Right ventricle morphological and functional phenotypes in heart failure with reduced ejection fraction: from pathophysiology to prognostic significance

Background

Right ventricle (RV) remodeling is a marker of advanced disease and impaired prognosis in heart failure reduced ejection fraction (HFrEF) patients [1]. The assessment of RV remodeling is limited with standard echocardiography. Three-dimensional speckle-tracking echocardiography (3DSTE), with advanced post-processing, allows for RV shape and regional function assessment, potentially providing additional information [2].

Purpose

1) to describe global and regional RV shape and function in a HFrEF cohort of patients; 2) to define RV remodeling phenotypes according with pulmonary haemodynamics; 3) to test the prognostic significance of RV shape and functional parameters.

Methods

81 HFrEF patients were prospectively enrolled and followed-up (median time 760 days) for the composite end-point of death, heart failure hospitalization, heart transplant and left ventricular assist device implantation. They received standard 3DSTE evaluation, consisting of end-diastolic volume index (EDVi), end-systolic (ES) volume index (ESVi) and ejection fraction (EF) measurement via commercial software (TomTec Imaging Systems GmbH, Germany). Advanced post-processing provided RV free-wall and septal mean curvatures (Km) and minimum principal strain (MPS) [3] quantification. A subgroup of 40 subjects underwent right heart catheterization (RHC) and were classified in: group A – no pulmonary hypertension (PH) (n=15), group B – PH but normal pulmonary vascular resistance (PVR) (n=15) and group C – PH and increased PVR (n=10). Roc curves were used to identify RV parameters able to discriminate subjects belonging to group A. Prognostic significance of RV remodeling parameters was tested for the composite end-point.

Results

Patients who did receive RHC showed lower ES free-wall Km (0.052 vs 0.058 mm-1, p<0.01) and impaired RV EF (35.9 vs 40.9%, p=0.04) if compared to those who didn't. A progressive RV dilatation, global and regional dysfunction were observed according with the degree of pulmonary haemodynamic worsening (ES free-wall Km 0.054, 0.052, 0.044 mm-1, p<0.02 and free-wall MPS −23.1, −21.3, −19.2%, p<0.02, for groups A, B and C, respectively, Fig. 1). RV ESVi, ES free-wall Km, global and regional MPS showed a good ability to discriminate patients without PH (ES free-wall MPS Sensitivity=0.72, 1-Specificity=0.4, area under curve=0.71). At univariable Cox Regression, the presence of more than moderate mitral regurgitation (MR), RV EF <38% and free-wall MPS >−22.4% (threshold discriminating normal pulmonary hemodynamic) resulted statistically associated with prognosis (Fig. 2).

Conclusion

In HFrEF patients, RV remodeling is progressively associated with unfavourable pulmonary haemodynamic, with a free-wall negative remodeling (abnormal curvature) resulting in loss of systolic function. RV free-wall function is tightly associated with the development of PH. 3DSTE indexes of RV global and regional function showed prognostic significance together with MR coexistence.

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): IRCCS Policlinico San Donato is a clinical research hospital partially funded by the Italian Ministry of Health Figure 1. End-systolic MPS distributionFigure 2. Kaplan-Meier survival analysis

4D Flow analysis of intracavitary blood flow dynamics and energetics in the systemic right ventricle

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health

Background

The systemic position of a morphologically right ventricle (SRV) makes it vulnerable to fail, leading to high incidence of heart failure and cardiac death [1]. Understanding SRV intracavitary blood flow dynamics and energetics could improve patient risk stratification.

Purpose

Testing the potential of three-dimensional time-resolved phase contrast cardiac magnetic resonance (4D Flow) in quantifying SRV blood flow dynamics and energetics.

Methods

4D Flow prototype sequences were acquired on 3 patients (1 male, 2 females) with SRV in D-loop transposition of great arteries after atrial switch operation (D-TGA/ASO), 3 male patients with SRV in L-loop TGA (L-TGA) and healthy controls (2 males, 1 female).

Kinetic energy (KE), viscous energy loss (EL), dissipation index (DI) calculated as EL to KE ratio, and hemodynamics forces (HFs) resulting from pressure gradients, were computed for the D-TGA/ASO and L-TGA SRVs, and for the control left ventricles (LVs) and right ventricles (RVs). HFs were decomposed in inferior-anterior, septal-lateral and basal-apical components (HFIA, HFSL, HFBA, respectively)

Results

Figure 1 reports the time-course of HF components and the general features of the enrolled subjects.

