Surgical management of HOCM

1. SURGICAL MANAGEMENT FOR
HYPERTROPHIC OBSTRUCTIVE
CARDIOMYOPATHY
Dr. Hari Kumar Sampath
CTVS Resident , NUH
Moderator: Dr. SorokinVitaly
Sr Consultant Cardiac Surgeon, NUH

2. Definition
♥ Left ventricular hypertrophy in the absence of underlying cause –
Hypertension, Aortic stenosis
♥ LVOTO results from septal hypertrophy combined with systolic anterior
Motion of the mitral valve (SAM) which also produces variable degree of MR
♥ Obstruction - 70% (J Maron et al 2009)

3. Genetics
 1 in 500 . Genetically determined 60-80%
familial
 De - Novo 20-40%
 0.2% of phenotypically expressed disease
 >400 mutations in 1 or more of the 15
identified genes that encode components
the cardiac sarcomere complex
 Mutation to 3 protein encoding genes
 30-70 % in beta Myosin heavy chain (MYH7)
 15-25% in Myosin binding protein
(MYBPC3)
 15-20% in CardiacTroponinType 2 (TNNP2)
Benefits of genetic analysis
■ Pre clinical diagnosis in patients with
family history of SCD
■ InThose with a malignant mutation
that predisposes them to a severe
phenotype
■ To know the precise genetic defect in
HCM among asymptomatic family
members who carry the mutation and
might be at risk of SCD
Richard P, Charron P, Carrier L, et al. Hypertrophic cardiomyopathy: distribution of disease genes, spectrum of
mutations, and implications for a molecular diagnosis strategy [published correction appears in Circulation. 2004
Jun 29;109(25):3258]. Circulation. 2003;107(17):2227‐2232. doi:10.1161/01.CIR.0000066323.15244.54

4. Anatomical classification
HCM can be divided into those with and without left ventricular outflow tract
obstruction (LVOTO)

5. From a surgical perspective, sub-classified on the basis of the site of maximum
septal hypertrophy, although other wall segments are usually also hypertrophied:
♥ Subaortic HCM—hypertrophy of the basal interventricular septum that creates a
relatively elliptical left ventricular (LV) cavity with a marked nodule.This results in
LVOTO caused by SAM
♥ Midventricular HCM—mid septal hypertrophy that forms a crescent-shaped LV
cavity and may be also associated with SAM and LVOTO
♥ Apical HCM—a predominantly apical distribution of hypertrophy that reduces the
size of the apical region of the LV cavity. Isolated apical HCM is not associated with
LVOTO

6. Morphology of Septal Hypertrophy

7. Morphology of Mitral valve apparatus
■ Mitral anterior leaflet moves anteriorly in systole
■ Posterior mitral leaflet moves and closes against
the free edge of the anterior leaflet and narrows
the LVOT
■ Causes MR with jet directed posterolaterally
■ Whitish endothelial scar is the guide during septal
myectomy
■ 15-25% Papillary muscle anamoly –
 Direct insertion of papillary muscle into
anterior leaflet
 Papillary muscle fusion to septum
 Accessory muscles & Accessory anamolous
Chordae

8. Morphology of Coronary Artery Disease
■ Atherosclerotic coronary artery
disease (CAD) 5-15% in HCM
■ Mayo clinic – 26% of patients
underwent coronary angiogram had
significantCAD
■ 15% had bridging of epicardial
coronary disease – which is more
significant in children with angina
compared to adults (Yetman et al. N
Eng J med 1998)
■ Survival is reduced in presence of
significantCAD

9. Diastolic
dysfunction
• Elevation of LV end diastolic pressure is the principle pathophysiology
• Results in LA enlargement,
• Increase in Pulmonary pressure
• Atrial arrhythmias
• Insufficient myocardial oxygen supply because of the very thick and hypertrophied myocardium;
LVOTO
• Direct effect on increasing end diastolic pressure
• Indirect effect on hemodynamics through association with MR
Mitral
regurgitation
• Intrinsic mitral valve disease may contribute to valvular lesion
• Rupture of chordae leads to CCF
Pathophysiology

