Extended septal myectomy using a combined trans-aortic and apical approach for long basal and mid-cavity hypertrophic cardiomyopathy

Abstract

Surgical septal myectomy is the treatment of choice for patients of hypertrophic cardiomyopathy who are symptomatic despite maximal medical therapy. Residual obstruction results in the persistence of symptoms and poorer outcomes. The length (depth) of the septum excised as far towards the apex is important. A combined approach of trans-aortic and trans-apical is needed to achieve this in specific cases with associated mid-cavity obstruction. We present a case of a complex long-segment septal hypertrophy which underwent a successful septal reduction using a combined trans-aortic and trans-apical approach.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-022-01377-4.

Introduction

Hypertrophic cardiomyopathy (HCM), once described as ‘tumours of the heart’ by Teare, is a genetic myocardial disease wherein the left ventricular muscle hypertrophies in the absence of other causes [1]. HCM may be obstructive or non-obstructive. The clinical presentation may vary from asymptomatic to sudden death. Septal myectomy is the procedure of choice in symptomatic patients with obstructive HCM refractory to medical therapy.

Recurrent symptoms after myectomy are usually due to the residual gradients at the left ventricular outflow tract (LVOT) or mid-ventricular obstruction (MVO) [2]. The spectra of cases involving obstruction at multiple levels are the ones that pose a surgical challenge. A combined trans-aortic and trans-apical approach eliminates this and achieves better long-term outcomes [2]. We describe one such case successfully corrected by the combined approach.

Case report

A 62-year-old gentleman, known case of hypertrophic cardiomyopathy with insignificant family history, presented to us with progressively worsening dyspnoea on exertion and two episodes of syncope over the last 3 years in spite of maximal medical therapy with beta-blockers and calcium channel blockers. Transthoracic echocardiography (TTE) confirmed the diagnosis with a resting LVOT gradient of 56 mm Hg. Cardiac magnetic resonance imaging (CMRI) was performed and confirmed the findings of hypertrophic cardiomyopathy with asymmetrical septal hypertrophy with a septal thickness of 25 mm (Fig. 1a). CMRI was also suggestive of a MVO; hence, we were prepared for an additional apical approach, if the need arose.

Fig. 1.

a Cardiac magnetic resonance imaging (CMRI) showing the complex long-segment hypertrophic cardiomyopathy. b Intra-operative trans-oesophageal echocardiogram picture demonstrating the left ventricular outflow tract obstruction (yellow arrow) and the associated systolic anterior motion of the anterior mitral leaflet (pink arrow). c Intra-operative trans-oesophageal echocardiogram demonstrating the turbulence in the left ventricular outflow tract with associated mitral regurgitation. d Intra-cavitary aortic (red font) and left ventricular(yellow font) gradients measured during the surgery

Operative technique

The patient was taken up for trans-aortic extended septal myectomy. Intra-operative trans-esophageal echocardiography (TEE) confirmed the TTE findings (Fig. 1b, c). There was an associated systolic anterior motion (SAM) of the anterior mitral leaflet leading to moderate mitral regurgitation (Fig. 1c). On table, intra-cavity measurement showed a gradient of 44 mm Hg (Fig. 1d). After we induced a premature ventricular ectopic, the measured gradient was 66 mm Hg. Cardiopulmonary bypass (CPB) was instituted and the aorta cross clamped. Oblique aortotomy was made extending down to the non-coronary sinus, cardioplegia was administered and the heart was arrested. The sub-aortic hypertrophied interventricular septum was exposed well with three commissural sutures. Cardiotomy suction was put across the aortic valve and the anterior leaflet of the mitral valve was pushed towards the surgeon. The contact lesion was identified. Septal myectomy was carried out as described by Schaff et al. involving two cuts [3]. The ‘first’ cut was made starting at the base of the right aortic leaflet just below the nadir and to the left of the right ostia, which was extended distally and to the left (Fig. 2a, b). The anterior wall of the left ventricle was depressed to expose the septum better. Another ‘second’ cut was made beyond the endocardial scar towards the apex of the heart after exposing the septum by depressing the anterior wall of the left ventricle using sponge forceps (Fig. 2c, d). The limit on the left side was just to the right of a line drawn down from the left ostia. Care should be taken not to injure the mitral and aortic leaflets and also not to get the excision very close to the insertion of the aortic leaflets. The removed muscle mass was the size of the thumb. The perfusionist was asked to fill the right heart to see if any dark blood comes out suggesting a septal perforation. The left ventricle was flushed thoroughly with saline to remove any muscle debris. Aortotomy was closed and the patient separated from CPB but not decannulated. The adequacy of resection was measured by intra-cavitary pressures and TEE. Post-CPB, TEE demonstrated a significant residual mid-cavity obstruction with a gradient of 38 mm Hg, which was nearly the same when measured by a direct intra-cavitary needle (Video 1). Hence, as initially planned, we decided to reinstitute CPB and proceeded to perform a trans-apical myectomy to relieve the MVO to achieve completeness. The left ventricular apex was brought anteriorly using two sponge pads. Apical ventriculotomy was performed lateral to the left anterior descending artery (LAD) in the bare area as described by the Mayo Clinic group in their publications by Kotkar et al. and Nguyen et al. [4, 5]. Care was taken to make the incision small and extended little by little to achieve exposure such that the length of the incision was kept as minimal as possible (Fig. 3a). The interventricular septum was exposed and myectomy was carried out from below making sure that the mitral valve and its sub-valvular apparatus were protected. The resection was carried out as a tunnel to meet the cut made from above (Fig. 3b). Pituitary rongeur was used to nibble as much as possible after completing the cut. No anomalous hypertrophied papillary muscles or anomalous insertions were noted. After presumably satisfactory resection as by visual inspection, ventriculotomy was closed in two continuous layers with Teflon felt strips in place (Fig. 3c). The patient was weaned off CPB in sinus rhythm.

