MRI of patients with cardiac pacemakers: a review of the medical literature.

OBJECTIVE: Numerous studies testing the use of pacemakers with MRI have been published. Our aim was to analyze these trials to determine the safety of MRI for patients with cardiac pacemakers. We performed a systematic search of peer-reviewed databases. A total of 31 articles were reviewed. CONCLUSION: The data are heterogeneous with regard to MRI being considered for patients with pacemakers, and the benefits of the imaging should outweigh the risks.

Multislice coronary computed tomographic angiography in emergency department presentations of unsuspected acute myocardial infarction.

BACKGROUND: Coronary computed tomographic angiography (CCTA) is not indicated in the setting of acute myocardial infarction in the emergency department (ED). Nonetheless, acute coronary syndromes may have atypical presentations, and CCTA may be inadvertently performed in this setting. OBJECTIVES: This study was designed to determine the frequency and characteristics of CCTA imaging of unsuspected acute myocardial infarction in the ED. METHODS: All CCTAs performed in the ED at Lenox Hill Hospital were reviewed for clinical indications and subsequent course; patients with documented acute myocardial infarction were identified. RESULTS: Of the 500 CCTAs performed on ED patients in the Lenox Hill laboratory, 5 patients (1%) were imaged during the initial phase of an unsuspected acute myocardial infarction; in all cases the CCTAs were key to the diagnosis. The imaging characteristics were (1) total or subtotal occlusion and (2) transmural hypodensity in the infarct area. CONCLUSION: Although acute myocardial infarction on CCTA in ED patients is an infrequent event, proper and prompt recognition is critical for appropriate patient care, particularly as applications to the ED increase.

Stent gap by 64-detector computed tomographic angiography relationship to in-stent restenosis, fracture, and overlap failure.

OBJECTIVES: The goal of this study was to define the frequency of stent gaps by 64-detector computed tomographic angiography (CTA) and their relation to in-stent restenosis (ISR), stent fracture (SF), and overlap failure (OF). BACKGROUND: SF defined by catheter angiography or intravascular ultrasound has been implicated in ISR. METHODS: A total of 292 consecutive patients, with 613 stents, who underwent CTA were evaluated for stent gaps associated with decreased Hounsfield units. Correlations with catheter coronary angiography (CCA) were available in 143 patients with 384 stents. RESULTS: Stent gaps were noted in 16.9% by CTA and 1.0% by CCA. ISR by CCA was noted in 46.1% of the stent gaps (p < 0.001) as determined by CCA, and stent gaps by CTA accounted for 27.8% of the total ISR (p < 0.001). In univariate analysis, stent diameter > or =3 mm was the only CCA characteristic significantly associated with stent gaps (p = 0.002), but was not a significant predictor by multivariate analysis. Bifurcation stents, underlying calcification, stent type, location, post-dilation, and overlapping stents were not observed to be predisposing factors. Excessive tortuosity and lack of conformability were not associated with stent gaps; however, their frequency was insufficient to permit meaningful analysis. CONCLUSIONS: Stent gap by CTA: 1) is associated with 28% of ISR, and ISR is found in 46% of stent gaps; 2) is associated with > or =3-mm stents by univariate (p = 0.002) but not by multivariate analysis; 3) is infrequently noted on catheter angiography; and 4) most likely represents SF in the setting of a single stent, and may represent SF or OF in overlapping stents.

How much calcium is too much calcium for coronary computerized tomographic angiography?

The coronary artery calcium (CAC) score above which it is recommended that coronary computerized tomographic angiography (CTA) not be performed has been steadily increasing. Currently, calcium scores > 1000 are thought to prohibit CTA accurate interpretation. However, a reasoned approach suggests that there is no absolute upper limit that applies to all patients and imaging centers. To anticipate the problems posed by calcium, a CAC scan must be obtained before CTA. Understanding the clinical goals of the CTA and the source and recognition of CAC-based imaging artifacts can enable accurate clinical CTA examinations even in the setting of high calcium scores.

Unusual left atrial appendage mass: atypical presentation of papillary fibroelastoma.

Papillary fibroelastomas are small, histologically benign neoplasms that are typically found on the valvular endocardium. We report a patient with a papillary fibroelastoma in an unusual location: the left atrial appendage. Although the mass was visualized both by computed tomography (CT) and transesophageal echocardiography, the diagnosis was histologically confirmed after surgical excision.

Evaluating cardiac sources of embolic stroke with MRI.

The evaluation of patients with stroke includes identifying its etiology in order to appropriately tailor therapy. Currently, the diagnostic work-up includes imaging of the brain, the arteries of the head and neck, the aorta, and the heart. Traditional methods of imaging include magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), duplex ultrasound, and transthoracic echocardiography (TTE) and/or transesophageal echocardiography (TEE). While echocardiography remains a cornerstone in the field of cardiac imaging, MRI is increasingly able to assess for the most common causes of cardioembolic stroke such as left atrial/left atrial appendage thrombus, left ventricular thrombus, aortic atheroma, cardiac masses and patent foramen ovale. This review will focus on the advantages and limitations of echocardiography and cardiac magnetic resonance (CMR) imaging in diagnosing patients suspected of having an embolic stroke and the role these modalities play in clinical practice today.