Transmitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic Cardiomyopathy: Preadolescence, Mitral Valve Disease, and Midventricular Obstruction

Septal myectomy is indicated in patients with obstructive hypertrophic cardiomyopathy (HCM) who have persistent symptoms despite medical therapy, intolerance of medication side effects, or severe resting or provocable gradients. Septal myectomy at high volume centers is safe, with low operative mortality (1%) and low rates of complications such as complete heart block or ventricular septal defect (3% and 0.5%, respectively). Additionally, improved survival following myectomy has been observed when compared to patients with obstructive HCM managed medically or those with nonobstructive HCM. As a longstanding, quaternary referral center for septal myectomy, our institution has built significant experience and expertise in the surgical and medical management of HCM, including atypical HCM, defined as preadolescent patients, those with mitral valve disease, and those with isolated midventricular obstruction. The most important factor of septal myectomy in achieving complete resolution of obstruction and avoiding recurrence is the apical extent of the myectomy trough, which must extend to the septum opposite the papillary muscles. If this cannot be fully achieved via a transaortic exposure, especially in preadolescents and patients with midventricular obstruction, then a transapical approach may be needed. Mitral valve repair is rarely necessary as SAM-mediated MR resolves with adequate myectomy alone, but mitral repair is performed in cases of intrinsic valvular disease. In this manuscript we provide a summary of current operative techniques and outcomes data from our institution on the management of these various categories of HCM.

Management of the mitral valve in thoracoscopic trans-mitral myectomy for hypertrophic obstructive cardiomyopathy

Objective

This study aimed to compare clinical outcomes of different mitral valve (MV) management methods in thoracoscopic transmitral myectomy (TTM) and guide surgeons' decision making for hypertrophic obstructive cardiomyopathy (HOCM).

Methods

Seventy-three consecutive patients (41 females; mean age, 53.7 ± 13.6 years) with HOCM who underwent TTM between January 2019 and October 2022 were enrolled and divided into 3 groups according to MV surgical strategy. Clinical outcomes were analyzed and compared among the groups.

Results

None of the patients experienced postoperative residual left ventricular outflow tract obstruction. Percentages of patients with mitral regurgitation (MR) grade ≥3+ (57.5% vs 1.4%) and systolic anterior motion (95.9% vs 2.7%) were significantly decreased postoperatively (P < .001 for both). The preoperative anterior mitral leaflet length was longer in patients in the anterior mitral leaflet direct reattachment group (median, 2.9 cm [interquartile range (IQR), 2.7-3.3 cm] vs 2.7 [IQR, 2.4-2.9 cm]; P = .018), but the postoperative coaptation length was shorter (mean, 8.3 ± 2.1 mm vs 11.1 ± 3.8 mm; P = .038). After a median echocardiography follow-up of 11.8 months, the left ventricular outflow tract gradient (LVOTG) and mitral regurgitation grades remained significantly improved in all 3 groups (P < .05 for all).

Conclusions

Total TTM in selected patients is safe and effective, and all 3 MV management strategies can significantly reduce the LVOTG while improving MR. Mitral valvuloplasty is the preferred initial management strategy over valve replacement except in the scenario of irreparable intrinsic MV disease and valvuloplasty failure.

Review of Contemporary Invasive Treatment Approaches and Critical Appraisal of Guidelines on Hypertrophic Obstructive Cardiomyopathy: State-of-the-Art Review

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is a heterogeneous disease with different clinical presentations, albeit producing similar dismal long-term outcomes if left untreated. Several approaches are available for the treatment of HOCM; e.g., alcohol septal ablation (ASA) and surgical myectomy (SM). The objectives of the current review were to (1) discuss the place of the standard invasive treatment modalities (ASA and SM) for HOCM; (2) summarize and compare novel techniques for the management of HOCM; (3) analyze current guidelines addressing HOCM management; and (4) offer suggestions for the treatment of complex HOCM presentations.

METHODS

We searched the literature and attempted to gather the most relevant and impactful available evidence on ASA, SM, and other invasive means of treatment of HOCM. The literature search yielded thousands of results, and 103 significant publications were ultimately included.

RESULTS

We critically analyzed available guidelines and provided context in the setting of patient selection for standard and novel treatment modalities. This review offers the most comprehensive analysis to-date of available invasive treatments for HOCM. These include the standard treatments, SM and ASA, as well as novel treatments such as dual-chamber pacing and radiofrequency catheter ablation. We also account for complex pathoanatomic presentations and current guidelines to offer suggestions for tailored care of patients with HOCM. Finally, we consider promising future therapies for HOCM.

CONCLUSIONS

HOCM is a heterogeneous disease associated with poor outcomes if left untreated. Several strategies for treatment of HOCM are available but patient selection for the procedure is crucial.

