Analysis of 3-dimensional interventricular septum and abnormal muscle bundles models for septal myectomy.

OBJECTIVES: We compared the effectiveness of virtual 3-dimensional (3D) models with 2-dimensional (2D) transthoracic echocardiography (TTE) for evaluating the anatomy of the interventricular septum (IVS) and abnormal muscle bundles (AMBs) in planning septal myectomy (SM). METHODS: Between January 2017 and July 2020, 103 consecutive symptomatic patients with hypertrophic cardiomyopathy underwent 2D TTE and cardiovascular magnetic resonance imaging in 49 (47.6%) or computed tomography angiography in 54 (52.4%) patients with 3D IVS modelling for SM planning. We evaluated maximal IVS thickness and location, length and thickness of AMBs. RESULTS: The mean maximal IVS thickness by 2D TTE was 7.3 [standard deviation (SD) 4.8] mm less than that based on the 3D model analysis: 21.4 (SD 3.7) vs 28.6 (SD 5.5) mm, respectively (P < 0.001, 95% confidence interval 6.4-8.2). The planned volume of ideal SM was larger than that of performed SM: 26.2 (18.4-39.4) vs 10.3 (7.4-12.8) cm3, respectively (P < 0.001). The sensitivity and specificity of 2D TTE in diagnosing AMBs were 36.9% and 95%, and those of cardiovascular magnetic resonance and computed tomography angiography with 3D modelling were 97.1% and 100% for cardiovascular magnetic resonance and 98% and 100% for computed tomography angiography, respectively. AMBs occurred in 84 (81.6%) patients. No patient required mitral valve replacement. The 30-day mortality was 1 patient. There were 4 late non-cardiac deaths (3.9%) within 18.1 (standard error 1.32) months. CONCLUSIONS: Anatomical analysis of the IVS and AMBs based on their virtual 3D models is highly effective for SM planning.

Multimodal Multiparametric Three-dimensional Image Fusion in Coronary Artery Disease: Combining the Best of Two Worlds.

PURPOSE: To allow for comprehensive noninvasive diagnostics of coronary artery disease (CAD) by using three-dimensional (3D) image fusion of CT coronary angiography, CT-derived fractional flow reserve (CT FFR), whole-heart dynamic 3D cardiac MRI perfusion, and 3D cardiac MRI late gadolinium enhancement (LGE). MATERIALS AND METHODS: Seventeen patients (54 years ± 10 [standard deviation], one female) who underwent cardiac CT and cardiac MRI were included (combined subcohort of three prospective trials). Software facilitating multimodal 3D image fusion was developed. Postprocessing of CT data included segmentation of the coronary tree and heart contours, calculation of CT FFR values, and color coding of the coronary tree according to CT FFR. Postprocessing of cardiac MRI data included segmentation of the left ventricle (LV) in cardiac MRI perfusion and cardiac MRI LGE, co-registration of cardiac MRI to CT data, and projection of cardiac MRI perfusion and LGE values onto the high spatial resolution LV from CT. RESULTS: Image quality was rated as good to excellent (scores: 2.5-2.6; 3 = excellent). CT coronary angiography revealed significant stenoses in seven of 17 cases (41%). CT FFR was possible in 16 of 17 cases (94%) and showed pathologic flow in seven of 17 cases (41%), six of which coincided with cases revealing significant stenoses at CT coronary angiography. Cardiac MRI perfusion identified eight of 17 patients (47%) with hypoperfusion (ischemic burden of 17% ± 5). Cardiac MRI LGE showed myocardial scar in three of 17 cases (18%, scar burden of 7% ± 4). Conventional two-dimensional readout of CT coronary angiography and cardiac MRI resulted in eight of 17 cases (47%) with uncertain findings. Most of these divergent findings could be solved when adding information from CT FFR and 3D image fusion (six of eight, 75%). CONCLUSION: Multimodal 3D cardiac image fusion is feasible and may help with comprehensive noninvasive CAD diagnostics.Supplemental material is available for this article.© RSNA, 2020.

Early results of optimal septal myectomy using 3-dimensional printed models.

INTRODUCTION: The completeness of septal myectomy (SM) is the key to surgery of hypertrophic obstructive cardiomyopathy (HOCM), but its planning is still based on echocardiographic findings. The need to perform radical SM requires the development of new cardio-visualisation techniques for monitoring myectomy quality. AIM: To improve results in centres treating few patients with HOCM using a new method of optimal SM with the help of 3-dimensional models to achieve an 'ideal' interventricular septum (IVS) thickness of 10-11 mm. MATERIAL AND METHODS: Between 2017 and 2018, 30 patients underwent optimal SM after computed tomography angiography, creation of a virtual 3-dimensional model of the IVS, computer-aided mapping, virtual SM and 3-dimensional printing of models of the 'ideal' IVS and the fragment to be removed. RESULTS: Initial isolated extended SM (n = 29, 97%) was effective in 23/29 (79%) patients. Four non-fatal complications were observed. A permanent pacemaker was implanted in three patients. No patients required mitral valve replacement. The mean postoperative left ventricle (LV) resting systolic gradient was 7.5 ±4.4 mm Hg, and at the latest follow-up this value was 7.1 ±4.2 mm Hg. The average weight of the excised myocardium was 12.0 g (range: 5.8-22.5 g). At follow-up both volumetric and dimensional LV echocardiography parameters increased compared with preoperative values (p ≤ 0.007). CONCLUSIONS: The proposed optimal SM provides intraoperative monitoring of the shape and volume of the myocardium resected to achieve the 'ideal' IVS, true radicality and an increase in the volumetric and dimensional parameters of the LV.

Virtual and real septal myectomy using 3-dimensional printed models.

We present 2 cases of extended septal myectomy using low-cost 3-dimensional (3D) printed models of the interventricular septum with its fragment cut out mechanically or by initial 'virtual' myectomy. 3D prints exhibited excellent cardiac imaging and planning of the 'optimal' volume and shape of the resection, as well as intraoperative quality control of septal myectomy by filling a trough in the 3D-printed interventricular septum with excised myocardium.