Einthoven Dissertation Prizes
2003
For the fifteenth year in a row, the Netherlands Society of Cardiology (NVVC), the Interuniversity Cardiology Institute ofthe Netherlands, and the sponsor, Sanofi Synthelabo, are supporting the competition for the best three PhD theses published last year on a cardiovascular subject. The prizes carry the name of one of the great men in the history of Cardiology: Willem Einthoven (1860-1927), the pioneer of the human ECG. The jury, consisting of representatives of the NVVC, ICIN, and Sanofi Synthelabo, were offered 20 dissertations to review. The jury members were impressed and pleased by the scientific quality ofthe work ofthe young doctors. Hence, it was not easy to decide upon the winners. The three nominees will present their work at the spring meeting of the NVVC, which will be held in Amsterdam on 23 April 2004. The winner of the first, second and third prize will be chosen by the audience. Summaries ofthe three nominated PhD theses are given below.
Professor C.A. Visser Chairman of the Jury
Coronary spiral CT While mechanical CT was long regarded as unsuitable for cardiac imaging, the latest generations of multi-slice spiral computed tomography (MSCT) scanners allow detailed imaging of the heart and coronary arteries. The coronary lumen is enhanced by an intravenously injected contrast medium and the scan is performed during a single breath hold. CT data acquisition continues throughout the cardiac cycle, while ECG-synchronised images are reconstructed retrospectively. Three-dimensional datasets ofthe heart during a particular phase can be reconstructed at any point within the cardiac cycle. Stenosis detection With four-slice MSCT, significant coronary narrowing could be detected with a sensitivity of 82% and specificity of 93% in coronary segments with a minimal diameter of 2.0 mm and with sufficient image quality. However, 30% of the coronary segments could not be interpreted due to motion artefacts and extensive coronary calcification. Particularly the right coronary artery is vulnerable to motion artefacts because of its large motion radius and shorter motion-free interval. With lesions in nonassessable segments classified as false-negative
194
interpretations, the sensitivity dropped to 61%. Comparing patients with a low, intermediate or high heart rate, significantly fewer motion artefacts, better interpretability and more accurate detection of coronary obstruction could be achieved in the group with the slowest heart rate. With the experiences from the fourslice studies, a study with 16-slice computed tomography with thinner slices and faster gantry rotation was performed with heart rate modulation by 5-receptor blocking medication. Without exclusion of less assessable coronary arteries, 95% of the coronary arteries with significant stenosis were detected, using conventional angiography as reference (figure 1). The high sensitivity came at the expense of a slightly lower specificity of 86%.
Imaging of grafts and stents The usefidness ofMSCT in patients who had undergone bypass surgery was explored using four-slice MSCT. While particularly venous bypass grafts were visualised well with accurate interpretation of proximal and distal segments, evaluation of the diffusely diseased, and often calcified coronary arteries proved to be more challenging. Imaging of in vitro and in vivo
coronary stents is complicated by metal-related blooming artefacts, which interfere with visualisation of the in-stent lumen. Technical innovations, such as thinner detector rows, seem to improve the interpretation of stented coronary
artenes. Plaque imaging Apart from the coronary lumen assessment, MSCT can visualise the diseased coronary wall. While detection and quantification of coronary calcium by (nonenhanced)
Figure 1. MSCT angiogram showing severe stenosis (arrow) of the left main bifurcation. The insert allows appreciation of the shape and contents of the plaques, i.e. bright calcified and dark noncakified material.
Netherlands Heart Journal, Volume 12, Number 4, April 2004
CT has been described extensively, current studies focus on the interpretation of noncalcified plaque material.
Conclusion MSCT coronary angiography is a minimally invasive and relatively simple procedure that allows accurate evaluation ofthe coronary lumen. The time has come to determine the place of noninvasive coronary angiography in clinical practise, either as an alternative to invasive angiography, or at an earhler stage in the diagnostic work-up of patients with (suspected) coronary artery disease. l K. Nieman, Erasmus University Rotterdam, Rotterdam
Heparin derivatives in acute coronary syndromes This thesis focuses on several issues regarding the use of anticoagulants in patients with acute coronary syndromes.
