TRACK 5: CARDIOLOGY AND THE IMAGING REVOLUTION Volume 10 • Number 1 Abstract no: 1 Summer 2013 Real time 3-D echocardiographic characteristics of left ventricle and left atrium in normal children Bao Phung Tran Cong, Nii Masaki, Miyakoshi Chihiro, Yoshimoto Jun, Kato Atsuko, Ibuki Keichiro, Kim Sunghae, Mitsushita Norie, Tanaka Yasuhiko and Ono Yasuo Cardiac Department, Shizuoka Children’s Hospital, Shizuoka, Japan Background: The accurate assessment of left atrial (LA) and/or left ventricular (LV) volume and contractility is crucial for the management of patients with congenital heart disease. The real time 3-dimensional echocardiography (RT3-DE) is reported to show better correlation with magnetic resonance imaging (MRI) in estimating LV and LA volume than conventional 2-dimensional echocardiography (2-DE). On the other hand, the volume measurement in RT3-DE is also reported to be significantly smaller than those in MRI, necessitating the establishment of normal values of RT3-DE itself. Aim: To identify the normal values of LV and LA volume measured by RT3-DE in Japanese children. Methods: Sixty four normal school students (age: median 9.6 years; range (5.5 - 14.5); male 26, female 38) were enrolled in this study. End-diastolic and end- systolic LV and LA volumes were analysed using M-mode in short-axis view, 2-D biplane method, and RT3-DE. We used IE-33 (PHILIPS) with matrix probe X7 and X4. Off-line assessment to calculate LA and LV volume was done using QLAB 8.1 (Philips). Results: Forty nine children (age: median 9.1 years, range (6 - 14); male 21, female 28) had adequate RT3-DE data sets and were analysed. ■ RT3-DE: LV end-diastolic volume index (LVEDVI) = 51.4±5.7ml/m2, LV end-systolic volume index (LVESVI) = 21.0±4.2ml/m2, max LA volume index (LAVI) = 21.4± 5.0ml/m2, min LAVI = 7.7± 2.7ml/m2, LV ejection fraction (LVEF) = 59.1±6.9%, and LA volume change ((max LAV-min LAV)/max LAV *100%) = 63.7±9.3%. ■ M-mode: LVEDVI = 70.9±10.8ml/m2, LVESVI = 23.5± 5.5ml/m2, LVEF = 66.8±6.1%. ■ 2-DE biplane: max LAVI = 22.8± 5.6ml/m2 LV end-diastolic volume on RT3-DE showed good linear correlation with body surface area (BSA): LVEDV = -4.52+55.75*BSA, R^2=0.746 Conclusion: Approximately 77% of normal children had adequate RT3-DE images. The discrepancy of LVEDV between RT3-DE and M-mode was significant and the measurements of RT3-DE were constantly smaller than those of M-mode. Abstract no: 4 Reduced aortic elasticity and ventricular dysfunction late after paediatric meningococcal septic shock: A precursor of atherosclerosis? Heynric Grotenhuis*, Hennie Knoester*, Jeanine Sol* and Albert de Roos# *Emma Children’s Hospital, Academic Medical Centre, Amsterdam, The Netherlands #Leiden University Medical Centre, The Netherlands Objectives: To prospectively assess aortic elasticity and biventricular systolic and diastolic function in pediatric patients after meningococcal septic shock (MSS) by using magnetic resonance imaging (MRI). Background: Given the strong similarities in inflammatory pathways between septic shock and atherosclerosis, aortic wall abnormalities and associated ventricular sequelae may be expected after MSS. Methods: Eighteen pediatric MSS survivors (8 male; age 14.5 years ± 3.9; MRI 8.2 years ± 2.4 after MSS) treated with at least 2 inotropic and vasoconstrictive agents for >48 hours and 18 matched controls were studied. Routine MRI was used to assess aortic pulse wave velocity (PWV) and systolic and diastolic biventricular function. Results: MSS patients showed reduced aortic elasticity vs. controls (PWV aortic arch: 4.1m/s±0.3 vs. 3.3m/s±0.5, p<0.01; PWV descending aorta: 3.9m/s±0.9 vs. 3.2m/s±0.4, p<0.01). Systolic biventricular function was preserved (LV ejection fraction 57%±8 vs. 56%±6, p=0.74; RV ejection fraction 56%±8 vs. 52%±6, p<0.01), whereas biventricular mass was increased (LV 52.1gram/m2±8.4 vs. 36.0gram/m2±9.9, p<0.01; RV 26.8gram/m2±6.5 vs. 10.4gram/m2±5.0, p<0.01). Also, delayed biventricular relaxation was found after MSS: E -wave deceleration time was significantly prolonged across the mitral valve (MV) (184msec±61 vs. 116msec±28, p<0.01) and tricuspid valve (TV) (192msec±67 vs. 126msec±40, p<0.01) with loss of diastasis time (MV: 22msec±35 vs. 159msec±92, p<0.01; TV: [13msec±24 vs. 113msec±70, p<0.01]). Also, peak filling rates corrected for end-diastolic-volume (PFREDV) across the MV and TV were significantly reduced (MV: PFREDV of E-wave 2.54±0.56 vs. 3.08±0.63, p=0.01; PFREDV of A-wave 1.10±0.26 vs. 1.31±0.30, p=0.03; TV: PFREDV of E-wave 1.81±0.44 vs. 2.09±0.29, p=0.04; PFREDV of A-wave 1.11±0.22 vs. 1.42±0.39, p<0.01). Increased PWV in aortic arch and descending aorta were associated with increased LV mass (r=0.62, p<0.01, and r=0.51, p<0.01, respectively) and delayed LV relaxation parameters (MV diastasis: r=0.50, p0.01, and MV E deceleration time r=0.38, p=0.03, MV diastasis r=0.34, p=0.04, respectively). Conclusions: Despite adequately preserved systolic biventricular function, reduced aortic elasticity in pediatric patients