Septal myectomy with a carbon dioxide laser for hypertrophic cardiomyopathy

Transthoracic echocardiography guided percutaneous laser ablation of the interventricular septum: A successful sheep model for septal thickness reduction and one year follow-up

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a common genetic cardiovascular disease, causing breathlessness, chest pain, syncope and sudden death. One-year outcome of echo-guided transthoracic percutaneous laser ablation (TPLA) of the sheep interventricular septum was studied as a novel treatment to reduce the septal thickness. It may partially address the limitations of surgical myectomy and alcohol septal ablation in terms of trauma, safety, and efficacy.

METHODS

Twelve healthy adult sheep were randomly categorized into two groups: with and without the laser application of TPLA of the interventricular septum (IVS) at the energy level of 5 W for 3 min. Echocardiography, electrocardiography (ECG), cardiac magnetic resonance (CMR), serological and pathological examinations were performed over a 12-month follow-up.

RESULTS

After the laser ablation all animals survived with normal cardiac function; No severe complications or bundle branch block were noted. The septal thickness (3.11 ± 1.14 vs. 8.40 ± 0.45 mm, p < 0.05), regional movement of ablated IVS and longitudinal strain significantly decreased when comparing the experimental and control groups. The Troponin I level was significantly elevated after the operation, which validated immediate cardiac coagulation necrosis. On cardiac magnetic resonance (CMR) imaging, the ablated myocardium showed significant fibrosis evidenced by late gadolinium enhancement. Pathological results revealed damaged ultra-structure of the ablated myocardium and development of fibrosis.

CONCLUSIONS

TPLA is a safe and effective minimally invasive method to reduce IVS thickness in the long term, making it a potential alternative for HOCM treatment.

Bimanual examination for septal myectomy for hypertrophic cardiomyopathy

OBJECTIVES

Left ventricular septal myectomy is the therapeutic 'gold standard' for patients with obstructive hypertrophic cardiomyopathy whose symptoms are refractory to medical therapy. We describe our initial clinical experience with a new surgical technique for septal myectomy utilizing the 'bimanual examination' in order to more reliably complete extended septal myectomy during cardioplegic arrest.

METHODS

The bimanual examination was performed by inspecting the interventricular septum with two fingers inserted through the aortotomy (left index finger) and a small right atriotomy (right index finger). From January 2012 to February 2014, septal myectomy was performed in 35 patients. The mean patient age was 59.6 ± 13.7, and 60% were men. Systolic anterior motion was present in 30 (86%) patients. Most patients (94%) had moderate to severe mitral regurgitation (mean 2.1 ± 0.9). Of these, 16 (46%) underwent a concomitant mitral procedure. A total of 12 (34%) consecutive patients had bimanual examination utilized during extended myectomy. Patients were grouped into a standard (n = 23) and bimanual group (n = 12).

RESULTS

There were no significant differences between groups with respect to age, gender or New York Heart Association class. No mortality occurred. The bimanual group demonstrated a trend towards a lower postoperative left ventricular outflow tract gradient, compared with the standard group (2.5 ± 5.7 vs 7.4 ± 8.8 mmHg, P = 0.07), without the need for repeat cardiopulmonary bypass for inadequate myectomy/residual systolic anterior motion in any patient. Among those without organic mitral disease, the completeness rate of septal myectomy, defined by the percentage of patients avoiding mitral replacement, with residual systolic anterior motion or left ventricular outflow tract gradient greater than 20 mmHg, was 73 and 90% in the standard and bimanual group, respectively.

CONCLUSIONS

Our early clinical experience of bimanual examination for septal myectomy has proved to be clinically valuable. This technique should be utilized in order to facilitate a determined and well-performed myectomy.

Spark erosion myectomy in hypertrophic obstructive cardiomyopathy

The design features of the cutting electrode and the electrical characteristics of a monopolar electrosurgical device were specially adapted for performing a septal myectomy in patients with hypertrophic obstructive cardiomyopathy. Both the cutting behavior and electrode design were found to facilitate myectomy.

Cardiovascular applications of laser technology

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrhythmias and/or laser diagnostics are directed at improving upon conventional non-laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy.