case presentation cerebral infarction after surgery for acute type i aortic dissection r1 王佳茹

Case presentation

Cerebral infarction after surgery for acute type I aortic dissection

R1 王佳茹

Patient data

Chart number: 4304428Age/Sex: 49 y/o, MaleDate of admission: Sep. 3, 2003Date of operation: Sep. 3, 2003

Brief history

Chronic hypertension for more than 10 years without regular medical control

Sudden-onset chest pain with radiation to back on the morning of Sep. 3, 2003

He went to ER of En-Chu-Kong H. where CXR was arranged and revealed cardiomegaly and widened mediastinum.

Echocardiography

linear echoes in the ascending aorta are suggestive of dissection of the ascending aorta.

Intimal flap visualized in the ascending and descending aorta.

There is no pericardial effusionLVEF = 78%

Computed tomography

Ascending aorta, aoric arch and descending aorta are involved.

There is no pericardial effusionAortic valves and orifices of coronary

arteries are intact.Abdominal aorta above the level of renal

arteries is involved.

Brief history

Under the impression of acute type 1 aortic dissection, he was transferred to our hospital for surgical intervention.

Physical examination

Vital sign: HR 70/min, RR 20/min, BP 197/103 mmHg, BT 37C,

Conscious clear, E4V5M6Acute ill-looking, Regular heart beat without murmurSymmetric and intact peripheral pulseDifference of BP measured on both arms is

prominent.

At OR

BW: 100kg, Hb : 14ASA classification : IIIeSet up monitorsArterial cannulation on both wrists Induction with fentanyl 250ug, Rapifen

1000ug and pentothal 500mg Muscle relaxant with Esmeron 100mg

initially, and changed to Pavulon thereafterOn Endo and CVP

Maintenance

Gas: isoflurane, initially

desflurane, during CPBO2 combined with air, without N2O BP control with Perdipine and Millisrol

TEE

DAA, type I, intima tear at aortic arch near brachiocephalic trunk

Mod-severe AR due to paradoxical movement of intimal flap

Brachiocephalic trunk involvement is equivocal. The possibility is very high according to hemodynamic profile. ( R’t arm 86/65 mmHg while L’t arm 130/70 mmHg)

Median sternotomy is performed, the patient is placed on CPB.

Cannulation of Right axillary artery, SVC and IVC

Prime with albumin, lactate Ringer’s, solumedrol, 20% Mannitol and Sod. Bicarbonate

After systemic hypothermia to 15°C, Pentothal was given and circulatory arrest was started.

The head is covered with ice bags

OP finding

Good LV contractilityNo pericardial effusionAsAo dissection: intimal tear at lesser

curvature side of aortic archAsAo about 5cm in diameter with eccymosisPre-op AR: moderate,

During circulatory arrest

Retrograde cerebral perfusion via SVC was failed

Intermittent antegrade cerebral perfusion via right axillary cannula, with a balloon occluder placed in brachiocephalic artery, was performed during distal aortic anastomosis with an open technique.

During circulatory arrest

Ascending aortic grafting with 30 mm hemashield vascular graft was performed.

After distal anastomosis was completed, the vascular graft was clamped; systemic perfusion was restarted, and rewarming was done.

Aortic valve suspension and proximal anastomosis were done during rewarming.

At OR

The patient was weaned from CPB successfully, and he was send to SICU for post-op care.

Duration

Partial bypass time: 5 hrs and 39 minsTotal bypass time: 5 hrs and 18 minsAorta X-clamp time: 2 hrs and 46 minsCirculatory arrest time: 1 hr and 10 mins

Post-op condition

Focal seizure and generalized seizure

Glasgow Coma Scale: E1VtM4

CT of head revealed decreased density with loss of gray-white matter differentiation at Right fronto-temporal lobe, and Right side MCA infarction with brain edema was impressed.

Post-op condition

Fever Acute renal failure, r/o nephrotoxicity of

aminoglycoside related.

-> CVVHDICExpire on 9/30

Discussion

Classification of aortic dissection

Surgery on the ascending aorta

median sternotomy and CPBconcomitant aortic valve replacement and

coronary reimplantation ( Bentall precedure)

Surgery involving the aortic arch

median sternotomy and CPB with deep hypothermic circulatory arrest (DHCA)

Achieve optimal cerebral protection with systemic and topical hypothermia.

Hypothermia to 15°C, thiopental infusion to maintain a flat EEG, methylprednisolone or dexamethasone, mannitol, and phenytoin are also commonly used.