Chapter 1 provides an overview of clinical trials comparing unfractionated heparin (UFH) with lowmolecular-weight heparin (LMWH) for the treatment of venous thrombosis and arterial thrombosis (unstable angina, non-Q-wave infarction and stroke). Fixed-dose subcutaneous LMWH is a safe and effective alternative for doseadjusted intravenous heparin in the treatment of patients with acute venous thrombotic disease as well as in patients with acute unstable coronary syndromes. The effectiveness of LMWH in patients with acute myocardial infarction is less well documented. There seems to be no beneficial effect of LMWH treatment as compared with placebo in patients with acute ischaemic stroke, while the risk of major bleeding was increased.
onary syndromes (ACS), namely an intravenous loading dose plus subcutaneous enoxaparin versus subcutaneous alone. The impact ofthese regimens on the coagulation system was quantified in 14 combinedregimen patients and 11 singleregimen patients. A clear time benefit was obtained with the combined regimen as reflected in an earlier reduction of thrombin generation without leading to unacceptably high anticoagulant levels. We postulate that this earlier suppression of coagulation may translate into clinical benefit, as the risk of thrombotic complications is greatest in the early hours after admission.
Chapter 3 The INSTAP I Study performed after several observations were published where UFH cessation in stabilised ACS patients resulted in a clustering of
was
recurrent ischaemic events within
24 hours after cessation, which is accompanied by a reactivation ofthe coagulation system to levels higher than before treatment. Since LMWHs were becoming the treatment of choice, this study investigated whether biochemical rebound could be observed after LMWH cessation. This is the first published study showing that
LMWH cessation has a comparable reactivation of coagulation effect as seen with UFH. The difference with UFH is the time of occurrence; maximal reactivation of coagulation
after IJFH is six to 12 hours after cessation. With LMWH, rebound occurred 24 hours after the last administration. Chapter 4 In the TESSMA Study (Acombined analysis ofthe Essence/ TIMI lb trial) we investigated whether the discontinuation of LMWH resulted in clustering of clinical rebound events shortly after cessation of treatment. These data were derived from two large clinical trials, on which we performed a retrospective analysis. The results were consistent with our previous biochemical study, and showed a dustering of ischaemic events in the first 24 hours of cessation oftherapy which was comparable with the rebound seen after UFH cessation in other studies. The incidence of death, MI, and urgent revascularisation on the first day after cessation was 2.3%, while the incidence on the following day was only 0.8% (figure 1). Interestingly, patients who were treated with prolonged out-ofhospital LMWH administration did not show this early rebound -
2.5
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| ~~~~ |ShortEnox
_
s LongEnox
1.5-
to 0.5
0.0
-
-
-1
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'3 4 Day before (-1) _S e (1 to 7) i
5 o
6 7 oof therapy
UFH=unfractioned heparin (n=2617) ShortEnox-short-term enoxaparin (n=1498) LongEnox-Iong-term enoxaparin (n=1043)
Chapter 2 In the BOLUS Study, we compared two different LMWH Figure 1. Hazard of rebound ischaemic events (death, MI, or urgent revascularisation) regimens in the initiation of treat- after discontinuation of unfractionated heparin (UFH) or short-term enoxaparin in ment of patients with acute cor- patients treatedfor acute coronary syndromes (-1), and dayw (1 to 7). Netherlands Heart Journal, Volume 12, Number 4, April 2004
195
phenomenon. Based on these results, we postulate that cessation of LMWH or UFH treatment in ACS patients should be followed by a 24hour in-hospital observation period since a substantial number ofpatients could suffer from early recurrent ischaemic events. Prolonged treatment or weaning of LMWH treatment should be prospectively evaluated.
partial normalisation at high levels ofidraparinux, i.e. three hours after administration. The effect ofrFVIIa was proportionally identical during high and low plasma levels of idraparinux and lasted two to six hours. As a result, we postulate that rFVIIa is a potential candidate to reverse the anticoagulant effect of both fonda- and idraparinux in case of serious bleeding complications. u
Chapter 5 The INSTAP II Study was designed as a result of the findings from the previous two studies. Since rebound thrombosis after LMWH discontinuation is evident, and platelets are involved in this process as shown in other studies, we postulated that the addition ofanother platelet inhibitor on top of aspirin might reduce rebound coagulation. The findings described in this chapter are an interim analysis ofthe first 20 patients included. The findings indicate a significantly higher increase of thrombin generation in the aspirin-alone group than in the clopidogrel group. Furthermore, the clear rise of the thrombin activation marker TAT seen in the aspirin-alone group was not seen in the clopidogrel group. We therefore conclude that clopidogrel partly inhibits rebound coagulation and postulate that part of the clinical benefit of clopidogrel in ACS may by due to this phenomenon.
