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Computational flow in reconstructed, branched, three-dimensional coronary arteries
Heart,
Lung
and Circulation
2003;
Selected
12
Comparison of fat intake in Australian and New Zealand CHD patients: The lipid (long-term intervention with pravastatin in ischaemic disease) study Paul Nestel’, Katrine Baghur&, Adrienne Kirby3, David M Colquhoun”, Harvey White5, Ralph Stewarts, Paul Glasziou6, Sandi Pirozzo6 ‘Baker Research Institute, Melbourne, Australia; *CSlRO Health Sciences rind Nutrition, Adelaide, Australia; 3NH b MRC Clinical Trials Centre, University of Sydney, Australia; 4Core Research, Brisbane, Australia; 5Green Lane Hospital, Auckland, New Zealand; 6University of Queensland, Brisbane, Australia Background Patients with coronary heart disease (CHD) are advised to reduce their intake of foods rich in saturated fatty acids (SFA) and substitute foods rich in complex carbohydrates, polyunsaturated fatty acids (PUFA) and monosaturated fatty acids (MUFA). Methods In the LIPID Study, 9014 patients were randomised to pravastatin 40 mg/day or placebo and followed up for a mean of 6 years. Dietary advice was given to all patients to reduce fat intake to less than 30% of energy intake, with equal amounts of SFA, PUFA and MUFA. Mortality and CHD event rates were higher in New Zealand patients. Baseline characteristics of patients were similar in both countries. However in New Zealand, median low-density lipoprotein cholesterol was higher (3.95 vs. 3.81 mmol/L, P = 0.0002) and highdensity lipoprotein cholesterol was lower (0.88 vs. 0.94 mmol/L, P < 0.001). A validated questionnaire was used to assess adherence to the diet in 3 different years (1991, 1992, 1995) in 1077, 951 and 849 patients, respectively Results Total energy intake was higher in New Zealand in 1991,1992 and 1995, and declined in both countries. Total fat and SFA and MUFA in absolute amounts and as a percentage of energy intake were higher in New Zealand. PUFA, as a percentage of energy intake, were similar in both countries. Diet components n Energy 1991 (MJ/day) Energy 1995 (MJ/day) SFA 1991 (g/day) SFA 1995 (g/day) MUFA 1991 (g/day) MUFA 1995 (g/day) PUFA 1991 (g/day) PUFA 1995 (g/dav)
684 532 684 532 684 532 684 532
Australia mean+SD 8*2
7?2 23 f 22 + 22 t 21+8 13 + 12+6
11 9 10
7
New Zealand n mean ? SD 393 317 393 317 393 317 393 317
9?2 8?2 28 f 13 24+9 25 + 9 22 5 7 14 k 7 13 + 6
P < 0.001 0.001 < 0.001 0.001 < 0.001 0.002
0.001 0.03
Conclusion The higher intake of fat in New Zealand patients may partly explain the higher CHD event rates observed in the LIPID study. Key words: Coronary heart disease, Diet, Lipid modifying agents, Prevention Short-term predictors of maintenance of normotension post withdrawal of antihypertensive drugs in the second Australian national blood pressure study (ANBPL) Mark R Nelson’, Chris M Reid*, John J McNei13, Phillip Ryan4, Lindon WH Wing”, Henry Krum” ‘Department of Epidemiology and Preventive Medicine,Monash University, Australiu; *Australia; 3Department ofEpidemiology and Preventive Medicine, Monash University, Australia; 4Department of Public Health, Faculty of Health Sciences, University of Adelaide, Australia; 5School of Medicine, Faculty of Health Sciences, Flinders University of South Austmliu, Australia Background Once initiated, antihypertensive drug therapy is most often considered life-long. However for patients whose underlying cause of hypertension is unknown or has changed since the initiation of therapy, drug withdrawal to determine the requirements for pharmacotherapy may enhance compliance to treatment if re-initiation is necessary and may prevent unnecessary treatment when adequate blood pressure control is maintained. Methods Monitoring of a drug cessation program of 25 867 subjects aged 65-84 years currently receiving antihypertensive medication for primary hypertension as part of the screening program for the 2nd Australian National Blood Pressure Studyl. Subjects were classified as failed to complete drug withdrawal, or completed drug withdrawal and either returned to hypertension or maintained normotension. Predictors
