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013 THE EFFECT OF TIME TO THROMBOLYSIS ON THE LV FUNCTION POST ANTERIOR MI AND THE MOST ACCURATE AND REPRODUCIBLE METHOD OF ASSESSMENT
T. A. Fox, P. Finn, N. J. Carline, K. F. Murt, J. Rees, A. Amadi. Aintree Cardiac Centre, Liverpool, UK
Background: Previous clinical trials have demonstrated that there is a reduction in mortality by thrombolytic therapy in acute MI in relation to a shorter time between onset of symptoms and treatment. This study analyses the link between time to thrombolysis and early recovery of LV function. It also assesses the most accurate and reproducible method of assessing the function itself.
Methods: 35 patients with Anterior MI but no previous cardiac history received thrombolysis. These patients had echocardiograms performed 5 days post MI. The LV function was assessed using a visual eyeballing method and the LV function graded as good or showing mild, mild-moderate, moderate, moderate-severe or severe LV dysfunction. An LV ejection fraction was then calculated 3 times per patient using the Modified Simpson’s package. Thrombolysis times were compared to LV function as assessed by each method.
Results: Mean call to needle times increased with a more severe degree of LV dysfunction. Mean times were, Severe-254 mins, Moderate-Severe-122 mins, moderate-78 mins, mild-moderate-62 mins, mild-45 mins and good-42 mins. There was poor correlation between Modified Simpson’s measurements and thrombolysis times.
Conclusions: LV systolic function was found to be better with a shorter time between symptoms and treatment. The patients with the poorer graded function had mostly had a lengthened call to needle time. The visual eyeballing method was found to be the most accurate and reproducible method of LV assessment, as the Modified Simpson’s showed poor correlation and variability.
014 CHARACTERISATION OF A NEWLY DEVELOPED ULTRASONIC CONTRAST AGENT
C. M. Moran1, J. Ross2, I. Ansell2, C. Oliver2, M. Butler1, J. Williamson1, T. Anderson1, N. McDicken1, K. A. A. Fox3. 1Medical Physics, 2Dept. Clinical and Surgical Sciences, 3Dept of Cardiovascular Research University of Edinburgh, Edinburgh EH3 9YW, UK
Background: The size and composition of commercially available ultrasonic contrast microbubbles are such that when insonated at routinely used diagnostic frequencies (2–7 MHz), the bubbles resonate and strongly scatter ultrasound. Recently there has been increasing interest in imaging and manipulating these microbubbles at higher frequencies (30–40 MHz) for possible applications in targeting microbubble-encapsulated drugs to specific plaque sites in arteries and to image such sites using intravascular ultrasound. Due to commercial sensitivity re shell constituents and manufacture, targeting of specific commercial agents was not possible.
Aim: To produce an ultrasonic contrast microbubble capable of resonating at 30–40 MHz and to use such an agent for targeting specific cell-lines found in the arterial wall.
Method: A lipid-encapsulated nitrogen-filled microbubble was developed in-house. The agent was diluted to various concentrations using saline and blood-mimicking fluid (BMF). Using a ClearView Ultra system, an Atlantis SR intravascular probe was inserted into each solution and one frame of unprocessed ultrasonic data was acquired. The data was downloaded onto a PC. A region-of-interest (ROI) of 128 data points and 9 ultrasonic lines was chosen. Over these ROIs, mean backscatter power was calculated and referenced to data collected from a water-air interface. The ability of the agent to be targeted to specific cells was assessed microscopically by labelling the microbubbles with an antibody (CD54) and then passing these microbubbles over endothelial cells grown on an agar interface.
Results: At concentrations of 25 mg/ml, mean backscatter power was approximately 9 dB less than a commercially available agent (Definity). This level of backscatter is adequate for arterial plaque studies. Under physiological flow conditions the microbubbles were observed (both optically and acoustically) to be attached to the endothelial cells.