N.R. Bijsterveld, University ofAmsterdam, Academical Medical Center, Amsterdam
Chapter 6 and chapter 7 The PENTI and MAJOT Studies are similarly designed studies with an identical objective: can recombinant factorVIIa (rFVIIa) reverse the anticoagulant effect of the short-acting pentasaccharides fondaparinux (PENTI study), and of the longacting pentasaccharide idraparinux (MAJOT study) in healthy volunteers? The results of the PENTI study showed a complete normalisation by rFVIIa of the thrombin generation and clotting tests inhibited by fondaparinux, with a duration of two to six hours. In the MAJOTstudy, we observed a similar complete normalisation during low plasma levels of idraparinux, i.e. one week after administration, and a 196
Therapeutic arteriogenesis: from experimental observations towards clinical application Arteriogenesis, or the development of large collateral conductance arteries, constitutes a natural escape mechanism to ameliorate the harmful effects of arterial occlusion on organ perfusion and function. Positive pharmacological modulation of this process holds great promise as a potential new treatment for peripheral or coronary artery disease. The present thesis comprises studies on arteriogenesis, dealing with basic mechanisms, experimental pharmacological modulation and clinical application. A
summary ofthe content ofthe thesis is presented here. Studies on basic mechanisms of arteriogenesis Using knockout strains we were able to show that TNF-a is a prerequisite for a normal arteriogenic response upon vascular occlusion and that this effect is mediated via the p55 receptor. We also identified, for the first time, the modulating role of CD44 during arteriogenesis. We demonstrated that CD44 is strongly upregulated during natural arteriogenesis in control mice and, moreover, that the natural arteriogenic response is strongly reduced in CD44 knockout mice. It was shown that this is caused by both defective leucocyte trafficking and decreased stability of vascular growth factors. Interestingly, a decrease in CD44 expression was found on monocytes that were isolated from patients with poorly developed collateral arteries ('bad responders') as compared with patients with well-developed collateral arteries ('good responders'). Studies on pharmacological
modification of arteriogenesis MCP-1 is a potent proarteriogenic factor. In this thesis, studies are presented on the proarteriogenic effects of MCP- 1 on collateral artery
Figure 1. Immunohistological staining of rabbit hind limb tissue, harvested 7days after
fomoralartery ligation. A collateral artery isshown in its long axis. The typical corkserew appearance of the collateral artery is clearly shown. As another hallmark of collateral arterke, maziveproliferation ofvasculartissuecan berecogniwed. KI-67 (yllow-red) isused as markerforprolifration, smooth musck cells in the vascular wall are coloured with antialpha SM (green) and a nuckar countermaining isperformed with Hoechst 33342 (blue). Netherlands Heart Journal, Volume 12, Number 4, April 2004
..
growth in a small animal model as well as a preclinical large animal model. A new discovery was the proarteriogenic effects oftwo other factors. TGF-01 showed arteriogenic effects in the rabbit hind-limb model that are comparable with MCP-1. Moreover, in contrast to arteriogenesis, angiogenesis was left unaffected by treatment, reducing the risk for negative side effects, such as carcinogenesis and atherosderosis that are both specifically propelled by angiogenesis. In combination with the apparent plaque-stabilising effects of TGF-01, this justifies further investigations in the potential for TGF-P1 as a clinical compound for stimulation of arteriogenesis. GM-CSF was also found to be proarteriogenic in the rabbit hind-limb. In-vitro evidence is provided that GM-CSF inhibits apoptosis of monocytes/macrophages as a potential mechanism for stimulation of arteriogenesis. Also
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the additive effects of GM-CSF and MCP-1 are described.
unwanted side effects on atherosclerosis from these two factors.
