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Perf tech 3 > THORACIC AND AORTIC SURGERY > Flashcards

THORACIC AND AORTIC SURGERY Flashcards

1
Q

Ascending Aorta:

A

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

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2
Q

Transverse Arch

A

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

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3
Q

Descending Thoracic and Thoracoabdominal Aorta

A

Lies just beyond the subclavian to the aortoiliac bifurcation

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4
Q

Dissection

A

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

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5
Q

Aneurysm

A

 Dilation of all 3 layers

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6
Q

AORTIC DISSECTIONS

 Incidence

A

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

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7
Q

AORTIC DISSECTIONS risk factors

A

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

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8
Q

AORTIC DISSECTIONS

 Causes (Inciting Events)

A

Increased Physical Activity Emotional Stress Blunt Trauma

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

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9
Q

AORTIC DISSECTIONS

 Mechanism

A

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.

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10
Q

aoritc dissections prevalence based on location

A

Ascending (61%)  Descending (24%)

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

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11
Q

AORTIC DISSECTIONS

 Propagation

A

Occurs within seconds Driven by pulse pressure and ejection velocity

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12
Q

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

A

Aortic Dissections

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

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13
Q

DeBakey Classification

A

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

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14
Q

DEBAKEY CLASSIFICATION

 Type I

A

Intimal Tear: Asceding Aorta

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

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15
Q

DEBAKEY CLASSIFICATION

 Type II

A

Intimal Tear: Asceding Aorta

 Dissection: Ascedng Aorta only  Stops before innominate artery

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16
Q

DEBAKEY CLASSIFICATION

 Type IIIA

A

Intimal Tear: Descending Aorta

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

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17
Q

DEBAKEY CLASSIFICATION

 Type IIIB

A

Intimal Tear: Descending Aorta  Dissection: Below diaphragm

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18
Q

“Easier” Classification system

 Type A

A

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

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19
Q

Easier” Classification system

 Type B

A

Distal aorta  Any part of aorta distal to left subclavian

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20
Q

Prognosis for untreated ascending dissection  DISMAL

 2 day mortality =  3 month mortality=

A

50%,90%

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21
Q

usual cause of death from dissection

A

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

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22
Q

Other causes of death from dissections

A

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

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23
Q

AORTIC DISSECTIONS

 Surgical Mortality

A

 3-24%

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

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24
Q

ANEURYSMS

 Incidence:

A

European Studies show 460/100,000 Thoracic Aneurysms

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25
Q

aneurysm percentage by location

A

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

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26
Q

fusiform aneurysm

A

Entire circumference of the aortic wall

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27
Q

saccular aneurysm

A

Involves only part of the circumference of the aortic

wall

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28
Q

ARCH aneurysms are typically

A

saccular

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29
Q

ANEURYSM – CRAWFORD CLASSIFICATION

A

 Used to classify Thoracoabdominal Aortic Aneurysms

 Used to describe the extent of the aorta requiring replacement

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30
Q

ANEURYSM – CRAWFORD EXTENT I

A

Extent I :

 Involves most or all of the descending thoracic aorta and upper abdominal aorta.

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31
Q

ANEURYSM – CRAWFORD EXTENT II

A

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

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32
Q

ANEURYSM – CRAWFORD EXTENT III

A

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

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33
Q

ANEURYSM – CRAWFORD EXTENT IV

A

Involves most or all abdominal aorta

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34
Q

ANEURYSMS

 Natural History

A

 Progressive dilation

 More than 1⁄2 of aortic aneurysms rupture

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35
Q

Untreated 5 year survival of a thoracoabdominal aortic aneurysm is

A

13-39%

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36
Q

Other complications of aneurysm include:

A

 Mycotic infection  Atheroembolisation  Dissection (rare)

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37
Q

ANEURYSMS

 Predictors of poor prognosis:

A

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

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38
Q

THORACIC ARTERY TEARS - ETIOLOGY

 Majority occurs after

A

a trauma. Involve deceleration injury (MVA)

 Large shear stress on points of aortic wall that are relatively immobile.

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39
Q

thoracic artery tear leads to

A

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

40
Q

THORACIC ARTERY RUPTURE - LOCATION

A

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.

41
Q

diagnosis for dissection aneurysm and trauma rupture

A

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

42
Q

INDICATIONS FOR SURGERY – ASCENDING AORTA

A

 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

43
Q

INDICATIONS FOR SURGERY – AORTIC ARCH

A

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

44
Q

INDICATIONS FOR SURGERY – DESCENDING AORTA

A

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.

45
Q

PERFUSION – AORTIC SURGERY

 Considerations

A

 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?

46
Q

CPB W/O CIRC ARREST

A

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!

47
Q

CPB W/ DHCA AND ACP

A

Bloodless field Uncluttered by clamps and cannulas

Studies have shown it doesn’t necessarily abate cerebral metabolic demands

48
Q

Significant cerebral metabolic activity occurs

A

at temperatures at which DHCA is initiated.