Fig. 2.

a Intra-operative image showing the first cut being made. b Graphic representation demonstrating the first cut being made (reprinted from [3]). c Intra-operative image showing the second cut with the anterior wall of the left ventricle depressed using a ‘swab on a stick’ (black arrow). d Graphic representation demonstrating the first cut being made (reprinted from [6])

Fig. 3.

a Intra-operative image showing the trans-apical approach. b Graphic representation of the combined approach to respective portions of the hypertrophied septum. c Intra-operative image showing the left apical ventriculotomy closed with Teflon felts on either side. d Intra-operation; post bypass measurement of the intra-cavitary gradients. Aortic gradient (red font) and ventricular gradient (yellow font)

TEE demonstrated an enlarged left ventricular cavity with no significant turbulence across the LVOT, no SAM and no residual mitral regurgitation. Intra-cavitary pressures measured confirmed a gradient of 2 mm Hg in the mid-ventricle with no significant gradient across the LVOT (Fig. 3d). The patient was extubated after 5 h in the intensive care unit (ICU) and discharged home on post-operative day (POD)-5. Histopathological examination of the excised septum confirmed the presence of hypertrophied cardiomyocytes. The patient is in New York Heart Association (NYHA) -1 at 15-month follow-up and doing well.

Discussion

Teare in 1958 had first given a detailed review in an autopsy case series of 8 patients with a ‘tumour’ of the heart and its autosomal dominant genetic predisposition [1]. These were later described as hypertrophic cardiomyopathy. In the surgical context—hypertrophic cardiomyopathy is sub-classified as (a) sub-aortic, (b) mid-ventricular and (c) apical [5]. Septal myectomy is indicated in patients with NYHA – III/IV symptoms despite maximum medical management; as in our case. The majority of the patients with HCM have only an outflow obstruction and the surgical treatment consists of sub-aortic myectomy.

The goal of the surgical reduction is to reduce the anatomical resistance for left ventricular ejection, and improve the left ventricular end-diastolic volume (LVEDV) which in turn improves the diastolic dysfunction and also stroke volume.

Schaff et al. have described the well-practised trans-aortic septal myectomy [3]. However, in cases where there is a combined obstruction or combined long-segment hypertrophy or diffuse septal hypertrophy, a combined approach will be required [5–7]. Messmer has described techniques for extended septal myectomy, wherein there are abnormal or hypertrophied papillary muscles, which were not seen in our case [8]. Schaff et al. first described the outcomes of apical myectomy [9]. It is of utmost importance to ensure haemodynamic improvement inside the operation theatre. Only a haemodynamic improvement will be accompanied by symptomatic benefit [9]. There must not be any significant residual obstruction at any level—mitral valve, apical, mid-ventricular or outflow/sub-aortic, lest the patient’s symptoms will persist. Repeat obstruction in the LVOT is uncommon after a trans-aortic septal reduction procedure. If a ‘recurrence’ does occur, it is usually due to limited or incomplete myectomy during the first sitting; wherein the myectomy excision was not extended far enough towards the apex. Some of the other causes of recurrence of LVOT obstruction include (a) mid-ventricular level obstruction which was not addressed, (b) presence of diffuse septal hypertrophy and c) presence of anomalous or hypertrophied papillary muscles.

