Nathan Manghat

Accessory mitral valve tissue: appearance on cardiac computed tomography.

Accessory mitral valve tissue is an uncommon congenital malformation and a rare cause of left ventricular outflow tract obstruction. Although echocardiography provides a gold standard for evaluation of valves, the high temporal and spatial resolutions of computed tomography technology makes it useful in the assessment of valvular structure and function.

Presence of left atrial diverticula, accessory appendages, and normal variant pulmonary venous anatomy diagnosed using MDCT and adverse outcomes following radiofrequency catheter ablation therapy in patients with drug-refractory atrial fibrillation: An exploratory study

AIMnTo determine the frequency of normal variation left atrial anatomy (NVLAA) (diverticula, accessory appendages) and normal variation pulmonary venous anatomy (NVPVA) in patients with atrial fibrillation (AF), and to determine whether the presence of these entities is associated with an increased recurrence of atrial arrhythmias following radiofrequency catheter ablation (RFCA).nnnMATERIALS AND METHODSnAll cardiac MDCT images performed prior to RFCA between November 2009 and May 2011 in patients with drug-refractory AF were retrospectively evaluated. The presence, type, and location of NVLAA and NVPVA, and outcome of RFCA were recorded. Success was defined as restoration of sinus rhythm.nnnRESULTSnForty-six consecutive patients with a mean age of 59.8 (±9.7) years (76.1% male) underwent cardiac MDCT for anatomical planning prior to RFCA procedures. Fourteen (30.4%) patients had NVLAA, 35% of patients had NVPVA. Thirty (65%) patients had successful RFCA: 57% of these had a NVLAA, 67% had NVPVA. Sixteen (35%) patients had unsuccessful RFCA: 63% of these had a NVLAA, 56% had NVPVA. There was no significant association between the presence of NVLAA (p = 0.699), NVPVA (p = 0.197), or NVLAA in the presence of normal pulmonary venous anatomy (p = 0.589) and the outcome of RFCA.nnnCONCLUSIONnThe presence of NVLAA and NVPVA appears unrelated to adverse outcome in patients undergoing RFCA for the treatment of drug-refractory AF.

The In Vivo Morphology of Post-Infarct Ventricular Septal Defect and the Implications for Closure

OBJECTIVESnThe aim of this study was to define the dynamic inxa0vivo morphology of post-infarct ventricular septal defect (PIVSD), which has not been previously described in living patients.nnnBACKGROUNDnPIVSD is a devastating complication of acute myocardial infarction.nnnMETHODSnThe anatomic features of PIVSD, as demonstrated by computed tomography or magnetic resonance imaging, were retrospectively reviewed.nnnRESULTSnThirty-two PIVSDs were assessed, 16 left coronary artery and 16 right coronary artery PIVSDs. PIVSDs were large (mean maximum dimension 26.5 ± 11.5 mm, mean area 5.2 ± 4.2 cm2) and oval (mean eccentricity index 1.7 ± 0.5), with thin margins (diastolic mean thickness 5 mm from the edge of the PIVSD 6.4 ± 3.0mm), and only 22% of PIVSDs were entirely confined to the septum. The defects could be larger in diastole or systole. The stem of the largest available Amplatzer occluder stem (St. Jude Medical, St. Paul, Minnesota) filled only 50% of defects. Patients with small defects may survive without closure. Without closure, those with large defects die. If accepted for closure, PIVSD size and coronary territory did not predict survival >1xa0year (overall 60%).nnnCONCLUSIONSnThis is the first detailed anatomic description of PIVSD in living patients. Defects may be larger in systole or diastole, meaning that single-phase measurement is unsuitable. Its complex nature means that the most commonly available occluder device is frequently unsuitable. Successful closure leads to prolonged survival and should be attempted where possible. This study may lead to improved patient selection, closure techniques, and device design.

Application of TWIST MR angiography to aid successful central venous access in challenging patients: initial single-centre experience.

