Age: 20 years
Gender: Female
Occupation: Office clerk
Working diagnosis: Tricuspid atresia and severe pulmonary stenosis, prior Fontan (atriopulmonary connection)
HISTORY
The patient was born at term but was cyanotic, and a diagnosis was made of tricuspid atresia with pulmonary stenosis. A right modified BT shunt was constructed at the age of 2 months, followed by the addition of a left-side modified BT shunt at 2 years. Subsequently, at the age of 5 years a Fontan circulation was established by means of an atriopulmonary anastomosis (direct anastomosis between the RA and the confluent pulmonary artery (PA) on the right posterior side of the ascending aorta). Her BT shunts were ligated. Her postoperative course was smooth and uneventful.
At the age of 6 years, a routine postoperative cardiac catheterization demonstrated no obstruction within the pulmonary circulation, a low cardiac index (1.97 L/min/m 2 ), and mild hypoxemia (Sa o 2 92%).
Comments: Tricuspid atresia is usually palliated by the creation of a Fontan circulation. The method originally reported by Fontan in 1971 involved the interposition of a homograft between the RA and the left PA on the right and posterior aspect of the ascending aorta. In that patient, the right PA had already been isolated from the left PA and the SVC had been anastomosed in a conventional Glenn fashion. Direct anastomosis of the RA to the confluent pulmonary arteries was described by Kreutzer in 1973.
Generally our patient continued to do well through her primary and secondary education. She participated in physical training throughout and could climb three flights of stairs. During her follow-up visits, abnormal weight gain, edema, and hepatomegaly were occasionally noted when oral diuretics were not regularly taken or skipped.
At the age of 16 years, routine catheterization, 10 years after the Fontan procedure, demonstrated “normal” pressures through the venous pathways (SVC and IVC pressure of 13 mm Hg and PA pressure of 12 mm Hg), and again a low cardiac index (1.5 L/min/m 2 ). The arterial oxygen saturation was 96%. Contrast echocardiography showed a small right-to-left shunt at the atrial level, and cardiopulmonary exercise testing demonstrated a peak V o 2 of 20.5 mL/kg/min with an anaerobic threshold of 13.65 mL/kg/min.
She was seen again for routine clinical follow-up at age 20 years. She had started working full time.
CURRENT MEDICATIONS
Furosemide 30 mg twice daily
Spironolactone 25 mg twice daily
Enalapril 5 mg daily
Comments: Diuretics and ACE inhibitors are commonly used in single ventricle patients (37% and 39%, respectively, from a large multicenter descriptive study), although there is no clinical evidence supporting their use in this setting.
PHYSICAL EXAMINATION
BP 110/66 mm Hg, HR 70 bpm, oxygen saturation 94% on room air
Height 144 cm, weight 40 kg, BSA 1.26 m 2
Surgical scars: Median sternotomy and bilateral posterolateral thoracotomy scars
Neck veins: No visible JVP
Lungs/chest: Normal vesicular breath sounds
Heart: The rhythm was regular. There was no murmur audible. The second heart sound was single.
Abdomen: The liver was palpable 2 cm below the ribs at the midclavicular line. There was no ascites.
Extremities: Mild cyanosis was noted. There was no edema.
Comments: Because the jugular veins are no longer in direct communication with an atrium that fills and empties in the typical manner, the usual rise and fall of the venous pulse (including x and y descent) are not seen in the Fontan patient. Various patterns of jugular venous distension may reflect respiratory changes in flow, but clinical interpretation of the neck veins is difficult, and the usual rules are not easily applied.
LABORATORY DATA
| Hemoglobin | 15.5 g/dL (11.5–15.0) |
| Hematocrit/PCV | 46.8% (36–46) |
| MCV | 90.3 fL (83–99) |
| Platelet count | 144 × 10 9 /L (150–400) |
| Sodium | 139 mmol/L (134–145) |
| Potassium | 4.2 mmol/L (3.5–5.2) |
| Creatinine | 0.61 mg/dL (0.5–1.0) |
| Blood urea nitrogen | 14 mg/dL (6–24) |
| Total bilirubin | 1.0 mg/dL (0.2–1.2) |
| AST | 22 U/L (0–40) |
| ALT | 17 U/L (0–35) |
| Total cholesterol | 105 mg/dL (130–220) |
OTHER RELEVANT LAB RESULTS
| BNP | 267.1 pg/mL (<20.0) |
| Renin activity | 11.2 ng/mL/hr (0.5–2.5) |
| Aldosterone | 24.0 ng/dL (3–16) |
Comments: Activation of the renin-angiotensin-aldosterone system in ACHD is increasingly recognized. The pattern of neurohormonal activation perhaps justifies empiric use of pharmacotherapy to counteract such activation, though no clinical trials exist to support or refute this.
There was minimal erythrocytosis, which is associated with mild cyanosis.