Balance between arteriogenesis and atherosclerosis
The START trial This thesis includes the design ofthe START trial, which is being conducted in the Academic Medical Centre in Amsterdam, the Rijnland Hospital in Leiderdorp and the University Clinic of Freiburg. A total of 40 patients with peripheral artery disease are being treated for two weeks with subcutaneous injections of GM-CSF. Efficacy ofthe treatment will be assessed at day 14 as well as day 90. The primary endpoint is treadmill walking time and in addition we will be measuring ankle-brachial index and LaserDoppler flux. In a subgroup, measurements of volume flow are to be performed with the use of MRI. c N. van Royen, University ofAmsterdam, Amsterdam
The proarteriogenic efficacy of MCP-1 was preserved under conditions of hyperlipidaemia. However, in atherosclerotic ApoE -/mice the exogenous application of MCP- 1 induced atherosclerotic plaque formation and changed cellular composition of plaques. Under the influence of MCP-1 treatment we found increased neointima formation, atherosclerotic plaque progression and modulation of cellular content of plaques. This stresses the delicate balance between vascular growth and atherosclerosis. Current investigations seek to inhibit the proatherogenic effects of MCP-1 with the use of co-factors. Both TGF-P1 and GM-CSF have been reported to exert antiatherogenic effects, reducing the risk of
~
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Answer to the rhythm puzzle on page 178 This is a typical example of ventriculophasic sinus arrhythmia: PP intervals encompassing a QRS complex are consistently shorter than those without an intervening QRS complex. It is most likely that arterial pressure-induced changes in baroreceptor-mediated vagal input to the sinus node underlie this
phenomenon. Obviously, one cannot be absolutely certain about the level of the 2:1 AV block. Nevertheless, there are several clues. The QRS duration is 160 ms and QRS axis is about -45o indicating peripheral conduction disturbance and, thus, block at the infra-His level. Also, the fact that this case involves a symptomatic, female patient older than 60 years with structural heart disease favours infra-nodal disease. The PR interval is prolonged at 240 ms. In the presence of a narrow QRS complex this would have been suggestive of an AV nodal conduction disturbance. In this case, however, the QRS is prolonged and coexistence of nodal delay cannot be ruled out. As discontinuation of digoxin did not affect the PR interval, it is concluded that severe impairment of intra-
Netherlands Heart Journal, Volume 12, Number 4, April 2004
~ ~
~ ~
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.!
1840mks940mnis18 960mn1 I r| | I rl|
Figure 1. or infra-His conduction is the cause of the long PR interval. She became free of symptoms after implantation of a DDD pacemaker. U
197
i*
2003
For the fifteenth year in a row, the Netherlands Society of Cardiology (NVVC), the Interuniversity Cardiology Institute ofthe Netherlands, and the sponsor, Sanofi Synthelabo, are supporting the competition for the best three PhD theses published last year on a cardiovascular subject. The prizes carry the name of one of the great men in the history of Cardiology: Willem Einthoven (1860-1927), the pioneer of the human ECG. The jury, consisting of representatives of the NVVC, ICIN, and Sanofi Synthelabo, were offered 20 dissertations to review. The jury members were impressed and pleased by the scientific quality ofthe work ofthe young doctors. Hence, it was not easy to decide upon the winners. The three nominees will present their work at the spring meeting of the NVVC, which will be held in Amsterdam on 23 April 2004. The winner of the first, second and third prize will be chosen by the audience. Summaries ofthe three nominated PhD theses are given below.
Professor C.A. Visser Chairman of the Jury
Coronary spiral CT While mechanical CT was long regarded as unsuitable for cardiac imaging, the latest generations of multi-slice spiral computed tomography (MSCT) scanners allow detailed imaging of the heart and coronary arteries. The coronary lumen is enhanced by an intravenously injected contrast medium and the scan is performed during a single breath hold. CT data acquisition continues throughout the cardiac cycle, while ECG-synchronised images are reconstructed retrospectively. Three-dimensional datasets ofthe heart during a particular phase can be reconstructed at any point within the cardiac cycle. Stenosis detection With four-slice MSCT, significant coronary narrowing could be detected with a sensitivity of 82% and specificity of 93% in coronary segments with a minimal diameter of 2.0 mm and with sufficient image quality. However, 30% of the coronary segments could not be interpreted due to motion artefacts and extensive coronary calcification. Particularly the right coronary artery is vulnerable to motion artefacts because of its large motion radius and shorter motion-free interval. With lesions in nonassessable segments classified as false-negative
194
interpretations, the sensitivity dropped to 61%. Comparing patients with a low, intermediate or high heart rate, significantly fewer motion artefacts, better interpretability and more accurate detection of coronary obstruction could be achieved in the group with the slowest heart rate. With the experiences from the fourslice studies, a study with 16-slice computed tomography with thinner slices and faster gantry rotation was performed with heart rate modulation by 5-receptor blocking medication. Without exclusion of less assessable coronary arteries, 95% of the coronary arteries with significant stenosis were detected, using conventional angiography as reference (figure 1). The high sensitivity came at the expense of a slightly lower specificity of 86%.
