**3.1. American-based guidelines**

Complications include rupture into the coronary sinus, left circumflex artery, or the pericardial space [14]. The presence of mitral annular calcification (MAC), especially caseous calcification, can make diagnosis of annular abscess more challenging due to acoustic shad-

New dehiscence of a prosthetic valve occurs when there is disruption of the annular sewing ring due to a breakdown of supporting tissue adjacent to the prosthesis (**Figure 6**). This results in perivalvular regurgitation and may be associated with an abnormal rocking motion. If the area of dehiscence around a bioprosthetic aortic valve is <30%, concordant motion of the valve with the aortic root will occur; however, if >40% of annular area is dehisced, discordant or

**Figure 7.** TEE color flow imaging from the 'long-axis' window demonstrating severe periprosthetic aortic valve regurgitation complicating annular dehiscence (arrow). A large region of dehiscence results in a 'rocking' motion of the

Minor echocardiographic findings include but are not limited to perforation, valve aneurysm,

**Figure 8.** TEE color compare imaging of mitral valve vegetation with perforation (arrow) and severe regurgitation.

fistula, pseudoaneurysm, valve leaflet destruction, and flail leaflet [2].

rocking valvular motion will be present (**Figure 7**) [18].

**2.2. Minor Duke echocardiographic findings**

owing artifact.

64 Contemporary Challenges in Endocarditis

prosthetic valve.

According to the 2014 ACC/AHA guidelines [27], TTE is indicated in patients with suspected IE to identify vegetations and assess valve hemodynamics, ventricular function, pulmonary pressures, and cardiac complications (class I recommendations). Transesophageal echo is indicated when TTE is nondiagnostic in suspected or known IE, including when intracardiac devices are present and to assess intracardiac complications of IE (class I recommendations). Up to 30% of *Staphylococcus aureus* bacteremia are associated with IE, and therefore, TEE should be strongly considered. In cases where fever defervesced within 72 h and there is a clear extracardiac source (excluding osteomyelitis, spinal involvement, intracardiac device, hemodialysis, structural cardiac disease, prolonged bacteremia, or risk factors), TEE may not be necessary [27].

Another set of independent Guidelines that were published in 2011 by the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Groups in consultation with other key organizations, developed a scoring system graded from 1 to 9, with 7–9 being an appropriate echo referral, 4–6 uncertain, and 1–3 inappropriate [28]. A summary of the guideline is provided as follows:

#### *3.1.1. Transthoracic imaging*

Imaging of native or prosthetic valves is considered most appropriate (grade 9) where endocarditis is clinically suspected and associated with positive blood cultures or a new murmur. In addition, TTE is indicated for reevaluation of IE if any of the following are present as follows: (a) high risk of progressive disease, (b) change in clinical status of the patient, and/ or (c) new clinical findings on cardiac examination [28].

Inappropriate reasons for performing TTE include transient fever (without bacteremia or new murmur) and cases of transient bacteremia with a non-IE pathogen and/or documentation of noncardiovascular infection. Also, performing echocardiography for routine surveillance without complications or when findings would not change management, is considered inappropriate and should be avoided [28].