015 DIFFERENTIATION OF ISCHAEMIC AND IDIOPATHIC DILATED CARDIOMYOPATHY: TISSUE DOPPLER CHARACTERISTICS IN PATIENTS WITH GLOBAL SYSTOLIC LEFT VENTRICULAR DYSFUNCTION
R. S. Sharma, P. M. Elliott, W. J. McKenna, C. Veyrat, D. Pellerin. The Heart Hospital, University College London, UK
Many studies have shown that conventional echocardiographic parameters are unable to distinguish between ischaemic and non-ischaemic aetiologies in patients with global severe left ventricular dysfunction when history of coronary artery disease lacks. A coronary angiogram is usually performed but an ischemic origin is rarely found. The aim of this study was to determine whether colour tissue Doppler imaging and strain could make this distinction. The study cohort comprised 18 controls (53±10y, 9 M), 37 patients, with idiopathic dilated cardiomyopathy (DCM) (62±10y, 28 M, LVEF 30±9 %, LV EDD 6.1±0.4 cm) and 16 patients with ⩾3-vessel coronary artery disease (IHD) (67±11y, 13 M, LVEF 29±10 %, LV EDD 6.4±0.3 cm). Colour tissue Doppler velocities and strain were measured in the left ventricular posterior wall on M-mode recordings. When the posterior wall was akinetic and thin, measurements were performed in the septum. Wall motion score index (2.34±0.39 versus 2.25±0.42) and the number of akinetic LV segments per patient were not significantly different between patients with IHD and those with DCM. During systole, ejection epicardial velocity measured at the time of peak endocardial velocity was higher in DCM than in IHD (21±13 versus 10±9 mm/s, p=0.04). The ratio of preejection to ejection endocardial velocity was lower in DCM compared to IHD (25±27 versus 72±44, p=0.01). During early diastole, peak endocardial velocity (68±33 versus 42±24, p=0.03), peak epicardial velocity (53±31 versus 26±17, p=0.01), and endocardial velocity measured at peak epicardial velocity (36±27 versus 10±9, p=0.003) were higher in DCM than in IHD. Systolic strain and tissue Doppler derived myocardial velocity gradients were similar in both groups of patients. Conclusion, analysis of colour tissue Doppler echocardiograms in endocardial and epicardial layers may be able to identify those patients with global severe left ventricular dysfunction that have ischaemic heart disease.
016 ROLE OF TWO DIMENSIONAL AND DOPPLER ECHOCARDIOGRAPHY IN PATIENTS WITH DUCHENNE CARDIOMYOPATHY
L. Desforges, A. Stefanidis, G. Koutroulis, M. Kinali, F. Muntoni, P. Nihoyannopoulos. Echo Lab, Dept of Paediatrics, Hammersmith Hospital, NLHI, ICSM, London, UK
Patients (pts) with Duchenne dystrophy (DMD) constitute a population of poor clinical state. DMD cardiomyopathy is one of the main reasons of morbidity and mortality in these pts. In this echocardiographic retrospective study several 2-D and Doppler variables were assessed in asymptomatic (a-DMD) or symptomatic heart failure DMD pts (s-DMD) and in a control group of healthy children. We also focused on Doppler-index (DI), a new, reproducible variable capable to assess the myocardial performance in many clinical settings. We assessed the echocardiograms of 24 normal controls (aged 9±3 yrs) and 58 DMD-patients [(a-DMD, n:35;8±2 yrs) (s-DMD, n:23;16±3 yrs)]. One investigator with no access to any clinical information calculated all the echo variables. The DI was calculated using the sum of isovolumetric contraction plus relaxation time divided by ejection time (ET) [(ICT+IRT)/ET]. The statistics were performed by using unpaired t-test and ANOVA method with Bonferroni’s correction. The ROC curve for the DI values was also estimated in an attempt to discriminate the best predicting value between controls and DMD pts.
Results: The LV fractional shortening (FS) of DMD pts in comparison with controls was significantly lower (28±9% vs. 36±6%, p<0.001). The peak E to A transmitral velocities ratio and the DI were significantly different too (E/A: 2.2±0.7 vs. 1.6±0.4 p<0.001, DI: 0.50±0.15 vs. 0.39±0.06, p<0.001). The only differences between a-DMD and controls were the E/A (1.7±0.4 vs. 2.2±0.7, p<0.01) and LV ET (256±22 vs. 232±15 msecs, p<0.001). The DI between controls and a-DMD was similar (0.39±0.06 vs 0.43±0.09 p: NS). Finally, a DI value of 0.50 was the best cut-off value between normal subjects and DMD pts.
Conclusions: The FS, E/A ratio and DI are useful echocardiographic variables for the assessment of DMD pts. However, from all the measured variables only E/A and ET were different between controls and a-DMD pts.
