7.1 RSIE in people with intravenous drug addiction (IVDA)

The majority of cases of RSIE reports in the literature are in drug abusers. This kind of populations of RSIE represents the 32–86% of all IE [2, 3].

There are multiple explanations about the preference of infection in the right side of the heart at this group of the population, being the leading causes of the poor hygiene with unsafe injection practices and the affected immunology well-being. The higher bacterial load and the variety of effects of injected substances over the endocardium also play an essential role in the physiopathology of the infection [7].


AVF: arteriovenous fistula, HD: hemodialytic, HIV: human immunodeficiency virus, IE: infective endocarditis, RSIE: right-sided infected endocarditis, VSD: ventricular septal defect.

#### Table 2.

Characteristics of principal risk factors in the right-sided infective endocarditis.

The incidence of reinfections and reoperations is about 28 and 20%, respectively; however, the survival described in some papers is almost equal between drug abusers and not drug abusers, in which results are very striking [7].

Sometimes IVDA also presents human immunodeficiency virus (HIV) which can aggravate the predisposition to IE if this disease is not well-controlled. The death rates in this subgroup of patients are about 5–10% [1]. The HIV affects both humoral and cellular immunities which provoked a predisposition for recurrent episodes of bacteremia that cause valve damage, fibrin deposition, thrombus formation, and adherence by bacteria in the endocardium; it is common to find abscess developments and large vegetations, which are indications for early surgical treatment [18].

The choice of empiric antimicrobial therapy depends on the suspected microorganism and type of drug and solvent used by the addict and the location of infection.

As previously was described, the empirical antimicrobial therapy must cover S. aureus; the combination of penicillinase-resistant penicillins or vancomycin or daptomycin with gentamicin is recommended [5].

The 2015 ESC IE guidelines recommend an antipseudomonal therapy in patients with pentazocine addiction if IE is suspected; nevertheless, there are few and relatively old studies about this issue [5, 19, 20].

If an IVDA uses brown heroin dissolved in lemon juice, Candida spp. (not Candida albicans) should be considered and antifungal treatment added [5].

#### 7.2 RSIE in people with no IVDA

Although the majority of IE at the right side of the heart is fairly reported in IVDA, there is an increasing incidence in another type of patients, mainly highlighting the people with indwelling catheters and cardiac devices. The 5–10% of RSIE occur in nonaddicted patients [3].

#### 7.2.1 Indwelling catheters

It is estimated that more than 3 million people worldwide require dialysis for end-stage renal disease, and this number is expected to rise sharply because of the aging of the population and an increasing prevalence of diabetes and cardiovascular comorbidities paralleled by a decline in cardiovascular mortality, particularly in very elderly patients (>80 years). For instance, in the United States, this augmentation is about 3.2% per year [21, 22].

Hemodialysis patients are at increased risk for bacteremia, including an estimated 37,000 central line-associated bloodstream infections related to outpatient hemodialysis in the United States in 2008. The elevated incidence of bacteremia increases the risk for infective endocarditis [22, 23].

The average duration on HD before the diagnosis of IE was 30 months (range, 4–66 months). IE is one of the most important causes of increased mortality and morbidity among hemodialysis patients [24].

The European Heart Journal states that more than two-thirds of patients undergoing hemodialysis suffer from some infection and that one-third of these patients experience IE [24].

IE occurs 18 times more frequently in chronic HD patients than in the general population [25, 26].

The use of temporal or permanent central catheters, the constant puncture of arteriovenous fistulas, the long and frequent hospitalizations that some of these patients have to suffer during their disease, the various surgical procedures related

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

with the creation of fistulas, and the underlying alteration of their defenses become susceptible to this population to develop IE.

The IE in HD patients is calculated about at 8% of all observed IE cases regarding the largest international cohort collected to date [27].

The incidence of IE usually increases with the time after the initiation of hemodialysis; however, some studies found a rise of this incidence in the first 5 months after the initiation of hemodialysis [26, 28]. This contradictory results can be probably due to the aseptic technique during the manipulation of the catheter and arteriovenous fistulas of these patients.

Patients in HD also present an increase in the incidence of endocarditis after aortic valve replacement surgery, affecting at the same time the short-term and long-term survival [22].

Most of the studies show that central catheters are a risk factor for bacteremia and endocarditis [6, 7, 10]; nevertheless, Farrington et al. did not find an increase of endocarditis in patients with central catheters in comparison with patients with arteriovenous fistulas [22].

Besides, the rates of IE are more significant in patients with non-cuffed catheters than cuffed catheters; the vascular grafts have more incidence of IE than AV fistulas. Furthermore, peritoneal dialysis has then lesser rates of IE due to the lack of contact of the line with luminal vessels [29].

The morbidity and mortality are higher than the general population; in the 20% of hemodialysis-related IE, the tricuspid valve is the principal place affected at the right side of the heart.

