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De-huis T.J. UFS Bloemfontein

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1 De-huis T.J. UFS Bloemfontein
AORTIC STENOSIS De-huis T.J. UFS Bloemfontein

2 Aortic Stenosis Introduction ~ Etiology:
Calcification ~ normal trileaflet aortic valve: most common cause in adults with normal trileaflet or Congenital bicuspid valve Pathophysiology similar to atherosclerosis, thus predisposing factors include ~ Age Male gender Hyperlipidaemia Evidence of active inflammation Use of statins may retard the disease process early but not late

3 Aortic Stenosis Etiology ~ Calcification:
Usually in 6th to the 8th decade of life Mainly caused by solid calcific deposits in the cusps than commissural fusion Calcification of congenital bicuspid aortic valve~ 1-2% of babies are born with a bicuspid Ao valve Mostly males Contributes more to the total number of AS cases than the trileaflet Develops earlier than in Tricuspid leaflet ~ about the 2nd decade This earlier occurrence Is probably due to the unfavorable haemodynamics in bicuspid leaflet

4 Aortic Stenosis Etiology ~ Congenital Aortic Stenosis :
Usually detected and treated early in childhood and adolescence Usually a unicuspid unicommissural valve Sudden dearth is common due to LV strain Ejection fraction is usually supra normal with concentric ventricular hypertrophy

5 Aortic Stenosis Etiology ~ Rheumatic Valve Disease :
Becoming rare in developed countries Mitral valve almost always affected Commissural fusion present

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7 Aortic Stenosis Pathophysiology ~
Pathophysiology and relation to symptoms :

8 Aortic Stenosis Pathophysiology ~
Pathophysiology and relation to symptoms Asymptomatic patient have a good outlook even with severe stenosis, whereas An individual with symptoms has a mortality rate of 25% per year Pressure Overload Hypertrophy Narrowing of valve orifice to half the normal diameter of 3 cm² causes little obstruction to LV-outflow tract with a small gradient across the valve Blase R Carabello

9 Aortic Stenosis

10 Aortic Stenosis Pathophysiology ~ Pressure Overload Hypertrophy:
LV hypertrophy → a major compensatory mechanism, off setting the pressure overload Pressure overload →  LV afterload → ↓ ejection performance Afterload ~ wall stress σ = pr/2th ( Laplace Equation) P ~ ventricular pressure R ~ventricular radius th ~ ventricular thickness Blase R Carabello

11 Aortic Stenosis Pathophysiology ~ Pressure Overload Hypertrophy:
As the LV pressure  so does the thickness ( concentric hypertrophy) ~ thus keeping the afterload normal Maintenance of normal afterload → normal EF and stroke volume Note ~ Hypertrophy is a double edged sword, on the one hand maintaining normal EF and on the other impeding coronary artery blood flow reserve, It reduces diastolic function and Is associated with increased mortality Blase A Carabello

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13 Aortic Stenosis Natural History ~ Severity of stenosis  with time
Average rate of decrease in Ao valve ~ 0.12 cm² per year Progression is more in pts with degenerative disease than in congenital or rheumatic etiology Survival 35% of unoperated with usual AS symptoms are alive at 10 yrs ~ Grant Wood stated that 46% of such pts were alive at 1 to 7 yrs later ACC/AHA guidelines ~ after onset of symptoms , average survival is < than 2 to 3 yrs

14 Aortic Stenosis Survival ~

15 Aortic Stenosis Natural History ~ Survival :
15% to 20% of all deaths in AS are sudden VF Acute pulmonary edema from sudden LV failure Gradual cardiac failure after 5 yrs of diagnosis A few patients may display signs of moderate pulmonary arterial hypertension and, Others develop RV failure Kirklin/Barratt-Boyes

16 Aortic Stenosis Natural History ~ Survival: Asymptomatic patients ~
¼ develop symptoms within a year ½ by 3 yrs and ¾ by 4rs Sudden death occurs in < 1% Otto and colleagues

17 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Asymptomatic Symptomatic Classic triad (in 1/3 of pts) ~ Angina pectoris 50% to 70% of pts Common in pts with AS and CAD In severe AS than pts with less severe disease Syncope 30% to 50% of pts Peripheral vasodilatation from faulty baroreceptor mechanisms Pulmonary Venous Hypertension 30% to 40% Dyspnea, orthpnea, PND, or frank pulmonary edema Associated with  LVEDP and systolic wall stress, ↓ CO and EF

