P. Mottram

Current and Evolving Clinical Applications of Multidetector Cardiac CT in Assessment of Structural Heart Disease

Multidetector computed tomography (CT) has an established role in the evaluation of selected patients suspected of having coronary disease; however, in addition to coronary assessment, multidetector CT can be used to evaluate numerous noncoronary structures in the same examination. In particular, the use of multidetector CT to provide pulmonary and cardiac venous anatomic information prior to electrophysiology procedures is well established, and its important role in the periprocedural evaluation of patients undergoing percutaneous procedures, such as transcatheter aortic valve replacement and left atrial appendage device occlusion, is being increasingly recognized. Such advances have resulted in multidetector CT being increasingly used as a complementary imaging technique to echocardiography and magnetic resonance imaging for the comprehensive evaluation of cardiac structure and function in particular clinical situations. This review provides an overview of the noncoronary cardiac structures that can be evaluated with multidetector CT, and outlines the established appropriate clinical uses of multidetector CT in the assessment of structural heart disease, as well as evolving periprocedural clinical applications.

Transcatheter Closure of Secundum Atrial Septal Defects: Results in Patients with Large and Extreme Defects

BACKGROUND Transcatheter closure of moderate sized atrial septal defects (ASD) has been demonstrated to be safe and effective. However, the feasibility of transcatheter closure of very large defects is less clear, particularly when an aortic rim of septal tissue is absent. METHODS The study included patients referred for transcatheter ASD closure with maximal ASD diameter ≥ 20 mm at pre-procedural transoesophageal echocardiography. Patients were grouped according to presence of moderately large (20-29 mm), very large (30-39 mm), or extremely large (≥ 40 mm) ASD size. Procedural success was defined by successful device deployment and absence of complications. RESULTS Forty-two patients (median age 40 years, range 12-85 years, 76% female) were included in the study. The mean maximal ASD diameter was 29.0 ± 7.4mm. Twenty-three patients had moderately large ASDs (23.0 ± 2.8mm); 13 had very large ASDs (33.1 ± 2.9 mm) and six had extremely large ASDs (41.3 ± 1.6 mm). The aortic rim was absent in 22 patients, and present in 20 patients (4.7 ± 2.9 mm). Transcatheter defect closure was successful in 36 of 42 patients (86%). Procedural success was 100% in the moderately large ASD group, 92% in the very large group but only 17% (one out of six) in the extremely large group. If patients with ASD ≥ 40 mm were excluded (n = 6), the overall success rate was 97%. A single complication (device dislodgement) occurred in a patient with a 42 mm defect and a deficient postero-inferior rim. The presence or absence of an aortic rim of septum did not influence procedural success. CONCLUSION The vast majority (97%) of large ASDs in the range 20-39 mm can be successfully closed percutaneously with a low or zero complication rate. However, procedural success is poor when attempting closure of extreme defects (≥ 40 mm), regardless of whether an aortic rim of septal tissue or present or absent.

Echocardiographic quantification of left ventricular systolic function.

Assessment of left ventricular (LV) systolic function is the most common indication for performing an echocardiogram and, correspondingly, the detection and quantification of systolic dysfunction hold major implications for patient diagnosis and management. However, no perfect measure of ‘systolic function’ exists and there are fundamental limitations inherent to all currently available surrogates. In this clinically focussed editorial, we examine what can actually be measured by echocardiography, identify the techniques with established practical utility and consider their current and potential roles in guiding clinical practice. What can be measured by echocardiography? The physiological parameter that most accurately represents systolic function is contractility - the ability of myocardium to contract against a specific load for any given preload. Assessment of contractility requires simultaneous and continuous measurement of LV pressure and volume over multiple cardiac cycles with manipulation of preload to generate pressure-volume loops across a range of loading conditions. At present, this can only be achieved accurately by invasive methods using conductance catheters. In contrast, all of the commonly utilised echocardiographic (and other non-invasive imaging) techniques for assessing systolic function measure contraction ‐ essentially the degree of myocardial fibre shortening that occurs during systole. This is dictated by the degree of preceding myocardial stretch (preload) and the pressure against which it contracts (afterload) as well as intrinsic contractile function. Consequently, all techniques based on assessment of contraction provide ‘load-dependent’ measurements of systolic function. Nonetheless, a comprehensive echo study provides important insight into the prevailing loading conditions and integration of this information with the indices of LV contraction informs the overall evaluation of systolic function. It should also be borne in mind that our aim, ultimately, is not to quantify systolic function as a physiological parameter but to detect and grade clinically meaningful systolic dysfunction. It is therefore preferable to evaluate echo-based indices of systolic function against a clinical standard rather than a pure physiological one. Clinically useful measures should ideally correlate with symptoms of heart failure, predict the subsequent development of adverse events and, most importantly, provide a proven basis for therapeutic decision making.

