How GDPR Enhances Transparency and Fosters Pseudonymisation in Academic Medical Research.

The European General Data Protection Regulation (GDPR) has dotted the i's and crossed the t's in the context of academic medical research. One year into GDPR, it is clear that a change of mind and the uptake of new procedures is required. Research organisations have been looking at the possibility to establish a code-of-conduct, good practices and/or guidelines for researchers that translate GDPR's abstract principles to concrete measures suitable for implementation. We introduce a proposal for the implementation of GDPR in the context of academic research which involves the processing of health related data, as developed by a multidisciplinary team at the University Hospitals Leuven. The proposal is based on three elements, three stages and six specific safeguards. Transparency and pseudonymisation are considered key to find a balance between the need for researchers to collect and analyse personal data and the increasing wish of data subjects for informational control.

Influence of left-ventricular shape on passive filling properties and end-diastolic fiber stress and strain.

Passive filling is a major determinant for the pump performance of the left ventricle and is determined by the filling pressure and the ventricular compliance. In the quantification of the passive mechanical behaviour of the left ventricle and its compliance, focus has been mainly on fiber orientation and constitutive parameters. Although it has been shown that the left-ventricular shape plays an important role in cardiac (patho-)physiology, the dependency on left-ventricular shape has never been studied in detail. Therefore, we have quantified the influence of left-ventricular shape on the overall compliance and the intramyocardial distribution of passive fiber stress and strain during the passive filling period. Hereto, fiber stress and strain were calculated in a finite element analysis of passive inflation of left ventricles with different shapes, ranging from an elongated ellipsoid to a sphere, but keeping the initial cavity volume constant. For each shape, the wall volume was varied to obtain ventricles with different wall thickness. The passive myocardium was described by an incompressible hyperelastic material law with transverse isotropic symmetry along the muscle fiber directions. A realistic transmural distribution in fiber orientation was assumed. We found that compliance was not altered substantially, but the transmural distribution of both passive fiber stress and strain was highly dependent on regional wall curvature and thickness. A low curvature wall was characterized by a maximum in the transmural fiber stress and strain in the mid-wall region, while a steep subendocardial transmural gradient was present in a high curvature wall. The transmural fiber stress and strain gradients in a low and high curvature wall were, respectively, flattened and steepened by an increase in wall thickness.

Feasibility of strain and strain rate imaging for the assessment of regional left atrial deformation: a study in normal subjects.

AIMS: There are no data on the use of Myocardial Velocity Imaging (MVI) to study the left atrium (LA) wall deformation. The aims of this study were to assess the feasibility of measuring regional longitudinal strain/strain rate (epsilon/SR) profiles in the LA wall, to define the normal values and to validate these measurements. METHODS AND RESULTS: MVI data were recorded in 40 healthy young individuals using a GE Vivid7 for the lateral, anterior and inferior LA walls. The peak epsilon/SR values and total epsilon values during the contractile, reservoir and conduit LA phases were measured. For the LA lateral wall, the total epsilon values were correlated with the LA volumetric indicators (LA active emptying fraction: LA AEF; LA expansion index: LA EI; and LA passive emptying fraction: LA PEF). The correlations were significant for all three periods: contractile (total epsilon vs. LA AEF, r=-0.78, P<0.001), reservoir (total epsilon vs. LA EI, r=0.43, P<0.01) and conduit (total epsilon vs. LA PEF, r=-0.46, P<0.005). CONCLUSION: SR/epsilon imaging for the quantification of longitudinal myocardial LA deformation was shown to be feasible and the normal values were reported and validated. These data may improve the understanding of the LA pathophysiology.

Quantifying myocardial deformation throughout the cardiac cycle: a comparison of ultrasound strain rate, grey-scale M-mode and magnetic resonance imaging.

Strain rate imaging (SRI) is a new ultrasound (US) approach to the quantification of regional myocardial deformation. It previously has been validated in vitro and in vivo against other imaging techniques. However, in all such studies, only peak strain values were compared, and the temporal evolution of the strain curve was not studied. Yet, it is the temporal evolution of the strain curves that contains the more important clinical information (e.g., asynchrony, viability, etc). Thus, the aim of this study was to compare the evolution of strain during the complete cardiac cycle as measured by US SRI, US grey-scale M-mode and magnetic resonance imaging (MRI). In 10 healthy volunteers and 20 patients with chronic ischaemic heart disease, radial deformation of the inferolateral segment of the left ventricle was measured by US SRI, US M-mode and MRI. The correspondence of the temporal characteristics of these strain curves were compared by defining an intraclass correlation coefficient (ICC). In healthy volunteers, an overall good agreement (mean ICC: 0.75 and 0.63 for systole and diastole) was found between the different methods. However, in patients with abnormal segmental deformation and low peak strain values, the agreement was less (mean ICC: 0.42 and 0.32), but remained within acceptable limits for clinical decision making. Myocardial deformation measurements using SRI correlated well with MRI and US M-mode measurements throughout the complete cardiac cycle.