It is known that the total cholesterol level is often lower in patients with cyanotic ACHD.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 68 bpm
QRS axis: +85°
QRS duration: 100 msec
Comments: The P-wave is wide and biphasic in the limb leads. In V1, the P-wave illustrates high negative voltage with a sharp deflection, probably related to a dilated or hypertrophied morphologic RA. The P-wave is broad and notched in leads I and II, suggesting LA overload as well.
In addition, there are widespread and nonspecific T-wave inversions.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 64%
Cardiomegaly. The RA shadow was enlarged, with the rightward border of the SVC and the IVC shadow more obviously seen than normal. The pulmonary vasculature was normal or reduced. No sign of pulmonary venous congestion was seen. Left aortic arch with situs solitus was noted. There was evidence of previous sternotomy.
Comments: The aortic knob appeared less prominent, indicating a prolonged low cardiac output. The enlarged cardiac silhouette is mainly due to RA enlargement.
FINDINGS
Enlargement of the RA. Retrosternal filling of uncertain origin.
EXERCISE TESTING
| Exercise protocol: | Modified Bruce |
| Duration (min:sec): | 6:00 |
| Reason for stopping: | Dyspnea |
| ECG changes: | Wandering P-wave morphology. No ST change. Nonsustained atrial tachycardia (HR 180–200 bpm) during latter portion of the test. |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 80 | 138 |
| Percent of age-predicted max HR: | 69 | |
| O 2 saturation (%): | 94 | 94 |
| Blood pressure (mm Hg): | 110/66 | 134/76 |
| Peak V o 2 (mL/kg/min): | 15.9 | |
| Percent predicted (%): | 48 | |
| Ve/V co 2 : | 30 | |
| Metabolic equivalents: | 4.3 | |
Comments: The amplitude and dispersion of the P-wave may be abnormal long after an atriopulmonary Fontan palliation.
An arrhythmia had not been seen during exercise in the last examination at 16 years of age.
Her exercise capacity is low, and even lower compared with her previous values.
ECHOCARDIOGRAM
FINDINGS
The RA was severely enlarged, measuring 70 mm × 60 mm ( arrow ). No thrombus was present in the RA. There was mild-to-moderate aortic regurgitation through the center of the valve orifice. The SVC was normal in size (11 mm, flow velocity was normal at 0.29 m/sec), but the IVC was dilated (18 mm × 22 mm). Flow velocity in the hepatic vein was normal at 0.28 m/sec. There was tiny bidirectional flow between the hypoplastic RV cavity and RA. The left PA had a slight narrowing at its origin from the pulmonary trunk. The LV was within normal limits (LVEDd 49 mm), with mildly reduced systolic function (LV ejection fraction 47%). There was only trace mitral regurgitation.
Comments: Until this echo investigation found a small communication between the RA and the small RV, the diagnosis had been tricuspid atresia. The finding changes the anatomic diagnosis to critical tricuspid stenosis, which is a small but noteworthy distinction. With critical tricuspid stenosis, mild desaturation after the Fontan procedure can be partly explained. A small right-to-left shunt at the atrial level shown on contrast echocardiography (see “ History ”) probably reflected the flow across the very severe tricuspid stenosis. Because of tricuspid stenosis, there must be a VSD between the main LV and the rudimentary RV.
While not perfect, the findings suggest satisfactory Fontan physiology. The enlarged RA has the potential to be both arrhythmogenic and thrombogenic.
CT ANGIOGRAPHY
FINDINGS
The connection between the RA and PA was widely patent. The RA cavity, IVC, and the coronary sinus were markedly dilated.
Contrast injected via an upper arm vein was stagnant and flowed slowly into the RA. A small amount of contrast from the RA entered the LA around the origin of the right pulmonary veins. The ostia of the right pulmonary veins into the LA were flattened and compressed by the remarkably dilated RA, but there did not seem to be significant pulmonary vein stenosis.
No thrombus was present within the RA. The right and the left PAs were confluent and generally slender, about 8 mm bilaterally.
Comments: There was a deformity of the hilar PA, particularly the left, which appeared pulled superiorly ( center right ). This was presumably related to the previous BT shunts, which can distort the branch PAs. At the time of the Fontan procedure, these tubes were ligated, but not divided.
Not all of the myocardium had uniform enhancement, suggesting the presence of perfusion abnormalities or myocardial scar. This finding, however, may merely reflect the abnormal flow patterns from Fontan physiology and should not be interpreted in the same way as in a patient with a normal circulation.
CATHETERIZATION
HEMODYNAMICS
| Calculations | |
|---|---|
| Qp (L/min) | 2.13 |
| Qs (L/min) | 2.39 |
| Cardiac index (L/min/m 2 ) | 1.89 |
| Qp/Qs | 0.89 |
| PVR (Wood units) | 1.41 |
| SVR (Wood units) | 25.57 |
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