Classical myectomy is the gold standard therapy for patients with severely symptomatic hypertrophic obstructive cardiomyopathy. Extended myectomy provides a complete relief from dynamical obstruction and is most effective in the prevention of sudden cardiac death.

At Burjeel Hospital, seven patients underwent extended myectomy in the last 5 years.

Surgical technique

A detailed preoperative transesophageal echocardiogram done in the operation theatre. LVOT gradients were assessed both by TEE and simultaneous pressure recording of LV cavity and ascending aorta. All patients were operated while on cardiopulmonary bypass with cardioplegic arrest. A low transverse aortotomy was the incision of choice in all cases. No additional ventriculotomy done in any of these patients. The extent of the hypertrophy is assessed by visual inspection and digital palpation. The muscle mass suitable for myomectomy is clearly defined by classical incisions on the thickened LV septum. All precautions were taken not to damage the aortic annulus and the cusps. The incision was extended towards the LV apex to get complete relief of the obstruction. The excision of the muscle mass was also extended behind the insertion of the mural leaflet of the mitral valve. Almost always we tried to remove the muscle mass in total in single piece. LV cavity was thoroughly washed and inspected well. Both the papillary muscles were completely inspected and all hypertrophied trabeculae as well as hypertrophied papillary muscles were resected. Additional muscle band from the papillary muscle to the septum was found in one case and resected without damaging the papillary muscle.

Again, the LV cavity was assessed both visually and also by digital palpation. While coming off bypass, TEE helped to identify complete relief of the pressure gradient. Four patients had significant mitral regurgitation where leaflet plication was done with no significant post-operative mitral regurgitation. Post-operatively, none of these patients had aortic regurgitation or significant mitral regurgitation or septal perforation or conduction block. One patient had an iatrogenic perforation in the aortic leaflet, which was repaired by pericardial patch. All of them had significant reduction in the pressure gradient on postop TEE assessment. All these patients were regularly followed up by our cardiology team. Two of the patients required elective implantable defibrillator.

Conclusion

In our experience, with the technique of extended myectomy, sustained relief was achieved in surgically treated HOCM patients, without SAM or significant mitral regurgitation, at long-term follow-up. No patient had sudden cardiac death during follow-up till date. Referrals for HOCM surgical interventions are still restricted to severely symptomatic patients with significant LVOT gradients under basal conditions.

HOCM – PATIENT PROFILE

S.No	Date of Surgery	Age/Sex/Nationality	Symptoms
1	24/05/2017	31, Male, Bangladesh	Dyspnea, chest pain
2	10/01/2018	54, Female, Philippines	Exertional dyspnea, chest pain and dizziness3
3	10/03/2018	23, Female, Pakistan	Exertional dyspnea4
4	02/00/2019	55, Male, Syria	Exertional dyspnea5
5	03/10/2020	39, Female, India	Fatigue, dyspnea6
6	12/10/2020	34, Male, India	Exertional dyspnea7
7	17/07/2021	34, Male, Bangladesh	Exertional dyspnea

HOCM – INTRAOPERATIVE DETAILS

S.No	LVOT-AO Gradient, TEE	SAM	MR	Procedure	Additional Procedure
1	64 mmHg	Yes	Yes	Extended myectomy	MV repair2
2	80 mmHg	No	Yes	Extended myectomy	Aortic and mitral valve repair3
3	90 mmHg	Yes	Yes	Extended myectomy	MV replacement * outsidesurgeon4
4	100 mmHg	Yes	Yes	Extended myectomy	MV repair
5	65 mmHg	Yes	Yes	Extended myectomy	MV repair
6	140 mmHg	No	Yes	Extended myectomy
7	100 mmHg	No	Yes	Extended myectomy

Extended myectomy in hypertrophic obstructive cardiomyopathy