Surgery involving the descending thoracic aorta

Left thoracotomy without CPBOne-lung anesthesia greatly facilitates

surgical exposure and reduces pulmonary trauma from retractors.

Brain protection

Brain protection

The major complications associated with ascending/arch repair are stroke and encephalopathy.

The incidence of postoperative stroke ranged from 7-15% after thoracic aortic surgery with DHCA, and most of them are embolic in origin.

The major risk factors are circulatory arrest time and whether the transverse arch is involved.

Brain protection

Goals are to optimize CPP, decrease metabolic requirements, and possibly block mediators of cellular injury.

The most effective strategy is prevention.

Surgical consideration

Deep Hypothermic Circulatory Arrest (DHCA)

Permitting a field free of blood and cannulas, allowing thorough inspection of the aneurysm and a careful open distal anastomosis

Reducing the metabolic rate for oxygen, promoting preferential organ perfusion, and increasing tissue oxygen extraction


Cooling to 10-13°C in esophagousO2 sat. in the jugular venous bulb > 95%,

indicating maximal metabolic suppression.Cooling > 30mins to prevent a gradual

upright temp. and the intracranial temp. should be protected by packing the head in ice.


Gradual rewarming and avoidance of high perfusion temp. are essential.

A duration of DHCA exceeding 25 mins has been shown to produce temporary neurologic dysfunction.

from J. Toracic cardiovascular surgery March,2003


DHCA was demonstrated to have longer electroencephalographic recovery times and a higher incidence of clinical seizures in the early postoperative period.

from Miller

During deep Hypothermic Circulatory Arrest (DHCA)

Retrograde cerebral perfusion

Oxygenated blood is perfused in a retrograde direction through the superior vena cava and the internal jugular veins and to the brain.

providing continued cerebral cooling, delivering nutrition to the brain and flushing out cerebral emboli

Retrograde cerebral perfusion

Too little capillary flow occurs during RCP (even with occlusion IVC) to confer any meaningful metabolic benefit even during deep hypothermia.

Long durations of RCP are associated with high rates of temporary neurologic dysfunction and an increased risk of stroke and death after aortic surgery.


Antegrade cerebral perfusion

Total arch replacement using antegrade selective cerebral perfusion with right axillary artery perfusion is a safe and useful alternative for brain protection in total arch

replacement.

Eur J Cardiothorac Surg 2003;23:771-775


It allows a much longer interval of safe circulatory arrest, since the supply of nutrients and oxygen allows maintenance of appropriate level of oxygen metabolism at hypothermic temporature.

Ann Thorac Surg 2002;73:1837-1842


If the total time necessary for aortic arch repair requiring arrest is moderately long, between 40 and 80 mins, the incidence of temporary neurologic dysfunction is clearly lower with ACP than any other alternative.


Anesthetic considerations

Monitor

arterial cannula thermodilution PAC TEE EEG transcranial Doppler

transcranial oximetry


Prophylactic thiopental infusion ( completely suppressing electroencephalographic activity)

Prior to DHCA, corticosteroid (methylprednisolone 30mg/kg), mannitol (0.5 g/kg), and phenytoin (10-15mg/kg) are also usually administered.

The head is covered with ice bags.


Nitrous oxide is to be avoided because of its expansion of air emboli

hyperglycemia should be avoidedmaintain serum glucose in the 100 to 250

mg/dL range.

Barbiturate

reduce CMR inhibit free radical

formation reduce Ca2+ influx,, potentiate GABAergic

activity, enhance cyclic AMP

production, delay the loss of inotropic

glutamate receptor-mediated transmembrane electrical gradients

reduce glucose transport into cells,

block Na+ channels, reduce glutamate,

aspartate, lactate, and

catecholamines

ANESTHESIOLOGY

1998;89:289-291

Steroid

Timing of steroid treatment is important for cerebral protection during CPB and circulatory arrest, different timing of steroid administration results in different

inflammatory mediator response. Steroid in CPB prime is not significantly

better than no steroid treatment, while systemic steroid pre-treatment significantly decreases systemic manifestation of inflammatory response and brain damage.

Eur J Cardiothorac Surg 2003;24:125-132

Steroid

Systemic steroid pretreatment significantly reduced total body edema and cerebral vascular leak and was associated with better immunohistochemical indices of neuroprotection after DHCA.

Ann Thorac Surg 2001;72:1465-1472

The end

case presentation cerebral infarction after surgery for acute type i aortic dissection r1 王佳茹

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