Aorticvalve 97 (2)

PROF. KHWAJA N. MAHMOODHEAD OF THE DEPARTMENTCARDIAC SURGERY, NICVD

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AORTIC VALVULAR DISEASES

Etiology of Aortic stenosis

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1. Rheumatic – most common

2. Congenital-

Valvular (calcified bicuspic valve)- next common

Supravalvular

subvalvular

1. Sclerotic- senile calcific aortic stenosis

Etiology of Aortic regurgitation1. Primary valve disease 2. Aort ic root disease

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a) Rheumatic AR

b) Congenital- bicuspid aortic valve

or in association with VSD

c) Infective endocarditis

d) Aortitis- syphilitic aortitis or

ankylosing spondylitis , Giant cell

arteritis.

Annular ectasia from

a) Chronic aortic aneurysm

b) Dissecting aortic aneurysm

Annulo aortic ectasia from

c) Marfan’s syndrome

Causes depending on severitiy of AR

Acute ar Chronic ar

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1. Infective endocarditis

2. Trauma

3. Dissecting aortic

aneurysm

1. Rheumatic AR

2. Congenital – bicuspid

aortic valve

3. Aortitis- syphilitic ,

ankylosing spondylitis

4. Marfan’s syndrome

Natural history of AS & AR (surgically untreated )

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AORTIC STENOSIS Natural history is incompletely known Severity & symptoms are gradually increased Patient with untreated severe AS

A. May die suddenly due to VF within 1-2 years ( 15-20% of all death in AS are sudden)

B. May die from LVF – acute pulmonary edema within few hours or days of its onset, which occurs within 5 years of diagnosis

C. May develop chronic heart failureD. Occasionally complete heart block develops in patient with extensive calcification

Natural history of AS & AR (surgically untreated )

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AORTIC REGURGITATION- depends on severity

Mild to moderate AR has very little effect on activity & life expectency

Severe AR - develops symptoms and prognosis is limited because of symptoms

of cardiac failure, development of premature beats, Marked cardiomegally (CT

ratio > 0.6) and ECG evidence of LV hypertrophy which occurs within a

period of 3-10 years).

Acute development of severe AR – natural history is less favorable, only

10-30 % survive more than 1 year.

PATHOPHYSIOLOGY OF AS

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1. LV systolic pressure overload Increasing LV pressure Increasing large pressure gradient across the valve Concentric hypertrophy of LV - - Diastolic stiffness - Increased LVEDP

1. Angina pectoris Relatively low coronary diastolic pressure High LVEDP can impede flow to the subendocardium Lower duration of diastole because of tachycardia can lower subendocardial flow

Increased myocardial oxygen consumption due to increased muscle mass

1. LV contractility Decreased contractility per unit muscle mass in AS

1. Role of LA is reduced Because of diastolic stiffness – increased LVEDP more than LAP Since 30% of LV filling is by contraction of LA (normally 20%) which will be absent

PATHO PHYSIOLOGY OF AR

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1. LV under goes dilatation & concentric hypertrophy

• As compensatory mechanism

1. Sub endo-cardial ischemia and angina

• May occur even in normal coronary arteries because myocardial oxygen consumption is high

and decrease in diastolic pressure in aorta

1. LV contractility

• Remains in normal range until LV failure developes

• Patient with mild, moderate or severe AR can remain asymptomatic except for mild

dyspnoea.

Despite dilatation and hypertrophy

LVEDP, LAP & PCWP remain essentially normal

EF is maintained in the normal range in AR until LV failure

EF <50% indicates severe impairment of LV contractility

Classification of AR

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On the basis of regurgitant fraction (RF)

1. Trival AR- RF less than 10% & regurgitant flow <1 litre/min

2. Mild AR- RF 10-40% & regurtitant flow around 1-3 litre/min

3. Moderate AR- RF 40-60 % & regurgitant flow 3-6 litre/min

4. Severe AR- RF more than 60% & regurgitant flow > 6 litre/min

Classification of AR cont….

ANGIOGRAPHIC CLASSIFICATION

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o Grade -1:

a. Small regurgitant jet

b. Clear wash out of regurgitant contrast in nest systole

o Grade-2:

a. Partial and faint opacification of LV

b. Incomplete washout of regurgitant contrast in next systole

Classification of AR cont..