18 Aortic Stenosis Clinical Features and Diagnostic Criteria:
10% of patients survive typical symptoms long enough to develop secondary RV failure ~  right atrial and jugular pressure, Hepatomegaly, Cardiac cachexia Tricuspid regurgitation (rarely)

19 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Physical examination Auscultation ~ A crescendo-decrescendo systolic ejection murmur radiating to the neck From the collection of David Liff, MD, Emory University Hospital

20 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Physical examination Auscultation ~ In mild disease murmur peaks in early systole S2 is physiologically split and Carotid upstrokes are normal

21 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Physical examination Auscultation ~ As the AS progress The murmur becomes louder Peaks progressively later in systole, and Is associated with a thrill With further worsening of stenosis Murmur intensity becomes less due to ↓ in SV The carotid upstrokes are diminished in volume and rate of rise is delayed (parvus et tardus) The apex beat is increased Blase A Carabello

22 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Special Investigations ~ LV hypertrophy

23 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Special Investigations ~ ECG ~ Non specific ST-wave and T wave abnormalities ~ V6 lead – strain pattern) Chest Radiography ~ Non specific LV hypertrophy with boot shape +/- calcification of Ao valve

24 Aortic Stenosis

25 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Echocardiography ~ Thickened and calcified Ao valve with dense cusp echoes throughout cardiac cycle Decreased separation of leaflets in systole with reduced opening orifice ( mm mild, 8-12 mm moderate, and < 8 mm in severe) +/- doming in systole Dilated Ao root  thickness of LV wall (concentric LV hypertrophy) Hyperdynamic contraction of LV (in compensated state) ↓ mitral EF slope (↓ LV compliance) LA enlarged  Ao gradient (Doppler) ↓ Ao valve area (unreliable)

26 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Echocardiography ~

27 Fig 3 Continuous wave Doppler echocardiogram in patient with severe aortic stenosis (same patient as in figure 2). Fig 3 Continuous wave Doppler echocardiogram in patient with severe aortic stenosis (same patient as in figure 2). Transthoracic, two dimensional, apical, five chamber view (inset). A continuous wave Doppler records the maximal velocity across the narrowest point of the stenotic aortic valve and the spectral display is shown. The ratio of the velocity of the blood flow in the left ventricular outflow tract (1 m/s) to the aortic jet velocity (4.5 m/s) is <0.25, which is consistent with severe aortic stenosis Ramaraj R , Sorrell V L BMJ 2008;336: ©2008 by British Medical Journal Publishing Group

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29 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Bernoulli equation ~ Bernoulli equation is a statement of energy conservation for flowing fluids

30 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Bernoulli equation ~ G=4V² G ~ gradient V ~ peak transvalvular flow velocity

31 Aortic Stenosis Continuity principle states that flow through a nonstenotic region of the heart should equal flow through a stenotic area (assuming there is no regurgitation nor a shunt)

32 Aortic Stenosis Measurement of Aortic Valve Area ~ Continuity equation
Gorlin equation Hakki equation

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36 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Graded exercise testing ~ Not as risky in asymptomatic patients with AS May help in deciding on operative intervention, or if continued observation is advised, recommendations concerning vocational, recreational, or sports participation And is positive when ~ Symptoms occur Inadequate blood pressure or drop in more than 10 mmHg or greater Bradycardia Arrhythmia Conduction disturbances ST-segment depression (0.2 mV or more) Kirklin/Barrat-Boyes

37 Aortic Stenosis

38 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Cardiac Catheterization ~ Done if pt > than 40 yrs to asses coronary arteries If non invasive studies are inconclusive Transvalvular gradient and correct cardiac out assessment are important ~ Gorlin equation to determine Ao valve area Kirklin/Barrat-Boyes Blase A. Carabello Fick determination of cardiac out put can be used

39 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Cardiac Catheterization ~

40 Aortic Stenosis

41 Aortic Stenosis Clinical Features and Diagnostic Criteria:
Biomarkers and Symptomatic Status ~ Brain Natriuretic Peptide (BNP) A maker of hypertrophy and Use of preload reserve to maintain compensation Is high in AS with symptoms ? Usefulness in asymptomatic patients Renal failure, pulmonary hypertension and obesity interfere with the predictable value of BNP measurement Blase A. Carabello

