held transducer. The purpose of this study was to assess the feasibility of monitoring pericardiocentesis using a novel ultrasound transducer, which can be attached to the chest wall, developed in our laboratory (CONTISON).

METHODS

We studied nine patients with large pericardial effusions. The 2.5-MHz transducer is spherical in its distal part and mounted in an external housing to permit steering in 360 degrees. The external housing is attached to the chest wall using an adhesive patch. The CONTISON transducer was placed at the cardiac apex and an apical four-chamber view obtained. Pericardiocentesis was performed from the subcostal position. The pericardial effusion was continuously imaged. Mitral inflow velocity signals were recorded before and after pericardiocentesis. When fluid was first obtained, 50 mL of fluid were discarded after which 5 mL of agitated saline was injected through the needle.

RESULTS

In the first patient the pericardiocentesis needle was seen in the left ventricular cavity. Saline injection produced a contrast effect in the left ventricle. The needle was gradually withdrawn until contrast was seen in the pericardial sac. A total of 1100 mL was removed without further complications. The second patient had clear fluid followed by blood stained aspirate. The echocardiogram revealed gradual appearance of granular echoes within the pericardial sac, suggestive of intrapericardial clot that was subsequently surgically evacuated. In the remaining seven patients, agitated saline produced a contrast effect in the pericardial sac indicative of proper needle position. Mitral flow velocity paradoxus was noted in five patients, and it resolved after pericardiocentesis in four patients. No adjustment of the transducer was required.

CONCLUSION

The CONTISON transducer permitted continuous monitoring of pericardiocentesis. This technique could potentially facilitate pericardiocentesis.

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.