Role of magnetic resonance imaging in coronary heart disease.

Coronary heart disease (CHD) is the number one cause of morbidity and mortality in the developed countries. CHD involves a very broad clinical spectrum, ranging from stable angina pectoris to sudden cardiac death. Despite a huge improvement in treatment in the last 3 decades, significantly reducing the death rate, the prevalence of CHD will increase in the coming years due to an improved survival after a first acute myocardial infarction and due to an overall increased longevity, fueled by an epidemic of type-2 diabetes and obesity. This increased prevalence of cardiovascular disease will greatly impact the cost of health care. Moreover, new but often expensive imaging technologies are appealing for more accurate clinical and preclinical detection of CHD. Among these techniques, magnetic resonance imaging (MRI) is certainly one of the most promising. In this review we would like to highlight its potential in diagnosing CHD, against the background of a steadily increasing cost in health care and the need to choose the most cost-effective technique.

Regional nonuniformity of normal adult human left ventricle.

Regional nonuniformity is a feature of both diseased and normal left ventricles (LV). With the use of magnetic resonance (MR) myocardial tagging, we performed three-dimensional strain analysis on 87 healthy adults in local cardiac and fiber coordinate systems (radial, circumferential, longitudinal, and fiber strains) to characterize normal nonuniformities and to test the validity of wall thickening as a parameter of regional function. Regional morphology included wall thickness and radii of curvature measurements. With respect to transmural nonuniformity, subendocardial strains exceeded subepicardial strains. Going from base to apex, wall thickness and circumferential radii of curvature decreased, whereas longitudinal radii of curvature increased. All of the strains increased from LV base to apex, resulting in a higher ejection fraction (EF) at the apex than at the base (70.9 +/- 0.4 vs. 62.4 +/- 0.4%; means +/- SE, P < 0.0001). When we looked around the circumference of the ventricle, the anterior part of the LV was the flattest and thinnest and showed the largest wall thickening (46.6 +/- 1.2%) but the lowest EF (64.7 +/- 0.5%). The posterior LV wall was thicker, more curved, and showed a lower wall thickening (32.8 +/- 1.0%) but a higher EF (71.3 +/- 0.5%). The regional contribution of the LV wall to the ejection of blood is thus highly variable and is not fully characterized by wall thickening alone. Differences in regional LV architecture and probably local stress are possible explanations for this marked functional nonuniformity.

Remote myocardial dysfunction after acute anterior myocardial infarction: impact of left ventricular shape on regional function: a magnetic resonance myocardial tagging study.

OBJECTIVES: We sought to evaluate regional morphology and function in patients in their first week after having a reperfused anterior myocardial infarction (MI) using magnetic resonance (MR) myocardial tagging. BACKGROUND: The mechanism of myocardial dysfunction in the remote, noninfarct-related regions is an unresolved issue to date. METHODS: Sixteen patients with a first reperfused transmural anterior MI were studied with MR tagging at 5 +/- 2 days after the event, and the results were compared with those of an age-matched control group regions. The left ventricle (LV) was divided into infarct, adjacent and remote regions. Magnetic resonance tagging provided information on the regional ventricular morphology and function. RESULTS: Morphologically, an increase of the circumferential radius of curvature was found in the remote myocardium, whereas the longitudinal radius of curvature was increased in all regions of the LV. A significant increase in apical sphericity was also found. A significant reduction in strain and function was found not only in the infarct region, but also in the adjacent and remote myocardium. The loss in regional ejection fraction in the remote myocardium (61.4 +/- 11.7% in patients vs. 68.7 +/- 10.0% in control subjects, p < 0.0001) was related to a significant reduction of the longitudinal and circumferential strain, whereas systolic wall thickening was preserved. CONCLUSIONS: Remote myocardial dysfunction contributes significantly to the loss in global ventricular function. This could be secondary to morphologic changes in the infarct region, leading to an increased systolic longitudinal wall stress without loss of intrinsic contractility in the remote regions.

