M · E · S · M

Minimally Invasive Electro Septal Myectomy

Redefining HOCM surgery
through a hidden 5cm incision

The world's largest single-center series of minimally invasive septal myectomy for hypertrophic cardiomyopathy, via right infra-axillary incision with transaortic approach.

Zhejiang Provincial People's Hospital, Hangzhou, China

5,000+
MICS procedures
1,000+
HCM myectomies
95%
OR extubation

Surgery without visible scars

No sternotomy.
No visible scar.

A 5cm incision hidden in the right axilla — completely concealed beneath the arm's natural resting position. No bone cutting. No muscle division. No rib resection. Invisible in any clothing. The transaortic approach avoids the long-term uncertainties on mitral valve function associated with a trans-mitral route.

3rd
intercostal space
5
cm hidden incision
Right infra-axillary incision location — hidden beneath the arm

Why MESM

Three core
advantages

MESM bridges the traditional Morrow procedure with the advancements of minimally invasive surgery — offering a unique combination of visualization, instrumentation, and comprehensive repair capability.

1
Superior visualization
Straight-line geometric advantage
The right axillary approach aligns the skin incision, aortic valve, and LV cavity into a near-straight line — providing direct endoscopic visualization of all intra-ventricular structures that is not achievable through an anterior approach.
2
Purpose-built instrumentation
Sculpts rather than cuts
A long electrocautery hook (46cm) sculpts the septal muscle with precision, replacing traditional forceps and scalpels. Vaporizes tissue cleanly with no debris, reducing embolization risk. Paired with a long suction-irrigation tube that doubles as a retractor.
3
Comprehensive LV repair
Beyond septal reduction alone
Direct visualization enables assessment and treatment of all contributing structures in a single view — septum, abnormal connections and muscle bundles, papillary muscles, mitral leaflets, and chordae. The transaortic approach avoids the long-term uncertainties on mitral valve function associated with a trans-mitral route.

Comprehensive LVOT management

Restore a nearly normal intra-LV anatomy

MESM bridges the traditional Morrow procedure with the advancements of minimally invasive surgery. It addresses the full spectrum of obstructive HCM — including patients with mild-to-moderate septal hypertrophy but severe outflow tract obstruction driven by mitral and subvalvular anatomy. All procedures are performed through the same right axillary approach, in a single operation.

See better, work better.

Septal myectomy
Electro-excision sculpts the ventricular septal muscle rather than cutting it — thin, long, and flexible, reaching from base to apex. Vaporizes tissue cleanly, leaving no debris and reducing the risk of embolization. Facilitates resection in a single, intact piece.
Mitral and subvalvular intervention
Anterior leaflet plication or shortening for elongated AMVL. Papillary muscle realignment for anteriorly displaced papillary muscles. Restrictive secondary chordae release when limiting leaflet motion.
Concomitant atrial fibrillation
Surgical ablation (Maze procedure) for AF performed through the same right axillary access, eliminating the need for a separate procedure or lifelong anticoagulation in selected patients.
Multi-valve and combined procedures
Concurrent aortic valve replacement, tricuspid repair, double-valve procedures, ASD closure, and cardiac tumor excision — all via the same minimally invasive access without sternotomy.
Intraoperative checklist — every structure assessed
✓
Septal thickness
✓
Abnormal connections & muscle bundles
✓
Papillary muscles
✓
Mitral leaflets & chordae
✓
Abnormal connections
Septal myectomy
→
TEE re-evaluation
→
SAM persists?
→
Targeted mitral / subvalvular repair
Live endoscopic view of the left ventricle
Click to play intraoperative video (surgical content)

Endoscopic visualization through the right axillary approach provides an unprecedented direct view of all left ventricular structures — septum, papillary muscles, chordae, and mitral leaflets — enabling comprehensive assessment and repair in a single view. This perspective is unique to the MESM approach and has not been previously described.

Clinical outcomes

Evidence

Peer-reviewed publications, international conference presentations, and outcomes from the world's largest single-center minimally invasive HCM surgery program.