AIMnTo investigate whether time-resolved angiography with interleaved stochastic trajectories (TWIST) with GeneRalised Autocalibrating Partially Parallel Acquisitions (GRAPPA) parallel acquisition could be used successfully to non-invasively and efficiently image patients with more complex vascular access issues.nnnMATERIALS AND METHODSnTWIST magnetic resonance angiography (MRA) in the GRAPPA algorithm was performed on 15 patients at our centre using the 1.5 T Siemens Magnetom Avanto MRI system. Images were interpreted by cardiac radiologists.nnnRESULTSnTWIST provided excellent dynamic imaging of the venous system, demonstrating venous occlusion, stenoses, and collaterals, as well as providing good anatomical detail.nnnCONCLUSIONnTWIST MRA enables successful identification of candidate sites for central/tunnelled line access, whilst diagnosing complications of long-term access such as venous thrombosis or congenital venous anomalies.

Comparison between a fixed-dose contrast protocol and a weight-based contrast dosing protocol in abdominal CT.

AIMnTo compare a fixed-dose intravenous iodinated contrast medium protocol with weight-based dosing protocols for abdominal computed tomography (CT).nnnMATERIALS AND METHODSnFifty patients were scanned using a fixed-dose protocol, 50 patients were scanned using a full-dose weight-based contrast dosing protocol, and 13 patients were scanned using a reduced dose weight-based protocol. Radiodensity was measured at the portal vein, aorta, spleen, and liver. These values were plotted against contrast medium dose per unit weight. Images from all patients were anonymised and presented to two independent consultants who subjectively assessed contrast enhancement using a five-point Likert scale.nnnRESULTSnUsing a fixed-dose protocol, there was a statistically significant negative correlation and trend between patient weight and radiodensity at the portal vein, aorta, spleen, and liver. Using a full-dose weight-based contrast dosing protocol, there was no longer a statistically significant correlation or trend implying a more consistent degree of enhancement over a spectrum of patient weights. In addition, when the full-dose weight-based contrast dosing protocol was used, there was a statistically significant increase in the number of scans subjectively assessed as having ideal enhancement and a statistically significant decrease in the number of scans felt to have excessive enhancement when compared to a fixed-dose protocol. The weight-based dosing protocol used less contrast medium than the fixed-dose protocol and there was no evidence of contrast-induced acute kidney injury (CIAKI) in any of the patients that received a greater dose than that which they would have received using a fixed-dose protocol. The reduced-dose weight-based protocol showed less objective enhancement of the portal vein, abdominal aorta, spleen, and liver compared to the full-dose protocol and a reduction in the number of scans perceived as showing ideal enhancement. There was, however, no increase in the number of scans with poor or non-diagnostic enhancement.nnnCONCLUSIONnWeight-based contrast medium dosing has been shown to objectively provide more consistent vessel and solid-organ enhancement and subjectively improve image quality across a spectrum of weights. Depending on mean patient mass, it has also been shown to reduce overall contrast medium dose, and there is no evidence of CIAKI in patients that receive larger doses. This study also postulates that a standardised approach to contrast medium dose reduction in patients with renal impairment may be a viable strategy.

Role of cardiac MRI and CT in Fontan circulation

A Fontan circulation is a series of palliative surgical procedures, which result in the diversion of the systemic venous return into pulmonary arterial circulation without passing through a ventricle. It is one of the available surgical strategies for patients with cardiac defects that preclude a successful bi-ventricular repair, which encompass a range of complex anatomy. This surgical repair has gone through a series of modifications since the concept was introduced in 1971. Echocardiography remains a vital tool in assessing patients with Fontan circulations but its limitations are well recognised. Cross-sectional imaging modalities such as cardiac MRI and CT are essential components in the systematic clinical evaluation of these patients. The purpose of this review is to understand the information that can be obtained with each cross-sectional modality as well as highlight the challenges that each modality faces.

