THORACIC AND AORTIC SURGERY

Question 1

Ascending Aorta:

Answer 1

Begins at the AV annulus and extends to the proximal innominate artery

Question 2

Transverse Arch

Answer 2

Where 3 brachiocephalic
branches arise
 Treatment for Ascending and Transverse Arch are very similar.

Question 3

Descending Thoracic and Thoracoabdominal Aorta

Answer 3

Lies just beyond the subclavian to the aortoiliac bifurcation

Question 4

Dissection

Answer 4

Occurs when blood penetrates the intima of the Aorta  Creates an expanding hematoma between medial layers  True lumen is not usually dilated
 Compressed by dissection  Branching vessels may not be affected

Question 5

Aneurysm

Answer 5

 Dilation of all 3 layers

Question 6

AORTIC DISSECTIONS

 Incidence

Answer 6

According to European Autopsy Study Occurs in 3.2 dissections per 100,000 autopsies Results in more deaths than aneurysm rupture

Question 7

AORTIC DISSECTIONS risk factors

Answer 7

Hypertension, advanced age, male sex, Marfan’s Syndrome, Coarctation, Bicuspid AV, Pregnancy

Question 8

AORTIC DISSECTIONS

 Causes (Inciting Events)

Answer 8

Increased Physical Activity Emotional Stress Blunt Trauma

Can also occur without any physical activity  Ie. Cannulation for bypass

Question 9

AORTIC DISSECTIONS

 Mechanism

Answer 9

Intimal Tear  Presence of a weakened aortic wall  Areas experiencing greatest mechanical shear forces
 Points where the aorta is fixed, there is increased shear stress applied to the aortic wall.

Question 10

aoritc dissections prevalence based on location

Answer 10

Ascending (61%)  Descending (24%)

 Isthmus (Distal to Left Subclavian) (16%)  Arch (9%) Abdominal (3%)  Other (1%)

Question 11

AORTIC DISSECTIONS

 Propagation

Answer 11

Occurs within seconds Driven by pulse pressure and ejection velocity

Question 12

Origin of arteries (including coronary arteries) may be involved in

Answer 12

Aortic Dissections

 Vessel occlusions can also occur  Due to compression by the false lumen.

Question 13

DeBakey Classification

Answer 13

3 types based upon location of intimal tear and which section of the aorta is involved

Question 14

DEBAKEY CLASSIFICATION

 Type I

Answer 14

Intimal Tear: Asceding Aorta

 Dissection: All parts of thoracic aorta (ascending, arch, and descending)

Question 15

DEBAKEY CLASSIFICATION

 Type II

Answer 15

Intimal Tear: Asceding Aorta

 Dissection: Ascedng Aorta only  Stops before innominate artery

Question 16

DEBAKEY CLASSIFICATION

 Type IIIA

Answer 16

Intimal Tear: Descending Aorta

 Dissection: Descending Thoracic only distal to left subclavian, ends above diaphragm

Question 17

DEBAKEY CLASSIFICATION

 Type IIIB

Answer 17

Intimal Tear: Descending Aorta  Dissection: Below diaphragm

Question 18

“Easier” Classification system

 Type A

Answer 18

 Ascending Aorta  Any involvement regardless of where tear is
 Regardless of how far it propagates  Usually emergent/ urgent cases  More virulent course

Question 19

Easier” Classification system

 Type B

Answer 19

Distal aorta  Any part of aorta distal to left subclavian

Question 20

Prognosis for untreated ascending dissection  DISMAL

 2 day mortality =  3 month mortality=

Answer 20

50%,90%

Question 21

usual cause of death from dissection

Answer 21

Rupture of the false lumen into the pleural space or
pericardium
 Lower incidence with DeBakey Type III or Stanford B dissections

Question 22

Other causes of death from dissections

Answer 22

Progressive heart failure (AV involvement)  MI (Coronary Involvement)  Stroke (Occlusion of cerebral vessels)  Bowel Gangrene (Mesenteric artery occlusion)