 Promotes brain ischemia  Accumulation of metabolic wastes.

49
Q

Perioperative neurologic complications

 Higher when DHCA was

A

greater than 40 minutes

50
Q

Mortality

 Increased dramatically when DHCA

A

was greater than 65 minutes.

51
Q

RETROGRADE CEREBRAL PERFUSION

 Gained popularity in the and was first done

A

‘90s.  1st done in 1980 by Milles and Ochsner

 Treating massive air embolism

52
Q

benefits of rcp

A

 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.

53
Q

Experimental and clinical data do not consistently support the efficacy of

A

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

54
Q

HOW TO DO A CIRC ARREST CASE

 Need to monitor temperatures

A

 Nasopharyngeal / Bladder  Arterial  Venous

 Water

55
Q

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

A

EEG – Brain activity

 Electrocerebral silence dictates adequate cerebral cooling

56
Q

drugs for circ arrest

A

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

57
Q

cannulation for circ arrest

A

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

58
Q

HOW TO DO A CIRC ARREST CASE

 CPB is initated

A

Assess adequacy of perfusion  Especially important for femoral artery cannulation

59
Q

10°C drop in temperature – reduces rate of oxygen

consumption by

A

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

60
Q

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

A

20-25%

61
Q

Hemodilution to a

A

hct of less than 25 % to avoid stroke

62
Q

Hct kept low until

A

rewarm

 Hemoconcentrate

63
Q

hemodilution reduces o2 carrying capacity but

A

overall oxygen delivery improves

 Decreased viscosity enhances the flow in the microcirculation.

64
Q

HOW TO DO A CIRC ARREST CASE

 At fibrillation

A

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

65
Q

HOW TO DO A CIRC ARREST CASE

 Keep cooling until

A

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

66
Q

when not using an eeg cool to

A

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

67
Q

At EEG silence

A

Give pentobarbital  Circulate for 3 minutes

68
Q

Head is packed in ice to facilitate

A

surface cooling

69
Q

what position of the patent for circ arrest

A

Trendelenburg position

70
Q

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

A

nitiate ACP – 10mL/kg/min

 Right axillary – innominate artery – snare diverts blood antegrade through right common carotid – brain.

71
Q

when aorta is opened

A

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.

72
Q

HOW TO DO A CIRC ARREST CASE

 End of graft is sewn

A

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

73
Q

Put patient in steep

A

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.

74
Q

HOW TO DO A CIRC ARREST CASE

 Proximal graft attached  Slowly rewarm to

A

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

75
Q

OFF PUMP

 Want systolic BP

A

appx 100-120mmHg

76
Q

off pump mean

A

70-90mmHg

77
Q

off pump HR

A

60-80 BPM

78
Q

OFF PUMP CI

A

2.0-2.5 L/min/m2

79
Q

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

A

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.

80
Q

COMPLICATIONS OF AORTIC SURGERY AND DHCA

A

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

81
Q

OTHER PROCEDURES OF AORTIC CONDTIONS

A

Endovascular Repair  Left Heart bypass

82
Q

ENDOVASCULAR REPAIR HISTORY

A

 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

83
Q

Thoracic EndoVascular Aortic Repair (TEVAR)

A

Requires femoral access  Flouroscopy  Graft self-deploys

 Req’s flouroscopy to check position  Requires systemic heparinization

84
Q 
ENDOVASCULAR REPAIR (TEVAR)
 Requires proximaL
A

“Landing Zone” of 15mm length

 Distal end needs to be non-aneurysmal

85
Q

ENDOVASCULAR REPAIR (TEVAR) CON

A

Side branches – possibility of occluding a

vessel that branches off the aorta

86
Q

ENDOVASCULAR REPAIR (TEVAR) Considerations:

A

Aortic Tortuosity, calcification, atherosclerosis

87
Q

TEVAR

 Advantages:

A

 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.

88
Q

TEVAR

 Complications

A

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

89
Q

LEFT HEART BYPASS

A

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

90
Q

LEFT HEART BYPASS

 ECC Circuit

A

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

91
Q

LEFT HEART BYPASS

 If the patient needs volume

A

Anesthesia must give

92
Q

LEFT HEART BYPASS Heart pumps blood to the vessels p

A

proximal to the clamp (usually the head vessels)

93
Q

LEF HEART BYPASS ECC pumps

A

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

94
Q

LEFT HEART BYPASS arterial pressure

A

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

95
Q

CLINICAL APPLICATIONS – MARFAN’S SYNDROME

A

 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

96
Q

CLINICAL APPLICATIONS – AORTIC DEBRANCHING AND ENDOVASCULAR REPAIR

A

 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.

97
Q

CLINICAL APPLICATIONS – CASE REPORT AORTIC DEBRANCHING

A

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.

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