Transaortic Shallow Septal Myectomy and Cutting of Secondary Fibrotic Mitral Valve Chordae—A 5-Year Single-Center Experience in the Treatment of Hypertrophic Obstructive Cardiomyopathy

Background: Anomalies of the mitral apparatus have been shown to contribute to left ventricular outflow obstruction in patients with hypertrophic cardiomyopathy (HCM). We report our 5-year single-center experience with a shallow myectomy procedure associated with transaortic mitral valve repair in a cohort of HCM patients. Methods: We studied 83 consecutive patients who underwent surgical treatment of symptomatic left ventricular outflow obstruction. In all study patients, a transaortic shallow septal myectomy was performed. Fibrous or muscular structures connecting the papillary muscles to the septum or free wall were resected, and fibrotic secondary chordae of the anterior mitral valve were cut selectively. Results: We report one death (1.2%) during hospitalization, no iatrogenic ventricular septal defects, and two (2.4%) mitral valve replacements. At discharge, no patients were in New York Heart Association (NYHA) Class III/IV, from 49 (59%) preoperatively. Mean maximal septal thickness decreased from 24 ± 6 to 16 ± 3 mm. Mean outflow gradient decreased from 93 ± 33 to 13 ± 11 mmHg. Grade 3 or 4 mitral regurgitation was noticed in one patient postoperatively, from 32 (39%) before surgery. Conclusions: Shallow septal myectomy associated with secondary mitral valve chordal cutting and papillary muscle mobilization provided excellent results offering adequate treatment of outflow obstruction.

Minimally invasive right infra-axillary thoracotomy for transaortic septal myectomy

Extended left ventricular septal myectomy remains the gold standard for the treatment of hypertrophic obstructive cardiomyopathy (HOCM) with refractory symptoms. On the basis of traditional modified transaortic Morrow myectomy, we innovatively performed a minimally invasive, video-assisted single-port thoracotomy through the right infra-axillary region. Our procedure can provide good visualization of the left ventricular outflow tract and hypertrophic ventricular septum for accurate resection. It also ensures optimal exposure of the mitral valve in the presence of complex mitral subvalvular structures.

Thoracoscopic Trans-mitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy in the Elderly

Background

The thoracoscopic trans-mitral approach can not only facilitate exposure of the ventricular septum, mitral valve, and subvalvular apparatus, it also enables the surgeons to perform concomitant mitral valve intervention. This study aimed to determine the safety and efficacy of thoracoscopic trans-mitral septal myectomy in elderly patients with hypertrophic obstructive cardiomyopathy (HOCM).

Methods

We reviewed the demographic to clinical characteristics and outcomes of patients who underwent thoracoscopic trans-mitral septal myectomy in our center between April 2019 and April 2021. The population was divided into a younger group (<60 years) and an elderly group (≥60 years).

Results

There were 46 and 20 patients in the younger and elderly groups, respectively. The majority of patients in the elderly group were female (39.1 vs. 80.0%, P < 0.01). Patients in the elderly group were more likely to be in New York Heart Association Class IV (2.2 vs. 80.0%, P < 0.01). The European System for Cardiac Operation Risk Evaluation II predicted mortality rates were significantly higher (3.97 ± 1.81 vs. 1.62 ± 0.86%, P < 0.01) in the elderly group. In the elderly group, a patient converted to median sternotomy due to left ventricular posterior free wall rupture following septal myectomy and mitral bioprosthetic valve replacement. The patient then underwent double-patch sandwich repair for rupture and mitral mechanical valve replacement and was eventually discharged. All patients in the elderly group were discharged, while one in the younger group died. No patient in the elderly group required permanent pacemaker implantation vs. one in the younger group. Patients in the elderly group were more likely to spend more time in the intensive care unit than those in the younger group (5.44 ± 5.80 days vs. 3.07 ± 2.72, P < 0.05). However, there was no significant intergroup difference in in-hospital mortality or complications. Importantly, the left ventricular outflow tract pressure gradient was significantly decreased from 96.15 ± 32.89 mmHg to 8.2 ± 3.42 mmHg with no residual obstruction in the elderly group. The interventricular septal thickness was significantly decreased from 19.73 ± 3.14 mm to 11.30 ± 2.23 mm. Postoperative mitral regurgitation severity was significantly improved in the elderly group.

Conclusion

This study demonstrated that thoracoscopic trans-mitral septal myectomy is a feasible option for selected elderly patients with satisfactory outcomes similar to those of young patients.

