Cardiac Imaging Update

Impact of imaging landmark on the risk of MRI-related heating near implanted medical devices like cardiac pacemaker leads.

Magn Reson Med. 2010 Aug 30;

Authors: Nordbeck P, Ritter O, Weiss I, Warmuth M, Gensler D, Burkard N, Herold V, Jakob PM, Ertl G, Ladd ME, Quick HH, Bauer WR

Implanted medical devices such as cardiac pacemakers pose a potential hazard in magnetic resonance imaging. Electromagnetic fields have been shown to cause severe radio frequency-induced tissue heating in some cases. Imaging exclusion zones have been proposed as an instrument to reduce patient risk. The purpose of this study was to further assess the impact of the imaging landmark on the risk for unintended implant heating by measuring the radio frequency-induced electric fields in a body phantom under several imaging conditions at 1.5T. The results show that global radio frequency-induced coupling is highest with the torso centered along the superior-inferior direction of the transmit coil. The induced E-fields inside the body shift when changing body positioning, reducing both global and local radio frequency coupling if body and/or conductive implant are moved out from the transmit coil center along the z-direction. Adequate selection of magnetic resonance imaging landmark can significantly reduce potential hazards in patients with implanted medical devices. Magn Reson Med, 2010. (c) 2010 Wiley-Liss, Inc.

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Evaluation of Coronary Flow Velocity Reserve in Homozygous Familial Hypercholesterolemia by Transthoracic Doppler Echocardiography and Dual-source Computed Tomography.

Ultrasound Med Biol. 2010 Aug 27;

Authors: Yang Y, Zhang X, Li R, Ren H, Wang Z, Li Z, Lin J, Wang L, Yu W, Zhang Z

Homozygous familial hypercholesterolemia (HoFH) is a rare disorder characterized by the early onset of atherosclerosis and usually occurs at the ostia of coronary arteries. In this study, we used transthoracic Doppler echocardiography (TTDE) to evaluate the dynamic changes of coronary flow in HoFH patients and to detect aortic and coronary atherosclerosis by dual-source computed tomography (DSCT). We studied 20 HoFH patients (12 females, 8 males, mean age 13.1 +/- 5.3 years, with a mean low density lipoprotein (LDL) cholesterol of 583 +/- 113 mg/dL) and 15 control patients (8 females, 7 males, mean age 15.2 +/- 6.9 years, with a mean LDL cholesterol 128 +/- 71 mg/dL) using TTDE and DSCT. None of the patients showed evidence of ischemia with standard exercise testing. Though the baseline coronary flow was similar between HoFH patients and normal controls, the hyperemic flow velocities and, thus, the coronary flow velocity reserve (CFVR) were significantly lower in those with HoFH. All HoFH patients had aortic plaques, nine of them with the coronary artery ostia simultaneously, who had significantly higher LDL-cholesterol and lower CFVR than those without ostia plaques. Our data demonstrated that TTDE together with DSCT could be a useful noninvasive method for detection of coronary flow dynamics and atherosclerosis specifically in HoFH subjects with coronary ostia. (E-mail: lizhian_anzhen@yahoo.com.cn).

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The Role of Intraoperative Transesophageal Echocardiography in Robotic Mitral Valve Repair.

Echocardiography. 2010 Aug 24;

Authors: Wang Y, Gao CQ, Wang JL, Yang M

Background: Robotic mitral valve (MV) repair is a new surgical technique that uses small incisions. Previous studies have demonstrated the importance of intraoperative transesophageal echocardiography (TEE) for conventional MV surgery with the use of a median sternotomy incision. The aim of the present study was to delineate the utility of intraoperative TEE in robotic MV repair. Methods: Intraoperative TEE was performed in 22 consecutive patients undergoing robotic MV repair for severe degenerative mitral regurgitation (MR) over a period of 2 years. Before cardiopulmonary bypass (CPB), TEE was used to define the lesions of degenerative MR and the localization of the prolapsed leaflets, and to evaluate the severity of MR. During establishment of peripheral CPB, TEE was used to guide placement of the cannulae in the inferior vena cava (IVC), superior vena cava (SVC), and ascending aorta (AAO). After weaning from CPB, TEE was used to assess immediately the competency of the surgical repair. Results: Agreement between TEE and surgical findings was excellent: 92.3% (kappa, 0.873) for the lesions of degenerative MR, and 98.5% (kappa, 0.943) for the localization of the prolapsed leaflets. Under TEE guidance, all the cannulae (100%) in the SVC, IVC, and AAO were placed correctly. TEE demonstrated all the patients (100%) had successful robotic MV repairs. Conclusions: Intraoperative TEE is a valuable adjunct in the assessment of robotic MV repair. (Echocardiography, ****;**:1-7).

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Detection of Early Cardiac Dysfunction in Patients with Beta Thalassemia by Tissue Doppler Echocardiography.

Echocardiography. 2010 Aug 24;

Authors: Marcí M, Pitrolo L, Lo Pinto C, Sanfilippo N, Malizia R

Backgrounds: In this study we tried to evaluate the prognostic significance of several echocardiographic parameters on the occurrence of heart failure or arrhythmias in patients with beta thalassemia. Methods: We investigated possible differences in myocardial function between a population of 37 asymptomatic patients with beta thalassemia and 25 age-matched healthy controls, all of whom underwent an echocardiographic study, including tissue Doppler imaging (TDI), moreover plasmatic levels of N-terminal pro-BNP (NT-pro BNP) were measured in all patients. We followed the patients for 22 +/- 8 months to evaluate adverse cardiac events. Results: Conventional echocardiographic parameters of left ventricle were comparable in both groups. Whereas TDI peak systolic velocity (Sm) and diastolic parameter (E/Em ratio) were significantly abnormal in patients with thalassemia. Moreover eleven adverse cardiac events were observed during follow-up. Baseline systolic velocity (Sm) <7.9 cm/s was significantly associated with cardiac complications (P < 0.05). We also demonstrated that systolic velocity is inversely related to NT-proBNP plasmatic levels (P < 0.001). Conclusions: Our study suggests that mitral annular systolic velocity <7.9 cm/s is associated to the onset of adverse cardiac events. (Echocardiography, ****;**:1-6).

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Large Mass in Left Atrium by Transesophageal Echocardiography: An Unusual Case of Cardiac Angiosarcoma Mimicking a Cystic Mass.

Echocardiography. 2010 Aug 24;

Authors: Toledano FJ, Mesa D, Ortiz MR, Leon C

Primary cardiac tumors are extremely rare. Among them, malignant tumors constitute approximately 15% of primary cardiac tumors. Angiosarcomas are the most frequent. They often appear as mural masses in the right atrium and completely replace the atrial wall and fill the entire cardiac chamber. We report an unusual case of angiosarcoma in a 75-year-old woman with a cystic appearance, located in the left atrium and causing critical mitral stenosis. (Echocardiography, ****;**:E1-E2).

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