Age: 31 years
Gender: Female
Occupation: Supermarket clerk
Working diagnosis: Functionally univentricular heart after Fontan-type palliation, 16 weeks pregnant
HISTORY
The patient was cyanotic at birth and had her first palliative procedure (a classic left-sided BT anastomosis) in her native country at the age of 11 years. She felt well after this operation.
She immigrated to the United Kingdom at the age of 17 and by then had noticed dyspnea on exertion. She was investigated in a pediatric cardiology department and the diagnosis of functionally univentricular heart with pulmonary atresia was made. She underwent further surgery at the age of 20 years. A Fontan-type operation was performed with ligation of the BT anastomosis.
She felt much improved after this operation and her cyanosis resolved. She did not continue regular cardiological follow-up. She married at the age of 30. The couple did not practice any contraception. She became pregnant within a year and was referred at 16 weeks gestation from her local obstetrician.
Comments: The classic BT anastomosis was the first palliative procedure developed for “blue babies” and aims to increase pulmonary blood flow when pulmonary atresia or stenosis limits pulmonary blood supply. It originally involved an end-to-side connection of the subclavian artery to the ipsilateral pulmonary artery. This procedure resulted in an absent arterial pulse in the arm. Later versions of the BT shunt used an interposition tube graft to connect the subclavian or a central systemic artery with a pulmonary artery. PAH—an uncommon complication of classic BT shunts—was addressed with this modification in which different sizes tubes were employed for different sizes of patients and for varying degrees of cyanosis. Arterial pulse in the ipsilateral arm was less affected.
Fontan-type operations were developed for patients with a univentricular heart to direct the systemic venous blood to the pulmonary arteries without the interposition of a subpulmonary ventricle, and to abolish right-to-left shunting. These operations therefore approached normalization of oxygen saturation at the cost of nonpulsatile pulmonary blood flow and elevated systemic venous pressure. The original Fontan operation consisted of the interposition of a valved conduit between the right atrium and the main pulmonary artery and has been modified many times since.
It is common for patients with ACHD, complex or not, to leave proper follow-up, believing that their heart condition has been cured. Patients with ACHD need to know that lifelong follow-up is required for most of them and that further investigations and interventions might be needed. Women of reproductive age must be told of the impact of their heart condition on their childbearing potential. As cardiac disease, mostly congenital, is a leading cause of maternal death in developed countries, timely prepregnancy counseling must be offered to all women with congenital heart disease to prevent avoidable pregnancy-related risks and for crisis management.
CURRENT SYMPTOMS
The patient did not complain of any change in her well-being since becoming pregnant. She had not experienced shortness of breath nor had she noted a reduction in her exercise capacity.
She reported that she could walk without limitation on level ground and could climb three to four flights of stairs without any problems.
Furthermore, she has been free of palpitations, chest pain, and dizziness.
NYHA class: I
Comments: The risk for pregnant women with congenital heart disease of suffering an adverse cardiovascular event such as symptomatic arrhythmia, stroke, pulmonary edema, heart failure, or death increases with the anatomic complexity of the congenital heart lesion, the degree of cyanosis, myocardial dysfunction, poor functional class, and the severity of systemic outflow tract obstruction.
The fact that this patient presented in good condition, feeling well, and unlimited in her exercise capacity was therefore indicative of a relatively good prognosis for the pregnancy, even though all pregnancies in Fontan patients should be considered relatively high risk.
PHYSICAL EXAMINATION
BP 110/70 mm Hg, HR 73 bpm, oxygen saturation 97%
Height 160 cm, weight 56 kg, BSA 1.58 m 2
Surgical scars: Scars from a left lateral thoracotomy and a median sternotomy
Neck veins: Jugular veins were difficult to assess but not grossly dilated. Normal waveforms not present.
Lungs/chest: Chest was clear.
Heart: The heart rate was regular. The cardiac impulse was not displaced. She had a normal first heart sound and a single and loud second heart sound with a grade 1/2 short systolic ejection murmur at the upper left sternal border and no diastolic or continuous murmurs.