017 ELECTRICAL OR MECHANICAL DISPERSION: PREDICTOR OF CARDIAC RESYNCHRONISATION THERAPY
R. E. Lane, A. W. C. Chow, N. S. Peters, D. W. Davies, J. Mayet. St. Mary’s Hospital and Imperial College School of Medicine, London, UK
The ECG has been used to identify patients for cardiac resynchronisation therapy (CRT). However, 30% of selected patients fail to derive symptomatic benefit. Tissue Doppler imaging (TDI) can measure the dispersion of mechanical contraction between right and left ventricles (RV and LV) and within the LV, and may be a superior tool for predicting patient response.
Methods: 12 lead ECG, 2D echocardiography and TDI were performed at baseline and during synchronous CRT in 28 patients age 66±12 years with chronic heart failure, ejection fraction (EF) <35% and left bundle branch block. TDI was used to measure regional electro-mechanical delay of the LV and RV. Intraventricular mechanical dispersion (LVd) was calculated as the time between latest and earliest sites of LV contraction. Interventricular mechanical dispersion (IVd) was calculated as the maximal delay between LV and RV contraction. Responders (R) or non-responders (NR) to CRT were classified on the basis of symptomatic and functional improvement.
Results: Baseline QRS was positively correlated with IVd (r=0.5, p0.017) but not with LVd. Following CRT, mean QRS duration was unchanged, EF increased (19±7 to 24±10% p0.01), IVd decreased (103±62 to 61±42 ms p<0.001) and LVd decreased (76±49 to 43±30 ms p0.001). During CRT, IVd was reduced by 54% and 15% in R and NR respectively whilst LVd was reduced by 40% and −2% in R and NR respectively. A 20% reduction in both LVd and IVd had 91% sensitivity and 100% specificity in predicting clinical benefit following CRT.
Conclusion: QRS duration does not predict clinical response with CRT. TDI can be used to assess dyssynchrony and predict response to CRT. Optimal reductions in both IVd and LVd appear to be important for clinical improvement.
018 CONTRAST AGENT INCREASES DOPPLER VELOCITIES AND IMPROVES REPRODUCIBILITY OF AORTIC VALVE AREA MEASUREMENTS IN PATIENTS WITH AORTIC STENOSIS
L. A. Smith1, S. J. Cowell1, A. C. White2, N. A. Boon1, D. E. Newby1, D. B. Northridge2. 1Cardiovascular Research, University of Edinburgh, 2Cardiology, Western General Hospital, Edinburgh, UK
Purpose: Observer variability may limit assessment of aortic stenosis by Doppler echocardiography. The aim of this study was to assess whether echocardiographic contrast agent improves reproducibility of aortic valve area (AVA) measurements in patients with aortic stenosis.
Methods: 20 patients with aortic stenosis (67+/−10 years) underwent non-contrast and contrast Doppler echocardiography, on two occasions, three weeks apart.
Results: Intraobserver and interobserver coefficients of reproducibility were 0.36 and 0.20 cm respectively for left ventricular outflow tract (LVOT) diameter, and 0.38 and 0.24 cm2respectively for AVA. Whilst intraobserver reproducibility was unaffected, the use of contrast improved interobserver reproducibility for LVOT diameter (mean of differences −0.02+/−0.07 cm vs 0.01+/−0.10 cm, p<0.05) and AVA (mean of differences 0.02+/−0.10 cm2 vs 0.07+/−0.12 cm2, p<0.05). Pre- and post-valve velocities were increased with contrast compared to non-contrast imaging (pre: 1.07+/−0.20 m/s vs 0.94+/−0.19 m/s, p<0.01; post: 3.76+/−0.87 m/s vs 3.47+/−0.78 m/s, p<0.01). Mean AVA was unaltered.
Conclusions: Echocardiographic contrast significantly increases Doppler velocities and produces modest improvements in the reproducibility of LVOT diameter and AVA measurements. We suggest that, when assessing patients with aortic stenosis, contrast agents should be considered in the difficult-to-image patients with poor baseline LVOT images or Doppler studies, or when there appears to be marked variability in sequential echocardiographic studies.
019 CONTINUITY EQUATION AREA IN BILEAFLET PROSTHETIC AORTIC VALVES: VALVE SIZE CANNOT BE SUBSTITUTED FOR LV OUTFLOW TRACT DIAMETER
J. Chambers, L. Oo, A. Narracott, P. Lawford, C. Blauth. Valve Study Group, St Thomas Hospital and Sheffield University, UK
Background: The labelled valve size approximates the annulus in which it is implanted. A number of studies have suggested that it is more accurate than measuring LV outflow tract diameter for calculating the continuity equation area.