[Surgical approaches to interventricular septum in hypertrophic cardiomyopathy]

Hypertrophic cardiomyopathy (HCM) is a hereditary myocardial disease characterized by ventricular wall and interventricular septum thickening not associated with heart valve disease or any other external cause. Considering different localization of left ventricular obstruction, surgeons should be aware of various surgical approaches to various segments of interventricular septum. A personalized approach to each patient is essential to achieve favorable postoperative effect with minimal incidence of complications. This review is devoted to various surgical approaches to interventricular septum for different phenotypic variants of HCM.

Enlargement of left ventricular outflow tract using an autologous pericardial patch for anterior mitral valve leaflet and septal myectomy through trans-mitral approach for the treatment of hypertrophic obstructive cardiomyopathy

OBJECTIVE

Modified Morrow procedure is the gold standard of surgical intervention for hypertrophic obstructive cardiomyopathy (HOCM). However, there are certain cases without complete relief of obstruction through trans-aortic approach, we, therefore, described an unusual technique. We aimed to retrospectively analyze this series of patients to reveal its safety and efficiency.

METHODS

We retrospectively analyzed a total of 247 consecutive HOCM patients in our center from January 2016 to December 2019. Sixteen of them who underwent enlargement of left ventricular outflow tract (LVOT) using an autologous pericardial patch for anterior mitral valve leaflet and septal myectomy through trans-mitral approach were recruited in this study. Baseline characteristics, perioperative data, and the outcomes were studied.

RESULTS

Of the 16 patients, there was no operative mortality. No permanent pacemaker implantation and ventricular septal defects formation were observed. The peak pressure gradient of LVOT decreased from 97.56 ± 23.81 mmHg to 7.56 ± 2.13 mmHg (p < .01) after operation and 10.19 ± 2.93 mmHg (p < .01) 3 months later. The average septal thickness decreased from 18.38 ± 3.56 mm to 10.00 ± 2.74 mm (p < .01). During a mean follow-up of 34.25 ± 12.85 months (range, 15-57), no patient required cardiac reoperation. At the last follow up, the mean peak pressure gradient of LVOT was 10.12 ± 2.03 mmHg and no patient had more than moderate mitral regurgitation.

CONCLUSION

Enlargement of LVOT using an autologous pericardial patch for anterior mitral valve leaflet and septal myectomy through trans-mitral approach is feasible and reliable for the treatment of certain types of HOCM cases.

Videoscope-assisted transaortic myectomy in patients with hypertrophic cardiomyopathy with complex left ventricular anatomy

BACKGROUND

The transaortic approach is the most common method of septal myectomy. However, difficulties arise due to a limited view of the surgical field. Here, we report our experience with videoscope-assisted transaortic myectomy.

METHODS

We reviewed myectomy operations that were performed between July 2015 and June 2019 at Chung-Ang University Hospital, Seoul, South Korea. Patients who previously had cardiac surgery, alcohol septal ablation, or concomitant disease which required combined surgery, were excluded. Among the 21 patients included, 10 patients underwent videoscope-assisted transaortic myectomy (VA group), and 11 patients underwent myectomy in a conventional manner (CO group). The preoperative data, echocardiographic images, operative records, and postoperative outcomes of these patients were reviewed.

RESULTS

There were no differences in baseline characteristics between groups VA and CO. The main indications for videoscope-assisted transaortic myectomy in group VA were midventricular septal muscle resection (70%), abnormal papillary muscle resection (40%), and abnormal chordal connection resection (30%). Eight (80%) patients had multiple indications for videoscope-assisted transaortic myectomy. There was no surgical mortality in either group. Postoperative patients showed less than moderate mitral regurgitation and a New York Heart Association class either III or IV. There were no differences in hospital days (9.5 vs. 12.0 days; p = .383), nor postoperative pressure gradient (14 vs. 15 mmHg; p > .99).

CONCLUSIONS

Videoscope-assisted transaortic myectomy is an effective surgical technique in selective hypertrophic cardiomyopathy patients with complex intraventricular anatomy, diffuse hypertrophy, and midventricular obstruction.

"Do alternative approaches work in surgical septal myectomy?"

Trans-aortic septal myectomy is the gold standard for septal reduction therapy. This technique has low peri-procedural mortality and excellent long-term survival. Moreover, it relieves the heart failure symptoms and improves the quality of life. Secondary chordal cutting along with septal myectomy has shown to improve the outcome but can potentially cause deterioration of left ventricular function. In patients with relatively thin inter-ventricular septum, abnormalities of mitral valve apparatus may be the main reason for systolic anterior motion and left ventricular outflow tract obstruction. These patients may require additional procedures on the mitral valve to shift the coaptation plane away from outflow tract. Mitral valve replacement should be performed only in patients with intrinsic mitral valve abnormalities that are not suitable for repair and its routine use along with limited septal myectomy should be discouraged. Minimal access surgery although attractive in concept requires more robust data before universal application.