Imaging of grafts and stents The usefidness ofMSCT in patients who had undergone bypass surgery was explored using four-slice MSCT. While particularly venous bypass grafts were visualised well with accurate interpretation of proximal and distal segments, evaluation of the diffusely diseased, and often calcified coronary arteries proved to be more challenging. Imaging of in vitro and in vivo
coronary stents is complicated by metal-related blooming artefacts, which interfere with visualisation of the in-stent lumen. Technical innovations, such as thinner detector rows, seem to improve the interpretation of stented coronary
artenes. Plaque imaging Apart from the coronary lumen assessment, MSCT can visualise the diseased coronary wall. While detection and quantification of coronary calcium by (nonenhanced)
Figure 1. MSCT angiogram showing severe stenosis (arrow) of the left main bifurcation. The insert allows appreciation of the shape and contents of the plaques, i.e. bright calcified and dark noncakified material.
Netherlands Heart Journal, Volume 12, Number 4, April 2004
CT has been described extensively, current studies focus on the interpretation of noncalcified plaque material.
Conclusion MSCT coronary angiography is a minimally invasive and relatively simple procedure that allows accurate evaluation ofthe coronary lumen. The time has come to determine the place of noninvasive coronary angiography in clinical practise, either as an alternative to invasive angiography, or at an earhler stage in the diagnostic work-up of patients with (suspected) coronary artery disease. l K. Nieman, Erasmus University Rotterdam, Rotterdam
Heparin derivatives in acute coronary syndromes This thesis focuses on several issues regarding the use of anticoagulants in patients with acute coronary syndromes.
Chapter 1 provides an overview of clinical trials comparing unfractionated heparin (UFH) with lowmolecular-weight heparin (LMWH) for the treatment of venous thrombosis and arterial thrombosis (unstable angina, non-Q-wave infarction and stroke). Fixed-dose subcutaneous LMWH is a safe and effective alternative for doseadjusted intravenous heparin in the treatment of patients with acute venous thrombotic disease as well as in patients with acute unstable coronary syndromes. The effectiveness of LMWH in patients with acute myocardial infarction is less well documented. There seems to be no beneficial effect of LMWH treatment as compared with placebo in patients with acute ischaemic stroke, while the risk of major bleeding was increased.
onary syndromes (ACS), namely an intravenous loading dose plus subcutaneous enoxaparin versus subcutaneous alone. The impact ofthese regimens on the coagulation system was quantified in 14 combinedregimen patients and 11 singleregimen patients. A clear time benefit was obtained with the combined regimen as reflected in an earlier reduction of thrombin generation without leading to unacceptably high anticoagulant levels. We postulate that this earlier suppression of coagulation may translate into clinical benefit, as the risk of thrombotic complications is greatest in the early hours after admission.
Chapter 3 The INSTAP I Study performed after several observations were published where UFH cessation in stabilised ACS patients resulted in a clustering of
was
recurrent ischaemic events within
24 hours after cessation, which is accompanied by a reactivation ofthe coagulation system to levels higher than before treatment. Since LMWHs were becoming the treatment of choice, this study investigated whether biochemical rebound could be observed after LMWH cessation. This is the first published study showing that
LMWH cessation has a comparable reactivation of coagulation effect as seen with UFH. The difference with UFH is the time of occurrence; maximal reactivation of coagulation
after IJFH is six to 12 hours after cessation. With LMWH, rebound occurred 24 hours after the last administration. Chapter 4 In the TESSMA Study (Acombined analysis ofthe Essence/ TIMI lb trial) we investigated whether the discontinuation of LMWH resulted in clustering of clinical rebound events shortly after cessation of treatment. These data were derived from two large clinical trials, on which we performed a retrospective analysis. The results were consistent with our previous biochemical study, and showed a dustering of ischaemic events in the first 24 hours of cessation oftherapy which was comparable with the rebound seen after UFH cessation in other studies. The incidence of death, MI, and urgent revascularisation on the first day after cessation was 2.3%, while the incidence on the following day was only 0.8% (figure 1). Interestingly, patients who were treated with prolonged out-ofhospital LMWH administration did not show this early rebound -
2.5
* 2.0 -D
| ~~~~ |ShortEnox
_
s LongEnox
1.5-
to 0.5
0.0
-
-
-1
1
*
'3 4 Day before (-1) _S e (1 to 7) i
5 o
6 7 oof therapy
UFH=unfractioned heparin (n=2617) ShortEnox-short-term enoxaparin (n=1498) LongEnox-Iong-term enoxaparin (n=1043)
Chapter 2 In the BOLUS Study, we compared two different LMWH Figure 1. Hazard of rebound ischaemic events (death, MI, or urgent revascularisation) regimens in the initiation of treat- after discontinuation of unfractionated heparin (UFH) or short-term enoxaparin in ment of patients with acute cor- patients treatedfor acute coronary syndromes (-1), and dayw (1 to 7). Netherlands Heart Journal, Volume 12, Number 4, April 2004
195
phenomenon. Based on these results, we postulate that cessation of LMWH or UFH treatment in ACS patients should be followed by a 24hour in-hospital observation period since a substantial number ofpatients could suffer from early recurrent ischaemic events. Prolonged treatment or weaning of LMWH treatment should be prospectively evaluated.
