Tricuspid Valve Endocarditis: 3D TEE En Face View Helps Better Identification of Location and Extent of Involvement\

A 42-year-old gentleman with known h/o small previously unattended peri-membranous ventricular septal defect (VSD), who never had any symptoms previously related to the lesion, presented with off and on low-grade fever since April 2020. He was thoroughly investigated, but his investigations failed to pinpoint the etiology of persisting fever. Real-time reverse transcription polymerase chain reaction (RT-PCR) (for SARS-CoV-2) was done twice, test for tuberculosis, echocardiogram, and pan cultures all revealed negative results until in December 2020, when the third RT-PCR test came positive for COVID-19, and subsequently in January 2021, a transesophageal echo (TEE) examination revealed a vegetation involving the tricuspid valve, suggestive of infective endocarditis. Intravenous antibiotics, which he was already on, were continued for another 2 weeks before he was taken up for surgery. Written consent was taken from the patient for publishing this report.

After induction of anesthesia, a 3D matrix array TEE probe (Philips X 7-2t) was introduced and a comprehensive TEE examination ensued using Philips Affinity 70 ultrasound platform (Andover, MA, USA). A large vegetation involving the tricuspid valve was confirmed using multiple mid-esophageal (ME) (ME 4C, AV SAX, RV inflow outflow) transgastric (TG) Basal SAX and 3D zoom en face views.

Interestingly, while the vegetation was obvious on the ME views, it was confusing and difficult to tell from the ME views alone, from which of the three tricuspid leaflets the vegetation originated [Figure 1a and b, Video 1]. While it was clear from the ME 4C view that the septal leaflet was spared, these views could not conclusively tell whether the vegetation originated from the anterior or posterior or both these leaflets.

Figure 1.

(a). ME 4C view (live 3D image) showing a large vegetation (pink arrow) involving the tricuspid valve. It was impossible to tell correctly from this view alone, from which leaflet the vegetation originated, and whether the vegetation involved one or more leaflets. (b). ME RV inflow outflow view showing the vegetation (pink arrow) attached to the tricuspid valve. Even from this view, like it was using the ME 4C view, exact site of attachment of the vegetation to one or more the leaflets could not be told surely

However, identification of the three leaflets of the tricuspid valve was easier in views where all three leaflets were visible simultaneously, for example, TG basal SAX view, looking from the right ventricular (RV) aspect [Figure 2, Video 2], and 3D zoom en face [Figure 3, Video 3] view, looking at the tricuspid from the right atrial perspective. Using either or both these views, the broad-based attachment of the vegetation in our case was seen originating from midpoint of the anterior leaflet till the commissure between anterior and posterior leaflets with a small part of it seen involving the posterior leaflet close to the commissure. The patient underwent VSD closure and tricuspid valve replacement. Coming off cardiopulmonary bypass was uneventful, but soon after patient started desaturating associated with unexplained pulmonary edema with normal or low left-sided pressures, requiring high inotropic support, mimicking a vasoplegic state. Patient was on prolonged ventilation subsequently in the ICU with sustained inotropic requirement, on intravenous antibiotics and steroids. Patient recovered slowly over 2 weeks and was sent home after a month without any complications.

Figure 2.

Transgastric (TG) basal SAX view showing the broad-based attachment of the vegetation originating from the mid-part of the anterior tricuspid leaflet till the commissure between the anterior and posterior tricuspid leaflets (arrows indicating: A = anterior leaflet, P = posterior leaflet, S = septal leaflet)

Figure 3.

3D en face view from the right atrial perspective looking down toward the tricuspid valve (aortic valve seen anteriorly and left atrium/mitral valve on the left), showing the triangular-shaped large vegetation (green arrow) with broad-based attachment originating largely from the anterior tricuspid leaflet (a) extending from mid-part of the anterior leaflet till the commissure between anterior and posterior leaflets (A = anterior leaflet, P = posterior leaflet, S = septal leaflet)

DISCUSSION

Tricuspid is the largest and the most caudally located of all the four heart valves, and its leaflets are thinner than that of the mitral valve, which might pose some challenges in visualizing its leaflets. There is a greater degree of anatomic variability in the number of normal leaflets in tricuspid valves, which is usually three but can be two, four or more leaflets as well.[1]

While the anterior leaflet was the largest leaflet in 90% of patients studied, in the remaining 10%, all three leaflets were of identical size. The smallest leaflet could be either posterior (49%) or septal (41%).[1] In 8% of studied cases, it was not possible to clearly distinguish between the anterior and posterior leaflets, while in 4%, deep indentations between the scallops gave the valve a quadricuspid appearance.[1]

Identification of the individual tricuspid leaflets using echo is an important skill for an echocardiographer because not only does it help in identifying the pathology in one or more leaflets but also helps the surgeon or interventional cardiologist in the decision-making process, for example, in tricuspid repair or deployment of the TriClip. Failure of correct identification of individual tricuspid leaflet, therefore, may result in misguided and inappropriate therapy.

However, it is not easy to identify individual tricuspid leaflets[1] using ME views alone, because only two leaflets are visualized using these views at one point of time. For example, using a ME 4C view one can never be completely sure whether the lateral tricuspid leaflet, adjacent to the RV free wall, is anterior or posterior. Reviewing literature on guidelines for identification of individual tricuspid leaflets using standard 2D echo views where only two of the leaflets are visible (TTE views, ME TEE views) reveals conflicting data.[2,3] Also, the appearance of the tricuspid valve in standard 2D views alone is not indicative of unusual valve anatomy, while the same valves while examined using en face views (2D or 3D) can reveal the anatomical distortion.[1]

Using a TG basal SAX view, while looking from the ventricular aspect [Figure 2, Video 2], a 3D en face view looking at the tricuspid valve from the right atrium (surgical view) [Figure 3, Video 3] or manipulating the 3D dataset to view the valve from below (from the RV cavity looking at the under surface of the tricuspid valve) helps visualize all the three leaflets simultaneously and hence makes it much easier to identify the individual leaflets correctly and understand related pathology.

It is important to note, however, that even though the en face view of the TV using the subcostal approach appears to be superior (compared to standard transthoracic 2D imaging), its range of information remains limited compared with 3D imaging, which allows visualization of the valve from any perspective [Video 3].

Although simultaneous visualization of all three leaflets is needed for correct identification of the valve leaflets, however achieving an en face view using 2D is a difficult task.[4] While a subcostal approach (transthoracic echo) has been suggested[5] in achieving a tri-leaflet view of the tricuspid, its feasibility and usefulness is not yet established. TG basal SAX view in our experience is relatively easy to obtain and is a useful view for tricuspid assessment, in case 3D is unavailable.

3D TEE not only helps visualize en face view of the tricuspid valve but also helps in a comprehensive evaluation including assessment of valve leaflets (number, relative size, mobility), annulus, subvalvular apparatus, and surrounding structures.[1]

To summarize, 3D TEE is a useful modality to understand the morphology of the tricuspid valve. Using large data sets and slicing them as necessary, we can obtain life-like images that can identify the three leaflets more clearly compared to 2D imaging.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Glossary of Terms

3D = 3 Dimensional; TEE = transesophageal echocardiography; VSD = ventricular septal defect; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; COVID-19 = coronavirus 2019; RT-PCR = real-time reverse transcription polymerase chain reaction; ME = mid-esophageal; TG = transgastric; TVR = tricuspid valve replacement.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.