Interhospital conference ครั้��งที่�� 29

Acute Aortic Syndrome

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King George 2 of Great Britain died(october 25,1760)while training on the commode and was the first well documented case of an aortic dissection.

Historical Note

Recognized since 16 th century. Lannaec(French physician) introduced

term Dissection aneurysm in 1819.

Historical Note

First successful outcome of modern treatment of aortic dissection was attributed to Dr. DeBakey in his report, 1955 and later he devised a classification that is widely used today as Debakey classification.

Historical Note

Technological and technical improvements follow:

Cardiopulmonary bypass circuit. Synthetic placements. Hypothermic circulatory arrest in 1960s to

1975( Barnard , Schrire, Borst and Griepp with colleaques)

Open distal anastomosis technique by Livesay in 1982.

Bioglue has been approved by US FDA to strengthen the disrupted layer.

Classifications De Bakey

Type 1 = ascending aorta, aortic arch, descending aorta

Type 2 = ascending aorta only Type 3 = descending aorta distal to left

subclavian artery Type 3a= limit to descending thoracic aorta Type 3b= extend below diaphragm

Stanford (most common) Type A = involves ascending aorta Type B = no ascending aorta, distal

Type of Aortic Dissection The proportion of patients with

various types depend on the nature of series reported

Type one and two (or type A) comprised 35% of cases (from Debakey series).

From clinical and autopsy series, acute dissections involved the ascending aorta was found in 62% to 85% of cases.

Intramural Hematoma

Intramural hematoma involving the ascending aortaShould be treated like an acute type A aortic dissection

Aortic IMH is considered a precursor to classic aortic dissection

T sai TT. Acute aortic syndromes. Circulation 2005

Natural history

50% are dead within 48 hrs

Long term survival in untreated type A dissection: More than 25% died

in 24 hrs. More than 50% died

in the first week. More than 75% died

in 1 month. More than 90% died

in 1 year.

Mode of Death

Most patients who die acutely succumb from false channel rupture with hemopericardium, hemomidiastinum or hemothorax.

Death later can result from delayed rupture or organ dysfunction secondary to arterial occlusions.

Course after surviving acute dissection

False channel usually and gradually become aneurysmal, and then ruptures months or years after the acute episode.

A new dissection or redissection may occur.

Presentation

40% die immediately 30% who present to hospital are first

thought to have another diagnosis Most common symptom:

Severe, unrelenting chest pain Described as ripping or tearing/ sharp pain

Patients look agony ( nausea, vomiting, diaphoresis)

Symptoms of tamponade AR murmur Abnormal pulse exam Abnormal neurologic exam

Exam

Can be normal Hypertension ( normal or low does

not exclude dissection) If subclavian artery involved =

asymmetri pulses or BP ( > 20 mmHg difference between arms)

If proximal dissection Shock New murmur of AR/ HEART FAILURE

Initial diagnostic steps and decisions EKG

Normal in 1/3 ( in coronary involement) ST-T change

Initial diagnostic steps and decisions TTE

Useful screening tool in identifying type A dissection

Limited visualization to distal ascending, transverse and descending

Paramount in assessing cpx. AR/tamponade/EF

TEE TEE with color flow imaging is considered

as the most useful and accurate diagnostic technique

Initial diagnostic steps and decisions Coronary angiogram

selective coronary angiogram to identify involvement of the coronary arties is not indicated.(TEE, direct examination of coronary arteries after the aorta was opened)

Use of coronary angiogram to detect atherosclerotic disease in patients who are to undergo surgical treatment of acute dissection is arguable.

Aortic dissection diagnostic studies Helical CT sense-93% spec-100%

Most frequently used

MRI sens-98% spec 98% Presence of artifact in nearly 60% of cases

Echo TTE sense-59-85%, spec 63-96% Echo TEE sense-98%, spec 98% IVUS

Particulary useful for delineating the proximal and distal extent

Coronary angiography Controversial

What is the optimal treatment

General principles Acute aortic dissections involving the

ascending aorta are considered surgical emergencies.

General principles

In contrast, dissections confined to the descending aorta are treated medically unless there is/are complications.

Initial medical Therapy

The primary objective is to normalize pressure and to reduce the force of left ventricular ejection (dP/dt).