Management of Subaortic Left Ventricular Outflow Tract Obstruction After Aortic Valve Replacement

BACKGROUND

Residual or new left ventricular outflow tract (LVOT) obstruction after an aortic valve replacement poses special challenges with respect to operative techniques. Our study assesses this gap.

METHODS

From January 1993 to May 2019, 18 patients underwent a septal myectomy at Mayo Clinic for subaortic obstruction after aortic valve replacement. We evaluated their demographics, clinical presentation, and echocardiograms, and the type of prior valve replacement, need for repeat replacement, and their short- and long-term outcomes. The data were analyzed using descriptive statistics.

RESULTS

All patients underwent septal myectomy for LVOT obstruction at a median interval of 7 years (interquartile range, 3-15 years) from their prior aortic valve procedure. Preoperatively, the median left ventricular outflow tract gradient was 57 mm Hg (interquartile range, 44-77 mm Hg); 10 patients (55.5%) had systolic anterior motion (SAM) of the mitral leaflets. Repeat replacement of the aortic valve at the time of myectomy was needed in 14 patients, and septal myectomy alone was performed in 4 patients. One hospital death occurred 34 days after myectomy and aortic valve replacement, and 2 patients needed permanent pacemaker placement for complete heart block.

CONCLUSIONS

Septal myectomy after aortic valve replacement may be performed with repeat replacement of the valve, if there is coexisting prosthetic dysfunction, through a normally functioning bioprosthesis or through an apical approach when visualization through the aortic prosthesis is poor. The complexity of reoperation supports a liberal approach to myectomy at the time of aortic valve replacement when there is significant subaortic septal hypertrophy.

Degenerative Mitral Valve Repair Simplified: An Evolution to Universal Artificial Cordal Repair

BACKGROUND

Resectional and artificial cordal repair techniques are effective strategies for degenerative mitral valve (MV) repair. However, resectional repair requires a tailored approach using various techniques, whereas cordal repair offers a simpler, easily reproducible repair. The approach described in this study approach has evolved from resectional to cordal over time, and outcomes are compared between the eras.

METHODS

Clinical and echocardiographic outcomes of all patients undergoing MV repair for degenerative mitral regurgitation (MR) from January 2004 to September 2017 were reviewed. Patients were stratified by era: from January 2004 to June 2011 (era 1; n = 405), resectional techniques were used in 62% and artificial cordal techniques were used in 38%. From July 2011 to September 2017 (era 2; n = 438), artificial cordal repair was used in 98% of patients. The primary outcome was repair failure, defined as greater than moderate MR or MV reoperation.

RESULTS

Of 847 patients with degenerative MR, successful repair was achieved in 843 patients (99.5% repair rate). Leaflet prolapse was posterior in 66%, anterior in 8%, and bileaflet in 26%. Cardiopulmonary bypass time and cross-clamp times were shorter in era 2 (CPB: 109 [IQR, 92-128] minutes vs 97 [IQR, 76-121] minutes; P < .001; cross-clamp: 88 [IQR, 73-106] minutes vs. 79 [IQR, 61-99] minutes; P < .001). Predismissal echocardiography demonstrated no MR or trace MR in 95%, mild MR in 4.7%, and moderate MR in 0.3% of patients. Operative mortality was similar in the eras (0.5% vs 0.5%; P > .999). The rates of 5-year freedom from repair failure (95.1% vs 95.5%; P = .707), stroke (96.8% vs 95.3%; P = .538), and endocarditis (99.3% vs 99.7%; P = .604) were similar between the eras.

CONCLUSIONS

Artificial cordal repair for all patients with degenerative MR simplifies MV repair and yields equivalent, excellent outcomes compared with a tailored resectional approach.

Robotic Septal Myectomy Without Anterior Leaflet Incision during Mitral Valve Repair

Bulging subaortic septum in hypertrophic cardiomyopathy is a potential risk factor for systolic anterior motion after mitral valve repair. Systolic anterior motion may cause postoperative mitral regurgitation and left ventricular outflow tract obstruction despite conservative management. During "minimally invasive endoscopic" and "robotic" mitral repair procedures, systolic anterior motion is prevented with concomitant septal myectomy through the mitral valve orifice. Technically, the exposure of the bulging subaortic septum is traditionally done with detachment of the anterior mitral leaflet from its annulus, leaving a 2-mm rim of leaflet attached to the annulus. The leaflet is then sutured after myectomy. As an alternative technique in robotic surgery, the exposure of the subaortic septum is feasible without anterior leaflet incision with the use of dynamic atrial retractor in mitral repair procedures. Here, we present a patient who underwent concomitant robotic mitral valve repair with posterior chordal implantation, ring annuloplasty, and septal myectomy without anterior leaflet incision using the da Vinci surgical system.