Objectives: The aims of this study were to compare labelled size with an in vitro model of the LV outflow tract and to measure the orifice size in six designs of bileaflet mechanical heart valve.
Methods: The inflow aspect of each of 29 valves was photographed then digitised and the maximum internal diameter and orifice area calculated. The LV outflow tract was modelled using a series of machined polypropylene blocks.
Results: The modelled LV outflow diameter ranged from 1.0 to 3.0 mm larger than labelled valve size for the intra-annular valves and from 3.5 mm smaller to 1.5 mm larger than labelled size for the supra-annular valves. Using labelled size gave an estimate of LV outflow area from 140 mm2 smaller to 120 mm2 larger than the actual area. The internal orifice diameter ranged from 1.6 mm to 4.6 mm less than the manufacturer’s labelled size. The geometric orifice area varied widely between 159 and 222 mm2 for the six size 19 valves and between 316 and 405 mm2 for the six size 25 valves.
Conclusion: There are major differences between labelled size and actual size in bileaflet mechanical valves. Labelled size should not be used to compare haemodynamic function nor for the calculation of the orifice area using the continuity equation.
020 ATORVASTATIN DOES NOT REDUCE LV MASS OR AFFECT DIASTOLIC FUNCTION AFTER ONE YEAR OF TREATMENT
A. S. Sharp, A. Zambanini, A. D. Hughes, S. Byrd, D. Shields, D. Fitzgerald, S. Lyons, E. O’Brien, A. Stanton, N. Poulter, P. S. Sever, S. A. McG Thom, J. Mayet. Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin, Ireland, and St Mary’s Hospital, Imperial College, London, UK
Methods: It has been postulated that the statins may have beneficial affects on LV mass in the hypertensive population. We randomised 406 hypertensive patients with normal levels of serum cholesterol (⩽6.5 mmol/L) to take either 10 mg of Atorvastatin or placebo. All patients underwent echocardiography after one year of treatment.
Results: Data on LV mass was obtained from 406 patients; with a similar number providing data on transmitral Doppler flow (TMD) and Tissue Doppler Echocardiography (TDE) at the level of the mitral annulus on the lateral wall. Both groups were equivalent in terms of age, sex and BMI.
Conclusion: After one year of treatment Atorvastatin had no significant effect on LV mass or diastolic function. This large cohort of patients does not support preliminary data from small studies that statins have beneficial effects on cardiac structure.
021 ASSESSMENT OF THE DYNAMIC PERFORMANCE OF NATIVE AND PROSTHETIC AORTIC VALVES
J. Davies, A. Allen, J. McAdam, L. Hadjinikolaou, A. Sosnowski, M. Galinanes, D. Chin. Cardiorespiratory Directorate, University Hospitals of Leicester NHS Trust, Leicester, UK
Background: The assessment of aortic valve (AV) function by pressure gradients has limitations. Such gradients are dependent on flow across the effective AV orifice, which is affected by left ventricular stroke volume, heart rate and afterload. AV performance should therefore be characterised across a range of physiological flow rates. Measures such as the pressure-drop flow regression slope (PDFS) have been described. Due to nonlinear change, PDFS is not always obtainable; we hypothesized that measures of instantaneous AV resistance (mean pressure drop/flow, R) obtained during stress echocardiography could be used to define the performance of native and prosthetic aortic valves.
Methods: 23 patients with AV stenosis (Group A, continuity AV area at baseline <1 cm2), 29 with AV bioprostheses (B), 18 with AV mechanical prostheses (C) and 92 with no stenosis (D) underwent stress echocardiography. Mean pressure drop and flow was calculated from 2D and Doppler measurements at each stage of Dobutamine stress.
Results: Group A had higher R [p<0.05*, all groups compared to A] at baseline and low dose stress; maximal R occurred at baseline and decreased with stress. Prosthetic R increased with stress so that at peak, there was no statistical difference with Group A. Prosthetic R was higher than in group D, but no difference was seen between groups B and C.
Conclusions: AV stenosis causes a high R but such valves can still accommodate for increasing flow. Prostheses have lower R values but rigid orifices may reduce performance at higher flows.