LVMCO series — 132 consecutive patients
85→8.5mmHg
Peak gradient
0%
Iatrogenic VSD
62.6min
Mean clamp time
100%
SAM elimination
Key publications
Annals of Thoracic Surgery·2025
Minimally invasive electro septal myectomy for HOCM through a right infra-axillary incision
100 consecutive cases — presented at STS 2025
JTCVS Techniques·2024
An innovative minimally invasive approach for HOCM: transaortic septal myectomy via right infra-axillary incision
Cited by EJHF expert consensus 2026
Journal of Cardiac Surgery·2022
Minimally invasive right infra-axillary thoracotomy for transaortic septal myectomy
First description of the approach
JASE·2024
Mitral geometry on the mechanism of LVOT obstruction in HCM
Editorial by Sherrid MV
JASE·2026
Midsystolic Doppler signal void identifies mid-apical obstruction in HCM
Editorial by Massera & Sherrid
EJHF·2026
Expert consensus on diagnosis and management of hypertrophic cardiomyopathy
MESM cited as emerging technique (ref 88)
International conference presentations
2024
A novel minimally invasive approach for HOCM: transaortic modified Morrow procedure via right infra-axillary incision
AATS 104th Annual Meeting · Toronto
2024
Minimally invasive electro septal myectomy for HOCM via right infra-axillary incision
ISMICS Symposium · Osaka
2024
MESM for hypertrophic obstructive cardiomyopathy
AHA Scientific Sessions · Philadelphia
2025
Minimally invasive electro septal myectomy for HOCM via right infra-axillary incision
STS 61st Annual Meeting · Los Angeles
★ Selected as Best Abstract in Adult Cardiac Surgery
2025
MESM for hypertrophic obstructive cardiomyopathy
ASCVTS Annual Meeting
2025
MESM for HOCM via right infra-axillary incision — China Innovation Session
ISMICS 25th Annual Meeting · Istanbul
2025
Minimally invasive electro septal myectomy for HOCM: 331 consecutive cases
EACTS 39th Annual Meeting · Copenhagen
2025
Minimally invasive electro septal myectomy outcomes
ESC Congress
2026
MESM via right infra-axillary incision: a safe and effective treatment for left ventricular mid-cavity obstruction
AATS 105th Annual Meeting · Chicago
2026
Efficacy and safety of MESM for HCM with residual obstruction after prior septal reduction therapy
AATS 105th Annual Meeting · Chicago
2026
ERAS and ultra-fast-track cardiac anesthesia in LVOTO surgery: 671 patients
ISMICS Annual Meeting

The complete MESM ecosystem

Three disciplines, one team

Surgery, echocardiographic diagnosis, and perioperative care — integrated into a single, seamless pathway from evaluation to recovery.

Dr. Cui Yong
Cui Yong, MD, PhD
Cardiac surgeon
Fellowship-trained at the Mazankowski Alberta Heart Institute, Canada. 5,000+ minimally invasive cardiac procedures, 1,000+ HCM myectomies. Creator of the MESM technique. AATS oral presenter. Member of CSCS, STS, and ISMICS.
Dr. Wang Zhenzhen
Wang Zhenzhen, MD
Echocardiography / Diagnosis
Lead echocardiographer for the HCM program, with work published in the Journal of the American Society of Echocardiography (JASE). Her research focuses on the imaging mechanisms of dynamic outflow obstruction, forming the diagnostic front end of a complete diagnosis-to-treatment pathway for HCM.
Dr. Yan Meijuan
Yan Meijuan, MD
Anesthesia / Ultra-fast-track
Architect of our Ultra-Fast-Track Cardiac Anesthesia (UFTCA) protocol. Over 95% of HCM patients are extubated on the operating table — not in the ICU hours later, but on the table, immediately after surgery. 671 consecutive LVOTO patients. ISMICS 2026 poster presenter.

Ready to explore
your options?

Whether you're a patient seeking treatment or a surgeon interested in MESM training, we'd like to hear from you.