Keywords
pacemaker endocarditis - primary cardiac non-Hodgkin lymphoma
Introduction
Despite improvements in design and implantation techniques of cardiac devices, infection
remains a serious problem. Although the reported incidence of infection varies among
studies with infection rates between 0.13[1] and 19.9%[2] reported, infection rates seem to have increased over the recent years. A study
by Uslan et al showed an incidence of cardiac implant infections of 1.9 per 1,000
device-years[3] however, infection rates seem to be rising faster than implantation rates.[4] Like endocarditis in general, lead endocarditis is a malignant disease with a 1-year
mortality of 12% for pocket infections and 25% for endovascular infections.[5] Symptoms of a pacemaker endocarditis include erosion, sinus tracts, fevers, chills,
and sepsis. These symptoms are rather specific but are not sensitive. As for positive
blood cultures and valvular or lead vegetations, they are signs of more severe disease
and with a worse prognosis. In this patient, all clinical parameters indicated a pacemaker
endocarditis. As for the large vegetation found around the lead in the left and right
atrium, an open surgical approach was used to extract the pacemaker wires.
Case Description
A 78-year-old patient received a DDD pacemaker a year prior to the recent admission
due to an atrioventricular (AV) block II° (MOBITZ 2). Postoperative course was uneventful
and he was discharged 4 days after primary admission. Echocardiography was not performed.
He neither received a coronary angiogram despite known coronary artery disease with
percutaneous transluminal coronary angioplasty (PTCA) and stent implantation of the
left anterior descending and right coronary artery 6 years ago. He developed subfebrile
temperatures, deterioration of the general condition, as well as peripheral edema
and tachycardia within 3 weeks prior to the next admission. He was readmitted to a
general hospital. The initial diagnosis was a suspected pacemaker endocarditis. Echocardiography
seemed to confirm the diagnosis showing large vegetation in the right and left atrium,
connected via an atrioseptal defect ([Video 1]). The patient was placed on ampicillin and gentamycin. He was urgently referred
to our clinic for surgical removal of the pacemaker wires and provisional pacemaker
implantation.[6] We performed a coronary angiogram showing a mild progression of the known coronary
artery disease, especially for the right coronary artery with high-grade stenosis
before and after the stent. Transthoracic echocardiography confirmed the vegetation
in the left and right atrium as well as pericardial effusion. Drawn blood cultures
were negative; however, the patient showed an increased C-reactive protein of 122
mg/dL and leucocytes of 12.1 Tsd/µL. Pacemaker readout showed a decline in ventricular
and atrial sensing from 11.2 to 4 mV and 4.0 to 2.0 mV, respectively. Impedance decreased
accordingly for the atrium and the ventricle from 457 Ω to 313 Ω and 959 Ω to 490
Ω, respectively. The patient was scheduled for urgent open pacemaker explanation via
a median sternotomy, according to the size of the vegetation found in the atrium ([Video 1]).
After a median sternotomy, the patient was placed on cardiopulmonary bypass and the
atrium was opened. A large mass was encountered ([Fig. 1A]). Surprisingly, the vegetation turned out to be of solid consistence and was highly
tumor susceptive. Frozen section showed a cell rich neoplasmatic malignant tumor ([Fig. 1B]). The patient received a tumor resection with a partial septum and atrial resection
with an atrial septal defect closure, a reconstruction of the right atrium with a
pericardial patch as well as an explanation of the DDD pacemaker wires and epicardial
a left ventricular epicardial bipolar screwing electrode. The old pacemaker (which
had still ∼8 years of battery left) was connected to the epicardial pacemaker wires
as VVI. Due to the extensive operation and the fact that the patient did not show
any symptoms of coronary artery disease, no coronary artery bypass grafting was performed
for the treatment of the right coronary artery stenosis. The patient was extubated
timely on the intensive care unit. Postoperative course was uneventful and the patient
was readmitted to the department of hematology and oncology the 12th postoperative
day. Final pathology results of the explanted tumor showed a diffuse large cell B
non-Hodgkin lymphoma stadium IE, IPI: 2. He further received three courses of R-Benda
chemotherapy. Computed tomography after completion of the chemotherapy showed no indication
for suspicious thoracic lymph nodes. In the following course, a decline in right ventricular
(RV) sensing of the epicardial leads was detected and the patient received a RV and
right atrial leads for DDD pacing. He was later discharged home where he recovered
well from the operation. One year after the initial diagnosis, a reoccurrence of the
B cell lymphoma occurred at the left dorsal thoracic wall and the hypopharynx. He
again received chemotherapy. Today, 4 years after the initial diagnosis, he is tumor
free in overall acceptable condition.
Fig. 1 (A) The large tumor mass after atriotomy; (B) the explanted tumor mass, which turned out to be a cell rich neoplasmatic malignant
tumor.
Discussion
In this patient, almost every clinical hint leads us to believe pacemaker endocarditis
since the prevalence is significantly higher than a primary cardiac tumor. Especially
the encounter of a primary cardiac lymphoma is a rare entity, especially in an immune-competent
individual. Clinical presentation, fever, elevated C-reactive protein, and leucocytes
as well as the initially found suspected vegetation in the right and left atrium lead
to the suspicion of a pacemaker endocarditis. Nonetheless, as it turned out, the vegetation
was a tumor rather than of infectious cause. This is to our knowledge the first description
of a primary cardiac lymphoma disguised as a pacemaker endocarditis.
Retrospectively, as for primary cardiac tumors are known to cause arrhythmias, the
initial development of the AV block could have been caused by the tumor developing
a year prior to the recent event. We were surprised by the diagnosis of a tumor rather
than a lead endocarditis. If we had performed a computed angiogram before the operation,
we might have been able to identify the suspected vegetation as a tumor; however,
the patient's symptoms as well as history lead us to believe in our initial diagnosis.
Nonetheless, if we had been aware of the tumor, we probably would have chosen the
same operative approach. This case is a clear exemption from the known saying: “if
you hear hoof beats, think horses, not zebras.” In fact, the primary non-Hodgkin lymphoma
found in our patient was a quite rare breed of zebras. Altogether, our experience
clearly showed that our preoperative diagnostics were inadequate.
Primary cardiac tumors are a rare disease with autopsy incidence ranging from 0.001
to 0.030%. Most of the tumors (Three-quarters) are benign; nearly half the benign
heart tumors being myxomas and the rest are lipomas, papillary fibroelastoma, and
rhabdomyomas.[7] Primary cardiac lymphomas are even less frequent with only a few cases reported
over the years.[8]
A primary cardiac lymphoma is very rare with ∼60 cases reported in the literature.[9] To differentiate between a primary cardiac lymphoma and a cardiac involvement in
generalized lymphoma (stage IV), complete clinical and radiological staging is needed:
absence of lymphoma outside the pericardial sac after a complete autopsy examination
and bulk of the neoplasm within the pericardium or cardiac symptoms from lymphomatous
cardiac infiltration at the time of the initial diagnosis.[10] The mean age at presentation for cardiac lymphoma is ∼38 years with predominance
in men.[11] Patients with cardiac lymphomas present with various symptoms including cardiac
tamponade, heart failure, exertional dyspnea, and atrial fibrillation as well as right-sided
heart obstruction.[12] Morphologically, the lymphomas show multiple, firm, whitish-yellow nodules. Histologically,
they span the range of B cell proliferations and include follicle center-cell lymphomas,
immunoblastic lymphomas, diffuse large-cell lymphomas, and Burkitt lymphoma.
In conclusion, we hereby encountered an unexpected very rare entity of a primary cardiac
lymphoma around the pacemaker leads.
