2. Diagnosis

#### 2.1 Clinic manifestations

Common symptoms secondary to right-sided endocarditis are the respiratory symptoms characterized by a cough, hemoptysis, persistent fever, dyspnea, and chest pain [4].

In exceptional circumstances, right-heart failure can arise, generated by the increase in pulmonary pressure, severe tricuspid valve regurgitation, or obstruction of pulmonary circulation through multiple pulmonary emboli [4, 6].

The diagnosis of RSIE is often delayed because the signs and symptoms are relatively different concerning the LSIE clinical setting; the Duke's modified criteria do not have value in the RSIE. The low incidence of RSIE also plays an essential factor in the underdiagnosis of this disease.

There are reports in which the 76% of the patients had gotten an antibacterial treatment before the endocarditis's diagnosis because they developed some signs and symptoms that were misunderstood as a febrile syndrome or pneumonia [4].

An acute beginning of the disease is seen at the majority of the patients; only a few cases have been reported with chronic symptoms (more of 2 months) [4].

It is frequent that right-side vegetations dislodge microemboli to the pulmonary region. The pulmonary embolism (PE) can induce pulmonary infarction, abscesses, pneumothoraxes, and purulent pulmonary effusions.

Persistent fever associated with pulmonary events, anemia, and microscopic hematuria, the so-called "tricuspid syndrome," is the sign of clinical alert for tricuspid valve IE [3, 4, 7].

Revilla et al. found 24% of their patients with this syndrome, and the other 65% had at least two of the three signs [4].

#### 2.2 Complementary exams

#### 2.2.1 Laboratory

Nowadays it is routinary to order blood tests for any patient admitted at the hospital, and it is reasonably used if the suspicion of infection is thought. Some findings such as high titers of white blood cells, procalcitonin, and C-reactive protein can support the infection diagnosis; nevertheless, these variables are not used as criteria to diagnose infective endocarditis [5, 8].

The anemia has been described as part of the tricuspid syndrome, so the values of hemoglobin and hematocrit below the normal range can be found in the blood test, which probably will reveal a normocytic, normochromic anemia patron [3, 4, 7].

The urine test can show microhematuria which also is part of the tricuspid syndrome.

#### 2.2.2 Cultures

Right-sided endocarditis in IVDA is commonly caused by S. aureus and Pseudomonas aeruginosa, and other Gram-negative organisms, fungi, streptococci, and enterococci have also been found [4, 6].

In the majority of patients, the microorganism can be identified through blood cultures if they are adequately collected. The 2015 ESC endocarditis guidelines recommend a technique of recollection minutely sterile of at least three sets of samples with an interval of 30 minutes; each sample must contain 10 ml of blood

#### Right-Sided Infective Endocarditis DOI: http://dx.doi.org/10.5772/intechopen.85019

and should be incubated in both aerobic and anaerobic atmospheres. Another crucial aspect is the recollection of samples from a peripheral vein instead of central venous catheter due to the risk of contamination and wrong interpretation [5].

Occasionally, the blood cultures can be negative by different reasons, especially if an antimicrobial therapy was established before the acquisition of the samples. The blood cultures usually become negatives after 48 hours from the beginning of antibiotics [4].

## 2.2.3 Image

Currently, the diagnosis of IE requires the finding of an infective process inside the heart, reason why the imaging techniques are valuable to diagnose or discard IE. The echocardiography is the most important and more used tool to diagnose, manage, and monitor patients with IE [5].

However, other imaging methods have been developed in the last decades, allowing us to back the diagnosis of IE when the echography is not entirely clear in some cases (Table 1).