abstracts
from
the XIVth World Congress of Cardiology, May 5-9,2002
A77
of sustained normotension and drug cessation were identified using Cox regression. Results 19 033 subjects did not enter the withdrawal program. Of 6835 subjects participating in the drug withdrawal program 6292 (92%) completed it. Compared to subjects who did not complete withdrawal of medication, these subjects were younger and more likely to have been on monotherapy. 1228 (18%) ceased medication and maintained adequate blood pressure control for at least 2 weeks. Lower on-therapy systolic and diastolic blood pressure and the use of a single antihypertensive agent predicted medication cessation and maintenance of adequate blood pressure control. Conclusions Cessation of antihypertensive drug therapy is possible in a substantial proportion (18%) of patients attending general practice who are willing to do so. Key words: Drug therapy, Hypertension Computational Flow in Reconstructed, Branched, Three-Dimensional Coronary Arteries Stuart I’ Corneel, Peter R Johnston*, David Kilpatrick’ ‘University of Tasmania, Australia; *Grifith University, Australia Background Atheroma in human coronary arteries has a predilection for certain sites. Of the factors which are thought to contribute to atheroma formation, the patterns of flow and the structure of the wall are the only two which might relate to the position of atheroma. The conditions of blood flow at the arterial wall are bound by the wall shear stress. Methods Biplane digital coronary angiograms are used to construct a 3D model of the coronary arteries. The technique takes the angiogram images and automatically picks the centre line and radii to construct a three-dimensional model of the artery. Model arteries can be constructed throughout the cardiac cycle by using each recorded frame of the angiogram. The only checking required is to make sure that the branches have been appropriately recognised. This model, which includes branches, is then discretised and used to construct a finite volume mesh. The mesh is used as an input into a fluid dynamics package which solves the Navier-Stokes equations for flow, giving as output the wall shear stress throughout the cardiac cycle. Results Examination of arteries of several patients shows that the 3D flow produces regions of rapidly altering shear stress, both temporally and spatially. In some patients there are upwards of 15 peaks and troughs of shear stress throughout the length of the artery. Throughout the systolic phase of the cardiac cycle these regions change in size, move, merge or disappear. Lower shear stress regions appear to predominate at the proximal end of the arteries, reinforcing the low shear stress hypothesis of atheroma, however, significant regions of high shear stress do occur at times. Conclusion Regions of high and low shear stress cannot be easily predicted from two-dimensional angiographic images, as such regions are determined by three-dimensional effects such as helical flow. The rapidly changing nature of these regions may imply that the relationship between wall shear stress and atheroma formation is more complicated than presently thought. Key words: Angiography, Coronary circulation, Coronary Vessels, Image processing, computer-assisted Perindopril Attenuates Development Spontaneously Hypertensive Rats Lindsav Brown’, Andrew Fenning’, Anderson*, Cathy Wes@, Darryl Burstow* ‘The University of Queensland, Australia; Brisbane, Australia
of Heart
Failure
Kathleen
Wilson*,
*The Prince
Charles
in Ageing Bonita
A
Hospital,
Background ACE inhibition reduces progression and mortality in human heart failure. Methods Echocardiography and isolated Langendorff perfused hearts were used to determine whether the progression of heart failure in the ageing spontaneously hypertensive rat (SHR) could be prevented by chronic oral administration of perindopril(1 mg/kg/day) for 6 months in 15.month-old male SHR. Left ventricular M-mode measurements at the level of the papillary muscles included left ventricular end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), posterior wall in diastole (LVPWd) and fractional shortening (FS%). Pulsed-wave