High frame rate myocardial integrated backscatter. Does this change our understanding of this acoustic parameter?

AIMS: Integrated backscatter (IB) and its cyclic variation (CV) derived from radio-frequency (RF) data have been used as parameters to attempt myocardial tissue characterization. Prior imaging systems used to measure IB and its CV typically acquired data at frame rates of 20-30 Hz and at a resolution of 6-8 bits. If changes in IB levels are in part related to specific short-lived events, occurring within the cardiac cycle, this frame rate and resolution could have been too low to resolve adequately what might be a more complex data set. METHODS AND RESULTS: To investigate this possibility, we acquired real time two-dimensional (2D) myocardial IQ data (the 'in-phase quadrature' sampled RF data) at high frame rate (> 100 Hz), high dynamic resolution (theoretical 19-bit) and a sector angle of 20 degrees. Several consecutive heart cycles of myocardial data were acquired from individual cardiac walls in five closed chest dogs and 10 healthy, young volunteers at normal heart rates. On the reconstructed RF data regions of interest were indicated, and IB and its CV were calculated. The extracted high frame rate curves showed that the CV of IB is not a smooth sinusoidal-like curve, but is made up of multiple reproducible peaks and troughs with local minima and maxima which are temporally related to active or passive mechanical events, i.e. systolic contraction, early ventricular relaxation and ventricular filling due to atrial contraction. CONCLUSIONS: This study shows that increasing the rate of real-time RF data acquisition results in a more complex, reproducible IB curve. The resolved maxima and minima in IB levels are related to specific phases of the myocardial contraction. Furthermore, spectral analysis showed that IB curves acquired at normal heart rates contain information up to 40 Hz. Hence, cardiac imaging data sets used to analyse regional myocardial function obtained at frequencies lower than 80 frames per second can contain aliased information.

Functional recovery of subepicardial myocardial tissue in transmural myocardial infarction after successful reperfusion: an important contribution to the improvement of regional and global left ventricular function.

BACKGROUND: The transmural extent of myocardial necrosis after an acute coronary artery occlusion can vary considerably. The contribution of residual subepicardial viable myocardium to global left ventricular function is largely unknown. METHODS AND RESULTS: We studied 12 patients with single-vessel disease 1 week after successful reperfusion of a first transmural anterior myocardial infarction (MI). With PET, myocardial blood flow (MBF) and glucose metabolism were measured regionally, and the viability was graded as normal, mismatch, or match with severely (<50% of normal) or intermediately (50% to 80% of normal) impaired MBF. Magnetic resonance tagging was used to regionally quantify fiber strains, wall thickening, and ejection fraction in patients 1 week and 3 months after the MI and in age-matched healthy volunteers. From 1 week to 3 months, subepicardial fiber shortening improved significantly in the match region (MBF <50%, -5.1+/-7.0% to -9.9+/-8. 7%; MBF of 50% to 80%, -7.1+/-7.6% to -14.9+/-7.9%). This was associated with an improvement in regional ejection fraction in the infarcted myocardium (29.6+/-21.8% to 43.5+/-15.5%, P<0.0001) and in normal regions (54.3+/-15.1% to 56.5+/-13.1%, P=0.013), contributing to an increase in global ejection fraction from 44.2+/-22.2% to 49. 3+/-17.9% (P<0.0001). CONCLUSIONS: Functional recovery of viable subepicardial regions is a mechanism of late improvement in regional and global ejection fraction after a so-called transmural MI.

Diastolic indexes during dobutamine stress echocardiography in patients early after myocardial infarction.

The aim of this study was to determine whether Doppler parameters assessed during dobutamine stress echocardiography in the early phase after myocardial infarction could discriminate patients with residual ischemia from those without. Thirty-six patients after a recent myocardial infarction with and without residual ischemia underwent dobutamine stress echocardiography, adenosine sestamibi scintigraphy, and coronary angiography within 2 weeks after the acute event. The only diastolic Doppler parameter discriminating the two groups was the isovolumic relaxation time (IVRT) measured at the peak of the dobutamine infusion. It became shorter in both groups but significantly more in patients without than in those with residual ischemia despite a larger increase in heart rate in the latter group. IVRT at rest was 78 +/- 18 msec and decreased with high-dose dobutamine to 54 +/- 11 msec in the control group and to 69 +/- 16 msec in the ischemic group (p < 0.01). In addition, the rate-corrected IVRT (IVRTc) was calculated: IVRTc = IVRT/sqrtRR. The value of IVRTc = 80 at peak dobutamine infusion is able to discriminate patients with residual ischemia from those without with a sensitivity of 80% and a specificity of 70%.