10. Clinical presentation
♥ asymptomatic
♥ severely disabling symptoms of fatigue, dyspnea, chest pain, syncope and sudden
cardiac death (SCD)
♥ The overall mortality rate of patients with HCM is less than 1 % per year, most
commonly the result of SCD due to ventricular arrhythmias
♥ It is the most common cause of SCD in young athletes

11. Natural course of the disease
■ symptoms due to LVOTO
■ Asymptomatic with no pressure gradient until 4th -6th decade of life
■ Onset of AF (30%) precipitates symptoms leading to embolism in ( 6%) of the HCM
■ Infective endocarditis 1.4/1000 person per year
■ 1% mortality

12. Diagnosis
ECHO Findings - HCM patients are classified
as having obstruction based on
 the measurement of peak systolic
velocity in the left ventricular outflow
tract (LVOT) at rest and in asymptomatic
cases after provocation >30 mm Hg
 systolic anterior motion (SAM) of the
anterior leaflet of the mitral valve
resulting in a posteriorly directed jet of
regurgitation
 Presence of MR
 Differentiate MR jet & true LVOT velocity
 mid-systolic closure of the aortic valve
 Average LV wall thickness 20-22 mm, but
in 5-10% patients 30-50 mm
 LA dilatation, PHT, Diastolic dysfunction
Bos JM,Towbin JA, Ackerman MJ. Diagnostic, prognostic,
and therapeutic implications of genetic testing for
hypertrophic cardiomyopathy. J Am Coll
Cardiol 2009;54:201-211

13. Diagnosis
Cardiac MRI
 In case not recognised in 2D ECHO
in anterolateral free wall and apical
hypertrophy
 Detects the severity of myocardial
fibrosis which is known risk factor
for ventricular arrhythmias
Invasive Catheterization
■ Rarely indicated
■ Only if symptoms of angina
■ Family history of CAD
■ Abnormal Lipids
■ Older age

14. S
Refractory SymptomsTreatment Failure
Subaortic obstruction Non Obstruction
Severe Symptoms NYHA Class III/IV
Dysopyramide + Beta Blockers Verapamil + Diuretics
Mild to moderate symptoms Class I/II
Beta blockers Verapamil
Septal Myectomy
Alcohol Septal Ablation
HeartTransplantation

15. Supportive management
Avoid
■ dehydration
■ excessive alcohol consumption as volume depletion
exacerbates the pressure gradient
■ Similarly, vasodilating drugs including nitrates to be avoided
■ digoxin, which has positive inotropic effects

16. Medical management
♥ First-line medical therapy : β-adrenergic blocking agents,
- negative inotropic and negative chronotropic effects
- help alleviate obstruction, and
- dosage should be titrated to the maximum tolerated
♥ Second line management : Calcium antagonist Verapamil, which
- improves ventricular relaxation and decreases LV contractility.
♥ Disopyramide is a type I-A antiarrhythmic agent with an anticholinergic effect,
- often used in combination with a β-blocker if this is only partially effective
- In atrial fibrillation, used in combination with an AV node blocker, as AF may be
accompanied by a rapid ventricular response.

17. Prophylactic &Therapeutic Implantable cardioverter –
Defibrillator
♥ Prevention of SCD
♥ Prior cardiac arrest,
♥ SVT
♥ Family history SCD

19. Surgical management
♥ Goal of any surgical technique is to relieve LVOT obstruction,
♥ avoid the occurrence and/or recurrence of systolic anterior movement (SAM) of the
anterior mitral leaflet (AML) if present—reduce mitral valve (MV)
♥ Depending on the configuration of LVOT obstruction, myectomy with/without MV
replacement has been the “gold standard” in surgical treatment of HOCM.
♥ considering the known disadvantages of artificial valves, MV preserving techniques
will improve postoperative outcomes and decrease major adverse events in the
long term

20. Septal reduction therapy
♥ NewYork Heart Association functional classes III and IV despite maximum tolerated
pharmacotherapy.
♥ Specifically, with a peak outflow gradient of ≤50 mmHg as measured with Doppler
echocardiography either under resting conditions or by physiological provocation
through exercise
♥ Moreover, the required minimum thickness of the interventricular septum required
for surgery is specified at 15 mm
♥ By restoring diastolic activity, septal myectomy is able to provide long term
alleviation of HCM-related symptoms.