after MSS may indicate aortic wall pathology, being associated with ventricular hypertrophy and concomitant delayed ventricular relaxation. Long-term prognosis in MSS survivors may therefore be negatively affected considering the cumulative effects of cardiovascular disease and aging during a lifetime. Abstract no: 6 Predicting sub-endocardial ischaemia in humans Julien Hoffman* and Gerald Buckberg# *Department of Paediatrics, University of California, San Francisco, California, United States of America #Department of Cardiothoracic Surgery, University of California, Los Angeles, California, United States of America DPTI (1) Background: In 1972 we demonstrated that a ratio SPTI <0.8 predicted relative subendocardial ischaemia in normal dogs. (DPTI: area between aortic and left atrial diastolic pressures; SPTI: area below systolic LV pressure curve.) To correct for anaemia, multiply DPTI by arterial oxygen content (ml/100ml blood);(2) the critical ratio is ∼10. This ratio probably applies to normal human hearts,(3) but not to hearts with hypertrophy or dilatation in which SPTI underestimates 193 ABSTRACTS - SA HEART CONGRESS 2013 (4) myocardial oxygen demand (MVO2) in proportion to excess wall tension or wall thickness. In most abnormal hearts, wall tension remains normal, so that MVO2 ∝ mass or wall thickness, and the critical ratio must be multiplied by relative wall thickness. If wall tension rises because of ventricular dilatation, then the ratio must be multiplied also by the relative wall tension.(5) These variables can be quantitated easily by echocardiography and applied to patients. References: 1. G.D. Buckberg, et al. Experimental subendocardial ischaemia in dogs with normal coronary arteries. Circ Res 1972;30:67-81. 2. J. Brazier, N. Cooper, G.D. Buckberg, The adequacy of subendocardial oxygen delivery: The interaction of determinants of flow, arterial oxygen content and myocardial oxygen need. Circulation1974;49:968-977. 3. R.J. Barnard, et al. Ischaemic response to sudden strenuous exercise in healthy men. Circulation 1973;48:936-42. 4. W. Grossman, D. Jones, L.P. McLaurin. Wall stress and patterns of hypertrophy in the human left ventricle. J Clin Invest; 1975;56:56-64. 5. B.-E. Strauer Myocardial oxygen consumption in chronic heart disease: Role of wall stress, hypertrophy and coronary reserve. Am J Cardiol 1979;44:730-740. Abstract no: 7 Abnormal ventricular torsion: Key to diastolic dysfunction Julien Hoffman* and Gerald Buckberg# *Department of Paediatrics, University of California, San Francisco, California, United States of America #Department of Cardiothoracic Surgery, University of California, Los Angeles, California, United States of America Background: Helical muscles in the LV wall are essential for effective systolic emptying and subsequent refilling. During systole, the base of the heart rotates clockwise and the apex counter clockwise; the angular difference in these rotations (torsion) is measured by magnetic resonance imaging (MRI) or speckle tracking echocardiography. After systole, rapid untwisting is needed for ventricular suction and optimal LV filling. Torsion loses efficiency if the LV dilates and helical fibre angles become less steep, muscle contraction weakens with disease, or torsion is excessively prolonged. When the aortic valve closes, the right side of the ventricular septum (ascending segment of left helix) contracts for 60 - 90msec after relaxation begins in the muscle on the LV side of the septum and free wall (descending segment of right helix). Ascending segment recoil facilitates ventricular suction and early LV filling. The 60 - 90m/sec hiatus is essential for normal function. Results: In disease, excessive prolongation of torsion by persistence of contraction of LV free wall spiral and circumferential fibres decreases the hiatus, impairs untwisting, leaving less time for rapid early LV filling, a cardinal sign of diastolic heart failure. For example, during forceful contraction in aortic stenosis systolic torsion is exaggerated but also prolonged so that it encroaches on the early filling period after aortic valve closure. Conclusion: Suction cannot happen if torsion persists. Therefore the hallmarks of diastolic dysfunction–elevated LV diastolic pressure despite a normal ejection fraction, and a delayed fall of LV pressure after aortic valve closure are both manifestations of abnormal systolic muscle function leading to defective untwisting and filling of the LV. Abstract no: 17 Low recurrence rate in treating atrioventricular nodal reentrant tachycardia with triple freeze-thaw cycles Muhammad Qureshi*, Christopher Ratnasamy#, Mary Sokoloski‡ and Ming-Lon Young* *University of Miami, Miami, Florida, United States of America #Arkansas Children’s Hospital, Little Rock, AR, United States of America †Joe DiMaggio Children’s Hospital, Hollywood, Florida, United States of America Background: Cryoablation is an alternative to radiofrequency ablation in treating atrioventricular nodal reentrant tachycardia (AVNRT).