Corresponding author
Per Wierup, MD,
Department of Thoracic and Cardiovascular Surgery
Cleveland Clinic
9500 Euclid Avenue / Desk J4-1
Cleveland, OH 44195
Email: wierupp@ccf.org
ABSTRACT
Hypertrophic obstructive cardiomyopathy (HOCM) is one of the more common
genetic disorders. The pathophysiology and natural history of the
disease have been well studied. Left ventricular outflow tract (LVOT)
obstruction and systolic anterior motion (SAM) of the anterior mitral
leaflet can result in sudden cardiac death, progressive heart failure
and arrythmias. Surgical septal myectomy for HOCM is the standard of
care and is routinely performed through a median sternotomy. Septal
myectomy has also been performed using the trans-atrial, trans-mitral
approach either directly 1, 2 or with robotic
assistance 3, 4. In cases with severe LVOT obstruction
in the setting of only mild to moderate proximal septal hypertrophy,
intrinsic problems with the mitral valve contribute.5Typically, these are hypermobile papillary muscles and or excessive
height of the anterior mitral leaflet. Combining septal myectomy with
reorientation of hypermobile anteriorly positioned papillary muscles has
shown to prevent SAM and thereby additionally decrease the sub-valvular
aortic outflow obstruction.
Our extensive experience in both septal myectomy and robotic mitral
valve repair has given us a different perspective in approaching the
primary mitral regurgitation in HOCM patients where a combined septal
myectomy, papillary muscle reorientation and complex mitral valve repair
has been safely performed using the less invasive robotic-assisted
approach.
Our objective here is to discuss the technical aspects of the procedure.
SURGICAL TECHNIQUE
All patients undergo pre-operative CT angiography to rule out
aorto-iliac atherosclerosis in order to substantially decrease the risk
of stroke. Magnetic resonance imaging (MRI) assessment and multimodality
echo are used for the surgical planning of the myectomy and mitral valve
repair. After anesthesia, a trans-esophageal echocardiogram (TEE) is
done to assess the safety of a robotic approach as well as to provide an
accurate evaluation of the septal thickness in different areas. Routine
robotic mitral valve surgical setup was used for all the cases as
described by Gillinov and colleagues.6
After systemic heparinization, the femoral vein then artery are
cannulated. An additional right internal jugular vein cannula is added
according to the patient’s body surface are as required. Once
cardiopulmonary bypass (CPB) is instituted, both lungs are deflated. The
pericardium is then opened approximately 2-3 cm anterior to the right
phrenic nerve and tacked towards the chest wall. An antegrade
cardioplegia cannula is inserted and secured. A transthoracic aortic
cross-clamp is then inserted via a separate incision in the third or
fourth intercostal space laterally, and carefully placed along the
transverse sinus.
Once the aortic clamp is applied, del Nido crystalloid cardioplegia
solution is given. The robotic arms (DaVinci systems) are docked to the
ports.
The left atrium is incised. A left atrial retractor and cardiotomy
suction are inserted. The mitral valve is exposed (Figure 1). The
anterior mitral leaflet is incised superiorly a few millimeters away
from its annular attachment and detached from commissure to commissure
(Figures 2 and 3), and can be extended medially as required. This
exposes the interventricular septum and the undersurface of the aortic
valve (Figure 4). Septal Myectomy is performed using the robotic
scissors, while taking great care not to damage the aortic valve (Figure
5). The resection is wide, carried out across the area opposing both
fibrous trigones and extended towards the mid-cavitary portion,
resulting in a smooth and even interventricular septum. The amount of
resection is planned according to the pre-operative imaging from MRI and
TEE.
The anterior mitral leaflet is then reattached to its annulus using
continuous 4-0 polypropylene sutures, simultaneously reducing its height
(Figure 6). Any abnormally oriented hypermobile anterior papillary
muscle heads (Figure 7) are then re-oriented by fixing each to more
centrally located, posterior papillary muscle sub-heads (Figure 8) using
3-0 polyprolylene sutures with polytetrafluoroethylene (PTFE) felt
pledgets.
Typically, our surgical technique for mitral valve repair in
degenerative mitral regurgitation utilizes Gore-Tex CV-4 (W. L. Gore &
Associates, Flagstaff, Arizona) neo-chords, creating a more posteriorly
positioned zone of coaptation. This is achieved by purposely making
these neo-chords short, thereby moving the zone of coaptation well
posteriorly, in order to decrease the risk of SAM. In myectomy cases,
depending upon the LVOT and mitral valve, we sometimes complete the
repair with annuloplasty using an appropriately sized mitral
Medtronic Duran AnCore® Annuloplasty band System.
The left atrium is closed using Gore-Tex CV-4 after de-airing maneuvers.