In systole, all SRVs (Figure 1a-1b) presented a dominant HFIA and a minor HFSL, similarly to RVs (Figure 1c); however, HFSL had a positive peak, indicating septal contraction towards the SRV cavity, opposite to its normal motion. HFBA magnitude was similar to LVs (Figure 1d), suggesting that the shortening of the tricuspid anulus towards the apex is more pronounced than in RVs (Figure 1c).

Over the whole cardiac cycle, DI values were highest in D-TGA/ASO SVRs (0.40-0.55); in L-TGA SRVs, DI values (0.24-0.45) were comparable to healthy LVs (0.22-0.37) and RVs (0.23-0.36). This difference may be related to the fact that in DTGA/ASO the left atrium is functionally replaced by a pulmonary venous baffle, which lacks efficient contraction, as highlighted by the absence of a distinctive A-wave in the KE time-course (Figure 2a).

Due to the adaptation to systemic afterload, SRVs were hypertrophic (Figure 1a-1b), with indexed mass higher than normal RVs (Figure 1c), and presented reduced compliance to the diastolic filling, as suggested by increased KE E-wave slope in L-TGA (Figure 2b) compared to controls (Figure 2c-2d).

Conclusions

Intracavitary HFs in SRVs reveal a partial shift from a RV towards LV pattern. This occurs at the expenses of a higher energetic consumption in D-TGA/ASO than L-TGA, enlightening the crucial role of atrial contribution to impaired SRV diastolic filling. These findings corroborate the previous evidence that patients with D-TGA/ASO have abnormal decrease in stroke volume during exercise whereas L-TGA patients can reach values comparably to healthy controls [2].

A deep learning-based and fully automated pipeline for thoracic aorta geometric analysis and TEVAR planning from computed tomography

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Publich Health - Ricerca Corrente

Introduction

Thoracic endovascular aortic repair (TEVAR) represents a well-established alternative to open repair in selected patients. Its preoperative feasibility assessment and planning requires a computational tomography (CT)-based analysis of the geometric aortic features to identify an adequate proximal and distal landing zone (LZ) for endograft deployment. Yet, controversies persist on the definition and methods of measurement of specific geometric features of the LZs, including angulation and tortuosity, which are associated with an increased risk of postoperative endograft failure. In this respect, the development of a preoperative image processing method that provides an automatic and highly reproducible 3D identification of critical geometric features and specific anatomical landmarks, thus reducing the time and uncertainties related to manual segmentation, remains a largely unmet clinical need.

In this study, we developed and applied a fully automated pipeline embedding a convolutional neural network (CNN), which feeds on 3D CT images to automatically segment the thoracic aorta, recognize the relevant anatomical landmarks and LZs, and quantifies the geometry of the aortic arch in each proximal LZ s (i.e. 0 to 3).

Methods

Ninety  CT scans of healthy aortas were retrieved, being the study conceived as a proof of concept analysis. The thoracic aorta was manually segmented by five independent and expert operators. 72 scans with the corresponding ground truth segmentations were randomly selected and used to train the CNN, which was based on a 3D U-Net architecture. The other 18 scans were used to test the CNN-based segmentations. The fully automated pipeline was obtained by integrating the CNN, 3D geometry skeletonization, and processing of the aortic centerline and wall via computational geometry (Figure). The resulting metrics included aortic arch centerline radius of curvature, proximal landing zones (PLZs) maximum diameters, angulation and tortuosity calculated according to previously published work. These parameters were statistically analyzed to compare standard arches vs. arches with a common origin of the innominate and left carotid artery (CILCA), and the different landing zones in each arch type.

Results

The CNN segmentation yielded a mean Dice score of 0.94 with respect to manual ground truth segmentations. Standard arches were characterized by significantly larger radius of curvature (p = 0.002) and lower tortuosity in zone 3 (p = 0.004) vs. CILCA arches. For both standard and CILCA arches, comparisons among PLZs revealed statistically significant differences in maximum zone diameters (p < 0.0001), angulation (p < 0.0001) and tortuosity (p < 0.0001).