Adenosine technetium-99m sestamibi single-photon emission tomography for the assessment of jeopardized myocardium early after acute myocardial infarction. Paradoxical scintigraphic underestimation of jeopardized myocardium in patients with a severe infarct-related stenosis.

This study investigated the value of technetium-99m sestamibi scintigraphy in identifying patients at risk for post-infarct ischaemia (=jeopardized myocardium), especially within the reperfused infarct region. In 51 patients with a recent (<1 month) myocardial infarction, adenosine 99mTc-sestamibi single-photon emission tomography (SPET) and dobutamine stress echocardiography (DSE) were performed and correlated with the presence of significant coronary artery stenosis [% diameter stenosis (DS) >50%] on quantitative coronary angiography. Regional perfusion activity was analysed semi-quantitatively (score 0-4) on a 13-segment left ventricular model. DSE was used for the estimation of the infarct size (low-dose DSE) and for concomitant evaluation of ischaemia (high-dose DSE). A reversible perfusion defect within the infarct region was observed in 20 of the 37 patients with a significant infarct-related lesion (sensitivity of 54%) and only in one patient without a significant infarct-related lesion (specificity of 93%). Further analysis revealed that the scintigraphic assessment of jeopardized myocardium was fairly good in patients with a moderate (DS 51%-64%) infarct-related stenosis but was inadequate in patients with a severe (DS>/=65%) infarct-related stenosis (sensitivity of 80% vs 36%, P<0.01), while the echocardiographic detection of ischaemia was not influenced by stenosis severity (sensitivity of 73% in both subgroups). This scintigraphic underestimation of jeopardized myocardium was mainly related to a severely impaired myocardial perfusion under baseline conditions, as was evidenced by a significantly more severe rest perfusion score in the infarct region in patients with a severe stenosis as compared to those with a moderate stenosis (average score: 1.5+/-0.7 vs 2.1+/-0.6, P<0.01), while infarct size on echocardiography was similar for both subgroups. It may be concluded that early after an acute myocardial infarction, adenosine 99mTc-sestamibi SPET may underestimate reperfused but still jeopardized myocardium, particularly in patients with a severe infarct-related stenosis. In these patients the evaluation of the ischaemic burden on rest-stress scintigraphy is hampered by the presence of a severely impaired myocardial perfusion in resting conditions.

Noninvasive measurement of shortening in the fiber and cross-fiber directions in the normal human left ventricle and in idiopathic dilated cardiomyopathy.

BACKGROUND: Studies in anesthetized dogs have shown that myocardial fibers shorten approximately 8%. However, in the endocardium, shortening occurs to a much greater extent at 90 degrees to the fiber orientation ("cross-fiber shortening") than it does along the fiber direction. The purpose of this study was to estimate the extent of fiber and cross-fiber shortening in the normal human left ventricle and in patients with idiopathic dilated cardiomyopathy (IDC). METHODS AND RESULTS: Ten normal subjects and nine patients with IDC were imaged with magnetic resonance tissue tagging. Finite strain analysis was used to calculate endocardial and epicardial shortening in the fiber and cross-fiber directions using anatomic fiber angles from representative autopsy specimens as references. Anatomic fiber angles were not different between normal subjects and IDC patients. Epicardial fiber strain was -0.14+/-0.01 in normal subjects and -0.08+/-0.01 in IDC patients (P<.0001 versus normal subjects). Epicardial cross-fiber strain was -0.08+/-0.01 in normal subjects and -0.06+/-0.01 in IDC patients (P=NS). Endocardial fiber strain was -0.16+/-0.01 in normal subjects and -0.09+/-0.01 in IDC patients (P<.0001), and endocardial cross-fiber strain was -0.26+/-0.01 in normal subjects and -0.15+/-0.01 in IDC patients (P<.0001). Cross-fiber shortening was greater than fiber shortening at the endocardium in both normal subjects (P<.0001) and IDC patients (P<.05). CONCLUSIONS: In normal humans, the direction of maximal deformation aligns with the fiber direction in the epicardium but is perpendicular to the fiber direction in the endocardium. When strain in a coordinate system aligned to the fibers is estimated, cross-fiber shortening is found to be the dominant shortening strain at the endocardium. Normal fiber shortening is 15%, and this is markedly reduced in IDC. The normal transition in fiber orientation through the wall is not altered in IDC, and cross-fiber shortening is still the dominant strain at the endocardium, suggesting that interactions between myocardial layers persist in these patients.

