Age: 45 years
Gender: Male
Occupation: Sound engineer
Working diagnosis: Univentricular heart with pulmonary stenosis
HISTORY
The patient presented to his local hospital at the age of 9 years with mild cyanosis and dyspnea and an inability to keep up with his peers. The initial diagnosis was that of a large VSD, but subsequent cardiac catheterization at age 22 ultimately showed dextrocardia, functionally univentricular LV with a large VSD and a rudimentary RV, ventriculoarterial discordance, and subvalvar and valvar pulmonary stenosis.
He underwent a classic right BT shunt soon after his cardiac catheterization to enhance his pulmonary blood flow. Following surgery he was initially hemodynamically stable and less cyanosed with an improved exercise capacity. Two years after the BT shunt, at age 24, he developed paroxysmal atrial tachycardias, predominantly atrial fibrillation, but also atrial flutter (intra-atrial reentry tachycardia). Cardiac catheterization at the time showed mild pulmonary arterial hypertension with a mean pulmonary pressure of 25 mm Hg and high pulmonary blood flow. His ECG showed left atrial overload reflecting his increased pulmonary blood flow. He was treated with verapamil and digoxin, which controlled his symptomatic tachycardia until the age of 41.
The patient eventually developed persistent atrial fibrillation, and despite increased antiarrhythmic therapy and anticoagulation he was admitted in gross cardiac failure secondary to uncontrolled atrial fibrillation. A transthoracic echocardiogram showed a large RA thrombus and moderate pulmonary hypertension with impaired systemic ventricular function. Due to his ongoing hemodynamic instability he was direct current (DC) cardioverted despite the thrombus in his atrium. He experienced a systemic thromboembolic event (a transient ischemic episode, presenting with pins and needles in the left limbs and left side of his face). He was subsequently switched from verapamil to amiodarone (due to concern over his LV function) and had his dose of warfarin increased prior to being discharged. However, unfortunately, within a month he was readmitted with a gastrointestinal bleed secondary to a gastric ulcer after some alcoholic birthday celebrations.
Comments: The classic BT shunt was the first palliative procedure developed for blue babies and aimed to increase pulmonary blood flow if pulmonary atresia or stenosis was present. It involved the end-to-side anastomosis of the subclavian artery to the ipsilateral pulmonary artery.
Fontan-type operations were developed for patients with a functional “univentricular” heart to direct the systemic venous blood to the pulmonary arteries without the interposition of a subpulmonary ventricle. These operations therefore led to normalization in oxygen saturation at the cost of nonpulsatile pulmonary blood flow and elevated central venous pressure. The original Fontan operation consisted of the interposition of a valved conduit between the RA and the main pulmonary artery and has been modified many times since. Pulmonary arterial hypertension, even mild, is an absolute contraindication to any Fontan procedure, as blood must be able to flow through the pulmonary vasculature driven only by the systemic venous pressure.
Due to the presence of pulmonary arterial hypertension the patient was not considered suitable for a Fontan procedure. Although he remained well on follow-up, a routine CMR scan showed aneurysms at both ends of the BT shunt, that is, just above the right pulmonary artery and at the origin of the right subclavian artery anastomosis. Hypotensive therapy was therefore commenced to reduce the risk of further aneurysmal dilatation. Subsequent MRI scans over the following few years showed no further dilatation of the conduit aneurysm, and the atrial tachycardias remained quiescent. The patient complained of occasional intermittent palpitations but had no limitation of his exercise capacity or impact on his work, which involved long hours and much heavy lifting.
CURRENT SYMPTOMS
Dry cough, night sweats, and rigors were his predominant symptoms. Intermittent muscular chest pain was noted. He experienced diarrhea intermittently for several weeks. He felt himself slowing down at work and was increasingly tired on minimal exertion.
NYHA class: II
Comments: The history of this combination of symptoms, though somewhat vague and nonspecific in some respects, should alert the clinician to the possibility of a significant systemic illness such as infective endocarditis. Given the aneurysmal nature of the anastomotic graft sites and the likelihood of altered and turbulent flow this would represent a natural nidus for infection, as would the original stenotic native pulmonary valve.
PHYSICAL EXAMINATION
BP 110/60 mm Hg, HR 58 bpm, temp 37.5° C, oxygen saturation 80% on room air
Height 165 cm, weight 64 kg, BSA 1.71 m 2
Surgical scars: Right thoracotomy scar
Neck veins: JVP was 4 cm above the sternal angle with normal venous waveform.