ANGIOGRAPHIC CLASSIFICATION cont…..

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o Grade -3: Dense opacification of LV in 2nd

& 3rd diastole

o Grade-4: Dense & total opacification of

LV in only 1 diastole

NB. Grade III & IV AR- operation is required

Effects of AVR in Aortic regurgitation

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LV contractility may be slightly depressed soon after AVR because-

1. Myocardial effects of CPB

2. Ischemic period (X-clamp time)

3. Residual effect of cardioplegic drug

4. Increse in impedence to LV ejection that occurs when AR is abolished,

especially in 1st few hour of bypass, when SVR is increased

Indication for surgery in AS

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A. If symptomatic

Classic symptoms of syncope, angina or heart failure. ( angina is present

in about half of the patients requiring AVR in AS, all 3 symptoms are present

in one third of patients of AS)

A. If asymptomatic

If Aortic valve gradient is > 50 mmHg or

If AVA is < 0.8 cm2

A. Urgent operation is indicated

If patient has severe LVH & increasing pulmonary hypertension

Indication for surgery in AR

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Indication for surgery in AR

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ACUTE AR

1. Acute AR with CHF ( as in annular ectasia with aneurysm)

2. Acute infective endocarditis – vegetation of valve, recurrent embolisation,

systemic & persistent sepsis

N B. -

AVR can be done in all patients with AS, even with bad LV function with

later development. Whereas AVR may not give good result with long

standing ventricular dysfunction with bad LV ejection fraction in AR and

may kill the patient

Preoperative consideration

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1. CAG should be performed if

• age > 40 years.

• Angina is present

• Positive in ETT

1. Judicious use of drugs is necessary in AS . Drugs that reduces preload &

afterload should be avoided (eg. GTN, Ca++ blocker, β blocker) since these may

lower cardiac output & may precipitate cardiac arrest in a patient with

critical AS

Contd.

3. Dental work should be performed before surgery to minimise the risk of PVE

4. Selection of appropiate procedure & valve type should be done beforehand.

Depending upon

• Age of the patient

• child bearing age

• Patient desires to avoid anticoagulant or not

• Contraindication to long term anticoagulant or not

AVR- operating techniques Tits & Bits

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1. Approach

2. Vent

3. Cardioplegia

4. Aortotomy

5. Insertion of prosthesis

AVR- operating techniques Tits & Bits cont……..

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1. Approach- a) Standard sternotomyb) Mini sternotomyc) Heart port system with mini sternotomyd) Robotic technique with use of heart port system

1. Vent- keeps LV dry, help in maneuver of replacementa) Right superior pulmonary vein (most commonly used)b) Left ventricular apexc) Pulmonary artery

1. Cardioplegiaa) Antegrade selective cardioplegia to Rt & Lt coronary artery at 20

min intervalb) Antegrade + retrograde cardioplegiac) Retrograde cardioplegia only


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4. Aortotomy-

a) 2 cm proximal to annulus in case of prosthetic valve

b) 4 cm downstream from RCA orifice for space for intra aortic

positioning of allograft or autograft valve and to avoid damage of

RCA ostium

Exception- In ‘Mini’ aortic root replacement with Autograft pulmonary

valve cylinder, since autograft pulmonary trunk is relatively short,

aortotomy can be made close to RCA anteriorly in an idea to

preserve as much aorta as possible


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5. Insertion of prosthesis

a) Interrupted pledgeted 2-0 mattress Ethibond suture are used except those on

commissures, where non pledgeted suture is used

b) Left coronary cusp area is done 1st, then RCC area & lastly NCC area.

c) Care should be taken while taking suture in commissural area between

RCC & NCC so that stich doesn’t penetrate more than 2 mm beneath

the annulus – to prevent injury to bundle of His.

d) For supra annular positioning, suture should come from ventricular side of the annulus

up into aorta and then passed through the cusp. At commisure stiches are placed from

aorta into ventricular side. For infra and intra annular positioning suture is passed

from aortic side through the annulus down to ventricle and then passed through cuff

of prosthesis.