Question 23

AORTIC DISSECTIONS

 Surgical Mortality

Answer 23

 3-24%

 Depends on affected section of aorta  Aortic Arch – Highest mortality  Descending Thoracic – lowest mortality

Question 24

ANEURYSMS

 Incidence:

Answer 24

European Studies show 460/100,000 Thoracic Aneurysms

Question 25

aneurysm percentage by location

Answer 25

 45% Involved Ascending Aorta  10% Involved Arch  35% Involved Descending Aorta  10% Thoracoabdominal

Question 26

fusiform aneurysm

Answer 26

Entire circumference of the aortic wall

Question 27

saccular aneurysm

Answer 27

Involves only part of the circumference of the aortic | wall

Question 28

ARCH aneurysms are typically

Answer 28

saccular

Question 29

ANEURYSM – CRAWFORD CLASSIFICATION

Answer 29

 Used to classify Thoracoabdominal Aortic Aneurysms |  Used to describe the extent of the aorta requiring replacement

Question 30

ANEURYSM – CRAWFORD EXTENT I

Answer 30

Extent I : |  Involves most or all of the descending thoracic aorta and upper abdominal aorta.

Question 31

ANEURYSM – CRAWFORD EXTENT II

Answer 31

 Involves most or all of descending thoracic aorta and extends into infrarenal abdominal aorta

Question 32

ANEURYSM – CRAWFORD EXTENT III

Answer 32

 Involves the distal 1⁄2 or less of descending thoracic aorta and varying portion of abdominal aorta

Question 33

ANEURYSM – CRAWFORD EXTENT IV

Answer 33

Involves most or all abdominal aorta

Question 34

ANEURYSMS |  Natural History

Answer 34

 Progressive dilation |  More than 1⁄2 of aortic aneurysms rupture

Question 35

Untreated 5 year survival of a thoracoabdominal aortic aneurysm is

Answer 35

13-39%

Question 36

Other complications of aneurysm include:

Answer 36

 Mycotic infection  Atheroembolisation  Dissection (rare)

Question 37

ANEURYSMS |  Predictors of poor prognosis:

Answer 37

Larger size (less than 10cm max transverse diameter) Presence of other symptoms Associated CV Disease  CAD MI  CVA

Question 38

THORACIC ARTERY TEARS - ETIOLOGY |  Majority occurs after

Answer 38

a trauma. Involve deceleration injury (MVA) |  Large shear stress on points of aortic wall that are relatively immobile.

Question 39

thoracic artery tear leads to

Answer 39

immediate exsanguination and death  10-15% are lucky  Maintain the integrity of the adventitial covering of the aortic lumen  Survive to emergency care

Question 40

THORACIC ARTERY RUPTURE - LOCATION

Answer 40

Most occur distal to the origin of the left subclavian artery  Due to fixation at the point of the ligamentum arteriosum  2nd most common site  Ascending aorta just distal to the Aortic Valve.

Question 41

diagnosis for dissection aneurysm and trauma rupture

Answer 41

Dramatic onset, Asymptomatic until late in course  Medical evaluation for unrelated problem or complication of aneurysm If they survive trauma  Signs/symptoms similar to descending aortic aneurysm

Question 42

INDICATIONS FOR SURGERY – ASCENDING AORTA

Answer 42

 Dissection  Acute Type A  Virulent Course  High Mortality  Aneurysm  Persistent pain despite small aneurysm  AV Involvement creating MI  Angina  Rapidly expanding  Greater than 5-5.5 cm diame

Question 43

INDICATIONS FOR SURGERY – AORTIC ARCH

Answer 43

Dissections  Acute, limited to arch (rare)  Aneurysm  Repair of arch aneurysm is more complicated  Carries increased morbidity and mortality  Persistent symptoms  Greater than 5.5-6cm  Progressive expansion

Question 44

INDICATIONS FOR SURGERY – DESCENDING AORTA

Answer 44

Dissection  Medical management in acute phase  Failure to control hypertension medically  Continued pain  Enlargement on CXR, CT, Angio  Neurologic deficit  Renal/ GI Ischemia  Aneurysm  Greater than 5-6cm  Expanding  Leaking  Chronic, causing persistent pain.

