Aortic root measurement on CT: linear dimensions, aortic root area and comparison with echocardiography. A retrospective cross sectional study.

OBJECTIVE: We sought to assess the different CT aortic root measurements and determine their relationship to transthoracic echocardiography (TTE). METHODS: TTE and ECG-gated CT images were reviewed from 70 consecutive patients (mean age 54 ± 18 years; 67% male) with tricuspid aortic roots (trileaflet aortic valves) between Nov 2009 and Dec 2013. Three CT planes (coronal, short axis en face and three-chamber) were used for measurement of nine linear dimensions. TTE aortic root dimension was measured as per guidelines from the parasternal long axis view. RESULTS: All CT short axis measurements of the aortic root had excellent reproducibility (intraclass correlation coefficient, ICC 0.96-0.99), while coronal and three-chamber planes had lower reproducibility with ICC 0.90 (95% CI 0.84-0.94) and ICC 0.92 (0.87-0.95) respectively. CT coronal and short axis maximal dimensions were systematically larger than TTE (mean 2 mm larger, p < 0.001), while CT cusp to commissure measurements were systematically smaller (CT RCC-comm mean 2 mm smaller than TTE, p < 0.001). All CT short axis measurements had excellent correlation with aortic root area with CT short axis maximal dimension marginally better than the rest (Pearson's R 0.97). CONCLUSION: Systematic differences exist between CT and TTE dependent on the CT plane of measurement. All CT short axis measurements of the aortic root had excellent reproducibility and correlation with aortic root area with maximal dimension appearing marginally better than the rest. Our findings highlight the importance of specifying the chosen plane of aortic root measurement on CT. ADVANCES IN KNOWLEDGE: Systematic differences in aortic root dimension exist between TTE and the various CT measurement planes. CT coronal and short axis maximal dimensions were systematically larger than TTE, while CT cusp to commissure measurements were smaller. CT readers should indicate the plane of measurement and the specific linear dimension to avoid ambiguity in follow-up and comparison.

Modified Precordial Lead R-Wave Deflection Interval Predicts Left- and Right-Sided Idiopathic Outflow Tract Ventricular Arrhythmias.

OBJECTIVES: This study evaluated if modifying electrocardiographic (ECG) precordial leads to a higher intercostal position improved the accuracy of outflow tract ventricular arrhythmia (OTVA) localization. BACKGROUND: Precordial ECG prediction algorithms that use a standard lead configuration localize OTVA with variable accuracy. METHODS: Patients who underwent OTVA ablation were prospectively enrolled to have a standard and modified (high) precordial ECG. R- and S-wave amplitudes and intervals were measured to develop an algorithm that differentiated the right ventricular outflow tract (RVOT) and the left ventricular outflow tract (LVOT) with high accuracy-the modified lead R-wave deflection interval (RWDI). This interval was defined from the earliest QRS onset (using all modified leads) to the lead with longest R-wave deflection. The RWDI was compared with all other ECG algorithms. RESULTS: A total of 50 patients (38 women; mean age 51 ± 17 years) had successful catheter ablation for OTVA (RVOT 60%, LVOT 40%). The modified lead RWDI was significantly shorter in the RVOT group (18.5 ms, interquartile range 25th to 75th percentile [IQR25-75]: 0 to 29.5 ms) compared with the LVOT group (67.5 ms, IQR25-75: 56.5 to 77 ms; p < 0.05). Using a RWDI ≤40 ms to predict an RVOT focus, the sensitivity and specificity of the modified lead RWDI were 100% and 95%, respectively; the area under the receiver-operating characteristic curve was 0.96. This was superior to all previously developed algorithms. In a computed tomography analysis (n = 50), the modified leads were significantly closer to the outflow tracts compared with the standard precordial leads. CONCLUSIONS: The modified lead RWDI is a simple, easily interpretable algorithm that can potentially differentiate a right- or left-sided origin of OTVA with high accuracy.

Epicardial Adipose Tissue Accumulation Confers Atrial Conduction Abnormality.

BACKGROUND: Clinical studies have reported that epicardial adipose tissue (EpAT) accumulation associates with the progression of atrial fibrillation (AF) pathology and adversely affects AF management. The role of local cardiac EpAT deposition in disease progression is unclear, and the electrophysiological, cellular, and molecular mechanisms involved remain poorly defined. OBJECTIVES: The purpose of this study was to identify the underlying mechanisms by which EpAT influences the atrial substrate for AF. METHODS: Patients without AF undergoing coronary artery bypass surgery were recruited. Computed tomography and high-density epicardial electrophysiological mapping of the anterior right atrium were utilized to quantify EpAT volumes and to assess association with the electrophysiological substrate in situ. Excised right atrial appendages were analyzed histologically to characterize EpAT infiltration, fibrosis, and gap junction localization. Co-culture experiments were used to evaluate the paracrine effects of EpAT on cardiomyocyte electrophysiology. Proteomic analyses were applied to identify molecular mediators of cellular electrophysiological disturbance. RESULTS: Higher local EpAT volume clinically correlated with slowed conduction, greater electrogram fractionation, increased fibrosis, and lateralization of cardiomyocyte connexin-40. In addition, atrial conduction heterogeneity was increased with more extensive myocardial EpAT infiltration. Cardiomyocyte culture studies using multielectrode arrays showed that cardiac adipose tissue-secreted factors slowed conduction velocity and contained proteins with capacity to disrupt intermyocyte electromechanical integrity. CONCLUSIONS: These findings indicate that atrial pathophysiology is critically dependent on local EpAT accumulation and infiltration. In addition to myocardial architecture disruption, this effect can be attributed to an EpAT-cardiomyocyte paracrine axis. The focal adhesion group proteins are identified as new disease candidates potentially contributing to arrhythmogenic atrial substrate.

Percutaneous Transvenous Mitral Valve-in-Valve Implantation Using Commercially Available Transcatheter Valve. First Australian Experience.

In patients with a degenerative mitral bioprosthesis and prohibitive surgical risk there is emerging evidence for the feasibility of valve-in-valve procedures via a percutaneous transvenous transseptal approach. This paper describes the first time this procedure has been performed in Australia.

A rare case of a pericardial mass: Myelosarcoma from relapsed acute monoblastic leukaemia without bone marrow involvement.

INTRODUCTION: A 67-year-old male presented with progressive exertional dyspnoea, night sweats and 25 kg of weight loss over 2 years. He was febrile, 38.0°C, hypotensive and tachycardiac. Pulsus paradoxus was present. His electrocardiogram showed electrical alternans. He had previously had acute myeloid leukaemia treated with three cycles of chemotherapy. RESULTS: The patient was found to have a 3.6 cm pericardial effusion with features consistent with tamponade and three cardiac masses (largest 10 × 9 × 5 cm) and mediastinal lymphadenopathy. He had 825 mL of pericardial fluid drained from which cytology was consistent with extramedullary leukaemia. A bone marrow aspirate and trephine was normal. CONCLUSION: The findings suggested extramedullary recurrence of leukaemia in the pericardium, without bone marrow involvement.