Conclusions

We developed a CNN-based automated pipeline for the automated, and reliable geometric quantification of standard and CILCA aortic arches. This tool has the potential to support TEVAR pre-procedural planning in a real clinical setting.

Abstract Figure. Automatic pipeline scheme

The value of 3D-speckle tracking longitudinal strain for the assessment of left ventricular function recovery in ischemic heart failure patients undergoing surgical remodeling:the RECOVERY-IN study

Background

Three-dimensional (3D) speckle-tracking echocardiography is largely employed to evaluate left ventricle (LV) morphology and function.

Purpose

To investigate LV function before and after surgical ventricular reconstruction (SVR) through the analysis of global (GLS) and segmental (SLS) longitudinal strain, and the derived mechanical dispersion (MD).

Methods

Twenty patients eligible for SVR, with previous LV remodelling and ischemic heart failure (HF), received 3D echocardiographic evaluation before SVR and at 6-months follow-up; 15 normal controls, matched by age and BSA, were enrolled. Standard off-line GLS analysis was performed with 4D LV-ANALYSIS©; advanced segmental analysis was accomplished automatically through in-house numerical post-processing.

Results

Before SVR, GLS deteriorated compared to normal subjects (−6.7% vs. −19.6%, P<0.0001) as confirmed by SLS at each LV segment basal, mid and apical level (P<0.0001); MD was higher than in controls (P<0.001) and markedly increased from basal to apical LV segment. After SVR, GLS significantly improved from −6.7% to −11.3% (P<0.0001). Analysis of variance showed that SLS recovery was higher in the basal region (7.25%) than in both mid (4.06%, P=0.001) and apical (1.92%, P<0.0001) segments, respectively, with adjustment for baseline values.

Conclusions

After SVR, LV longitudinal strain mostly improves in the basal segments, outlining the role of the remote myocardium in enhancing LV function through an extensive volume reduction; post-surgical MD reduction indicates a more homogeneous myocardial contraction.

Heath map of longitudinal strain (%)

Funding Acknowledgement

Type of funding source: Private hospital(s). Main funding source(s): IRCCS Policlinico San Donato is a clinical research hospital partially funded by the Italian Ministry of Health.

Right ventricular functional changes detected by CMR during ajmaline challenge in patients with Brugada syndrome

Background

3D echocardiography has recently revealed alterations of right ventricular (RV) function in Brugada syndrome (BrS) during ajmaline challenge (AC). Cardiac magnetic resonance (CMR) is the gold standard for functional and anatomical RV assessment. CMR feature-tracking (FT) analysis is able to detect subtle functional changes in the underlying myocardial substrate.

Purpose

To investigate RV functional changes during AC in BrS patients using CMR-FT analysis.

Methods

24 consecutive BrS and 28 matched controls underwent CMR. CMR protocol included paraxial and parasagittal cine bSSFP sequences, acquired before and 2÷5 minutes after ajmaline infusion (1 mg/kg in 5 minutes), to obtain a comprehensive evaluation of the RV free wall. All patients were closely monitored with ECG. Semi-automatic threshold-based quantification of ventricular volumes, function and mass was performed in QMass. CMR-FT analysis of RV function was performed in QStrain. Values of longitudinal strain (LS) and transverse displacement (TD) of the RV wall before and after AC were compared in BrS patients and in the control group.

Results

AC induced Type 1 ECG pattern in all BrS patients and no ECG changes in controls. In BrS patients TD of the RV free wall was significantly reduced (P≤0.003) at peak ajmaline effect; controls reported sub-millimetric TD changes. LS of the RV wall was significantly impaired in BrS patients (P<0.0001) on both b SSFP sequences; LS remained comparable (P=0.62) in controls on the parasagittal sequence; minor but not negligible (P=0.01) LS changes were noticed on the paraxial stack. (Table 1)

Conclusions

In patients with BrS CMR-FT analysis during AC unveils dysfunctional RV wall mechanics in areas generally associated with abnormal electrical activity.