Lung
and Circulation
2003;
Selected
12
Comparison of fat intake in Australian and New Zealand CHD patients: The lipid (long-term intervention with pravastatin in ischaemic disease) study Paul Nestel’, Katrine Baghur&, Adrienne Kirby3, David M Colquhoun”, Harvey White5, Ralph Stewarts, Paul Glasziou6, Sandi Pirozzo6 ‘Baker Research Institute, Melbourne, Australia; *CSlRO Health Sciences rind Nutrition, Adelaide, Australia; 3NH b MRC Clinical Trials Centre, University of Sydney, Australia; 4Core Research, Brisbane, Australia; 5Green Lane Hospital, Auckland, New Zealand; 6University of Queensland, Brisbane, Australia Background Patients with coronary heart disease (CHD) are advised to reduce their intake of foods rich in saturated fatty acids (SFA) and substitute foods rich in complex carbohydrates, polyunsaturated fatty acids (PUFA) and monosaturated fatty acids (MUFA). Methods In the LIPID Study, 9014 patients were randomised to pravastatin 40 mg/day or placebo and followed up for a mean of 6 years. Dietary advice was given to all patients to reduce fat intake to less than 30% of energy intake, with equal amounts of SFA, PUFA and MUFA. Mortality and CHD event rates were higher in New Zealand patients. Baseline characteristics of patients were similar in both countries. However in New Zealand, median low-density lipoprotein cholesterol was higher (3.95 vs. 3.81 mmol/L, P = 0.0002) and highdensity lipoprotein cholesterol was lower (0.88 vs. 0.94 mmol/L, P < 0.001). A validated questionnaire was used to assess adherence to the diet in 3 different years (1991, 1992, 1995) in 1077, 951 and 849 patients, respectively Results Total energy intake was higher in New Zealand in 1991,1992 and 1995, and declined in both countries. Total fat and SFA and MUFA in absolute amounts and as a percentage of energy intake were higher in New Zealand. PUFA, as a percentage of energy intake, were similar in both countries. Diet components n Energy 1991 (MJ/day) Energy 1995 (MJ/day) SFA 1991 (g/day) SFA 1995 (g/day) MUFA 1991 (g/day) MUFA 1995 (g/day) PUFA 1991 (g/day) PUFA 1995 (g/dav)
684 532 684 532 684 532 684 532
Australia mean+SD 8*2
7?2 23 f 22 + 22 t 21+8 13 + 12+6
11 9 10
7
New Zealand n mean ? SD 393 317 393 317 393 317 393 317
9?2 8?2 28 f 13 24+9 25 + 9 22 5 7 14 k 7 13 + 6
P < 0.001 0.001 < 0.001 0.001 < 0.001 0.002
0.001 0.03
Conclusion The higher intake of fat in New Zealand patients may partly explain the higher CHD event rates observed in the LIPID study. Key words: Coronary heart disease, Diet, Lipid modifying agents, Prevention Short-term predictors of maintenance of normotension post withdrawal of antihypertensive drugs in the second Australian national blood pressure study (ANBPL) Mark R Nelson’, Chris M Reid*, John J McNei13, Phillip Ryan4, Lindon WH Wing”, Henry Krum” ‘Department of Epidemiology and Preventive Medicine,Monash University, Australiu; *Australia; 3Department ofEpidemiology and Preventive Medicine, Monash University, Australia; 4Department of Public Health, Faculty of Health Sciences, University of Adelaide, Australia; 5School of Medicine, Faculty of Health Sciences, Flinders University of South Austmliu, Australia Background Once initiated, antihypertensive drug therapy is most often considered life-long. However for patients whose underlying cause of hypertension is unknown or has changed since the initiation of therapy, drug withdrawal to determine the requirements for pharmacotherapy may enhance compliance to treatment if re-initiation is necessary and may prevent unnecessary treatment when adequate blood pressure control is maintained. Methods Monitoring of a drug cessation program of 25 867 subjects aged 65-84 years currently receiving antihypertensive medication for primary hypertension as part of the screening program for the 2nd Australian National Blood Pressure Studyl. Subjects were classified as failed to complete drug withdrawal, or completed drug withdrawal and either returned to hypertension or maintained normotension. Predictors
abstracts
from
the XIVth World Congress of Cardiology, May 5-9,2002