We use carbon dioxide throughout the procedure routinely to help us in
de-airing the heart. A ventricular pacing wire is inserted onto the
right ventricle. The aortic cross-clamp is then removed. We come off CPB
initially with left lung ventilation to assess the LVOT gradients,
mitral valve, aortic valve and ventricular contractility. Once satisfied
with the result, we go back on CPB again to reinforce the left atrial
suture line with 4-0 Prolene. The robotic arms are then undocked and the
patient is finally successfully weaned off CPB.
DISCUSSION
The robotic assisted trans-mitral septal myectomy and papillary muscle
re-orientation for HOCM is less invasive compared to the sternotomy
procedure and can be safely performed when combined with complex mitral
valve repairs.
Trans-aortic septal myectomy is a safe and reproducible technique for
relief of LVOT obstructions due to HOCM. Done in expert hands the
results are outstanding.7 Maneuvers like papillary
muscle reorientation are done concomitantly through the trans-aortic
approach.8 This approach also gives excellent exposure
for mid-cavitary obstructions.9
Introduced by Dr. Chitwood, robotic assisted septal myectomy has proven
itself as an alternate approach for myectomies3, 4.
From our extensive experience in both robotic mitral repairs and
trans-aortic myectomies, we found it appealing to approach patients
needing both myectomies and primary mitral valve repairs robotically.
The visualization of the interventricular septum is more direct and
better magnified with the robotic assistance and the entire septum is
well visualized. The aortic valve is not touched and hence the potential
complications from a trans-aortic septal myectomy can be avoided. It is
also easy to identify the papillary muscle heads with the direct
maneuvering of the robotic camera and the retractor. The detachment of
the anterior mitral leaflet and its subsequent reattachment shortens the
very tall anterior leaflet which helps to prevent SAM. The ideal
candidate is a patient with a combination of HOCM and primary mitral
valve disease, which then both can be addressed robotically.
A longer robotic scissor would facilitate easier resection, and is a
potential minor limitation of this technique. We need to study
additional data on long-term outcomes in a larger cohort of patients.
Nevertheless, our technique is a safe, reproducible alternative approach
for a well-established procedure.
REFERENCES
- Gutermann H, Pettinari M, Van Kerrebroeck C et al. Myectomy and mitral
repair through the left atrium in hypertrophic obstructive
cardiomyopathy: the preferred approach for contemporary surgical
candidates? J Thorac Cardiovasc Surg. 2014; 147: 1833-1836
- Gilmanov D, Bevilacqua S, Solinas M et al. Minimally invasive septal
myectomy for the treatment of hypertrophic obstructive cardiomyopathy
and intrinsic mitral valve disease. Innovations
(Phila). 2015; 10: 106-113
- Khalpey Z, Korovin L, Chitwood WR Jr, Poston R. Robot-assisted septal
myectomy for hypertrophic cardiomyopathy with left ventricular outflow
tract obstruction. J Thorac Cardiovasc Surg.
2014;147(5):1708‐1709. doi:10.1016/j.jtcvs.2013.12.017
- Chitwood, WR. Robotic trans-atrial and trans-mitral ventricular septal
resection. Ann Cardiothorac Surg 2017;
6: 54–59.doi:10.21037/acs.2017.01.06
- Maron MS, Olivotto I, Harrigan C, Appelbaum E, Gibson CM, Lesser JR,
Haas TS, Udelson JE, Manning WJ, Maron BJ. Mitral valve abnormalities
identified by cardiovascular magnetic resonance represent a primary
phenotypic expression of hypertrophic cardiomyopathy.Circulation . 2011; 124:40–47.
- M.MarinCuartas, H. Javadikasgari, B. Pfannmueller, J. Seeburger, A.M. Gillinov, R.M. Suri, et
al. Mitral valve repair: robotic and other minimally invasive
approaches
Prog Cardiovasc Dis, 60 (2017), pp. 394-404
- Hodges K, Godoy Rivas C, Aguilera J, et al. Surgical management of
left ventricular outflow tract obstruction in a specialized
hypertrophic obstructive cardiomyopathy center. J Thorac
Cardiovasc Surg. 2019; 157(6):2289-2299.
- Kwon DH, Smedira NS, Thamilarasan M, et al. Characteristics and
surgical outcomes of symptomatic patients with hypertrophic
cardiomyopathy with abnormal papillary muscle morphology undergoing
papillary muscle reorientation. J Thorac Cardiovasc Surg . 2010;
140(2):317-24.
- Kunkala MR, Schaff HV, Nishimura RA, et al. Transapical Approach to
Myectomy for Midventricular Obstruction in Hypertrophic
Cardiomyopathy. Ann Thorac Surg . 2013; 96(2):564-570.