TD and LS in a Brs patient post AC

Funding Acknowledgement

Type of funding source: None

Quantitative 4D Flow CMR analysis of intracardiac blood flow energetics in ischemic cardiomyopathy patients

Background

Ischemic cardiomyopathy (ICM) is often associated with negative LV remodelling after myocardial infarction, sometimes resulting in impaired LV function and dilation (iDCM). 4D Flow CMR has been recently exploited to assess intracardiac hemodynamic changes in presence of LV remodelling.

Purpose

To quantify 4D Flow intracardiac kinetic energy (KE) and viscous energy loss (EL) and investigate their relation with LV dysfunction and remodelling.

Methods

Patients with prior anterior myocardial infarction underwent a CMR study with 4D Flow sequences acquisition; they were divided into ICM (n=10) and iDCM (n=10, EDV>208 ml and EF<40%). 10 controls were used for comparison. LV was semi-automatically segmented using short axis CMR stacks and co-registered with 4D Flow. Global KE and EL were computed over the cardiac cycle. NT-proBNP measurements were correlated with average and peak values, during systole and diastole.

Results

Both LV volume and EF significantly differ (P<0.0001) between iDCM (EDV=294±56 ml, EF=24±8%), ICM (EDV=181±32 ml, EF=34±6%) and controls (EDV=124±29 ml, EF=72±5%). If compared to controls, both ICM and iDCM showed significantly lower KE (P≤0.0008); though lower than controls, EL was higher in iDCM than ICM. Within the iDCM subgroup, diastolic mean KE and peak EL reported good inverse correlation with NT-proBNP (r=−0.75 and r=−0.69, respectively). EL indexed (ELI) to average KE during systole was higher in the entire ischemic group as compared to controls (ELI(ischemic) = 0.17 vs. ELI(controls) = 0.10, P=0.0054).

Conclusions

4D Flow analyses effectively mapped post-ischemic LV energetic changes, highlighting the disproportionate intraventricular EL relative to produced KE; preliminary good correlation between LV energetic changes and NT-proBNP will deserve further investigation in order to contribute to early detection of heart failure.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health

P3734Feasibility of percutaneous pulmonary valve implantation in the native right ventricle outflow tract from in vivo dynamic regional strain analysis

Background

Patients surgically treated for congenital heart disease (e.g., Tetralogy of Fallot) frequently report long-term dysfunctions (i.e., pulmonary stenosis and/or incompetence) of the native right ventricle outflow tract (RVOT). The efficacy of percutaneous pulmonary valve implantation (PPVI) is recognized worldwide; however, the procedure is only feasible in RVOTs with appropriate size and functional substrate. Accordingly, a three-dimensional (3D) and dynamic assessment of the native RVOT function can be crucial to identify patients who can effectively benefit from PPVI, thus avoiding the risk of device embolization or fracture.

Purpose

We herein exploited an optical flow-based approach to develop a novel 3D framework for the quantitative in vivo assessment of dimension and dynamic changes of the native RVOT throughout the cardiac cycle. PPVI candidates (n=15) with previous surgery of the native RVOT were enrolled to demonstrate the additional contribution of our 3D patient-tailored analysis to the decision-making process.

Methods

Contrast-enhanced computed tomography (CT) was performed on a 64-slice dual-source multidetector CT system with retrospective ECG-gating. Multi-phase images of the RVOT were acquired at each 10% increment of the cardiac cycle (slice thickness = 1.5mm, increment = 1mm, pixel spacing = 0.35mm). We implemented a dedicated in-house framework, based on the optical flow tracking algorithm, to dynamically follow three anatomical cross-sections (i.e., proximal, mid and distal) of the native RVOT. The time course of area, perimeter and other relevant parameters (e.g., equivalent radius, elliptical ratio) were extracted and both areal (εA) and longitudinal strain (εlong) were computed on each the RVOT tracked cross-section. Maximum regional strain were calculated between the maximum and minimum value over the cardiac cycle. Dynamic changes in CT-derived variables were assessed using analysis of variance (p<0.05, statistically significant).

Results

All the enrolled anatomies were successfully analysed, locally pinpointing the in vivo pattern of deformation within each 3D RVOT anatomy (a). Anatomical regional RVOT dimensions (p<0.0001) and changes proved to be significantly different (p≤0.0002) throughout the cardiac cycle. In addition, the dysfunctional RVOT anatomy exhibited an irregular pattern of contraction and dilation: maximum regional strains markedly differed between RVOT regions, e.g., comparing the εA between RVOT mid (22.6%) and distal (46.0%) regions.

