Apical hypertrophic cardiomyopathy--diagnosis by contrast echocardiography and magnetic resonance imaging.
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Adult↗
Biomedical subjects
Nuno Jalles Tavares
Publications and source records attributed to Nuno Jalles Tavares.
The potential role of cardiac magnetic resonance imaging in selecting patients with ischemic left ventricular dysfunction for the implantation of a cardioverter-defibrillator.
OBJECTIVES: To develop a protocol to risk stratify patients before ICD implantation in ischemic left ventricular dysfunction using magnetic resonance imaging and a gadolinium-based contrast agent. Ejection fraction as determined by other methods was reconfirmed using cardiac MRI. METHODS: Five patients considered for implantation of an ICD were prospectively offered a cardiac MR exam between Novem-ber 2003 and June 2004. All had a history of MI and LV dysfunction, had undergone complete coronary revascularization or were considered ineligible for revascularization. RESULTS: In three patients the MR ejection fractions were less than 30%, confirming the values detected by echocardiography. One patient had a larger EF by MRI compared to echo and ICD implantation was deferred. One patient thought to have an EF greater than 35% by echo on three studies was confirmed to have a much lower EF by MRI and was selected to undergo ICD implantation. CONCLUSION: Cardiac MRI can be used to further stratify patients selected for an ICD. Ejection fraction can be more reliably estimated by MRI and the presence of extensive scar can be detected. The presence of extensive scar and a low ejection fraction, which are two factors known to predispose patients to sudden cardiac death in ischemic left ventricular dysfunction, can be studied reliably by MRI.
Algorithms↗
The complementary role of cardiac magnetic resonance imaging in the evaluation of patients with aortic stenosis.
OBJECTIVE: To compare direct planimetry of aortic valve area (AVA) by cardiac magnetic resonance (CMR) imaging with transthoracic echocardiography (TTE), using the continuity equation. METHODS: 15 symptomatic patients with aortic stenosis were studied. AVA was measured with CMR from steady state free precession imaging by planimetry. AVA was also calculated by TTE images using the continuity equation. RESULTS: The evaluation of AVA by both CMR and TTE was possible in twelve out of fifteen patients. CMR was able to determine the AVA in all fifteen patients. AVAs obtained by CMR and TTE were very similar and a good correlation existed between the values obtained by either technique. CONCLUSION: CMR planimetry is highly reliable and reproducible. AVAs obtained by CMR compare well with those obtained by TTE. Therefore, CMR planimetry of AVA with steady state free precession is a useful diagnostic tool, particularly if uncertainty exists.
Aortic Valve Stenosis↗
Magnetic resonance imaging in patients with pacemakers--possible or taboo?
The presence of a pacemaker or an implantable cardioverter-defibrillator was considered an absolute contraindication for a magnetic resonance imaging study until recently. The publication of numerous studies, albeit with small numbers of patients, has challenged this assumption. With no serious adverse effects detected, it is evident that more patients with these devices will undergo an MR study. While we feel that no patient with an implanted device should be denied a potentially beneficial exam, some caution is obviously prudent and planning the study will enhance the benefit that the patient will derive while minimizing the risks.
Contraindications↗
Magnetic resonance imaging of myocardial infarction using gadolinium-based contrast agent.
OBJECTIVES: To evaluate myocardial infarcts using a segmented inversion-recovery prepared gradient echo sequence on a 1.5 Tesla MR scanner after injection of a gadolinium-based contrast agent. METHODS: Fourteen patients were prospectively offered a cardiac MR exam between November 2003 and February 2004. Six patients had a history of anterior wall MI, six had a history of inferior wall MI and two patients had MI of undetermined location. RESULTS: Delayed enhancement indicating the presence of scarring was visualized in all fourteen patients. The scarring was transmural in ten patients and non-transmural in four patients. CONCLUSION: Delayed enhancement of infarcted areas in the myocardium after injection of gadolinium-based contrast agent represents scarring and adequate resolution exists to distinguish transmural from non-transmural scarring. This technique is useful in determining viability of infarcted myocardium, may detect infarcts missed by SPECT and may help in the selection of patients for implantation of defibrillators.
Contrast Media↗
A protocol to evaluate myocardial viability in ischemic left ventricular dysfunction using magnetic resonance imaging and a gadolinium-based contrast agent.
OBJECTIVES: A protocol to evaluate myocardial viability in ischemic left ventricular dysfunction using magnetic resonance imaging and a gadolinium-based contrast agent. METHODS: Twenty-two patients were prospectively offered a cardiac MR exam between November 2003 and June 2004. Twelve had a history of anterior wall MI, eight had a history of inferior wall MI and two patients had MI of undetermined location. Eight patients had left ventricular dysfunction. RESULTS: No patient with transmural scarring extending through more than 75% of the wall recovered normal wall motion despite revascularization when evaluated fourteen months later. Of the other three with scarring extending to less than 75% there was recovery in two patients. CONCLUSION: Viability assessment by cardiac MR using gadolinium contrast is a robust technique. No segment with >75% transmural enhancement (TE) recovers despite revascularization, while all segments with <25% TE recover contractility. Between these two extremes, methods other than extent of TE may have to be used, particularly low-dose dobutamine stress testing or evaluation of percentage of hyperenhanced area compared to the normal area in each segment.
Clinical Protocols↗