A77
of sustained normotension and drug cessation were identified using Cox regression. Results 19 033 subjects did not enter the withdrawal program. Of 6835 subjects participating in the drug withdrawal program 6292 (92%) completed it. Compared to subjects who did not complete withdrawal of medication, these subjects were younger and more likely to have been on monotherapy. 1228 (18%) ceased medication and maintained adequate blood pressure control for at least 2 weeks. Lower on-therapy systolic and diastolic blood pressure and the use of a single antihypertensive agent predicted medication cessation and maintenance of adequate blood pressure control. Conclusions Cessation of antihypertensive drug therapy is possible in a substantial proportion (18%) of patients attending general practice who are willing to do so. Key words: Drug therapy, Hypertension Computational Flow in Reconstructed, Branched, Three-Dimensional Coronary Arteries Stuart I’ Corneel, Peter R Johnston*, David Kilpatrick’ ‘University of Tasmania, Australia; *Grifith University, Australia Background Atheroma in human coronary arteries has a predilection for certain sites. Of the factors which are thought to contribute to atheroma formation, the patterns of flow and the structure of the wall are the only two which might relate to the position of atheroma. The conditions of blood flow at the arterial wall are bound by the wall shear stress. Methods Biplane digital coronary angiograms are used to construct a 3D model of the coronary arteries. The technique takes the angiogram images and automatically picks the centre line and radii to construct a three-dimensional model of the artery. Model arteries can be constructed throughout the cardiac cycle by using each recorded frame of the angiogram. The only checking required is to make sure that the branches have been appropriately recognised. This model, which includes branches, is then discretised and used to construct a finite volume mesh. The mesh is used as an input into a fluid dynamics package which solves the Navier-Stokes equations for flow, giving as output the wall shear stress throughout the cardiac cycle. Results Examination of arteries of several patients shows that the 3D flow produces regions of rapidly altering shear stress, both temporally and spatially. In some patients there are upwards of 15 peaks and troughs of shear stress throughout the length of the artery. Throughout the systolic phase of the cardiac cycle these regions change in size, move, merge or disappear. Lower shear stress regions appear to predominate at the proximal end of the arteries, reinforcing the low shear stress hypothesis of atheroma, however, significant regions of high shear stress do occur at times. Conclusion Regions of high and low shear stress cannot be easily predicted from two-dimensional angiographic images, as such regions are determined by three-dimensional effects such as helical flow. The rapidly changing nature of these regions may imply that the relationship between wall shear stress and atheroma formation is more complicated than presently thought. Key words: Angiography, Coronary circulation, Coronary Vessels, Image processing, computer-assisted Perindopril Attenuates Development Spontaneously Hypertensive Rats Lindsav Brown’, Andrew Fenning’, Anderson*, Cathy Wes@, Darryl Burstow* ‘The University of Queensland, Australia; Brisbane, Australia
of Heart
Failure
Kathleen
Wilson*,
*The Prince
Charles
in Ageing Bonita
A
Hospital,
Background ACE inhibition reduces progression and mortality in human heart failure. Methods Echocardiography and isolated Langendorff perfused hearts were used to determine whether the progression of heart failure in the ageing spontaneously hypertensive rat (SHR) could be prevented by chronic oral administration of perindopril(1 mg/kg/day) for 6 months in 15.month-old male SHR. Left ventricular M-mode measurements at the level of the papillary muscles included left ventricular end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), posterior wall in diastole (LVPWd) and fractional shortening (FS%). Pulsed-wave