A 51 year old farmer presents with low-grade fever and a recent history of weight loss. He has been investigated by his GP and general physicians but no cause has been identified for his symptoms. His inflammatory markers are raised and a TTE shows a 0.5 × 0.3 cm echogenic mass attached to the non-coronary cusp of the aortic valve. Endocarditis is suspected, although multiple blood cultures are negative.
Which one of the following organisms is the most likely cause of persistently negative cultures?
Infective endocarditis associated with constantly negative blood cultures can be caused by intracellular bacteria such as Coxiella burnetii, Bartonella, Chlamydia, and, as recently demonstrated, Tropheryma whipplei. These account for up to 5% of all IE. Diagnosis in such cases relies on serological testing, cell culture,or gene amplification. The HACEK group (Haemophilus parainfluenzae, H.aphrophilus, H.paraphrophilus, H.influenzae, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae, and K.denitrificans), Brucella, fungi, and nutritionally variant streptococci may also cause infective endocarditis that is frequently associated with negative blood cultures.
Which one of the following statements regarding outpatient parenteral antibiotic therapy (OPAT) for infective endocarditis is true?
The following criteria determine the suitability of outpatient parenteral antibiotic therapy (OPAT) for infective endocarditis.
A 60-year-old man presents to the emergency room with complaints of weakness, lethargy, and severe dyspnea. One week prior, his family notes that he complained of chest pressure that lasted for several hours. On physical examination, he appears to be in respiratory distress. Blood pressure (BP) is 80/50 mmHg. Heart rate is 130 bpm. His oxygen saturation is 87% on room air. Chest examination reveals diffuse crackles. Cardiac examination reveals a nondisplaced point of maximum impulse (PMI). Third and fourth heart sounds are heard, as is an apical systolic murmur. No thrill is present. Electrocardiogram reveals inferior Q waves without ST-segment elevation. He is urgently intubated and pressors are started. An intra-aortic balloon pump is placed. A surface echocardiogram reveals a normal-sized left atrium and a mild jet of mitral regurgitation (MR).
What test do you perform first?
Transesophageal echocardiography (TEE). The clinical history is of a patient who had an inferior wall myocardial infarction approximately 1 week ago. He now presents in shock with acute congestive heart failure. Mechanical complication of myocardial infarction is first on the differential. The presence of a ventricular gallop and an apical murmur without a thrill makes papillary muscle rupture the leading diagnosis (as opposed to ventricular septal defect). Transthoracic echocardiography may miss eccentric jets in this setting. TEE should be performed to make the diagnosis. He will certainly need a cardiac catheterization (at which time a saturation run may be performed), but a TEE should be done quickly at the bedside to confirm the diagnosis so that the surgical team can be mobilized.
A TEE is performed urgently (Fig. below) shows a 3D view of the mitral valve from above).
What is the most likely diagnosis?
Posterior papillary muscle rupture as it has a single blood supply. The 3D reconstruction of the mitral valve shown here is orientated in the “surgeons view,” looking down on the mitral valve from the left atrium with the aortic valve situated on top, the anterior mitral valve leaflet adjacent to it, and the posterior mitral valve leaflet inferiorly. We see a bulky mass (the posterior papillary muscle) protruding into the left atrium in systole. The middle panel (early diastole) clearly shows that the mass is attached to the posterior leaflet. The posterior papillary muscle has a single blood supply (usually the right coronary artery), while the anterior papillary muscle often has dual blood supply. For this reason, post infarction rupture of the posterior papillary muscle is more common.
A 65-year-old woman presents to your office for follow-up of a murmur she was told about several years prior. She denies any symptoms, but is not very active. Her past medical history is significant for hypertension and diabetes, both of which have been well controlled. On examination, she is in no acute distress. BP is 125/75 mmHg, with a resting heart rate of 70 bpm. Lungs are clear. Cardiac examination reveals a displaced PMI. S1 is soft. S2 reveals an increased P2 component. There is a right ventricular (RV) lift. An S3 is present. There is a grade III/VI holosystolic murmur heard at the apex radiating to the base. She has no peripheral edema. Chest X-ray demonstrated cardiomegaly with prominence of the central pulmonary vasculature.
An echocardiogram is performed on this patient (Fig. below).
Left ventricular (LV) systolic dimension is 4.7 cm. Ejection fraction is 45%. There is posterior leaflet prolapse. There is a very eccentric jet of MR, which is read out as 2+.
Which of the following is most likely?
She likely has more severe MR than is evident on the echocardiogram. Her examination is suggestive of severe MR. The echo confirms LV dilation and mitral leaflet pathology, which could be consistent. The eccentric nature of the jet suggests that it may have been underestimated by transthoracic imaging. A more definitive imaging procedure such as TEE will be helpful here.
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