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Insertion of prosthesis continued….

e) Prosthetic valve is slided down to aortic annulus.

f) Sutures are 1st tied in the RCC then LCC & then NCC.

Advantage is if RCC stich or LCC stich breaks then the valve can be lifted

and it is easy to place another stich. If a suture breaks while tying RCC

stiches one can salvage the situation by giving a pledgeted stich from

outside of the aorta up through the aortic valve seweing ring.

g) Valve opening is tested to detect any restriction of movement of cusp. If

any restriction of opening is noted valve is rotated


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Insertion of prosthesis continued….

h) Deaeration :

i. LV vent is stopped

ii. Aortic root vent is placed

iii. Head end is lowered

iv. Valsalva maneuver is done with simultaneous compression of heart

to expel air through aortic root vent & pressure on RCA is applied

not to allow air to enter into it.

v. Aortic X-clamp is removed

vi. LV vent stopped again & needle to aspirate the dome of LA & apex

of LV is done

vii. Partial X-clamp on aorta is placed to allow air to pass through

aortic root vent, when heart starts beating.

Surgical option of AS

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1. AVR- is the standard treatment. It should be considered in all patients with

severe AS, no matter how bad is EF, because these patients will certainly do

better after AVR. Whereas this may not be true for long-standing ventricular

dysfunction with AR.

2. Repairative procedure - like commisurotomy & debridement either with

mechanical or ultrasonic device have been performed but result is not good due

to high prevalence of recalcification & restriction . This is only done in children

Surgical option of AR

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1. AVR

2. Bioprosthetic valve

3. Stent mounted Allograft

4. Valved conduit

5. Pulmonary Autograft

6. Pulmonary Allograft

7. Freehand cryopreserved or antibiotic preserved Allograft

8. Insertion of Allograft as a cylinder inside the aorta

9. Mini aortic root replacement

10. Aortic valve reconstruction procedure

Surgical option of AR continued…

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1. AVR- can be done with prosthetic mechanical valve with anticoagulant

2. Bioprosthetic valve – which may be

a) Sent mounted Xenograft /Heterograft ( porcine or bovine pericardial) or

b) Stenless Xenograft (porcine) valve. This has lower transvalvular gradient,

goes near to Homograft valve

3. Stent mounted Allograft- is not satisfactory for AVR due to dehisence of the

Allograft from the struts

4. Valved conduit (prosthetic)- is placed in patients with annular ectasia

from chronic aortic aneurysm or aortic dissection (Bental procedure)


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5. Pulmonary Allograft cylinder

6. Pulmonary Autograft- (Ross procedure)


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7. Freehand cryopreserved or antibiotic preserved allograft

(Homograft)

Indication: mandatory in prosthetic valve endocarditis, also in young

women contemplanting pregnancy

Contraindication: dilated aortic root (>30mm)

Less desirable:

a) When ascending aorta is diffusely enlarged and thin walled

b) When severe uncontrolled systemic HTN is present

Advantage:

a) Absence of gradient

b) Removal of increased risk of AV rupture


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What is freehand Allovital Homograft?

Valve that are implanted within 48 hours of death of the donour (also

known as fresh homograft)

Current recommendation for storage is by cryopreservation in liquid

nitrogen at minus(-) 1960 C.

Alternatively valves are procured & treated with antibiotics to decrease

the amount of early failure due to thinning & tearing of leaflets, which are more

common when formaldehyde, chlorhexidine or Gamma radiation is used



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10. Aortic valve reconstruction procedure in AR has been recommended by few

surgeons, but have not widely acceted, particularly after development of

prosthetic valves. Stil repair in AR is more promising than AS.

a) Trussler repair

b) Aortic cusp retraction (by fibrosis or calcification) is treated by extending

or replacing the cusp with gluteraldehyde treated bovine or autologous

pericardium

c) Cusp prolapse is treated with a triangular resection of prolapsed cusp

d) Cusp perforation is repaired with pericardial patch.

Aortic valve repair is well established in children but not in adults


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What are the 3 techniques for Homograft valve insertion?