Initial medical Therapy

If beta-blockers alone do not control blood pressure, vasodilators such as NTP ( the first vasodilator of choice)

Good pain control as morphine.

Volume titration.

Intubation early.

Hypotensive patients

Cardiac tamponade Severe AR True-lumen obstruction Acute MI Contained rupture of the false lumen

into pleural space or mediastinum ### every scenarios mandate

immediate operative intervention####

Pericardiocentesis

Associated with recurrent pericardial bleeding and associated mortality

Several articles from Asian literature suggest that it may be safe in the setting of acute type A IMH

Except for cases who cannot survive until surgery, pericardiocentesis can be done by withdrawing just enough fluid to restore perfusion

Purpose of Surgical Treatment

To treat or prevent the common and lethal complications such as

Aortic rupture Stroke Visceral ischemia Cardiac tamponade Circulatory failure

Principle of repair

Excision of intimal tear Obliteration of entry into FL Reconstitution of aorta with

interposition graft +/- coronary reimplantations

Restoration of aortic valve incompetence Valve resuspension Aortic valve replacement Aortic root replacement

European Society of Cardiology task force on acute type A Dissection

Operative mortality

Operative mortality in experienced centers with large surgical series varies widely between 15%-35%, still below the 50% mortality with medical therapy

General considerations

Establishing CPB in traditional way. Rt radial a. line/ femoral a. line opposite

to cannulation site. Routine TEE

If FEM-FEM bypass is chosen. CFA with the most normal pulse CFV on the right should be used ( easily

positioned to RA )

General considerations

If circulatory arrest is needed, the core temp should be lower to less than 20 celsius with good LV venting.

If aortic cross clamping is planning, clamp should be placed several centimeters proximal to innominate artery.

AHA Guidelines 2010

Treatment acute type A Dissection

All of aneurysmal aorta and the proximal extent of the dissection should be resected.

A partially dissected root may be repaired by aortic valve resuspension.

AHA Guidelines 2010

Patients with Type A Dissection

Extensive aortic root dissection should be treated with aortic root replacement with a composite graft or with a valve sparing root replacement.

In DeBekey Type 2 dissection the entire dissected aorta should be replaced

Arterial Access for Cannulation Possible cannulationtion sites

Femoral cannulation

Right axillary artery Left common carotid artery Direct cannulation of aorta by TEE

control Direct cannulation( cut open under

visual control) Transapical cannulation.

Axillary Cannulation

Axillary Cannulation

Advantages Disadvantages Antegrade perfusion. No manipulation of the

ascending aorta. Recomended over femoral

cannulation as prophylaxis against malperfusion, lower extrmity ischemia,retrograde dissection and retrograde embolization of debris

Time consuming. Impossible to CNS

perfusion if dissected. Brachial plexus injury. Vascular complication.

Axillary artery cannulation in type A aortic dissection operations. J Thorac Cardiovasc Surg 1999

Axillary cannulation in acute ascending aortic dissectionsAnn Thorac Surg 2000

Left Common Carotid Artery Cannulation for Type A Aortic Dissections

For cases that neither right axillary artery nor femoral artery can be used Abdominal aortic stenosis/

dissection both axillary arteries

Tex Heart Inst J. 2003; 30(2): 128–129

Useful in all patients with acute type A dissection.

A major advantage is quicker than others conventional methods as no purse-strings or additional dissection is required.

Surgical options for repair Supracommissural ascending aorta

replacement.(ascending aortic replacement)

Composite conduit root replacement.

Aortic valve-sparing root replacement. ± Hemiarch Replacement ± Total Arch Replacement ±Hybrid-Procedures ( Frozen-elephant trunk)

Bentall AVR

Straightforward ( standard technique)

Shorter cross-clamp and bypass time compared to valve sparing operations.

Potential rationale for Valve-Sparing Root Replacement

Excellent aortic valve function with physiological hemodynamics (Avoidance of PPM)

Lifelong good functionality ( Avoidance of reoperations)

Avoidance of prosthetic valve related complications.

Absolute Contraindications for Valve-Sparing Root Replacement

Advanced degenerative calcification of the aortic valve.

Overstretched and thin cusps with stress fenestrations and perforations.

Acute infective endocarditis.

Relative Contraindications for Valve-Sparing Root Replacement

Patients who are in need of concomitant procedures, who have impaired left ventricular function.