In vivo tracking of RVOT dynamic changes

Conclusions

The combination of patient-specific in vivo imaging and bioengineering strategies can improve our understanding of RVOT dysfunctions in congenital patients referred to PPVI. Our optical flow-based and clinically-oriented framework can support the patient selection process and the planning of the percutaneous procedure in order to enhance its efficacy and shorten the operating time while improving the patient safety.

Acknowledgement/Funding

IRCCS Policlinico San Donato is a clinical research hospital partially funded by the Italian Ministry of Health

A novel approach to the quantification of aortic root in vivo structural mechanics

Understanding aortic root in vivo biomechanics can help in elucidating key mechanisms involved in aortic root pathologies and in the outcome of their surgical treatment. Numerical models can provide useful quantitative information. For this to be reliable, detailed aortic root anatomy should be captured. Also, since the aortic root is never unloaded throughout the cardiac cycle, the modeled geometry should be consistent with the in vivo loads acting on it. Achieving such consistency is still a challenge, which was tackled only by few numerical studies. Here we propose and describe in detail a new approach to the finite element modeling of aortic root in vivo structural mechanics. Our approach exploits the anatomical information yielded by magnetic resonance imaging by reconstructing the 3-dimensional end-diastolic geometry of the aortic root and makes the reconstructed geometry consistent with end-diastolic loading conditions through the estimation of the corresponding prestresses field. We implemented our approach through a semiautomated modeling pipeline, and we applied it to quantify aortic root biomechanics in 4 healthy participants. Computed results highlighted that including prestresses into the model allowed for pressurizing the aortic root to the end-diastolic pressure while matching the image-based ground truth data. Aortic root dynamics, tissues strains, and stresses computed at relevant time points through the cardiac cycle were consistent with a broad set of data from previous computational and in vivo studies, strongly suggesting the potential of the method. Also, results highlighted the major role played by the anatomy in driving aortic root biomechanics.

Outstanding survival and regeneration process by the use of intelligent acellular dermal matrices and mesenchymal stem cells in a burn pig model

A pig model with a deep large burn was used to study the regeneration process induced by mesenchymal stem cells (MSCs) and acellular pig dermal matrices, made intelligent by the combination with biodegradable nanofibers loaded with growth factors (granulocyte-macrophage colony-stimulating factor and epidermal growth factor) and coated with the anti-CD44 monoclonal antibody (intelligent acellular dermal matrices, IADMs). These IADMs are specially designed to integrate in the wound bed as new biological scaffolds as well as to specifically recruit and attach circulating and/or externally applied MSCs through the anti-CD44 antibody while delivering precise amounts of growth factors. In this way, the reparative process as well as the aesthetic and functional results were enhanced in our burn model. The animal survived, the wound was completely closed, and total regeneration of the skin was obtained without much scarring. Surprisingly, hair follicles and other skin appendages developed despite the severity and deepness of the burn. Even burned muscles and ribs seemed to have undergone a regenerative process by the end of the study. Based on these findings, we have proposed the use of IADMs and autologous, allogeneic or xenogeneic MSCs, as a new paradigm for the future treatment of large burns and probably other dermatological and cosmetic human conditions.

The next generation of burns treatment: intelligent films and matrix, controlled enzymatic debridement, and adult stem cells

We describe a novel technology based on nanoengineered multifunctional acellular biologic scaffolds combined with wound dressings and films of the same kind. This method allows selective delivery and release of shielded biomaterials and bioactive substances to a desired wound or damaged tissue while stimulating the selective anchoring and adhesion of endogenous circulating repairing cells, such as mesenchymal stem cells, to obtain a faster and more physiologic healing process. We also present a new controlled enzymatic debridement process for more effective burned tissue scarolysis. In light of our preliminary in vitro and in vivo data, we are convinced that these approaches can include the use of other kinds of adult stem cells, such as endometrial regenerative cells, to improve the vascularization of the constructs, with great potential in the entire tissue and organ regeneration field but especially for the treatment of severely burned patients, changing the way these lesions may be treated in the future.