partial normalisation at high levels ofidraparinux, i.e. three hours after administration. The effect ofrFVIIa was proportionally identical during high and low plasma levels of idraparinux and lasted two to six hours. As a result, we postulate that rFVIIa is a potential candidate to reverse the anticoagulant effect of both fonda- and idraparinux in case of serious bleeding complications. u
Chapter 5 The INSTAP II Study was designed as a result of the findings from the previous two studies. Since rebound thrombosis after LMWH discontinuation is evident, and platelets are involved in this process as shown in other studies, we postulated that the addition ofanother platelet inhibitor on top of aspirin might reduce rebound coagulation. The findings described in this chapter are an interim analysis ofthe first 20 patients included. The findings indicate a significantly higher increase of thrombin generation in the aspirin-alone group than in the clopidogrel group. Furthermore, the clear rise of the thrombin activation marker TAT seen in the aspirin-alone group was not seen in the clopidogrel group. We therefore conclude that clopidogrel partly inhibits rebound coagulation and postulate that part of the clinical benefit of clopidogrel in ACS may by due to this phenomenon.
N.R. Bijsterveld, University ofAmsterdam, Academical Medical Center, Amsterdam
Chapter 6 and chapter 7 The PENTI and MAJOT Studies are similarly designed studies with an identical objective: can recombinant factorVIIa (rFVIIa) reverse the anticoagulant effect of the short-acting pentasaccharides fondaparinux (PENTI study), and of the longacting pentasaccharide idraparinux (MAJOT study) in healthy volunteers? The results of the PENTI study showed a complete normalisation by rFVIIa of the thrombin generation and clotting tests inhibited by fondaparinux, with a duration of two to six hours. In the MAJOTstudy, we observed a similar complete normalisation during low plasma levels of idraparinux, i.e. one week after administration, and a 196
Therapeutic arteriogenesis: from experimental observations towards clinical application Arteriogenesis, or the development of large collateral conductance arteries, constitutes a natural escape mechanism to ameliorate the harmful effects of arterial occlusion on organ perfusion and function. Positive pharmacological modulation of this process holds great promise as a potential new treatment for peripheral or coronary artery disease. The present thesis comprises studies on arteriogenesis, dealing with basic mechanisms, experimental pharmacological modulation and clinical application. A
summary ofthe content ofthe thesis is presented here. Studies on basic mechanisms of arteriogenesis Using knockout strains we were able to show that TNF-a is a prerequisite for a normal arteriogenic response upon vascular occlusion and that this effect is mediated via the p55 receptor. We also identified, for the first time, the modulating role of CD44 during arteriogenesis. We demonstrated that CD44 is strongly upregulated during natural arteriogenesis in control mice and, moreover, that the natural arteriogenic response is strongly reduced in CD44 knockout mice. It was shown that this is caused by both defective leucocyte trafficking and decreased stability of vascular growth factors. Interestingly, a decrease in CD44 expression was found on monocytes that were isolated from patients with poorly developed collateral arteries ('bad responders') as compared with patients with well-developed collateral arteries ('good responders'). Studies on pharmacological
modification of arteriogenesis MCP-1 is a potent proarteriogenic factor. In this thesis, studies are presented on the proarteriogenic effects of MCP- 1 on collateral artery
Figure 1. Immunohistological staining of rabbit hind limb tissue, harvested 7days after
fomoralartery ligation. A collateral artery isshown in its long axis. The typical corkserew appearance of the collateral artery is clearly shown. As another hallmark of collateral arterke, maziveproliferation ofvasculartissuecan berecogniwed. KI-67 (yllow-red) isused as markerforprolifration, smooth musck cells in the vascular wall are coloured with antialpha SM (green) and a nuckar countermaining isperformed with Hoechst 33342 (blue). Netherlands Heart Journal, Volume 12, Number 4, April 2004
..