Lungs/chest: Vesicular breath sounds, no wheeze or crepitations
Heart: Regular rhythm. There was a prominent ventricular lift over the right precordium with a nondisplaced right-sided apex, grade 4 ejection systolic murmur at the upper left sternal border, and single second heart sound. In addition, a grade 3 continuous murmur could be heard over the right chest.
Abdomen: No organomegaly; soft, nontender abdomen
Extremities: Moderate clubbing and cyanosis, normal left radial and bilateral femoral pulses, but absence of a right radial pulse. There were no Janeway lesions or Roth spots identified.
Comments: The lack of fever does not exclude subacute endocarditis.
The right thoracotomy scar and the lack of a right radial pulse are suggestive of a previous right BT shunt, when, in the past, the subclavian artery was transected and anastomosed end to side to the pulmonary artery. Since about 1980, a tube graft, often Gore-Tex has been used to make such a side-by-side connection between the subclavian and the ipsilateral pulmonary artery without the complete interruption of the subclavian artery. This type of shunt provided better control of the degree of additional pulmonary blood flow through the shunt and abolished the risk of pulmonary arterial hypertension (compared to the old, classic BT shunt).
The single second heart sound is indicative of the stenotic pulmonary valve. The loud ejection systolic heart murmur is consistent with turbulent flow across a severe valvar obstruction. In addition there is a loud and long heart murmur due to the turbulent flow in the aneurysmal BT shunt. Usually, such murmurs can be heard continuously in the back. The large unrestrictive VSD would not cause a murmur due to the lack of gradient from the left-to-right cardiac chambers.
LABORATORY DATA
| Hemoglobin | 13.4 g/dL (13.0–17.0) |
| Hematocrit/PCV | 38% (41–51) |
| MCV | 79 fL (83–99) |
| Platelet count | 170 × 10 9 /L (150–400) |
| WCC | 9.0 × 10 9 /L (3.6–9.2) |
| Neutrophils | 7.5 × 10 9 /L (1.7–6.1) |
| Lymphocytes | 1.1 × 10 9 /L (1.0–3.2) |
| Sodium | 133 mmol/L (134–145) |
| Potassium | 4.2 mmol/L (3.5–5.2) |
| Creatinine | 0.7 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 3.7 mmol/L (2.5–6.5) |
| Iron | 6.7 µmol/L (12.6–26.0) |
| Ferritin | 50 µg/L (32 – 284) |
| Transferrin saturation | 14% (20–45) |
Comments: The indolent nature of endocarditis is often reflected in only subtle changes in the hematologic and biochemical markers.
It is not unusual for the total white cell count to remain normal in endocarditis, as in this case. Neutrophilia and raised C-reactive protein (see below) indicate a likely bacterial infection.
The normal hemoglobin is also worrying in this case, as the patient has resting saturations of 80%. A compensatory erythrocytosis (rather than polycythemia, see Case 17 ) would be expected with hemoglobin levels between 18 and 20 g/dL. His relative anemia is likely due to iron deficiency, although subacute endocarditis may have also been contributory; the former (iron deficiency) should be treated with oral iron supplementation or intravenous iron if the oral form is not tolerated.
OTHER RELEVANT LAB RESULTS
| Bilirubin | 16 µmol/L (3–24) |
| ALP | 55 U/L (67–372) |
| ALT | 21 IU/L (8–40) |
| Total protein | 62 g/L (62–82) |
| Albumin | 23 g/dL (37–53) |
| CRP | 95 mg/L (0–10) |
| Blood cultures: Positive growth | |
| Gram stain showed gram positive cocci in chains. | |
| Urinalysis | |
| WBC | <10/mm 3 |
| RBC | >100/mm 3 |
Comments: The low albumin level may also relate to the systemic infection, although other causes such as nephrotic syndrome and/or PLE should be excluded (the latter is exceedingly rare in patients with non–Fontan type of palliation for univentricular heart circulation).
The growth of the gram-positive cocci in blood culture samples confirms the diagnosis of endocarditis, unless an alternative source of bacteremia is unequivocally identified. Treatment with a minimum of 4 weeks of intravenous antibiotics would be prudent given the underlying anatomy. In the absence of positive blood cultures the diagnosis of endocarditis remains a clinical one and somewhat speculative, although it should be seriously considered in a patient such as ours with an underlying shunt and a severely stenotic valve with complex ACHD.
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