The pathogenesis of IE in HD patient can be attributed to recurrent episodes of bacteremia, the immunological compromise of hemodialytic patients and heart valvular deterioration-calcification frequently founded in this patients.

It can sound logical that the majority of cases of IE in HD patients should happen on the right cavities, similar to what occurs in IVDA; however, the left-side heart (90%) is the more frequent infected place in HD patients, the mitral being the main valve affected. The affectation of the right cavities is roughly 10%. Nevertheless, some papers report an incidence of RSIE in HD patients of between 0 and 50% [30, 31].

Between the multiple explanations of pathogenesis RSIE in HD patients, the high turbulent flow throughout the valves can provoke a deterioration at these structures, becoming more susceptible to bacterial implantation. Nonetheless, the low pressures at the right cavities might not present the same effect in their valves. One possible cause can be the associated pulmonary hypertension that some patients express, due to multiple factors, such as an increased cardiac output (hypervolemic condition and arteriovenous fistula), an increased pulmonary vascular resistance (uremic endothelial dysfunction and pulmonary artery calcifications), and elevated pulmonary capillary wedge pressure caused by heart failure or mitral valve disease [17].

#### 7.2.1.1 Prevention

Patients in HD have an increased risk of developing IE due to all the reasons described before, so to take some measurements sounds logical to diminish the incidence of bacteremia which can result in an IE.

In some hospitals, their politics have been changed regarding the hemodialysis procedure with the intention to ameliorate the arteriovenous life expectancy and decrease the local and systemic infections. For instance, Oun HA et al. have published a lowering in the bacteremia and IE at his hospital adopting new strategies, such as changing the lock solution to taurolidine, cleaning the puncture site with chlorhexidine 2%, and using the buttonhole technique instead of the rope ladder technique.

Nonetheless, it is important to mention that the buttonhole technique had a modest but not significative rising of bacteremia following the move to buttonhole [26].

The arteriovenous fistula (AVF) must always be the best option to perform HD due to their low rates of bacteremia and IE, so, it is imperative to develop an adequate surgical technique and improve the care of the fistula. Whenever it is possible, the fistula must be carried out at the distal part of the arms, trying to preserve the proximal areas to future AVF if the distal fistula fails at some point. If the HD needs a temporary or permanent catheter, the cuffed ones always are preferable to non-cuffed catheters, because the former cause fewer rates of IE [29].

The patient and healthcare personnel must be informed and trained regarding the proper care of the AVF and catheters to lower the probability of bacteremia and IE. The cleaning of the surgical area is paramount as well as the correct AVF puncture.

#### 7.2.2 Intracardiac devices (ICD)

Nowadays ICD are widely used worldwide; their implementation in the cardiology area has improved the quality of life of many people and increased the survival; nonetheless, they have side defects, the endocarditis being one of the most severe complications.

The IE on a cardiac device is increased in the last 10 years in the first-world countries, even becoming the most common cause of IE in some regions. This phenomenon is caused mainly by the rise in the longevity in these countries which results in a growing number of intracardiac devices implanted (pacemakers, cardiac defibrillator, cardiac resynchronizer, or ventricle assist device) [32].

This IE is associated with a worse prognosis and high mortality (11–36%) [32–34]. The pacemaker generator or lead change is the higher factor of risk for IE on the cardiac device. The tricuspid valve is the most common site of RSIE associated with this kind of devices [7, 35].

The removal of the infected device is mandatory in the treatment of intracardiac device infective endocarditis (ICDIE) because it decreases the hospital mortality [32]. Patients with device-related infection and intracardiac vegetations higher or equal at 1 cm have historically undergone surgery for device removal due to the potential risk for septic embolization [34].

#### 7.2.3 Congenital heart disease (CHD)

The risk of IE in patients with adult congenital heart disease (ACHD) is substantially higher (15–140 times) than in the general population. The RSIE in CHD is more often in adults than pediatric patients [5, 36].

The ventricular septal defect (VSD) is the most frequent anomaly in right-sided IE with an incidence of 0.2–2% of all IE [37].

The risk of IE can occur either in repaired or not repaired VSD, with a higher increase in the last one [38].

A recent paper from Tutarel et al. found an incidence of 15.9% of IE in patients with VSD; the 50% of these cases were associated with infections of either the tricuspid valve or the right ventricular outflow tract [36].

The 2015 ESC IE guidelines describe that the distribution of causative organisms does not differ from the pattern found in acquired heart disease, with streptococci and staphylococci being the most common strains. Another study found the streptococci responsible for 50% of congenital heart disease infective endocarditis (CHDIE) and the staphylococci with a 31% incidence [5, 36].

The pulmonary valve is affected in almost 32% of patients from which over an 84% are prosthetic and near 16% native valve [36].