21. septal myectomy
- Best in patient with proximal LVOTO and mid ventricular
obstruction
- Not a great option for other variants (apical)

22. ♥ Predictable result with accurate removal of muscle in thickness, length &
width
♥ Can attend to mitral valve issues
♥ Low morbidity & mortality procedure
♥ Other manipulations if needed – CABG, MR
♥ Only high risk for PPM
septal myectomy

23. septal myectomy
♥ GA
♥ Midline sternotomy
♥ Cardiopulmonary by pass
♥ Transthoracic approach

24. Transaortic septal myectomy
♥ The pericardium is opened vertically over the centre of the ascending aorta.
♥ Multiple pericardial sutures are used to suspend the right pericardium to the adjacent
superior sternal edge.
♥ Left pericardial suspension sutures are placed from the aortic annulus level to the
pericardial reflection only as this allows the left ventricular apex to drop into the left chest.
♥ This maneuver elevates the aorta to the sternal level and facilitates visualization during the
procedure
♥ Cardiopulmonary bypass with single two-stage right atrial cannulation and
♥ venting of the left ventricle via the right superior pulmonary vein is established

25. The patient is systemically cooled to 34 degrees centigrade following placement of an aortic
cross clamp,
normothermic cardioplegia solution is used to arrest the heart followed by cooling until the
myocardium reaches 15 degrees centigrade.
A transverse aortotomy is fashioned approximately 0.5 cm above the sinotubular junction
(STJ).
It is important not to cross the STJ with the incision as this may distort the aortic valve with
closure of the aortotomy which can result in aortic insufficiency.
The distal aorta at the incision line is then tacked to the pericardial reflection at the level of the
superior vena cava for exposure

26. ♥ The first myectomy incision is made oriented towards the LV apex beginning 2mm below the right
coronary leaflet hinge point and 2 mm towards the membranous septum.
♥ The depth of the incision is usually 1-1.5 cm and length 3.5-5 cm as guided by the preoperative
echocardiogram.
♥ The incision is made parallel to the LVOT (towards the apex) to a depth of the proposed resection,
with the goal of a residual septal thickness of 0.8 to 1.0 cm.
♥ A tendency is to direct the incision too far to the left of the apex.
♥ To avoid this, the surgeon can make the incision with the left hand.
♥ The length of the incision depends on the extent of the hypertrophy
♥ but is generally 35–50 mm long.
♥ In patients with concomitant mid-ventricular obstruction, the incision should extend to at least the
level of the antero-septal papillary muscle head

27. The second incision is approximately 2.0 mm in depth and 2.0 mm below the right coronary leaflet hinge
and is carried into the sub-commissural area beginning at the base of the first incision.
The third incision begins in the subcommissural area running parallel and 2.0 mm below the left coronary
cusp hinge ending 4–5 mm from the mitral annulus

28. UsingArgentine forceps, the ‘LVOT flap’ is grasped and distracted inferiorly.
Now a second 2.0 mm deep incision is made at the superior border of incisions 2 and 3.
In the region of the sub-commissural area the two original incisions are rounded with subsequent
incisions.
The process is repeated eventually forming a flap in the LVOT resection is terminated by placing
downward traction on the specimen and incising across the base.

29. The lateral aspect of the resection at the mitral annulus is completed with scissors, again with care
to avoid trauma to the mitral sub-valvular apparatus

30. With the retractor placed in the resection site, the distal base of the resection can be
extended 1–2 cm laterally under the membranous septum with the resection narrowed as it
is carried towards the annulus.
By producing a traction point, the distal most portion of the resection can also be elongated
if necessary

31. Surgery for HOCM
Mitral valve replacement for HOCM
■ Popularized by Cooley as a quick and uncomplicated fix
■ Does solve the problem of the LVOTO
■ Technical concepts:
Has to be a low profile mechanical valve. Biological valve with struts or high profile
mechanical valves(currently unavailable)Can independently produce LVOTO
All leaflet tissue and chordal apparatus along with, occasionally, the heads of the papillary
muscles have to be resected to open up the LVOT and mid cavity completely.
Issues:
Creates a lifelong dependency on anti-coagulation in a relatively young person
Current role:
Residual LVOTO after previous surgery with inadequate muscle available for repeat resection