Question 45

PERFUSION – AORTIC SURGERY |  Considerations

Answer 45

 Where is the aneurysm located?  Where do we need to cannulate?  Do we need to circ arrest?  Median sternotomy versus Thoracotomy?  Full CPB or Left heart bypass?

Question 46

CPB W/O CIRC ARREST

Answer 46

Very proximal aneurysms limited to the Aortic Root or Ascending Aorta.  Cannulate in the ascending aorta or transverse aorta, and Dual stage in RA or Bicaval  Cross clamp proximal to the Innominate Artery  If patient is unstable prior to sternotomy – cannulate femoral to go on CPB prior to sternotomy  Normal LV/PA Vent  Normal CPG  Ie. NORMAL CBP CASE!

Question 47

CPB W/ DHCA AND ACP

Answer 47

Bloodless field Uncluttered by clamps and cannulas | Studies have shown it doesn’t necessarily abate cerebral metabolic demands

Question 48

Significant cerebral metabolic activity occurs

Answer 48

at temperatures at which DHCA is initiated. |  Promotes brain ischemia  Accumulation of metabolic wastes.

Question 49

Perioperative neurologic complications |  Higher when DHCA was

Answer 49

greater than 40 minutes

Question 50

Mortality |  Increased dramatically when DHCA

Answer 50

was greater than 65 minutes.

Question 51

RETROGRADE CEREBRAL PERFUSION |  Gained popularity in the and was first done

Answer 51

‘90s.  1st done in 1980 by Milles and Ochsner |  Treating massive air embolism

Question 52

benefits of rcp

Answer 52

 Homogeneous cerebral cooling  Air bubble wash out  Wash out of embolic debris  Wash out of metabolic wastes  Prevent cerebral blood cell micro aggregation  Delivery of oxygen and nutrients to brain.

Question 53

Experimental and clinical data do not consistently support the efficacy of

Answer 53

RCP for cerebral protection  Flow may not be adequate to meet the metabolic needs  RCP provide flow to brain microvasculature?

Question 54

HOW TO DO A CIRC ARREST CASE |  Need to monitor temperatures

Answer 54

 Nasopharyngeal / Bladder  Arterial  Venous |  Water

Question 55

HOW TO DO A CIRC ARREST CASE. Need to monitor the brain

Answer 55

EEG – Brain activity |  Electrocerebral silence dictates adequate cerebral cooling

Question 56

drugs for circ arrest

Answer 56

Mannitol (25g) and Steroids  Enhances cerebral protection  Put in the pump prior to turning off the pump (Prime?)

Question 57

cannulation for circ arrest

Answer 57

Axillary Cannulation is preferred  Artery is usually exposed prior to sternotomy  After heparin is given,  8mm graft is sewn to the artery  Cannula is placed in the 8mm graft.  In an emergency – femoral artery is used  If it’s a dissection, make sure that the cannula is in the true lumen!  Venous cannula – RA, Bicaval, Femoral  Depends on need and access

Question 58

HOW TO DO A CIRC ARREST CASE |  CPB is initated

Answer 58

Assess adequacy of perfusion  Especially important for femoral artery cannulation

Question 59

10°C drop in temperature – reduces rate of oxygen | consumption by

Answer 59

50%. Pump flows can be reduced to a CI of 1.6-1.8 L/min/m2

Question 60

A 10°C decrease in tempearture causes a _____increase in blood viscosity

Answer 60

20-25%

Question 61

Hemodilution to a

Answer 61

hct of less than 25 % to avoid stroke

Question 62

Hct kept low until

Answer 62

rewarm |  Hemoconcentrate

Question 63

hemodilution reduces o2 carrying capacity but

Answer 63

overall oxygen delivery improves |  Decreased viscosity enhances the flow in the microcirculation.

