Right-heart infective endocarditis: a propos of 10 cases

The prevalence and characteristics of right heart endocarditis in Africa are not well known. The aim of this study was to describe the epidemiological, clinical and laboratory profiles of patients with right-heart infective endocarditis. This was a 10-year retrospective study conducted in 2 cardiology departments in Dakar, Senegal. All patients who met the diagnosis of right heart infective endocarditis according to the Duke's criteria were included. We studied the epidemiological, clinical as well as their laboratory profiles. There were 10 cases of right-heart infective endocarditis representing 3.04% of cases of infective endocarditis. There was a valvulopathy in 3 patients, an atrial septal defect in 1 patient, parturiency in 2 patients and the presence of a pacemaker in one patient. Anaemia was present in 9 patients whilst leukocytosis in 6 patients. The port of entry was found to be oral in three cases, ENT in one case and urogenital in two cases. Apart from one patient with vegetations in the tricuspid and pulmonary valves, the rest had localized vegetation only at the tricuspid valve. However, blood culture was positive in only three patients. There was a favorable outcome after antibiotic treatment in 4 patients with others having complications; three cases of renal impairment, two cases of heart failure and one case of pulmonary embolism. There was one mortality. Right heart infective endocarditis is rare but associated with potentially fatal complications.


Introduction
Infective endocarditis is defined as more or less the extensive damage to the endocardium caused by microorganisms (bacteria or yeast). The microbes are "grafted during bacteraemia on either a healthy or on a previously injured endocardium". Isolated endocarditis of the tricuspid valve or associated with pulmonary valve defect are less frequent than those of the left.They occur mostly among intravenous drug users, immune-compromised patients and those with congenital heart disease [1,2]. Their prevalence and characteristics in Africa are not well known.

Methods
We conducted a 10-year retrospective descriptive multicenter study

Results
During the study period, there were 10 cases of right-heart infective endocarditis representing 3.04% of infective endocarditis and 0.055% of all hospitalizations. The average age of our patients was 31 years (range from 9 to 70 years).There was a female predominance with a sex ratio (F:M) of 2.33. The socio-economic profile was low in 3 patients, and was average or good in 7 patients.
Three patients had valvulopathies (a mitral stenosis associated with a tricuspid insufficiency, a mitral valve disease associated with a tricuspid insufficiency, an aortic insufficiency associated with a tricuspid insufficiency). A case of atrial septal defect was noted, two parturients and a patient with single chamber pacemaker. One patient reported a fever of long duration. The data of the patients are summarized in Table 1. Clinically 7 patients had a tachycardia with an average heart rate of 127.62 beats/min; nine patients had fever with an average temperature of 38.5°C (36.1 to 40°C). A tricuspid murmur was found in 9 patients. There were in two patients, a mitral diastolic rumbling; and in one patient an aortic diastolic murmur. There was an interstitial pneumonia and pleural effusion in 3 and 4 cases respectively, four patients had congested hepatomegaly, a case of hemiparesis was noted. The port of entry was found to be oral in three cases, ENT in one case and urogenital in two cases. In one case pacemaker lead was incriminated and in another an iatrogenic cause was found. Laboratory studies found anaemia in 9 cases with a mean hemoglobin of 9.5 g/dl (range from 6.6 g/dl to 11.2 g/dl); leukocytosis in 6 patients. The mean white blood cell count was 21,643.33 /mm3 (6400/mm3 to 44000/mm3).The erythrocyte sedimentation rate in the first hour was increased in four patients, a high CRP level in 8 patients Blood cultures were performed in 9 patients with an average of 2 sets/patient and were positive in 3 cases. Germs isolated respectively were Streptococcus pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa. Urinalysis was carried out in 8 patients but was positive in one case. ECG found two cases of a trial fibrillation, a patient with an S1Q3 pattern with background tachycardia. All patients had benefited from a transthoracic Doppler echocardiography and two of whom also had a trans-oesophageal echocardiography. A vegetation or more were found in all patients. dose of 3mg/kg/day for an average of 12 days, which was combined respectively with ampicillin in 4 cases, ceftriaxone in four cases, oxacillin in two cases. The outcome was favorable in four patients.
However it was associated with complications in others. There were three cases of renal impairment, heart failure in two patients and one case of pulmonary embolism. There was one mortality occurring in a 70-year-old who died from sepsis, after 8 days of hospitalization. The average hospital stay was 39.7 days (8 to 90 days).

Discussion
Right-heart endocarditis is less common. Its prevalence varies between 5 to 10% depending on the series [1]. Lejkó-Zupanc et al in a paper on 205 patients with endocarditis conducted in 1999, reported 13 cases of right heart endocarditis. It is common to find IV drug users in patients with a right heart endocarditis with the incidence in this population varying from 3 to 5%. In our series, no history of substance abuse was reported. The authors found four patients whose cause was iatrogenic (central venous catheter, pacemaker probe). In four others, there was an immunecompromised status (alcoholic cirrhosis, cancer) [2]. Genital port of entry is not uncommon [3]. Kimbally-kaky also reported 7 cases of endocarditis of the right-heart from illegal abortions in an aseptic environment [4]. We noted a difference in age and sex ratio between our series and those reported in the literature [5]. This is explained by differences in etiologic factors including rheumatic heart disease. Forms of endocarditis in congenital heart disease have been described [6]. Blood cultures are a vital test in the diagnosis of endocarditis. They may however be negative, 14% of cases by Delahaye [7]. The low rate of positive blood cultures found in our series is similar to other series in Africa [4].This finding could be explained by prior antibiotic treatment in most patients with fever, technical conditions in carrying out blood cultures (unsanitary conditions or sample delivery to laboratories), slow growing germs and sometimes a lack of culture plates in our laboratories. Doppler echocardiography plays a major diagnostic role [1]. Germs implicated in a French series were streptococcus in 48% of cases and staphylococcus in 29% [8]. Heart failure may complicate infective endocarditis. It is more common in African series [9] than in the West [10]. One of the most dreaded complications is probably septic pulmonary embolism. Lejkó-Zupanc et al reported in 9 cases out of 13 patients with endocarditis of the right heart. The image most frequently found was that of a pulmonary infiltrate and not that of a pulmonary infarction [1]. Similarly, renal involvement is not uncommon and should be monitored. Its existence, just as advanced age, would be a poor prognostic factor [9]. Mortality in infective endocarditis is still significant between 16-27%, despite the progress in terms of antibiotic therapy [6].

Conclusion
Right heart infective endocarditis is uncommon. This is a serious condition because of its potentially fatal complications.
Circumstances of occurrences and port of entry are variable.

Competing interests
The authors declare no competing interest  Table   Table 1: Summary of data of ten patients