growth in a small animal model as well as a preclinical large animal model. A new discovery was the proarteriogenic effects oftwo other factors. TGF-01 showed arteriogenic effects in the rabbit hind-limb model that are comparable with MCP-1. Moreover, in contrast to arteriogenesis, angiogenesis was left unaffected by treatment, reducing the risk for negative side effects, such as carcinogenesis and atherosderosis that are both specifically propelled by angiogenesis. In combination with the apparent plaque-stabilising effects of TGF-01, this justifies further investigations in the potential for TGF-P1 as a clinical compound for stimulation of arteriogenesis. GM-CSF was also found to be proarteriogenic in the rabbit hind-limb. In-vitro evidence is provided that GM-CSF inhibits apoptosis of monocytes/macrophages as a potential mechanism for stimulation of arteriogenesis. Also
~
.1-I'm
M.~
~ ~
~ ~
~ ~ ~
~
~ ~
~ ~
~
~ ~
~ ~
~ ~
~ ~
~
~
~~
~ ~
~ ~
the additive effects of GM-CSF and MCP-1 are described.
unwanted side effects on atherosclerosis from these two factors.
Balance between arteriogenesis and atherosclerosis
The START trial This thesis includes the design ofthe START trial, which is being conducted in the Academic Medical Centre in Amsterdam, the Rijnland Hospital in Leiderdorp and the University Clinic of Freiburg. A total of 40 patients with peripheral artery disease are being treated for two weeks with subcutaneous injections of GM-CSF. Efficacy ofthe treatment will be assessed at day 14 as well as day 90. The primary endpoint is treadmill walking time and in addition we will be measuring ankle-brachial index and LaserDoppler flux. In a subgroup, measurements of volume flow are to be performed with the use of MRI. c N. van Royen, University ofAmsterdam, Amsterdam
The proarteriogenic efficacy of MCP-1 was preserved under conditions of hyperlipidaemia. However, in atherosclerotic ApoE -/mice the exogenous application of MCP- 1 induced atherosclerotic plaque formation and changed cellular composition of plaques. Under the influence of MCP-1 treatment we found increased neointima formation, atherosclerotic plaque progression and modulation of cellular content of plaques. This stresses the delicate balance between vascular growth and atherosclerosis. Current investigations seek to inhibit the proatherogenic effects of MCP-1 with the use of co-factors. Both TGF-P1 and GM-CSF have been reported to exert antiatherogenic effects, reducing the risk of
~
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~ ~
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Answer to the rhythm puzzle on page 178 This is a typical example of ventriculophasic sinus arrhythmia: PP intervals encompassing a QRS complex are consistently shorter than those without an intervening QRS complex. It is most likely that arterial pressure-induced changes in baroreceptor-mediated vagal input to the sinus node underlie this
phenomenon. Obviously, one cannot be absolutely certain about the level of the 2:1 AV block. Nevertheless, there are several clues. The QRS duration is 160 ms and QRS axis is about -45o indicating peripheral conduction disturbance and, thus, block at the infra-His level. Also, the fact that this case involves a symptomatic, female patient older than 60 years with structural heart disease favours infra-nodal disease. The PR interval is prolonged at 240 ms. In the presence of a narrow QRS complex this would have been suggestive of an AV nodal conduction disturbance. In this case, however, the QRS is prolonged and coexistence of nodal delay cannot be ruled out. As discontinuation of digoxin did not affect the PR interval, it is concluded that severe impairment of intra-
Netherlands Heart Journal, Volume 12, Number 4, April 2004
~ ~
~ ~
~~i~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~h~i-
.!
1840mks940mnis18 960mn1 I r| | I rl|
Figure 1. or infra-His conduction is the cause of the long PR interval. She became free of symptoms after implantation of a DDD pacemaker. U
197
i*