Question 64

HOW TO DO A CIRC ARREST CASE |  At fibrillation

Answer 64

Give CPG via retrograde cannula  Remember aneurysm/dissection is probably in the ascending aorta or arch, therefore no antegrade CPG.  If the AV is competent and a AoXC can be safely put on the aorta w/o damaging tissue  Give antegrade CPG Arrest is maintained with deep hypothermia

Question 65

HOW TO DO A CIRC ARREST CASE |  Keep cooling until

Answer 65

EEG shows no cerebral electrical activity    Usually takes about 20-25 min. Brain Temp 18-20°C Cool no lower than 15°C

Question 66

when not using an eeg cool to

Answer 66

for at least 25 min to a target core temp of 18-20°C

Question 67

At EEG silence

Answer 67

Give pentobarbital  Circulate for 3 minutes

Question 68

Head is packed in ice to facilitate

Answer 68

surface cooling

Question 69

what position of the patent for circ arrest

Answer 69

Trendelenburg position

Question 70

HOW TO DO A CIRC ARREST CASE  Flow is turned off. Patient is drained  Innominate artery is snared

Answer 70

nitiate ACP – 10mL/kg/min |  Right axillary – innominate artery – snare diverts blood antegrade through right common carotid – brain.

Question 71

when aorta is opened

Answer 71

Bleed back from the L. Common Carotid and L. Subclavian obscure field view  Cardiotomy suction in distal arch  Possible use of balloon occluder in both vessels.

Question 72

HOW TO DO A CIRC ARREST CASE |  End of graft is sewn

Answer 72

to proximal descending thoracic aorta, transverse arch or distal ascending aorta  Attach head vessels  Island  Branched graft

Question 73

Put patient in steep

Answer 73

Trendelenburg  Cardiotomy suction placed in unattached graft  Release tourniquet on innominate  Slowly increase flow to full flow (50mL/kg/min) as the aorta and graft are deaired  If cannulated femorally, move the cannula to the arch  Systemic circulation re-estabilished.

Question 74

HOW TO DO A CIRC ARREST CASE |  Proximal graft attached  Slowly rewarm to

Answer 74

36.5°C  Not to exceed a 10°C gradient between arterial blood and nasopharyngeal / bladder  Proximal complete  Deair with venting needle through graft  AoXC removed  TEE is utilized to make sure there is no air present  CPB is terminated

Question 75

OFF PUMP |  Want systolic BP

Answer 75

appx 100-120mmHg

Question 76

off pump mean

Answer 76

70-90mmHg

Question 77

off pump HR

Answer 77

60-80 BPM

Question 78

OFF PUMP CI

Answer 78

2.0-2.5 L/min/m2

Question 79

Will see a coagulopathy after bypass, especially with DHCA SUCH AS

Answer 79

Platelet dysfunction secondary to extreme hypothermia  Usually requires FFP/ Platelets/ Cryo?  Often resort to Factor VII and IX  Usually use an antifibrinolytic to help with bleeding.

Question 80

COMPLICATIONS OF AORTIC SURGERY AND DHCA

Answer 80

Air Emboli  Clots  LV Dysfunction  MI (Reimplanting coronaries)  Renal Failure  Respiratory failure  Coagulopathy  Hemorrhage

Question 81

OTHER PROCEDURES OF AORTIC CONDTIONS

Answer 81

Endovascular Repair  Left Heart bypass

Question 82

ENDOVASCULAR REPAIR HISTORY

Answer 82

 1st done in 1991 on abdominal aortic aneurysm  Now we can do it on thoracic aneurysms due to increased technology which allows precise placement in a high pressure system  Before only open repairs

