Detection of cardiac right-to-left shunts by contrast-enhanced harmonic carotid duplex sonography.

OBJECTIVE: Paradoxical embolization by cardiac right-to-left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast-enhanced transcranial Doppler sonography (ce-TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. METHODS: Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose-based nontranspulmonary contrast agent. The B-mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce-TCDS recordings of high-intensity transient signals from the MCA were analyzed offline. RESULTS: In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high-intensity transient signals detected on ce-TCDS in the ipsilateral MCA. CONCLUSIONS: The results of this study indicate that contrast-enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.

Transcranial duplex sonography in the detection of patent foramen ovale.

PURPOSE: To determine the sensitivity of contrast material-enhanced transcranial color-coded sonography (c-TCCS) compared with that of contrast-enhanced transesophageal echocardiography (c-TEE) for detection of cardiac right-to-left shunt. MATERIALS AND METHODS: Forty consecutive patients with stroke or transient ischemic attack were admitted to the hospital and were examined by using c-TCCS and c-TEE. High-intensity transient signals (HITS) were counted for 25 seconds after the end of the Valsalva maneuver, and the numbers of HITS were classified in one of four categories (zero HITS, one to 10 HITS, >10 HITS without curtain, and curtain). A statistically significant difference was calculated with the Fisher exact test. RESULTS: HITS were counted in 21 (52%) patients by using c-TCCS and c-TEE. With both tests, no HITS were counted in 15 (38%) patients. In two (5%) patients, no HITS were counted with c-TEE but three HITS in one patient and five HITS in the other were counted with c-TCCS. In two (5%) patients, no HITS were counted with c-TCCS, but a small patent foramen ovale (PFO) was seen at c-TEE. With c-TCCS, the sensitivity was 91% (21 of 23) and the specificity was 88% (15 of 17). In 23 patients examined with c-TCCS, 14 (61%) patients had category 1 PFO; seven (30%) patients, category 2 PFO; and two (9%) patients, category 3 PFO. Mean HITS count in patients with category 1 PFO was 4.4 and that for those with category 2 PFO was 27.6. CONCLUSION: c-TCCS is a sensitive noninvasive method for detecting cardiac right-to-left shunt and is as sensitive as c-TEE.

Stentless xenografts and homografts for right ventricular outflow tract reconstruction during the Ross operation.

BACKGROUND: Shortage of homografts prompted us to replace the transplanted pulmonary trunk with stentless xenografts during the Ross procedure. The 5-year follow-up in comparison with pulmonary homografts is presented. METHODS: From April 1997 to March 2002, of 51 patients undergoing a modified Ross procedure 15 patients (age range 55 to 65 years, mean 59 +/- 5) received a stentless xenograft, and 36 patients (15 to 56 years, mean 36 +/- 11) a pulmonary homograft for right ventricular outflow tract (RVOT) reconstruction. Follow-up was complete for a mean of 3.1 years (range 6 to 60). Regularly performed echocardiography included determination of valve annulus, peak instantaneous gradient, leaflet performance, location of obstruction, and degree of regurgitation. RESULTS: There was 1 late death and 1 reoperation for homograft stenosis. The homograft annulus diameter decreased by a mean of 10% (range 3 to 10 mm; p < 0.01), and peak Doppler gradient increased significantly (p < 0.001). All patients except 1 had gradients less than 25 mm Hg. Gradients in xenograft patients were stable at a low level (6.5 +/- 4.3 mm Hg to 8.8 +/- 7.4 mm Hg at the latest follow-up). Mild pulmonary regurgitation was noted in 46.6% (xenografts) and 19.5% (homografts). Leaflet quality and mobility were maintained in all patients. CONCLUSIONS: Pulmonary homografts underlie a process of annular reduction after the Ross procedure, which is usually not associated with graft stenosis. Mild pulmonary regurgitation is more common in xenografts than in homografts. RVOT reconstruction using stentless xenografts represents a satisfactory treatment modality for aged patients.

Left ventricular remodeling after pulmonary autograft aortic valve replacement: evaluation with color-Doppler echocardiography and magnetic resonance imaging.

The superior hemodynamic performance of the pulmonary autograft in aortic position is expected to reflect complete regression of hypertrophy and improved ventricular function. We evaluated and compared early and midterm transthoracic color-Doppler echocardiography (TTE) and magnetic resonance imaging (MRI) assessment concerning left ventricular (LV) function, LV mass regression, and performance of the semilunar valves. A total of 42 consecutive patients, mean age 36 +/- 6 years (range 15 to 56 years), were studied. TTE and MRI were performed preoperatively, at discharge, and at 6 and 12 months postoperatively. Left ventricular diameters and function and LV wall thickness and mass were assessed. There was no early and one late postoperative death. Maximum and mean LV outflow gradients were significantly reduced (p = 0.0001 and p = 0.0001, respectively). There was a significant reduction in left ventricular mass to near normal for all patients (p = 0.001) seen after 6 months. This was paralleled by significant reductions in the interventricular septum and posterior wall thickness, but difference was slight during further follow-up. There was a strong correlation between the results obtained by TTE and MRI for LV mass and ejection fraction (r = 0.86 and 0. 87, respectively). The pulmonary autograft operation gives excellent results that are translated into greater, rapid, and near complete regression of LV hypertrophy. Magnetic resonance imaging is a sensitive and noninvasive methodology that provides reliable visualization and quantification of ventricular performance.