Antegrade selective cerebral perfusion at moderate hypothermia of 28 ̊C - how safe is the spinal cord? [Elektronische Ressource] / von Maximilian Lühr

Sujets

• Gesundheit

Informations

• Publié par: albert-ludwigs-universitat_freiburg
• Publié le: 01 janvier 2010
• Nombre de lectures: 12
• Poids de l'ouvrage: 11 Mo

Extrait

Aus der Abteilung für
Herz- und Gefäßchirurgie der Chirurgischen Universitätsklinik
der Albert-Ludwigs-Universität Freiburg im Breisgau
und
der Abteilung für Herz- und Thoraxchirurgie
der Mount Sinai School of Medicine in New York, USA




Antegrade Selective Cerebral Perfusion at Moderate
Hypothermia of 28 °C - How Safe is the Spinal Cord?





INAUGURAL-DISSERTATION
zur
Erlangung des Medizinischen Doktorgrades
der Medizinischen Fakultät
der Albert-Ludwigs-Universität Freiburg im Breisgau




Vorgelegt im Jahr 2010
von Maximilian Lühr
geboren in MünchenDekan: Prof. Dr. Dr. h.c. mult. Herbert Blum
1. Gutachter: Prof. Dr. med. Dr. h. c. Friedhelm Beyersdorf
2. Gutachter: Ass. Prof. Dr. Christian D. Etz

Jahr der Promotion: 2010Index

1 INTRODUCTION ...…………………………………………………………………… 6
1.1 Thoracic aortic aneurysms………………………………………………… 6
1.2 Thoracic aortic dissections 8
1.3 Endovascular stent-grafting for aortic arch pathology………………. 9
1.4 Aortic arch surgery……………………………………………………......... 10
1.4.1 Surgical indications………………………………………………. 10
1.4.2 Cerebral protection ……………………………………………… 10
1.4.3 Cerotection techniques…………………………………. 10
1.4.3.1 Various stages of hypothermia……...……………… 11
1.4.3.2 Hypothermic circulatory arrest (HCA)………………. 11
1.4.3.3 Antegrade selective cerebral perfusion (aSCP)……. 11
1.4.3.4 Retrograde cerebral perfusion (RCP)………………. 12
1.4.3.5 Axillary and femoral artery cannulation…………….. 13
1.4.3.6 pH-Management during CPB and HCA…………… 13
1.5 Paraplegia in aortic surgery……………………………………………….. 14
1.6 Moderate hypothermia during aortic arch repair…………..………….. 14
1.7 The need for experimental evaluation………………………………....… 14
1.8 Study design.....……………………………………………..……………….. 15
1.9 The porcine model for cardiovascular research…………………......... 18
1.9.1 Aortic arch and the supraaortic vessels………………………… 18
1.9.2 Thoracic and abdominal aortic segmental arteries (SA)……….. 20

2 MATERIALS AND METHODS…………………………………………………….… 21
2.1 Introduction…………………………………………………………………… 21
2.2 Housing and animal care…………………………………………………… 21
2.3 Perioperative management………………………………………………… 22
2.3.1 Ventilation and anesthesia……………………………………...... 22
2.3.2 Monitoring………………………………………………………… 23
2.4 Operative technique………………………………………………………… 23
2.4.1 Catheter placement for microsphere injections………………… 23
2.4.2 Intracranial pressure measurement……………………………… 25
2.4.3 Cannulation and cardiopulmonary bypass (CPB)……………… 26
2.4.4 Antegrade selective cerebral perfusion (aSCP)……………...…. 26
2.4.5 Rewarming and decannulation…………………………………. 27
2.4.6 End of operation………………………………………………….. 28
2.4.7 Weaning from ventilation and anesthesia………………………. 30
2.4.8 Postoperative monitoring and intensive care…………………… 30 2.5 Spinal cord blood flow (SCBF) determination………………………….. 30
2.5.1 Fluorescent microspheres……………………………………….. 30
2.5.2 Microsphere injections…………………………………………… 31
2.5.3 Tissue harvesting…………………………………………………. 31
2.5.4 Analysis for spinal cord blood flow (SCBF)……………………... 35
2.6 Postoperative neurobehavioral assessment…………………………….35
2.6.1 Physical therapy and mobilization………………………………..35
2.6.2 Videotaping and scoring………………………………………..... 35
2.7 Histopathological evaluation…………………………………………........ 36
2.8 Data analysis…………………………………………………………………. 38
2.8.1 Survival……………………………………………………………. 38
2.8.2 Histology and neurological outcome…………………………..... 38
2.8.3 Physiologic and hemodynamic parameters……………………..38
2.8.4 Regional blood flow………………………………………………. 38

3 RESULTS………………………………………………………………………………. 40
3.1 Experimental groups…………………………………………………………40
3.1.1 Comparability of the experimental groups……………………… 40
3.2 Intraoperative parameters…………………………………………………. 40
3.2.1 Cardiopulmonary bypass (CPB)…………………………………. 40
3.2.2 Antegrade selective cerebral perfusion (aSCP)……………….…41
3.3 Postoperative survival………………………………………………………. 42
3.4 Neurologic outcome 43
3.5 Spinal cord blood flow (SCBF)…………………………………………….. 45
3.6 Ischemic spinal cord damage……………………………………………... 47