Question 83

Thoracic EndoVascular Aortic Repair (TEVAR)

Answer 83

Requires femoral access  Flouroscopy  Graft self-deploys |  Req’s flouroscopy to check position  Requires systemic heparinization

Question 84

``` ENDOVASCULAR REPAIR (TEVAR)  Requires proximaL ```

Answer 84

“Landing Zone” of 15mm length |  Distal end needs to be non-aneurysmal

Question 85

ENDOVASCULAR REPAIR (TEVAR) CON

Answer 85

Side branches – possibility of occluding a | vessel that branches off the aorta

Question 86

ENDOVASCULAR REPAIR (TEVAR) Considerations:

Answer 86

Aortic Tortuosity, calcification, atherosclerosis

Question 87

TEVAR |  Advantages:

Answer 87

 Reduces mortality  Reduces morbidity  Less blood loss  Quicker recovery  Hemodynamic stability  Pulmonary and cardiac comorbidities that may have not made them a candidate for open surgeries, allow them to have this option.

Question 88

TEVAR |  Complications

Answer 88

Conversion to open procedure  Aortic Rupture / dissection  Malposition – causing visceral ischemia  Bleeding  Endoleak  Blood flows back into the aneurysmal sac after the endovascular graft is placed  Usually observe and hope it spontaneously resolves  Stroke  Paraplegia  Contrast Nephropathy

Question 89

LEFT HEART BYPASS

Answer 89

Basically, a shunt around the aneurysm/ dissection  Used on Descending legions  Heart pumps blood to the lungs  Lungs oxygenate  Venous cannula places in LA/ L. Pulmonary veins    Risk of air embolism Move tip of cannula – impair drainage Could cannulate Apex of LV  Great flow  Risk of LV injury  Arterial cannula placed in descending aorta

Question 90

LEFT HEART BYPASS |  ECC Circuit

Answer 90

Tubing  Centrifugal pump  No Reservior  NoH/E  No Bubble Trap  Excluding those help minimize the heparinization required.

Question 91

LEFT HEART BYPASS |  If the patient needs volume

Answer 91

Anesthesia must give

Question 92

LEFT HEART BYPASS Heart pumps blood to the vessels p

Answer 92

proximal to the clamp (usually the head vessels)

Question 93

LEF HEART BYPASS ECC pumps

Answer 93

distal to clamp  2/3 of CO to lower body

Question 94

LEFT HEART BYPASS arterial pressure

Answer 94

Monitored at radial or brachial artery (upper body)  Monitored at femoral artery (lower body)

Question 95

CLINICAL APPLICATIONS – MARFAN’S SYNDROME

Answer 95

 Connective Tissue Disorder  Connective Tissue provides strength and support to tendons, ligaments, cartilage, blood vessel walls, and heart valves.  They aren’t as stiff as they should be  Arteries are weakened, particularly the aorta  Aorta dilates – weakens  Under exertion the aorta can tear – dissection  Also have MV prolapse and AI

Question 96

CLINICAL APPLICATIONS – AORTIC DEBRANCHING AND ENDOVASCULAR REPAIR

Answer 96

 To repair an arch aneurysm  Can do an extra-anatomic bypass  Connect the aorta to the Innominate artery, L. Carotid, and L. subclavian arteries  Then, deploy an endograft in the arch and occlude the head vessels.  Head vessels get flow via the graft, and the aneurysm/ dissection is treated via the endograft.

Question 97

CLINICAL APPLICATIONS – CASE REPORT AORTIC DEBRANCHING

Answer 97

64y/o male  Acute type A dissection  Emergency AV replacement and hemiarch replacement  Post op day 4, CT showed expansion of the false lumen of the arch distal to the hemiarch graft  Did an extra-anatomic bypass to the innominate and left carotid. Access to the left subclavian was problematic  Deployed and endograft antegrade into the prior hemiarch graft.  Larger to cover/pass the graft  No endoleak.