SHA24/083005

“Open” Approach to Aortic Arch Aneurysm Repair Dr Adil Al Kindi, MD, MSc, FRCSC, FACCP Consultant Cardiothoracic Surgeon Director of Aortic & Endovascular Surgery Sultan Qaboos University Hospital Muscat, Sultanate of Oman

Disclosure No financial conflicts

Approach to Open Repair of Aortic Arch Aneurysms • • • •

Indications Arterial Cannulation Brain Protection and Monitoring Surgical Techniques

Natural History

Coady et al, J Thorac Cardiovas Surg 1997; 113

Natural History

Coady et al, J Thorac Cardiovas Surg 1997; 113

Indications • Isolated Arch, low risk, asymptomatic: ≥5.5cm (Level: B) • 4-≤5.5cm, image every 6 months • ≤ 4cm, image every 12 months • Replace if enlarged (≥4.5-5) when replacing ascending • Acute dissection: aneurysmal or extensive arch destruction and leakage 2010 ACCF/AHA/AATS/ACR/…..Guidelines

Challenges Bloodless Surgical Field Brain Protection

Approach to Arterial Cannulation for Aortic Arch Replacement

Femoral Cannulation • Advantages: • • • •

Easily Accessible Large Cannula (>18Fr) Flows >4l/min Access for Vein

Femoral Cannulation • Disadvantages: • Retrograde emboli from diseased thoracic aorta • Chronic Dissection: false lumen maybe over perfused and risk rupture 1/4

Subclavian/Axillary Cannulation

• Advantages:

• Clear of Atheroma/Dissection • Usable >97% of cases • Allows 1 site for cannulation for whole repair • Direct or with side graft

Subclavian/Axillary Cannulation • Disadvantage: • Time consuming • Needs a 2nd incision • Bleeding on your pants!

Inominate Artery • Advantages: • Single sternotomy incision • Free of plaques

• Disadvantages: • Emboli of plaques • Risk of air emboli is higher

Outcome By Site N= 1336Propensity matched

Svensson et al; JTCVS, 1993;106

Approach to Brain Protection • Hypothermic Circulatory Arrest (HCA) • Antegrade Cerebral Perfusion (ACP) • Retrograde Cerebral Perfusion (RCP)

Hypothermic Circulatory Arrest

Svensson et al; JTCVS, 1993;106 Svensson et al; JTCVS, 1993;106

HCA Method • Cool down slowly >20mins for homogenous cooling • Alpha stat pH Mx • At target core temp and EEG silence (<2μV), head down, arrest circulation and remove clamp • +/- start ACP/RCP, occlude head vessels • De-air after distal • Stay cold until all anastomosis done

HCA Method • Re-warm slowly, 10C gradient between perfusate & core temp • Pressure MAP>65mmHg, equal to age >65yrs • Stop rewarming at esophageal 35.5C, bladder 34C • Do not exceed 36C on perfusate temp • Leave OR @ 34-35C esophageal • Slow rewarming over 3hrs in ICU

Antegrade Cerebral Perfusion (ACP) • Advantages: • Maintains the brain cold • Supplies O2 and glucose, can arrest at higher temps • Washes out toxic metabolites • Allows longer periods of safe HCA

• Methods: • Via right axillary/subclavian cannulation • Direct cannulation of head vessels (Kazui)

Method Axillary: • Start at 5 and increase to 10ml/kg/min • Clamp/balloon inominate origin after de-airing • If not DHCA, need to cannulate left carotid • Measure BP from Rt arm and tip of balloon catheter

1/2

Axillary artery cannulation N=254

Without axillary artery cannulation N=144

2%

10.4%

0.0004

Neurological Dysfunction

12.6%

29.2%

<0.0001

Permanent

1.2%

4.2%

0.08

Temporary

11.4%

25.0%

0.0006

Hospital Mortality

P value

Kazui et al, Ann Thor Surg 2002

Axillary Artery with ACP

Kazui et al, Ann Thor Surg 2002

Retrograde Cerebral Perfusion Theoretical benefits: • Maintain cerebral hypothermia • Flush out embolic debris • Provide metabolic support

?? Difficult to prove any significant cerebral flow

479 pts HCA 60% had RCP RCP group lower mortality and stroke rate compared to HCA group BUT, RCP more recent group. HCA group higher incidence of CVA, DM & dissections Coselli et al; J Card Sur, 1997; 64

Mortality & RCP

Svensson et al; JTCVS, 1993;106

Predictors of Stroke • • • • • • • •

HTN Renal Failure CAD Emergency Atherosclerotic Aorta Descending aorta Mitral Valve Replacement Aortic vs Ax/Sc + SG • RCP

Svensson et al, Ann Thorac Surg 2004; 78

Neuro protection protocol

Lower Body Perfusion • Safe upto 60mins circ arrest at 20C • Vulnerability to ischemia: • • • • • •

Spinal Cord Kidneys Liver Pancreas Gut Skeletal Muscle

Approach to Brain monitoring • EEG • Near Infra-red Spectroscopy(NIRS) • Transcranial Doppler (TCD) • Jagular Venous Oxygen Saturation

Perfusion & Brain Protection Suggestion • <30 mins • Hemiarch • DHCA alone • SCA/Ax

• > 30mins • Total arch, Elephant Trunk • DHCA + ACP

Approach to Open Surgical Repair

3/4

Total Arch Replacement En bloc repair (Island Technique) • Reimplantation of head vessels as a single island • Less cumbersome • Shorter HCA • Leaves diseased tissue behind • Cannot be used if tissue in the island is severely damaged

Island Repair

Stage I Elephant Trunk Repair

Svensson et al, Ann Thorac Surg. 2004 Jul;78(1):109-16; discussion 109-16.

Separate Graft Technique • Bleeding from branch vessels easily controlled • Anastomosis done at distal nondiseased segment • Pathological portion of arch can be completely resected

Separate Graft Technique

Closing Remarks â&#x20AC;˘ Reported Mortality in the literature is 2.1-17% â&#x20AC;˘ Reported Stroke Incidence is 230% â&#x20AC;˘ Key to improved outcomes are arterial cannulation site, degree of hypothermia and brain monitoring

Thank You