Matrix superhighways configurations: new concepts for complex organ regeneration

New ideas and experimental models for tissue and organ regeneration are urgently needed. There are several exciting challenges in the field of organogenesis that need to be defined. The integrated signals and molecular repertoires that shape the particular architecture of specific organs like the kidney or the liver are not completely understood yet. To develop a new scientific platform to be able to build up complex organs we have established a research program using basically Acellular Xenogeneic Isomorphic Matrices (AXIMs) and mesenchymal stem cells (MSCs) generating the necessary concepts for the definition, production, and application of the specific configurations of these matrices for organ regeneration. New and interesting pathways for MSC differentiation were identified. We believe that all extracellular matrices were created fundamentally equal or at least very similar in nature. We also believe that there are true "matrix superhighway configurations" with different three-dimensional geometrical architectures as well as biochemical, electrical, and molecular properties that are tissue and organ specific that influence cell differentiation and organogenesis and will be fundamental for the in vitro regeneration of complex organs for transplantation.

Bloodstream cells phenotypically identical to human mesenchymal bone marrow stem cells circulate in large amounts under the influence of acute large skin damage: new evidence for their use in regenerative medicine

OBJECTIVES

Recent work has shown that human bone marrow contains mesenchymal stem cells (MSCs). However, little is known about their presence in peripheral blood. Since these cells are potentially responsible for tissue repair after injury, their number should be increased during these situations. To demonstrate their number during these situations, we measured MSCs in the peripheral blood of healthy donors and burn patients.

MATERIALS AND METHODS

Blood samples were obtained from 15 acute burn patients and 15 healthy donors. We performed flow cytometric analysis, using a large monoclonal antibody panel: CD44, CD45, CD14, DR, CD34, CD19, CD13, CD29, CD105, CD1a, CD90, CD38, CD25. MSC phenotype was considered positive for CD44, CD13, CD29, CD90, and CD105, and negative for the other monoclonals. The testing was performed on day 3 after injury. We correlated the results with the age, sex, and size and type of burns.

RESULTS

Cells expressing the MSC phenotype were detected in the peripheral blood of both groups. Noteworthy, compared with samples from healthy donors (0.0078 +/- 0.0044), blood obtained from burn patients showed a higher MSC percentage (0.1643 +/- 0.115; P < .001). The percentage of MSCs correlated with the size and severity of the burn. Increased values were also observed among younger patients.

CONCLUSIONS

MSCs have an important role in regenerative processes of human tissues. We found cells phenotypically identical to MSCs circulating in physiological number in normal subjects, but in significantly higher amounts during acute large burns. Therefore, they may represent a previously unrecognized circulatory component to the process of skin regeneration.

Human mesenchymal stem cells are tolerized by mice and improve skin and spinal cord injuries

INTRODUCTION

We sought to use human mesenchymal stem cells (HMSC) for skin and spinal cord repair in mice.

MATERIALS AND METHODS

Human bone marrow obtained from a young healthy donor was used to separate and culture human mesenchymal stem cells (HMSC). Ten mice were included in each of four groups. A full-thickness skin defect was surgically performed on all mice in groups 1 and 2. A transverse complete medullar section was performed in groups 3 and 4. Groups 1 and 3 received HMSC IV infusion and local HMSC polymer implant. Groups 2 and 4 received only the IV HMSC infusion. Five control animals from each group went through the same lesions but they didn't receive treatment.

RESULTS

After local administration of HMSC into the fibrin polymer combined with the IV infusion of HMSC, there was no immune rejection; all skin defects healed without scar or retraction at a median time of 14 days. Sixty percent of the animals treated with IV infusion and polymer with HMSC simultaneously had improved neurological activities, while all control mice with spinal cord injury experiments died or perpetuated their paralysis with worsening muscular atrophy and increasing propensity to skin damage.

CONCLUSIONS

HMSC are not immunologically reactive and can trespass species defense barriers. Animals treated with these cells repaired injuries better than controls. In this way we propose that universal HMSC from donors can be cultured, expanded, and cryopreserved to be used in human organ or tissue regeneration.

Anatomical and mechanical considerations of craniofacial fractures: an experimental study

By inflicting blows to cadavers, a study was made of injuries to the craniofacial bone lattice. On the basis of these experimental results, a classification of craniofacial fractures is offered.