Patients who are elderly and frail and might not tolerate extended cross-clamp and bypass times.

Lack of surgical experience.

What is the better choice for acute type A dissection

Bentall vs VSSR

Author NB/VSSR

Mean f/u

survival Event free survival

Bernhard A., Reichenspurner et al.2011

30/58 3.2 y 14Y-87% B14Y-89%VSSR

14Y-48% B14Y-44% VSSR

Freedom from Reoperation

Bekkers JA, Boggers Ad et al2012

75/157

7.2 Y Overall 10y-53.4% without significant difference

10y-100% B10Y-85% VSSR without significant diff.

Subramanian S, Mohr FW et al 2012

130/78

7.2Y Overall 8y-55% without significant diff

Overall 8y-95% without significant diff.

How to deal with the Arch? The false lumen( DeBakey 1) in the

arch and descending aorta remains untreated, potentially resulting in Aneurysmal(thoraco-abdominal) formation

10% Rupture 10% Malperfusion 10-

30% Redo-surgery ?%

Kirsch M, et al. JTCVS 2002Mehta R, et al. Circulation 2002

Total Arch Replacement in Acute Type A Dissection

Radical approach : resection of all diseased tissue

High risk High mortality Increased rate of stroke

Lower reoperation rate Improved event free long term

survival

CNS Protection Class 1

A brain protection strategy……should be a key element of the surgical, anesthetic and perfusion techniques…….(Evidence: B)

Class 2a

Deep hypothermic circulatory arrest, and selective antegrade brain perfusion are techniques that alone or in combination are reasonable to minimize brain injury……. Institution experience is an important factor……( Evidence: B)

AHA Guidelines 2010

How to protect the brain?

How to protect the brain? “bilateral antegrade cerebral perfusion is

superior to any other method of brain protection” Preservation of intracellular pH and energy

stores Neurological deficit and cognitive dysfunction

is lowered compared to other methods. Allow extended repair with prolonged

perfusion time. Monitoring is mandatory (NIRS)

Randall B Griepp. J Thorac Cardiovasc Surg 2011

Near Infrared Spectroscopy (NIRS) Monitoring

Continuous monitoring of regional cerebral oxygen saturation (rCSO2).

Under selective antegrade cerebral perfusion a drop of rCSO2 of 30% of baseline values require immediate control of perfusion modalities.

How much should we resect?

An aggressive surgical approach, including a full root or hemiarch replacement, is not associated with increased operative risk and should be considered when type A dissections extensively involve the valve, sinuses or arch.

Better survival with extended approach

Surgical extent to the Arch

Total arch replacement

Kasui et al. J Thorac Cardiovasc Surg 2000

German Registry for Acute Aortic Dissection type A

(GERRAADA)

658 PATIENTS

Hemiarch Total Arch P value

30 d mortality 18.7% 25.7% 0.067

Neurological deficit

13.6% 12.5% 0.78

Malperfusion 8.4% 10.7% 0.53

Is Arch Replacement beneficial?

No differences between isolated ascending replacement and ascending + arch replacement in the literature with regard to

long term survival and freedom from reoperation

Eleftriades et al.J Thorac Cardiovasc Surg 2005

The fate of the distal aorta after repair of acute type A aortic dissection

Conclusions: Growth of the distal aorta after repair of acute type A dissection is typically slow and linear. Distal reoperation is uncommon, and late risk of death is approximately twice that of a healthy population.

Halstead.JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Volume:133 Issue:1 Pages:127-U102 DOI:10.1016/j.jctvs.2006.07.043 Published:JAN 2007

Hybrid procedure withFrozen Elephant Trunk

Patients with type A acute aortic dissection presenting with major brain

injury: should we operate on them?

Postoperatively, cerebrovascular accident and coma resolved in 84.3% and 78.8% of cases, respectively. On logistic regression analysis, surgery was protective against mortality in patients presenting with brain injury (odds ratio 0.058; P < .001).

The 5-year survival of patients presenting with cerebrovascular accident and coma was 23.8% and 0% after medical management versus 67.1% and 57.1% after surgery (log rank, P < .001), respectively.

Of 1873 patients with type A acute aortic dissection enrolled in the International Registry

for Acute Dissection

J Thorac Cardiovasc Surg.2013