Bacteremia and the heart. Serial echocardiographic findings in 80 patients with documented or suspected bacteremia

The prospective role of transesophageal echocardiography in the diagnosis and management of patients with suspected infective endocarditis

STUDY OBJECTIVES

Transesophageal echocardiography (TEE) has a high sensitivity for the diagnosis of infective endocarditis (IE), but the prospective role of TEE when added to a careful clinical examination has not been well-studied.

DESIGN

We compared the results of TEE to a clinical evaluation by an infectious disease specialist in 43 consecutive patients in whom TEE was ordered to rule out IE. Prior to TEE, the patients were classified on clinical grounds as to their likelihood of IE using a modification of the von Reyn criteria. Changes in management occurring as a result of TEE also were evaluated.

MEASUREMENTS AND RESULTS

TEE was positive in 11 patients, negative in 29, and indeterminate in 3. TEE was positive in 6 (46%) of 13 high probability patients, 2 (67%) of medium probability patients, and 3 (11%) of 27 low probability patients. A change in management based on TEE occurred in 4 (31%) patients with high probability, in no patients with medium probability, and in 1 (4%) patient with low probability.

CONCLUSIONS

TEE confirms IE in patients with high probability of IE and often leads to a management change. However, TEE is unlikely to establish the diagnosis or change management in patients with low probability.

Myocardial dysfunction in septic shock

Over the last decade, it has become clear that myocardial depression, like vascular dysfunction, is typical of human septic shock. Human septic myocardial depression is characterized by reversible biventricular dilatation, decreased ejection fraction, and decreased response to fluid resuscitation and catecholamine stimulation (in the presence of overall hyperdynamic circulation). A circulating myocardial depressant substance, not myocardial hypoperfusion, is responsible for this phenomenon. This substance has been shown to represent low concentrations of TNF-alpha and IL-1 beta acting in synergy on the myocardium through mechanisms that include NO and cGMP generation. Despite major advances in our understanding of the hemodynamics and pathogenesis of cardiac dysfunction in sepsis, successful attempts to modulate these mechanisms to improve clinical outcomes in human trials have not been demonstrated to date. For the moment, the therapeutic approach to the patient with cardiac dysfunction in distributive or septic shock must be primarily aimed at reestablishing adequate organ perfusion and oxygen delivery by vigorous fluid resuscitation and vasopressor or inotropic support. In the long term, however, only continued research regarding the cellular mechanisms of organ dysfunction, including septic myocardial depression, will lead to successful therapeutic strategies. These strategies will likely involve direct manipulation of intracellular signaling processes that lead to organ dysfunction as manifested by septic myocardial dysfunction and septic shock.

Non-Q wave acute myocardial infarction in acute meningococcemia in a 10-year-old girl

INTRODUCTION

Children with acute meningococcemia may have impaired myocardial function resulting in low cardiac output despite normal intravascular volume. Severe meningococcal infection has been associated with acute interstitial myocarditis, endocarditis, and pericarditis, but not with myocardial infarction.

CASE

We present the case of a 10-year-old girl with positive family history for premature myocardial infarction who sustained an acute myocardial infarction temporally related to meningococcemia.

DISCUSSION

This is the first pediatric case of non-Q wave acute myocardial infarction associated with purpura fulminans in meningococcemia. Similarly, the association of high troponin I levels and meningococcemia has not been described previously. Although, the patient's genetic predisposition for myocardial infarction might have been a potential contributing factor, there was no angiographic evidence of coronary artery disease in this patient. Thereby, other factors related to shock, endotoxin, microthrombi of meningococcemia, and their treatment might have been also contributing. We propose possible mechanisms for this rare but serious complication of meningococcemia and review the literature.

Echocardiographic assessment of vegetations in patients with infective endocarditis: prognostic implications

Today, echocardiography is the most important technique next to clinical findings and blood cultures in the diagnosis of infective endocarditis. The sensitivity of echocardiography, particularly the transesophageal approach, for detection of vegetations and endocarditis related valvular destructions is high. In addition, echocardiographic findings may have some prognostic implications. The size and mobility of vegetations stratifies endocarditis patients into a high risk group for arterial embolism. In particular, mobile vegetations attached to the mitral valve with a maximal diameter > 10 mm may be prone to embolic events. Furthermore, increase in size of vegetations during antimicrobial treatment may identify patients with no, or at least a prolonged, healing process. Also, a lack of increase in the echo density of vegetations under adequate antibiotic treatment may indicate a poor healing process and may necessitate more aggressive management. The demonstration of paravalvular abscesses by echocardiography, particularly by transesophageal echocardiography, identifies a subgroup of patients who will need urgent cardiac surgery before widespread tissue destruction has occurred.

Tricuspid valve endocarditis due to Staphylococcus aureus. Correlation of two-dimensional echocardiography with clinical outcome

We studied 53 episodes (51 patients) of tricuspid valvular endocarditis caused by Staphylococcus aureus in a predominantly addicted population and correlated two-dimensional echocardiographic findings with clinical outcome. Thirty-eight episodes with (vs 15 episodes without) tricuspid vegetations on the two-dimensional echocardiogram were significantly associated with (1) longer duration of fever on therapy (mean of 12.3 days vs 6.8 days, respectively; p less than 0.005); and (2) higher frequency of increased right ventricular end-diastolic (RVED) dimension (25 of 38 cases [66 percent] vs two of 15 cases [13 percent], respectively; p less than 0.01). Only patients with increased RVED dimension (5/25; 20 percent) required tricuspid valvular surgery for prolonged fever or progressive right-sided heart failure (p less than 0.05 vs patients with normal RVED dimension). Tricuspid vegetations greater than 1.0 cm identified a subset of patients at increased risk for developing clinical right-sided heart failure during the active or convalescent phase of endocarditis (p less than 0.02 vs patients with tricuspid vegetations less than 1.0 cm). An unexpectedly high prevalence of asymptomatic prolapse of the mitral valve was observed in this population (23 of 53 episodes; 43 percent). Detection of tricuspid vegetations in patients with endocarditis due to S aureus is not a primary indication for early surgery, but identifies patients more likely to exhibit short-term and long-term complications of their infection.

The contribution of a non-invasive test to clinical care. The impact of echocardiography on diagnosis, management and patient anxiety

We prospectively studied the impact of echocardiography on a cardiologist's diagnosis and management plan and on patient anxiety for 300 consecutive referrals. There was an impact on diagnosis in 90% of patients. Most common was confirmation of diagnosis usually with the addition of information pertinent to management (81%); change of disease category or resolution of diagnostic doubt was uncommon (9%). The consultant cardiologist believed the heart to be normal in 48 patients who did not have any associated disease; none had any echocardiographic abnormality. The cardiologist reported increased diagnostic confidence in 74% of all patients but management changed in only 9%. One-third of all patients reported reduced anxiety when this was an important clinical issue but in less than half of them did the cardiologist consider that echocardiographic information was essential for reassurance. Anxiety was increased in 6%, and in 12% the anxiety response was inconsistent with the test result. The clinical contribution of the test report was most obvious for those patients (30%) in whom this data was required for (a) a decision concerning specific diagnostic or technical intervention (b) a change of management plan which implied obvious or likely health benefit (c) reassurance which was a clinically important issue. The magnitude of this contribution was related to the study indication. The value of echocardiography is obvious when assessing patients for invasive intervention or when proper treatment or adequate reassurance are impeded by diagnostic doubt. However, for many current indications, we need better definition of factors which predict a clinically useful result. In particular, when the aim is to rule-out disease, our results suggest that an expert cardiological opinion would often be more appropriate than an echocardiogram.