First successful trans-catheter aortic-valve replacement for native aortic stenosis in atrio-pulmonary Fontan

Fig. 1. Multi-detector computed tomography. Multi-planar reformatting performed to Any form of cardiac surgery, including aortic valve surgery, in an adult patient with a Fontan circulation is a very high risk procedure [1]. Trans-catheter aortic valve replacement (TAVR) has typically been reserved for inoperable and higher risk aortic stenosis (AS); and increasing used in bicuspid aortic valve [2]. Nevertheless, the use of TAVR in the complex congenital cardiac heart disease (CHD) remains scarce. We describe the first case where trans-catheter aortic valve (TAVR) was performed in a patient for native AS with an atriopulmonary Fontan. A 53 year-oldwoman presentedwith increasing breathlessness over 1 year (NYHA Class III). Her cardiac anatomy was tricuspid and pulmonary atresia which was initiated palliated with a Brock procedure (closed pulmonary valvotomy), followed by a right classic BlalockTaussig shunt, and finally with an atrio-pulmonary Fontan (right atrium to main pulmonary artery conduit) at 12 years of age. Echocardiography demonstrated severe aortic stenosis (peak gradient 85 mm Hg, mean gradient 50mmHg) together withmild ventricular systolic impairment. Chest X-ray revealed a large right pleural effusion. Her logistic Euroscore II aortic valve surgical morality score (10.2%) was lower than her American College of Cardiology (ACC) adjusted TAVR in-hospitalmortality risk score(2.1%) though neither of these adequately describe the risk of the procedure in an older atrio-pulmonary Fontan patient. Pre-procedural imaging was crucial in TAVR planning with a gated CT scan performed (Fig. 1) to facilitate accurate crucial measurements of the aortic valve morphology for valve selection.

008 Comparison of weight-based vs estimated contrast dose techniques in coronary computed tomography angiography

Introduction The purpose of this study was to compare weight based versus estimated contrast dosing techniques in coronary computed tomography angiography (CCTA). Methods This single centre retrospective observational study compared 47 patients undergoing CCTA. All imaging was performed on a 320 slice scanner at 100kV with bolus tracking. In the weight based protocol, patients received 22mg/kg/s of contrast for 14 s. In the estimated group, contrast dosing and rate was estimated by a consultant cardiac radiologist. Two tailed t tests determined significance between patient and contrast variables. Enhancement of cardiac chambers and coronary arteries was calculated through region of interest areas in Hounsfield units (HUs). Results There were no significant differences between the groups in terms of mean weight (p = 0.42) or mean heart rate (p = 0.29). The estimated group received a significantly higher volume of contrast than the weight based group (71mls vs 58mls, p= <0.001). There was a non-significant difference between groups in MEV of coronaries. Both groups produced diagnostic MEVs above 400 HUs. Right sided chambers were attenuated significantly more in the best guess than the weight based group, for example right ventricle MEV 279 vs 141 (p = 0.01). SDs in coronary arteries were similar between groups but weight based contrast protocol achieved lower standard deviation of HUs on the right sided chambers. Conclusion Weight based and estimated contrast regimes produce similar variability and adequate opacification in coronary arteries in CCTA. However, weight adjusted contrast dosing technique administers a lower dose of contrast, with lower enhancement of the right sided chambers.

Non-Invasive Imaging of Coronary Artery Disease — The Expanding Role of Coronary Computed Tomographic Angiography in the Management of Low- to Intermediate-Risk Patients and Dealing with Intermediate Stenosis

Non-invasive anatomic imaging modalities play a crucial role in the diagnosis of coro‐ nary artery disease (CAD), particularly in the case of the symptomatic patient presenting in the emergency department. Some of the key issues of discussion will be the appropriate use of coronary computed tomography (CT) in the anatomical assessment of CAD, the prognostic information that this assessment holds and how the role of CT may evolve in the coming years. The aim of this chapter is to summarise and evaluate the current best non-invasive ana‐ tomical strategies of CAD imaging, notably in those with a low to intermediate pre-test risk of CAD and those with an intermediate luminal stenosis.

Myocardial neuroendocrine tumour metastasis mimicking melanoma: multimodality imaging diagnosis

A 77-year-old woman was referred for transthoracic echocardiogram (TTE) following episodes of paroxysmal atrial flutter. TTE showed an echogenic mass within the apical interventricular septum ( Panel A , arrow). There was mild mitral and tricuspid regurgitation, but the valve leaflets were normal. On contrast-enhanced thoracic computed tomography (CT), the mass showed …