42 Aortic Stenosis Treatment : Medical Treatment ~
?role of statins in progression of disease Cowell and colleagues Showed no benefit Other retrospective studies Showed benefit ~ ? Disease severity (Moura and colleagues) Blase A. Carabello

43 Aortic Stenosis Treatment: Medical Treatment ~ Vasodilators
Generally contraindicated in AS Hypotension and Syncope Except in concomitant hypertension and decompensated heart failure ACE-I can be used Sodium nitroprusside ?  contractility ~ causes decrease ventricular filling pressure → increased myocardial blood flow → enhanced contractility Blase A. Carabello

44 Aortic Stenosis Treatment: Surgical Treatment ~ Indications
Symptomatic patients with severe stenosis Patients with moderate or severe stenosis having operation for coronary artery disease, other heart valve disease, or aortic disease Asymptomatic patients with severe aortic stenosis LV systolic dysfunction Abnormal response to exercise (hypotension) Ventricular tachycardia Marked LV hypertrophy (≥15 mm) Aortic valve area (<0.6 cm²) Kirklin/Barrat-Boyes

45 Aortic Stenosis Treatment: Surgical Treatment ~
Isolated Aortic Valve replacement: Initial Steps ~ Usual preparations Median sternotomy CPB established at 34˚C, single two-staged venous cannula Cardioplegia – antegrade +/- retrograde Body is cooled down to 28˚C Ascending Aorta is Cross clamped ~ promptly if ventricular fibrillation is allowed +/- LV vent

46 Aortic Stenosis Treatment: Surgical Treatment ~

47 Aortic Stenosis Treatment: Surgical Treatment ~

48 Aortic Stenosis Treatment: Surgical Treatment ~

49 Aortic Stenosis Treatment: Surgical Treatment ~
Prosthetic Aortic Valve Interrupted suture technique Continuous suture technique Allograft Aortic Valve Subcoronary technique Root enlargement technique

50 Nezic D. et al.; J Thorac Cardiovasc Surg 2008;135:1401-a-1402-a
Surgical techniques of posterior aortic root enlargement reported so far (Nick's-white arrow, Nunez's-black arrow, Manouquian's-black plus black dotted arrows) Nezic D. et al.; J Thorac Cardiovasc Surg 2008;135:1401-a-1402-a

51 Aortic Stenosis Special Features Of Postoperative Care:
Mechanical Prosthesis ~ Life long sodium warfarin (on the evening of the 2nd postoperative day) INR ~ around 2.5 (2-3) If AF or  atrium or impaired LV function ~ INR 3.0 ( ) ? Addition of aspirin ~ benefits v/s hemorrhage ?enoxaparin ~ 1mg.kgֿ¹ for five days until INR reaches therapeutic level

52 Aortic Stenosis Special Features Of Postoperative Care:
Bioprostheses (human, porcine, bovine) No need for anticoagulation Aspirin can be used for 1 month if risk of thromboembolism is great (81 mg daily) AF ~ if patients are still in AF 48 hrs after surgery, then warfarin is administered until sinus rhythm is restored

53 Aortic Stenosis Special Features Of Postoperative Care:
Patients with LV hypertrophy ~ These require high LV filling pressures, thus Mean LA pressure of > 10 mmHg (15 to 18 mmHg) Sinus tachycardia ~ If heart rate is > 100 beats . minֿ¹ for several days without returning to normal, then beta blockers can be started

54 Aortic Stenosis Results: Early (Hospital) Death ~
3.4% hospital mortality for primary isolated aortic valve replacement ( The Society of Thoracic Surgeons National Database) Risk higher for females than males (3.9% versus 3.0%) With CABG then STS National Database figures rise to 6.3%

55 Aortic Stenosis Results: Modes of Death ~ Early deaths
Acute cardiac failure Neurologic complications Hemorrhage and Infection Late deaths (20%) Cardiac failure Myocardial infarction Thromboembolism

56 Aortic Stenosis Results: Incremental Risk Factors for Premature Death
Older age ?Ethnicity ( African-Americans at increased risk) Functional Status (NYHA) LV morphology and Function Ao regurgitation Gender Angina AF Kirklin/Barrat-Boyes

57 Thank You


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