a 43-year - old man with a history of hypertrophic obstructive cardiomyopathy ( hocm ) was admitted to our hospital due to recently aggravated exertional dyspnea and palpitations .
transthoracic echocardiography revealed asymmetrical inter - ventricular septal hypertrophy with systolic anterior motion ( sam ) of the anterior mitral valve leaflet ( fig .
the septal wall thickness was 25 mm , the left ventricular outflow tract flow velocity was 4.6 m / sec , and the pressure gradient was > 90 mmhg .
the end - diastolic and end - systolic volumes of the left ventricle were 71 ml and 25 ml , respectively .
an elongated anterior leaflet of the mitral valve showed sam , resulting in grade iii eccentric mitral regurgitation toward the left atrial posterior wall .
12-lead electrocardiography , a sinus rhythm with left ventricular hypertrophy was confirmed , indicating a repolarization abnormality .
right thoracotomy was performed with a 4.5-cm incision in the fourth intercostal space , and four additional ports were inserted at the third ( left arm , chitwood clamp ) , fourth ( left atrial retractor ) , and sixth ( right arm ) intercostal spaces .
a 3-cm radial incision was made in the amvl from the right fibrous trigone to the left fibrous trigone , taking care to prevent aortic valve injury . through the incised amvl
asymmetric septal hypertrophy was present , but neither papillary muscle anomaly nor fusion was noted .
septal myectomy was then performed diffusely at the nadir of the right aortic sinus and cautiously continued leftward to prevent a conduction injury ( fig .
the total weight of the excised muscle was 11 g. the amvl incision was repaired using a continuous running suture .
an ink test using methylene blue showed an adequate coaptation surface , and a water test revealed no residual mitral regurgitation . in order to prevent possible micro - air embolism in the left chamber
, the left atrium was filled with blood before closure of the transatrial incision . after weaning from cardiopulmonary bypass ,
intraoperative transesophageal echocardiography performed immediately after weaning from cardiopulmonary bypass revealed mild mitral regurgitation ( grade i ) with a well - relieved left ventricular outflow tract obstruction ( pressure gradient , 15 mmhg ) without sam , as confirmed by the cardiologist on our team .
the patient remained in the intensive care unit for 18 hours , and no postoperative complications occurred .
postoperative transthoracic echocardiogram findings before discharge showed no left ventricular outflow tract obstruction ( vmax , 1.9 m / sec ) and only mild mitral regurgitation .
hocm is a heterogeneous disease , in which the aortic outflow tract is obstructed by an abnormally thickened ventricular septum .
since morrow introduced transaortic myectomy for the treatment of hocm , which has a complicated pathophysiology , resection - plication - release repair has become the standard treatment . due to the challenge of septal visualization using the transmitral approach , septal myectomy for left ventricular outflow tract obstruction relief
in addition , improved resolution of sam via the transaortic valve approach has decreased the occurrence of mitral regurgitation due to loss of coaptation with the posterior leaflet . however , the transmitral approach decreases the risk of aortotomy and aortic valve damage and speeds up postoperative recovery .
moreover , in cases of extensive mitral valve pathology , the transmitral approach allows more complex mitral valve repair and mitral valve replacement .
furthermore , as in our present case , mitral regurgitation with redundant amvl can be sufficiently treated with amvl incision and repair . as experience with minimally invasive mitral valve repair has been gained in several centers , minimally invasive transmitral septal myectomy through an amvl incision has become possible via a robotic approach , as first described by khalpey et al . .
in our center , we have successfully treated four cases to date , including the present case , by septal myectomy through a minimally invasive right mini - thoracotomy approach using the automated endoscope system for optimal positioning ( aesop ; computer motion inc .
, santa barbara , ca , usa ) in two cases and the da vinci system in two cases .
the aesop technology has advantages for the transmitral approach but requires a long instrument with a limited view , which makes the performance of this delicate procedure more difficult .
in addition to the well - known cosmetic advantages of minimally invasive approaches , the flexible joints and three - dimensional scope of the da vinci system allow for insertion inside the left ventricle below the plane of the mitral valve , which enables precise inspection of the submitral apparatus and a better view for determining the amount of septum that should be removed than is obtained using the transaortic approach . in summary , minimally invasive transmitral septal myectomy is a good surgical option for mitral repair in selected cases as an alternative to the conventional transaortic approach , because it can provide not only cosmetic advantages but also better visibility of the subvalvular apparatus and easier extension with good results .
 a 43-year - old man with symptomatic hypertrophic obstructive cardiomyopathy ( hocm ) was admitted to our hospital with aggravated exertional dyspnea and successfully treated with robotic transmitral septal myectomy . 
 minimally invasive transmitral septal myectomy may be a feasible surgical option for the treatment of hocm in selected cases as an alternative to transaortic myectomy . 
CASE REPORT
DISCUSSION