Role for the left atrial appendage occlusion device in managing thromboembolic risk in atrial fibrillation

Only 50% of patients who would benefit from warfarin therapy for atrial fibrillation (AF) receive treatment because of clinical concerns regarding chronic anti‐coagulation. Percutaneous strategies to treat AF, including pulmonary vein isolation with a curative intent or atrioventricular nodal ablation and implantation of a permanent pacemaker for palliative rate control, have not eliminated the need to manage thromboembolic risk. With the development of a percutaneous left atrial appendage (LAA) occlusion device (the WATCHMAN percutaneous left atrial appendage occluder – Atritech Inc., Plymouth, MN, USA) for thromboembolic protection in non‐valvular AF a significant therapeutic option for select patients may be available. We present the first case performed in Australia (24 November 2009) and explore this new methodology.

Timing of the carotid pressure wave inflection point is coupled to systolic myocardial motion

cyte and monocyte subset activation, inflammatory markers and ambulatory blood pressure were measured at baseline and at 3 and 6 months after RDN. Results: MAN-1 binding to monocytes significantly decreased at 3months (p<0.01) and 6months (p<0.01), indicative of a reduction in monocyte activation. In particular, classicalmonocyte subset activationwas reduced at 6months (p<0.05) after RDN. Monocyte-Platelet Aggregates were reduced at 3 months (p<0.01) but not at 6 months (p=0.1387). Plasma levels of MCP-1 (3 months p<0.0001; 6 months p=0.0747) and IL-1 (3 months p<0.05; 6 months p=0.2005) were also reduced after RDN. The ambulatory blood pressure was reduced from 152/81mmHg to 146/79mmHg (p<0.05). Conclusion: RDN induced reduction in renal sympathetic nerve activity is associatedwith reducedmonocyte activation and inflammation in hypertensive patients.

The Impact of Increased Pulmonary Velocity on Estimated Pulmonary Artery Pressure During Exercise Stress Echocardiography

Background: Assessing pulmonary artery pressure (PAP) during stress echocardiography (ESE) is recommended for patients with dyspnoea and valvular heart disease. Right ventricular systolic pressure (RVSP) equals PAP in the absence of significant right ventricular outflow tract gradient/obstruction. When reporting resting transthoracic echocardiograms, the antegrade pulmonary gradient is routinely subtracted from RVSP when the pulmonary velocity (PV)≥ 1.5m/s (9mmHg), however this correction has not been applied during ESE despite increased pulmonary flow associated with exercise. We evaluated the impact of increased PV with exercise on estimated PAP. Methods: We prospectively evaluated 114 consecutive patients referred for ESE (mean age 55, female 47%). Peak pulmonary and tricuspid velocities (TV) were obtained pre and post-exercise. RVSPwas calculatedwhere an adequate TR Doppler envelope was obtained. Results: PV was obtained in all patients preand post-exercise. PV increased from 1.03± 0.46m/s to 1.57± 1.0m/s post-exercise (p 1.5m/s, mean peak corrected PAP was significantly lower than if uncorrected (31.2± 9.3mmHg vs 43.6± 9.7mmHg, p 40mmHg (15% vs 60%, p= 0.003) and PAP>50mmHg (5% vs 25%, p= 0.07). Conclusions: In a cohort of patients undergoing ESE, a significant proportion of patients had a PV>1.5m/s postexercise.Correcting for PV resulted in a significantly lower calculatedPAPpost-exercise suggesting that current practise may overestimate PAP with exercise.

What is the Clinical Relevance of Pericardial Effusion Reported on Chest Computed Tomography Performed for General Indications in a Tertiary Hospital? A Comparison With Transthoracic Echocardiography

low ( 20%) and very high risk (>40%). Results: During follow-up (mean 2.3± 1 years), 57 patients suffered an event. The annualized event rate for patients with a normal CTA (n= 514, 36%) was 0.6%, 1.3% for non-significant CAD (n= 483, 34%) and 3.7% for significant CAD (442, 31%). In patients with a CAP-CT risk score 16 (n= 242, 17%). The CAP-CT risk score reclassified 287(20%) patients with non-significant or significant CAD to a lower risk group, and 443(31%) to a higher risk group. Conclusion: The integration of plaque extent, severity, composition and location on CTA into a single risk model provides good discrimination between low, high and very high risk for future cardiovascular events, compared to conventional CTA classification. doi:10.1016/j.hlc.2010.06.494