4 DISCUSSION………………………………………………………………………….. 50
4.1 Previous experimental studies51
4.2 The results of this experiment 51
4.3 Comparison with previous experiments….………………………………52
4.4 Experimental results in clinical context…………………………………. 53
4.5 Impaired neurological outcome – prolonged ischemia
and/or reperfusion injury?...................................................................... 55
4.6 Moderate versus deep hypothermia………………………………………57
4.7 Conclusion…………………………………………………………….…….…59
5 ABSTRACT…………………………………………………………………………….. 60
5.1 English abstract……………………………………………………………… 60
5.2 German abstract……………………………………………………………... 61

6 ADDENDUM…………………………………………………………………………… 62
6.1 List of abbreviations……………………………………………………….... 62
6.2 Semantics……………………………………………………………………... 62

7 REFERENCES………………………………………………………………….......…. 63

CURRICULUM VITAE………………………………………………………………..… 71
English…………………………………………………………………………....... 71
German………………………………………………………………………......... 72
Publications………………………………………………………………….....… 74
8.3.1 Authorships……………………………………………………….. 74
8.3.2 Co-Authorships…………………………………………………… 74
8.3.3 Abstracts………………………………………………………..… 77
8.3.4 Poster presentations……………………………………………… 81

ACKNOWLEGMENT……………………………………………………………….……83Antegrade Selective Cerebral Perfusion at Moderate Hypothermia of 28 °C -
How Safe is the Spinal Cord?
1 Introduction
1 Introduction
Treatment and management of thoracic aortic disease such as aortic
aneurysms or dissections remains a challenge for cardiothoracic and
vascular surgeons, especially when the aortic arch is involved and open
surgery becomes necessary.
The incidence of thoracic aortic aneurysms was reported to be 5.9 cases
per 100.000 person-years in 1982 [1]. In 2006, a study based on 14.000
cases by Olsson et al. reported an increase of thoracic aortic disease (TAD)
by 52 % in men and by 28 % in women to reach 16.3 per 100.000 per year
and 9.1 per 100.000 per year, respectively [2]. This increase in industrialized
countries appears to be a result of implemented routine screening studies,
improved imaging modalities, and increased clinical awareness.
1.1 Thoracic aortic aneurysms
Thoracic aortic aneurysms (TAA) do not occur as often as abdominal
aortic aneurysms [3]. However, they may be caused by several different
disease processes, especially in respect to their location which is distinctly
connected with the cause, course, and treatment of a TAA. The ascending
thoracic aorta is the most common location of a TAA (60 %), followed
by the descending segment (40 %), then the arch (10 %) [3]. Aortic
arch lesions may involve the proximal, transverse or distal arch. (Fig. 1)

Descending aortic aneurysms are most often associated with atherosclerosis
which generally plays an important role in aneurysmal disease [4]. The
most common cause for ascending aortic aneurysms is cystic medial
degeneration [5]. Genetic disorders which affect the connective tissue, such
as Marfan’s disease, Loeys-Dietz syndrome and Ehlers-Danlos syndrome,
are also associated with ascending aortic aneurysms [6-9]. Rare causes
of TAA include infections or syphilis [10]. Involvement of the aortic arch
often occurs by continuation of an ascending and/ or descending aortic
aneurysm. Aortic arch aneurysms can also be associated with Takayasu’s
arteritis [11] or atherosclerosis.
Page 6Antegrade Selective Cerebral Perfusion at Moderate Hypothermia of 28 °C -
How Safe is the Spinal Cord?
1 Introduction
Figure 1: Schematic figure of the anatomic segments of the aorta. Occurrence of thoracic aortic aneurysms
differs between the ascending (60 %), descending (40 %) and arch (10 %) segment [3]. Aortic arch lesions may
be categorized as proximal (A), distal (B), or total (C).
Page 7Antegrade Selective Cerebral Perfusion at Moderate Hypothermia of 28 °C -
How Safe is the Spinal Cord?
1 Introduction
1.2 Thoracic aortic dissections
Thoracic aortic dissections occur if the aortic blood flow is redirected via
an intimal tear into the media of the aortic wall. In this way the intima is
separated from the overlying adventitia by a dissection membrane, creating
a so-called “false lumen” along a variable length within the aortic media.

The cause of aortic dissection is still under investigation. Several risk
factors which may be associated with thoracic aortic dissection include
hypertension, connective tissue disorders (Marfan’s disease, Ehlers-Danlos
syndrome, Turner’s syndrome, and bicuspid aortic valve), cystic medial
degeneration, aortitis, atherosclerosis, pre-existing thoracic aortic aneurysm,
trauma, intramural hematoma, coarctation of the aorta, hypervolemia, and
polycystic kidney disease [7, 8, 12-16]. In addition, surgical manipulations
during cardiovascular operations, such as cannulation for cardiopulmonary
bypass, aortic cross-clamp