Abdomen: No hepatomegaly
Extremities: No clubbing and no left arm pulses. The right radial artery and femoral artery pulses were normal.
Comments: An oxygen saturation of 97% is optimal for a patient after a Fontan-type palliation and indicates that the vast majority of systemic venous blood enters the pulmonary arteries and that there are no major sources of right-to-left shunt within or outside the heart.
As central venous pressure is the driving force of blood flow through the lungs, it should be elevated in patients after a Fontan-type repair. An elevated JVP is therefore expected and not necessarily a matter of concern. The lack of pulsation of the jugular vein may indicate that the central venous pathways are disconnected from the atria, which is the case in newer modifications of the Fontan operation (e.g., total cavopulmonary connections).
A loud second heart sound in this patient may indicate the anterior position of the aorta and aortic valve. Pulmonary hypertension was certainly not present here and cannot be seen in a patient with a Fontan circulation where blood flows through the lungs passively driven by the venous pressure. A single second heart sound is common in Fontan patients, since antegrade flow from the heart to the pulmonary artery via the pulmonary valve is surgically interrupted as part of the Fontan procedure.
A low-grade systolic heart murmur at the upper sternal border indicates slight turbulent systolic blood flow within the heart or at the level of a heart valve. If there was blood flow across a severely stenotic pulmonary valve, the murmur would be much louder. Regurgitation of the mitral or tricuspid valve would be heard best at the lower sternal border. The patient’s murmur is therefore most likely due to a mild stenosis of the aortic valve or some turbulence in the outflow tract. The lack of the left radial pulse and the left lateral thoracotomy are in keeping with a previous BT anastomosis.
LABORATORY DATA
| Hemoglobin | 13.1 g/dL (11.5–15.0) |
| Hematocrit/PCV | 37% (36–46) |
| MCV | 87 fL (83–99) |
| Platelet count | 152 × 10 9 /L (150–400) |
| Sodium | 140 mmol/L (134–145) |
| Potassium | 3.7 mmol/L (3.5–5.2) |
| Creatinine | 0.7 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 4.4 mmol/L (2.5–6.5) |
OTHER RELEVANT LAB RESULTS
| Total bilirubin | 19 µmol/L (3–24) |
| ALP | 70 U/L (67–372) |
| ALT | 21 IU/L (8–40) |
| AST | 28 IU/L (13–33) |
| Total protein | 63 g/L (62–82) |
| Albumin | 41 g/dL (37–53) |
Comments: All laboratory tests were normal. There was no erythrocytosis and therefore no evidence of chronic cyanosis. At times Fontan patients have a relatively high hemoglobin to compensate for low-cardiac-output-introduced arterial oxygen saturation. This is not the case in this patient.
Hepatic dysfunction can be present in patients with a Fontan circulation as hepatic venous pressure is chronically elevated, although liver function tests are insensitive in assessing this. A condition called PLE is another long-term complication related to the Fontan circulation. The patients lose protein into their intestine. Protein-losing enteropathy leads to low protein and albumin levels and to peripheral edema (see Case 62 ). The exact pathophysiology of this condition is unclear, but the role of chronically elevated central venous blood pressures can be assumed.
In summary, normal liver function tests and protein levels were additional indicators of a well-functioning Fontan circulation in this patient.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 73 bpm
QRS axis: +267°
QRS duration: 95 msec
PR interval: 154 msec
There was sinus rhythm with normal AV conduction.
There was a superior QRS axis. The tall R-wave in lead V1 and persistently negative S-waves in leads V4–6 suggest RV hypertrophy, although criteria for ventricular hypertrophy are very difficult to apply in the setting of a functionally single ventricle.
Comments: Sinus rhythm and a normal pulmonary regurgitation interval are both favorable findings in a patient after Fontan-type surgery. Atrial scarring from surgery and RA enlargement from high systemic venous pressure commonly lead to atrial flutter/fibrillation or (less often) heart block.
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