Left ventricular myocardial tagging.

Nuclear Magnetic Resonance myocardial tagging is a potent non-invasive technique which enables the quantification of myocardial deformation, globally but also regionally at different time points during the cardiac cycle. By the use of presaturating pulses prior to the actual imaging sequence non-invasive markers or tags can be placed on the myocardium at end diastole, which move and deform with the underlying myocardium on which they were inscribed. Through combination of perpendicular sets of short- and long-axis images with tags, a three-dimensionally reconstructed left ventricle is obtained, subdivided in 32 myocardial cuboids for which the 3D coordinates of the corners are known at different time points in the cardiac cycle. From these data global and regional strains and quantitative measures of shape can be computed.

Follow-up of aortic dissection: contribution of MR angiography for evaluation of the abdominal aorta and its branches.

Spin-echo MR is an established method to evaluate thoracic aortic dissections, but is not well suited to study the abdominal aorta. In this study we evaluated whether MR angiography could provide a complete examination of the abdominal aorta. In 28 patients (40 MR studies) with suspected (n = 6) or known (n = 34) aortic dissection, MR studies were performed. Thoracic aorta was evaluated with spin-echo and gradient-recalled-echo MR imaging. Axial two-dimensional time-of-flight MR angiography with thin overlapping slices was used to study the abdominal aorta. Intermediate and high signal intensity on MR angiography was interpreted as patent flow, and low signal was interpreted as thrombus. The presence of an intima flap and the re-entry site could be depicted in all MR studies. Thrombus in the false channel was seen in 8 studies. The origin of the abdominal visceral branches and their relation to the false-true channel could be depicted, except in 4 of 80 renal arteries studied. Extension of the dissection into the coeliac trunk was seen in 2 and in the superior mesenteric artery in 10 studies. Dilatation of the suprarenal abdominal aorta was seen in 20 studies, and of the infrarenal aorta in 9 studies. MR angiography provides valuable information about the abdominal aorta and its branches in patients with aortic dissection. This makes MR imaging appealing as the preferred imaging modality for the diagnosis and follow-up of aortic dissection.

Comparative study of rest technetium-99m sestamibi SPET and low-dose dobutamine stress echocardiography for the early assessment of myocardial viability after acute myocardial infarction: importance of the severity of the infarct-related stenosis.

Rest technetium-99m sestamibi single-photon emission tomography (SPET) has been shown to underestimate viability in some patients with chronic ischaemic myocardial dysfunction. The present study was designed to appraise the value of 99mTc-sestamibi as a viability tracer in patients with a recent myocardial infarction and to determine factors that might influence its accuracy in assessing infarct size. Therefore, rest 99mTc-sestamibi SPET, low-dose dobutamines stress echocardiography and quantitative coronary angiography were performed in 51 patients with a recent myocardial infarction. Perfusion activity and regional wall motion were scored semi-quantitatively using the same segmental division of the left ventricle. Assessment of 99mTc-sestamibi uptake as a marker of viability was performed by comparing a binary uptake score (viable=>50% vs necrotic =/=65%-100%) and particularly those with "late" reperfusion therapy (time delay >/=180 min). In patients without a severe infarct-related stenosis, 99mTc-sestamibi was able to accurately distinguish viable from necrotic segments. Thus, rest 99mTc-sestamibi scintigraphy early after acute myocardial infarction may underestimate residual viability within the infarct region, particularly in patients with low flow state coronary anatomy, as a result of a severe infarct-related stenosis and/or late reperfusion therapy.

Left ventricular quantification with breath-hold MR imaging: comparison with echocardiography.

To evaluate the reproducibility of measurements of left ventricular (LV) dimensions, function, and myocardial mass, segmented k-space gradient-recalled-echo (GRE) magnetic resonance (MR) imaging was performed on two occasions on 12 healthy volunteers. To compare the MR data, all volunteers underwent a two-dimensional echocardiography with determination of LV dimensions and function. The left ventricle was imaged during breath-hold by consecutive, contiguous short-axis views at end-diastole and end-systole. An average of eight short-axis views was needed to encompass the whole left ventricle. This fast MR sequence limited the total acquisition time to 12 min. LV volumes and masses were calculated after manual delineation of epicardial and endocardial surfaces by two observers in a blinded fashion. Interstudy variability varied between 4.1% and 10.3% for LV end-diastolic volume and end-systolic volume, respectively. Differences in interobserver variability were smaller and varied between 3.6% and 7.3% for LV ejection fraction and end-diastolic volume, respectively. Intraobserver variabilities ranged between 2.0% and 7.0% for LV ejection fraction and end-systolic volume, respectively. These variability percentages agree very well with other studies in literature using other MR sequences. No significant differences in LV dimensions or function were found between MR imaging and echocardiography. In conclusion, this MR sequence allows fast and reproducible LV quantification.

