BICUSPID AORTIC VALVE

By Jyotindra Singh

adult cardiothoracic

BAV - PathogenesisGenetics

• Autosomal dominant, variable penetrance

• 9% prevalence in first-degree relatives

• 24% if >1 person affected

• Causal genes largely unknown

• NOTCH1 (9q34.3)

BAV - Diagnosis

Transthoracic Echo

• Sensitivity 92%, Specificity 96%

• Accuracy inverse to calcification

• Findings:

• Raphe

• Systolic doming & eccentric closure line

(LAX)

• Evaluate in systole; raphe may appear

trileaflet

Diastole Systole

Raphe

Doming

BAV - Natural History

• Valvular dysfunction - AS, AR, endocarditis

• Aortopathy

BAV - Natural History

The largest study (n=642) in symptomatic/asymptomatic BAV pts:

10-year 96% survival

Similar to normal population

Tzemos et al. JAMA;2008:300;11:1317-1325.

BAV - AS

Surgical series of 932 resected aortic valves for AS:

• 49% had BAV

• Age at intervention

• BAV: 67±11

• Tricuspid: 74±8

Roberts et al. CirculaGon. 2005;111:920-925.

BAV - AS

Disease progression

• Similar degenerative changes as seen in tricuspid

valves

• Exacerbated by BAV folding/creasing/turbulent flow

• Results in accelerated disease progression

• Most common reason for valve replacement

Roberts et al. CirculaGon. 2005;111:920-925.

BAV - ASInfluence of valve morphology

• 310 patients with BAV

• 202 (65%): R-L fusion, 108 (35%): R-N fusion

• Follow-up 14±7 yrs

• 49 (16%) had interventions

• Freedom from intervention: 64% R-N vs. 91% R-L

• AS more progressive in R-N pts

Fernandes et al. JACC 2007:2211-4.

BAV - ARLess frequent occurrence than AS

• Surgical series of 542 pts who underwent AVR (1991-1996):

• 13% (pure AR) vs 75% (pure AS)

• Mean age:

• 46 yrs (AR) vs 65 yrs (AS)

Low intervention rates

• Olmsted county (Michelena): 47% had some degree of AR at baseline; 3% had

intervention for severe AR

• Toronto study (Tzemos): 21% had moderate/severe AR at baseline; 6% had

intervention for symptomatic AR

Mechanisms

• Valve prolapse

• Aortic root/annular dilatation

• Endocarditis

.)

BAV - Endocarditis

Recent studies suggest low incidence:

• Olmsted county:

• 2% per year incidence

• Toronto study:

• 0.3% per year incidence

AHA guidelines no longer suggest bacterial endocarditis

prophylaxis, except if prior history of endocarditis.

Tzemos et al. JAMA;2008:300;11:1317-1325Michelena et al CirculaGon. 2008;117:2776-2784.)

BAV - AortopathyPatterns of Aortic Dilation

Type 1: Dilation of tubular ascending aorta primarily

along convexity with mild-moderate root dilation.

Most common; associated with R-L cusp fusion & AS

Type 2: Isolated tubular ascending aorta dilation,which may extend into the arch, with relative sparing of

aortic root.

Associated with R-N cusp fusion.

Type 3: Root phenotype - isolated root dilation, normal

tubular/arch dimensions.

Rarer; associated with younger age at diagnosis;

genetic.

BAV - AortopathyPathophysiology

Haemodynamic evidence

Recent MRI studies -

• Abnormal transvalvular-flow patterns despite apparent normally

functioning BAVs

• Regional increases in wall-shear stress

However, valve morphology did not predict events in population studies

BAV - AortopathyNatural History

Ascending aortic aneurysm:

• Rate of growth higher in persons with BAV c/f tricuspid valve

• Tricuspid: 0.16 mm/yr uniformly over 6 decades

• BAV: 0.20 - 1.9 mm/yr

Accelerating rate of aortic

dimension increase with

increasing age

BAV - ManagementAHA 2014: Surgical Intervention

Class 1

Diameter of the aortic sinuses or ascending aorta is greater than 5.5 cm [B]

Class 2a

Diameter of the aortic sinuses or ascending aorta is greater than 5.0 cm and a

risk factor for dissection is present (family history of aortic dissection or if the

rate of increase in diameter is 0.5 cm per year) [C]

