When a structural defect in the mitral valve leads to regurgitation, it is known as primary or organic mitral regurgitation (MR). Mitral valve prolapse is the most common cause of primary MR in developed countries. While rheumatic heart disease is the second most common cause overall, it remains the most common etiology in developing countries. Congenital heart disease and infective endocarditis are other causes of primary MR. Remodeling of the left ventricle resulting in incomplete closure of a structurally normal mitral valve is known as secondary or functional MR. Patients with MR due to left ventricular dysfunction usually present at an advanced stage of heart failure leading to an underestimation of MR [4]. Prognosis of patients with functional MR depends on the severity of left ventricular dysfunction.

The prevalence of aortic stenosis (AS) in adults is approximately 2% for patients aged 70–80 and increases to 3–9% after 80 years of age. Atherosclerosis and AS have common risk factors, such as age, hypertension, and smoking [4]. The rate of progression from moderate to severe AS significantly varies between individuals and is unpredictable. In the USA, bicuspid aortic valve is the most common congenital anomaly leading to AS. Unfortunately, bicuspid aortic valve may be difficult to detect in the outpatient setting, leading to an underestimation of the prevalence of the condition. The majority of patients with bicuspid aortic valve progress to AS after age 50, which highlights the importance of early diagnosis of this condition [5].

Degenerative valve disease is the leading cause of aortic regurgitation (AR) in developed countries, while rheumatic heart disease is the most common etiology in developing countries. Bicuspid aortic valve is the most common cause of AR in patients under 50 [4]. Aortic root dilation and calcific valve disease are other etiologies [6]. Factors such as old age, hypertension, dyslipidemia, smoking, and diabetes lead to aortic dilation that can cause secondary AR. Trace AR is common and has been found in up to 13% of men before 50 years of age. The prevalence of mild AR increases from 3.7% in the sixth decade to 12.2% in the eighth decade, whereas that of moderate-to-severe AR increases from 0.5 to 2.2% [7].

Mitral stenosis (MS) is the least common VHD in the USA and other developed countries. This is due to the fact that MS is most commonly caused by rheumatic heart disease. In the last decade, the proportion of mitral valve surgeries dedicated to correcting mitral stenosis has decreased from 30 to 14% in the USA [1]. Other rare causes of MS are mitral annular calcification, radiation exposure, and certain congenital metabolic conditions [8, 9].

Systemic inflammatory conditions such as systemic lupus erythematosus (SLE) can cause fusion of valve commissures and thickening of the leaflets. Drug-induced VHD, postradiation VHD, endocarditis, and device implantation are some other reasons for increased burden of VHD. Isolated tricuspid and pulmonic valve lesions are very rare.

Rapid prototyping (RP) is a promising and rapidly growing technology for the evaluation and management of VHD [10]. Potential uses of RP in VHD include ex vivo valve analysis, hemodynamic testing, surgical planning, teaching, and design of patient-specific prostheses. However, despite all these uses, there are currently no clear guidelines for application of RP for VHD; therefore, it is a technology awaiting specific indications.

There are several limitations that may make RP difficult to apply in VHD (Table 13.3). First, cardiac valves are thin and mobile structures, which require a high spatial and temporal resolution to obtain adequate 3D datasets for segmentation and modeling [11]. These high temporal and spatial resolutions usually require electrocardiogram (ECG) gating and reconstructive imaging, so that absence of patient motion and a stable cardiac rhythm are necessary. Second, imaging artifacts and inadequate image optimization (e.g., high-ultrasound gain settings, acoustic shadowing, blurring, and blooming) may decrease the accuracy of the structure’s 3D representation. Third, associated conditions (e.g., calcification and prosthetic material) may hinder adequate visualization of the leaflet tissue [12]. This is an important concern for degenerative VHD such as AS, which is frequently associated with significant valve leaflet calcification. Fourth, although the anatomic structure of the valve leaflets is important for adequate valve function, the functional valve apparatus (i.e., valve annulus, papillary muscles, sinuses of Valsalva, and loading conditions) is equally important. Replicating these structures is challenging with currently available methods. Fifth, cardiac valves are dynamic structures that need adequate closure to avoid regurgitation and adequate opening to avoid stenosis. Although imaging-derived RP of valves is currently possible, these models are generated during a specific part of the cardiac cycle and may not be completely representative of the structural changes that the valve undergoes during the systolic and diastolic phases [13.]. Sixth, although feasible with new technologies, so far it has not been possible to create exact models that replicate the heterogeneous thickness and flexibility of the different valvular components. Lastly, the use of RP at the point of care is still limited by the timely availability of models. Imaging data acquisition, exporting Cartesian-type Digital Imaging and Communications in Medicine (DICOM) files, segmentation, generation, and refinement of a stereolithography (.stl) file are all time-consuming processes. Furthermore, commonly used RP modalities such as fused deposition modeling and stereolithography require at least some level of postprocessing. Removal of supports, ultraviolet curing of resin, and print soaking in water or alcohol can significantly increase the time required for model availability at the point of care (e.g., operating room and interventional suite).

In this section, we will discuss the different imaging modalities used to evaluate VHD, the use of 3-dimensional (3D) transesophageal echocardiography (TEE) to assess VHD in the perioperative period and the potential applications of RP in patients with VHD.

Imaging is essential for evaluating patients suffering from VHD. In these patients, imaging is used to identify the type of valve dysfunction and quantify its severity, evaluate the repercussions of the underlying VHD in cardiac function, establish a prognosis, and select the appropriate management (surgical, interventional, or medical) [14]. Imaging modalities may also be used for preoperative surgical planning, intraoperative procedural guidance, and postoperatively for patient follow-up.

Imaging modalities that can be used to assess VHD include MRI, computerized tomography (CT), and echocardiography [14, 15]. Despite great improvements in MRI and CT technology, echocardiography is the imaging modality of choice to evaluate VHD. The reasons for this are its increased portability, low risk, low comparative cost, its ability to image valve tissue with high temporal and spatial resolutions and to provide reliable qualitative and quantitative information regarding transvalvular flows. Furthermore, in order to produce high-quality reconstructions, CT and MRI usually require intravenous contrast, sedation, and use of ionizing radiation [16]. 3D TEE is a particularly useful imaging modality in VHD and will be discussed during the next section.