Determination of left ventricular volume by two-dimensional echocardiography: comparison with magnetic resonance imaging.

Left ventricular volume was determined in 12 healthy volunteers using a newly developed two-dimensional echocardiographic delineation method. The results were compared with those of magnetic resonance imaging, which served as the method of reference. Left ventricular end-diastolic volume was 123 +/- 12 ml, echocardiographically defined, and 121 +/- 12 ml calculated with magnetic resonance imaging. End-systolic volume was 41 +/- 7 ml on echocardiography and 37 +/- 6 ml on magnetic resonance imaging. Left ventricular ejection fraction was 67 +/- 4%, echocardiographically defined, and 70 +/- 5%, calculated with magnetic resonance imaging. There was no statistical difference for any of the measured parameters. Interstudy and inter-observer variability was minimal. In conclusion, in healthy volunteers left ventricular volume was accurately defined, using this newly developed two-dimensional echocardiographic delineation method. During endocardial delineation a dynamic display is continuously available on a second window, allowing precise visual edge-detection. Moreover, corrections can be made easily and quickly. These two advantages enhance the accuracy of the method, even in cases of poor echogenicity.

Rotational deformation of the canine left ventricle measured by magnetic resonance tagging: effects of catecholamines, ischaemia, and pacing.

OBJECTIVE: The aim was to investigate the generation of rotation of the left ventricular apex with respect to the base by magnetic resonance tagging, a non-invasive method of labelling the myocardium, in a canine model. METHODS: 18 dogs were imaged at baseline and during: (1) inotropic stimulation with dobutamine; (2) chronotropic stimulation with atrial pacing; (3) anterior wall ischaemia; (4) posterior wall ischaemia; and (5) varying left ventricular activation site; six dogs underwent each intervention. Apical rotation of the apex (torsion) was quantified. The epicardium and the endocardium were considered separately, as were the anterior and posterior walls. RESULTS: Mean torsion of the epicardium [anterior 3.1(SEM 1.2) degrees, posterior 9.9(1.0) degrees] was less than that of the endocardium [anterior 8.1(2.6) degrees, posterior 14.9(2.0) degrees, p < 0.05 for both]. Anterior torsion was less than posterior torsion for both the epicardium, p < 0.05, and the endocardium, p < 0.05. Dobutamine increased torsion of both the epicardium [anterior 13.3(2.2) degrees, posterior 12.6(1.7) degrees, p < 0.05 for both] and the endocardium [anterior 24.6(2.3) degrees, posterior 16.5(2.1) degrees, p < 0.05 for both]. Atrial pacing at 160% baseline rate increased torsion of both the anterior wall [epicardium 6.6(1.0) degrees, endocardium 11.3(1.2) degrees, p < 0.05] and the posterior wall [epicardium 13.0(1.3) degrees, endocardium 19.4(1.9) degrees, p < 0.05]. Anterior wall ischaemia reduced torsion of the anterior wall only [epicardium -2.0(1.0) degrees, endocardium 6.7(2.3) degrees, both p < 0.05]. Posterior wall ischaemia reduced torsion of the posterior wall of the epicardium only [7.1(1.2) degrees, p < 0.05] but also reduced torsion of the anterior wall [epicardium 0.7(1.0) degrees, endocardium 2.4(1.6) degrees, p < 0.05 for both]. Altering the pattern of left ventricular activation by atrioventricular pacing reduced torsion of the posterior wall of the epicardium [6.6(1.2) degrees, p < 0.05] and of the anterior [3.6(1.9) degrees, p < 0.05] and posterior [7.1(1.6) degrees, p < 0.05] walls of the endocardium. CONCLUSIONS: Rotational deformation of the left ventricle is dependent on the pattern of left ventricular activation and the contractile state. That a decrease in the contractile state in one area (by ischaemia) can cause a decrease in rotation in another suggests that this rotation depends on the complex fiber arrangement of the whole ventricle.