Three-Dimensional Heart Modeling of Hypertrophic Obstructive Cardiomyopathy for In Situ Patient-Specific Simulation to Optimize Septal Myectomy

Abstract

Objective: Hypertrophic obstructive cardiomyopathy (HOCM) develops in at least 1 out of 715 young adults. Patients who are refractory to medical therapy qualify for septal myectomy. Due to anatomy, serious complications such as ventricular septal defect and heart block may occur. Establishing cardiovascular magnetic resonance (CMR)-based 3-dimensional (3D) models as part of preoperative planning and training has the potential to decrease procedure-related complications and improve results.

Methods: CMR images were used to segment cardiac structures. Left ventricular wall thickness was calculated and projected on top of the in silico model. A 3D model was printed with a red layer indicating a wall thickness exceeding 15 mm and used for preoperative resection planning and patient counseling. To provide preoperative patient-specific in situ simulation, the planned resection volume was replaced with silicone in a second model. For perioperative quality control, resected silicone was compared with resected myocardial tissue. The impact of the models was evaluated descriptively through consultation of both the cardiothoracic surgeon and patients and through patient outcomes.

Results: Three-dimensional in silico and 3D-printed heart models of 5 patients were established preoperatively. Since the introduction of the models in October 2020, the surgeon feels better prepared, more confident, and less difficulty with making decisions. In addition, patients feel better informed preoperatively.

Conclusions: Using 3D heart models optimized preoperative planning and training, intraoperative quality control, and patient consultation. Reduction of procedure-related complications and clinical outcome should be studied in larger cohorts.

Keywords: 3D printing; Morrow procedure; in situ simulation; magnetic resonance imaging; simulation-based training; virtual surgical planning.

Visual abstract

Fig. 1.

Cross section of a heart with hypertrophic obstructive cardiomyopathy (HOCM) with reduced left ventricular outflow and mitral regurgitation (left). The dotted line represents the incision line for a transaortic septal myectomy (inset) and restoration of outflow after resection of the left basal ventricular septal wall (right). From N Engl J Med, Nishimura RA and Holmes DR Jr, Hypertrophic Obstructive Cardiomyopathy, volume 350, pages 1320–1327, Copyright ©2004 Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.

Fig. 2.

In silico heart model with a color map representing the left ventricle myocardium thickness in millimeters. The right ventricle is visualized in transparent blue, the proximal ascending aorta and left ventricular outflow tract are in transparent red, and the origin of the left coronary artery and right coronary artery are in red and blue, respectively. Arrows in complementary colors point toward these structures.

Fig. 3.

A 3-dimensional–printed heart model in 2 different views. The red color represents the left ventricle with a wall thickness exceeding 15 mm. Black arrows indicate the left ventricular outflow tract obstruction.

Fig. 4.

(a) (b) The 3-dimensional–printed mold of the ascending aorta, left ventricular outflow tract, coronary arteries, and part of the interventricular septum. Black arrows indicate the position where the mold is opened. (c) Casting material after removal of the mold. (d) Training model consisting of a nonflexible polylactic acid part and a flexible silicon part (red) from a surgical view. (e) Nonsurgical side view of the left ventricle.

Fig. 5.

In situ preoperative training of septal myectomy with surgical blade 11 and forceps through simulated transaortic access.

Fig. 6.

Intraoperative comparison of the resected myocardial tissue (black arrow) to the preoperatively resected model (red arrow). The resected myocardial tissue consists of 2 components, which visualizes the decision of the surgeon to extend the initial excision, partially based on the intraoperative comparison.

Fig. 7.

Preoperative NYHA class, NYHA class during follow-up, and the difference in NYHA class. Green values indicate a decrease in NYHA class following surgery. The † symbol indicates the patient is deceased. NYHA, New York Heart Association.