James Pemberton

Delineation of cardiac twist by a sonographically based 2-dimensional strain analysis method: an in vitro validation study.

Objective. Normal left ventricular contraction involves a twisting component that helps augment stroke volume, the unwinding of which also very usefully contributes to early diastolic filling. Abnormalities of cardiac twist have been related to abnormal cardiac function. We sought to quantify the twisting action using a new sonographically based angle‐independent motion‐detecting echo method. Methods. A twist model was developed with a variable‐speed motor to rotate a wheel in water bath. A freshly harvested pig heart was mounted on it as a twist phantom. Short axis views were acquired with a GE/VingMed Vivid 7 system (GE Healthcare, Milwaukee, WI) at 3.5 MHz and more than 100 frames/s. Eight different speeds (30–100 cycles/min of winding and unwinding) were studied at 5 degrees of rotation (10°, 20°, 30°, 40°, and 50°). Data were analyzed off‐line for twist analysis with a new 2‐dimensional speckle‐tracking–based program (2‐dimensional strain rate method [2DSR]) embedded in EchoPac software (GE Healthcare). Ten freshly harvested pig hearts were studied in this model. Results. The 2DSR program tracked the twist well (mean determination at 10° = 16.88° ± 1.81° [SD]; at 20° = 26.5° ± 1.05°; at 30° = 36.47° ± 1.31°; at 40° = 44.03° ± 1.39°; and at 50° = 54.1° ± 1.96°). Conclusions. The 2DSR program can be used to study twisting action of the heart.

Accuracy of real-time, three-dimensional Doppler echocardiography for stroke volume estimation compared with phase-encoded MRI: an in vivo study.

To the editor: Accurate measurement of cardiac output (CO) is important in clinical medicine. Current methods of calculation use two-dimensional echocardiography and ventricle volumetry or spectral Doppler pulse wave. Phase-encoded MRI is an accurate technique for volume assessment; however, is not suitable for many clinical situations, such as in those who are critically ill.nnPrevious work by our group has shown that real-time, three-dimensional Doppler echocardiography (RT3DDE) can accurately compute stroke volume (SV) and CO in an animal model against a “gold standard” of aortic flow probe using the left ventricular outflow tract colour Doppler signal,1 and this technique can be used in patients transthoracically.2 3nnWe tested the accuracy of RT3DDE of the left ventricular outflow tract for calculation of SV in a series of patients and healthy volunteers against a “gold standard” of phase-encoded MRI.nnTwo patients and 12 healthy volunteers took part in the study. The patients were undergoing MRI as part of their clinically indicated investigations for cardiac disease (both patients for aortic coarctation). All subjects gave written informed consent in accordance with the local Institutional Review Board.nnThe Philips Live 3D 7500 Sonos echocardiography system with a 3000-element 2–4 MHz xMATRIX transthoracic probe (Philips Medical Systems, Andover, Massachusetts, USA) was used for imaging. Subjects underwent echocardiography immediately before MRI.nnBetween three and five ECG-gated, three-dimensional colour Doppler volumes were acquired from …

Accuracy of 3-dimensional color Doppler-derived flow volumes with increasing image depth

We and others have reported on the use of digital color Doppler sonography from real‐time 3‐dimensional (3D) echocardiography and its use in accurately calculating cardiac flow volumes, namely stroke volume (SV) and, hence, cardiac output. However, in some patients, image depth is higher than average, and this may affect the accuracy of volume calculation. We sought to investigate the impact of image depth and the accompanying change in signal strength, spatial resolution, and pulse repetition frequency on the accuracy of SV calculation from 3D color Doppler data in an in vitro model.

Clinical application and technical challenges for intracardiac ultrasound imaging catheter based ICE imaging with EP mapping

A 9F combination intracardiac imaging and electrophysiology mapping catheter has been developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology procedures. A 7.5 MHz, 64 element, side looking phased array was used for sector scanning from the tip of the catheter. Multiple electrophysiology (EP) mapping sensors were mounted as ring electrodes just proximal to the array for electrocardiographic synchronization of ultrasound images. The catheter has been used in vivo in a porcine animal model and has demonstrated useful intracardiac echocardiographic (ICE) visualization of both cardiac tissue and electrophysiology catheters in the right atrium. The catheter performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures.

Development of an electrophysiology (EP)-enabled intracardiac ultrasound catheter integrated with NavX 3-dimensional electrofield mapping for guiding cardiac EP interventions: experimental studies.

We have developed an integrated high‐resolution intracardiac echocardiography (ICE) catheter for electrophysiology (EP) testing, which can be coregistered in 3‐dimensional space with EP testing and ablation catheters using electrofield sensing.

Stuck mitral valve replacement

This 30 year old woman had undergone a mitral valve replacement with a bileaflet prosthesis one year previously. Postoperatively she had been well until she presented with a two week …

Perforated mitral valve leaflet

A 40 year old man presented with general malaise, pyrexia, and microembolic phenomena. Blood cultures were positive for α haemolytic streptococcus. A transthoracic echocardiogram showed several small masses on the aortic valve …