1. Sub coronary:

o Requires scalloping of the Homograft valve

1. Cylindrical (mini-root technique):

o Implantation of an intact cylinder, less prone to geometric distortion

1. Aortic root replacement:

o Least subject to geometric distortion

o Root replacement with Homograft is performed as Bental’s procedure

Management of small Aortic Annulus

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1. If prosthetic valve are used one size larger than aortic annulus cab be used by

a) Supra annular positioning- placing pledget on ventricular side by taking suture

from ventricle to aorta

b) Tilting the valve along the non coronary sinus. Here suturing the valve along the

annulus of left and right coronary sinus pledgeted mattress sutures are placed

from outside in of aorta

c) St. judes HP (hemodynamic plus) valve achieves larger orifice area for a given

size. The effective orifice are (EOA) of St. judes 19mm HP has nearly EOA of

standard St. judes 21mm valve.

2. Freehand aortic allograft (Homograft) is the best device because small size Allograft is

available in graft bank. (down to 16mm size). It can be inserted with minimal gradient

3. When supraannular AS a patch graft into the non coronary sinus of valsalva is used

(preformed pericardium)

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4. When sub valvar discrete stenosis due to fibro muscular ring- excision of fibrous band

is necessary ( care must be taken not to injure th AML below, aortic valve above & IVS)

5. When supra annular & annular enlargement is necessary it can be done in 2 method

a) Manoguian proecedure: done by extending the aortotomy through left coronary

noncoronary commisural area and into the underlying aortico mitral annulus.

The incision doesn’t reach the hinge point of mitral leaflet. A broad tear drop

shaped patch is positioned

b) Nicks et al- continues aortic incision into the noncoronary sinus, dividing the

aortic annulus & extended only as far as the origin of the AML.

NB. Aortic valve annulus is usually widened a few mm & one size larger than aortic

annulus can be positioned

Management of small Aortic Annulus continued….

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Management of small Aortic Annulus continued….

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7. In congenital obstruction of LVOT

Mcgoon; Cooley et al., Bernhard et al., used a conduit between left

ventricle and ascending, thoracic and abdominal aorta

7. An alternative to all these method is replacement of the aortic valve and

first part of the ascending aortra with either

i. Allograft aorrtic valve cylinder or

ii. Autograft pulmonary valve cylindr

NB. A 24-26 mm cylinder will fit in 17-19 mm aortic root

Effects of AVR in AS

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1. LVEDP decreases – fall in pulmonary capillary pressure

2. Myocardial oxygen consumption decreases –due to fall in systollic and

diastolic LV wall tension

3. Slight increase in diastolic coronary pressure

4. LV contractility increases- after AVR . Due to reduction of hypertrophied LV

NB. There may be slight decrease of LV contractility immediately after

AVR, possibly due to myocardial effects of CPB, which may persist for

first 4 post operative day

Effects of AVR in AS cont…

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5. Transvalvular gradient

o Depends on size and type of the valve

o Systolic transvalvular gradient across aortic valve is not eliminated

after AVR

NB. Small 19 mm valve has more gradient.

15-20 mmHg in monoleaflet with EOA 0.98 -1.06 cm2

3-28 mmHg in bileaflet SJM with EOA 1.09-1.22 cm2

Less gradient in freehand Autograft or cryopreserved Allograft

Effects of AVR in AR

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LV contractility may be slightly depressed soon after AVR,

because

A. Myocardial effects of CPB

B. Residual effects of cardioplegic drugs

C. Ischemic period (X-clamp time)

D. Increase in impedence to LV ejection that occurs when AR is

abolished, especially in first hew hours after bypass, when SVR is

increased.

Modes of death after AVR

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1. Late death due to cardiac failure & myocardial infarction- commonest

modes of death

2. Sudden death- occurs in 20% of late death and may be due to

thromboembolism

3. Some deaths, perhaps 20% are related to the device inserted

o Thromboembolism

o Prosthetic thrombosis

o Anticoagulant related hemorrhage (10%)

o Prosthetic valve endocarditis

o Device failure like bioprosthetic degeneration

Results after AVR

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Overal survival is about

75% at 5 years 60% at 10 years 40% at 15 years

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Health & Medicine

Aorticvalve 97 (2)