After the initial CPB run, our patient had a residual obstruction at the mid-ventricular level, as evident by the TEE and by intra-cavitary pressures, which was the reason for residual gradients (Video 1). The urge to just relieve the outflow obstruction and ‘get out’ should be restricted. These residual MVO cannot be addressed effectively by other procedures such as alcohol septal ablation [2]. The importance of haemodynamic parameters and intra-operative TEE imaging cannot be emphasised. After the initial surgical resection, the TEE and provocative testing did show significant residual gradients at the level of the mid-ventricle, and hence, we proceeded for the second run of CPB, as planned.

In the study by Hang et al., ~ 16% of the patients had a second run of the bypass as a result of residual MVO which was identified after the initial procedure [2]. In our case also, the MVO was evident only after the outflow tract hypertrophied muscle was resected, which unmasked the mid-ventricular obstruction, making it more pronounced and evident. This residual obstruction has to be addressed by other approaches else the purpose of surgery remains defeated [10]. ~ 22% of patients needed multiple bypass periods to achieve completeness of the procedure [2].

Another approach to reach the MVO is a trans-apical approach [7, 9, 10]. The trans-apical approach, which involves an apical ventriculotomy, does produce a small area of hypokinesia/akinesia; however, this small area does not lead to left ventricular systolic dysfunction. Possible complications of an apical incision such as mild hypokinesia, ventricular arrhythmias and bleeding should not shy the surgeon from the complete treatment of the underlying residual surgical problem [2, 7, 9]. Multiple literatures recommend the use of a combined trans-apical and trans-aortic approach to these kinds of cases, wherein there are obstructions at different levels (Fig. 3b) [4, 10]. Untreated MVO is associated with persistence of symptoms, reduced survival, increased need for reoperation and also the persistent risk of sudden cardiac death [2, 10]. Hence, we decided to proceed with a second run for the CPB. Mayo Clinic group has explained the steps in detail [2, 4–7, 9, 10]. Trans-apical resection is often guided by visual inspection of the remaining cavity after adequate muscle resection. After the second run on CPB, and presumably adequate resection, we were able to get acceptable residual gradients (in single digits) by echo and intra-cavitary measurements with no SAM suggesting completeness (Fig. 3d). Some surgeons prefer to use the trans-mitral approach to access the mid-ventricular obstruction; however, this involves taking down the anterior mitral leaflet and reconstructing it later, which risks mitral regurgitation.

There are certain patients with predominantly outflow HCM who appear to have obstruction at MVO and apical level as well, which are responsible for the symptoms of the patient. It is often difficult to identify patients with MVO before relieving the sub-aortic obstruction [2]. A second run on the CPB is not associated with worsened outcomes and it should not shy the surgeon away [2]. Hang et al. and Kotkar et al. suggest using the combined approach—trans-aortic and trans-apical, during the initial procedure itself [2, 4]. Pre-operative 3D models may also help in operative planning. Multiple articles quote a good 1-year survival of ~ 95% with combined approaches [2]. The excision of the hypertrophied muscle in all three dimensions of length, depth and width is the key to preventing residual obstruction. It offers a complete and long-lasting treatment for complex long-segment HCM.

Conclusion

Symptomatic hypertrophic cardiomyopathy refractory to medical management needs surgical septal myectomy. Complete resection to achieve close to zero gradients is the key to good outcomes. Intra-operative TEE and invasive measurements are important to assess adequate resection. Every effort should be made to achieve this by adopting a combined approach for a good outcome. Diligent know-how of the myriad levels of obstruction and judicious utilisation of the available combined approaches to tackle these multiple levels is the key to a successful outcome.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

None.

Declarations

Ethics committee approval

Not required as per institutional policy for case reports.

Informed consent

Informed consent was obtained from the patient.

Conflict of interest

The authors declare that there is no conflict of interest.

Statement of human and animal rights

This case included no experiments on human or animal subjects.