32. Resection-Plication-Release operation
■ Abnormal positioning and size of the mitral valve contributes to the dynamic LVOTO
independent of the PSH only
■ Transaortic approach and standard septal myectomy
■ The anterior mitral leaflet is foreshortened by applying 2-4 vertical sutures in the mid body
of the leaflet where it is usually devoid of chords
■ The abnormal attachments of the papillary muscles are release to allow the chordal
apparatus of the MV to fall away from the LVOT
■ Excellent operation for a dynamic LVOTO from complex pathophysiology

33. Correcting a bad result from a septal myectomy
 Evaluate the operation andTEE
IS there any scope for more muscle resection?
Are there independent MV issues or mild cavity issues?
 Back on bypass
Muscle- Extended resection
Modified Konno procedure for augmenting the LVOT
 Mitral valve
Plication
Release of papillary muscle
MV Replacement
Role foe the Alfieri edge to edge suture
Limited –Bailout only cause the whole assembly to move into the LVOT

34. Evaluating a septal myectomy
 Gradients
Can be done byTEE or direct needle measuremnts
Reduction in the resting gradient and most importantly the post ectopic potentiation must be
abolished
Role of administration of chronotropes foe evaluation
 Mitral valve
SAM to be abolished completely
Trace to mild MR
 Why is it adequate?
Inadequate muscle resection
independent mitral valve pathology

35. Pitfalls in a septal myectomy
The trough is not long enough-residual gradient
Damage to aortic valve
Injury during retraction of the leaflet
Trough too close to the base of the RCC destabilzing it.
Damage to mitral valve
Injury to leaflet or chordal apparatus during muscle resection
Ventricular septal defect
Too much muscle resected. Cavalier in evaluation and resection
Heart block

36. Outcomes
Early
■ 1% mortality in experienced centre
■ Complete heart block<1-2%
■ Iatrogenic ventricular septal
perforation
Late
■ >90% shown improvement from
more 2 classes
■ Relief of gradient decrease the atrial
size
■ Decreases AF

37. Survival
■ 98, 96, 83% in 1,5 & 10 years post operatively ( omen et al study)
■ Extent of LVH important determinant of survival
successful myetectomy results in regression LVH
In patients with ICD , myectomy group had less discharges compared to non operative
patients ( Mc Cleod and associates)

38. Alcohol Septal Ablation – Pros & Cons
■ less invasive technique
■ more suitable for elderly or high-risk patients than surgical myectomy because there
may be reduced procedural all-cause mortality rate.
■ However, there is an increased risk of heart block
■ permanent pacemaker requirement, and
■ slightly higher post-procedural resting LVOT gradients

39. QUIZ

40. Which of the following is not true
regarding morphology of HCM?
■ A.The phenotype closely correlates with genotype
■ B. Upto 20 % of patients will have anamolies of papillary muscles
■ C. Coronary flow is reduced
■ D. CAD is present in 5-15 % of the patients
■ E. LAD muscular bridging is found in 15%

41. Which of the following histopathologic and
genetic findings are true in patients with
HCM?
■ A.The myocardial fibres are hypertrophied and arranged in parallel sheets
■ B.There is organised whirling of fibres
■ C. Most cases are not familial
■ D. It is genetically diverse disease
■ E.All family members should undergo genetic testing

42. HCM results in?
■ A. Systolic dysfunction
■ B. LVOTO
■ C. Functional mitral stenosis
■ D.Asymmetrical left ventricular free wall thickening
■ E. Central mitral insufficiency due to SAM

43. Surgical repair of HCM may include all of
the following except:
■ A. Septal myectomy
■ B. Incision of the ventricular wall below the commissure between the left and right
coronary cusps
■ C. Mitral valve replacement
■ D. Unroofing of the LAD
■ E. Extension of the ventricular incision towards the apex

44. Results after surgery for HCM include?
■ A. Operative mortality of 5%
■ B. Heart block & pacemaker incidence around 5%
■ C. Relief of symptoms in over 90% of the patients
■ D. Long term survival below the general population
■ E. Higher incidence of new right bundle branch block compared to Alcohol septal
ablation

45. ThankYou