Replacement of the ascending aorta is reasonable in patients with a bicuspid

aortic valve who are undergoing aortic valve surgery because of severe AS or

AR if the diameter of the ascending aorta is greater than 4.5 cm. [C]

Bicuspid Aortic Valve and Aortopathy: Diagnosis and Follow-Up

Recommendations COR LOEAn initial TTE is indicated in patients with a known bicuspid aortic valve to evaluate valve morphology, to measure the severity of AS and AR, and to assess the shape and diameter of the aortic sinuses and ascending aorta for prediction of clinical outcome and to determine timing of intervention

I B

Aortic magnetic resonance angiography or CT angiography is indicated in patients with a bicuspid aortic valve when morphology of the aortic sinuses, sinotubular junction, or ascending aorta cannot be assessed accurately or fully by echocardiography

I C

Bicuspid Aortic Valve and Aortopathy: Diagnosis and Follow-Up

Recommendations COR LOESerial evaluation of the size and morphology of the aortic sinuses and ascending aorta by echocardiography, CMR, or CT angiography is recommended in patients with a bicuspid aortic valve and an aortic diameter greater than 4.0 cm, with the examination interval determined by the degree and rate of progression of aortic dilation and by family history. In patients with an aortic diameter greater than 4.5 cm, this evaluation should be performed annually

I C

Bicuspid Aortic Valve and Aortopathy: Intervention

Recommendations COR LOE

Operative intervention to repair the aortic sinuses or

replace the ascending aorta is indicated in patients

with a bicuspid aortic valve if the diameter of the

aortic sinuses or ascending aorta is greater than 5.5

cm

I B

Operative intervention to repair the aortic sinuses or

replace the ascending aorta is reasonable in patients

with bicuspid aortic valves if the diameter of the

aortic sinuses or ascending aorta is greater than 5.0

cm and a risk factor for dissection is present (family

history of aortic dissection or if the rate of increase in

diameter is ≥0.5 cm per year)

IIa C

Bicuspid Aortic Valve and Aortopathy: Intervention

Recommendations COR LOEReplacement of the ascending aorta is reasonable in patients with a bicuspid aortic valve who are undergoing aortic valve surgery because of severe AS or AR (Sections 3.4 and 4.4) if the diameter of the ascending aorta is greater than 4.5 cm

IIa C

BAV - Management

Medical

• Scarce evidence of efficacy

• No evidence for altering natural history in BAV

• AHA recommendation

• Dilated aortic root/ascending aorta:

• ACEI/ARB & BB to reduce SBP to the lowest tolerated

levels

• AS/AR:

• Treatment of systemic hypertension

Current trial:

Atenolol and Telmisartan in BAV aortopathy - RCT

BAV - Management

Repair of BAV

• Attractive given young cohort of BAV pts with AI

• No RCTs of repair vs replacement

• When to consider:

• Regurgitant valves

• Pliable leaflets

• Minimal fibrosis/calcification

• No more than mild cusp thickening

• Minor fenestrations

BAV - ManagementRepair of BAV - Techniques

Restore cusp integrity

• Closing tears/perforations by direct suture or autologous

pericardial patching

Line-up discloses presence of tissue redundancy

Sufficient tissue; closure of cleft

Excess tissue; triangular resection, plication

BAV - ManagementRepair of BAV - Techniques

Deficient tissue

• Overcorrecting free margin of the conjoint cusp to a length

shorter than free margin of reference cusp

• Increases systolic doming

BAV - ManagementRepair of BAV - Techniques

Commissural repair

Resuspension of detached commissure Misalignment & splaying

-pledgeted sutures & plication -pledgeted oblique Cabrol-like stitch

BAV - ManagementBentall's

Survival similar to age/sex matched controls at 12 yrs

Etz et al. Ann Thorac Surg 2007;84:1186-94

Much more to come

Are we all still awake?

"The key overall conceptual question in

front of the cardioaorticsurgical community is: Can

we repair virtually every pure BAV AI presentation

as we presently perform in the mitral valve repair

arena?

Factors – Poor repair Outcomes

• excessive calcification of the leaflets, including the commissures or raphe;

• severely enlarged annular diameters without robust subannularstabilization;

• leaflet surface areas that are not adequate to provide excellent cusp coaptation (and therefore would require leaflet augmentation);

• and reimplantation with very extensive cusp repair.