Age: 27 years
Gender: Female
Occupation: Teacher
Working diagnosis: Pregnancy in a patient with a systemic right ventricle
HISTORY
The patient was cyanotic at birth due to D-TGA (simple transposition). She underwent balloon septostomy in infancy and Mustard repair at 11 months of age.
She required reoperation at 12 years of age for a residual atrial septal defect and pulmonary venous obstruction. She recovered fully and had no further problems throughout adolescence.
At age 26, sinus node dysfunction was noted and required placement of a dual-chamber permanent pacemaker.
At age 27, she expressed a desire to become pregnant. She reported occasional palpitations but no shortness of breath or sustained arrhythmias. An exercise treadmill test demonstrated normal exercise capacity for age. She completed 9.5 minutes on a standard Bruce protocol with a peak heart rate of 182 (93% maximum predicted heart rate), an appropriate blood pressure response, and no arrhythmias. Her echo showed a moderately hypertrophied systemic RV with mildly reduced systolic function (see Fig. 54-4 ). Mild-to-moderate tricuspid regurgitation was present (systemic AV valve). The SVC and IVC limbs of the atrial baffle were unobstructed as was the pulmonary venous to tricuspid valve connection. Cardiac catheterization was performed to determine whether any intervention might be required prior to pregnancy. The study demonstrated no baffle obstruction or residual ASD. Systemic RV systolic function was preserved with mild tricuspid regurgitation.
After a discussion of potential risks of pregnancy, she decided to proceed. During the first trimester, she had two short episodes of supraventricular tachycardia that were terminated with the Valsalva maneuver.
She had no further cardiac complaints until the 35th week of pregnancy when she developed orthopnea. She found it difficult to climb one flight of stairs without stopping and required two pillows to sleep. An echocardiogram demonstrated worsening tricuspid regurgitation. Her symptoms responded to diuretic therapy. She had an uncomplicated cesarian section for obstetrical indications but 1 week later developed worsening dyspnea and bilateral pedal edema treated with diuretics and an ACE inhibitor. Symptoms of heart failure persisted. Two months later, she developed sustained tachycardia, which was treated with radiofrequency ablation. Repeat cardiac catheterization was planned for three months post ablation.
Comments: D-TGA, or ventriculoarterial discordance with AV concordance, is a form of cyanotic heart disease that typically presents during the first week of life. If untreated, it carries a greater than 90% mortality in the first year. Balloon septostomy (the Rashkind procedure) is performed when necessary to improve intracardiac mixing in preparation for subsequent cardiac repair. In the 1960s, the atrial switch operations (Senning and Mustard repair) were introduced, wherein systemic venous blood is baffled across the atrial septum after which it passes through the mitral valve and morphologic LV and into the pulmonary artery. Pulmonary venous blood is directed across the tricuspid valve through the RV and into the aorta.
While the medium-term results are generally good, significant late complications following the atrial switch have been observed including failure of the systemic RV, systemic AV valve regurgitation (tricuspid valve), atrial flutter/fibrillation, sinus node dysfunction, baffle obstruction, and sudden death. Some reports suggest less baffle obstruction with the Senning repair, although overall morbidity and mortality are similar.
Most women with a systemic RV after atrial switch repair are now of reproductive age. Although there are no large studies evaluating the pregnancy risks in women after atrial switch procedures, several small retrospective series have reported successful outcomes in the majority of patients, although a significant number experienced deterioration in functional class. A recent retrospective study of 28 pregnancies in 16 patients reported a good clinical outcome; however, a reduction in systemic RV function was seen in 25% of cases that persisted for a mean follow-up of 2 years.
When considering medical therapy of arrhythmias in pregnancy, proarrhythmia and other potential adverse effects to the mother and fetus must be considered. It is probably best to avoid antiarrhythmic drugs as much as possible during the first weeks of gestation when the risk of developing congenital malformations is greatest. However, if needed, some drugs are considered safe. Beta-blockers are often used despite their reported association with small gestational size. Digoxin is safe during pregnancy. It crosses the placenta freely and is used to treat fetal supraventricular tachycardia.
CURRENT MEDICATIONS
Digoxin 0.25 mg orally daily
Furosemide 40 mg orally daily
K-dur 20 mEq orally daily (potassium supplement)
Lisinopril 5 mg orally daily
Comments: Diuretics are initial therapy in patients with a failing systemic RV and congestive symptoms. Although there is evidence that ACE-inhibitor therapy reduces mortality, hospitalizations, and recurrent cardiac events in adult patients with congestive heart failure unrelated to congenital heart disease, its use in patients with a systemic RV and Mustard or Senning repair has not been rigorously investigated. Small studies have not shown an improvement in exercise capacity or ventricular function after short-term ACE-inhibitor therapy. However, given the limitations of these small nonrandomized studies, no absolute conclusions regarding the cardioprotective benefit of ACE-inhibitor therapy in this population can be drawn.
During pregnancy, ACE inhibitors are contraindicated. Hydralazine, nitrates, and/or beta-blockers may be used as alternatives if required.
Digoxin has been extensively used without documented adverse effects to the mother or the fetus.
PHYSICAL EXAMINATION
BP 105/65 mm Hg, HR 80 bpm, oxygen saturation 98%
Height 168 cm, weight 86 kg, BSA 2.00 m 2
Surgical scars: Healed sternotomy scar
Neck veins: JVP was mildly elevated.
Lungs/chest: Clear lung sounds were heard in all fields.
Heart: An RV heave was present. S1 was normal. S2 was single and accentuated. A grade 2–3/4 holosystolic murmur was present at the lower left sternal border. No third heart sound was heard.
Abdomen: No hepatosplenomegaly was appreciated, and the liver was not pulsatile.
Extremities: Pedal edema was present; there was no cyanosis.
Comments: This patient had a prominent RV heave typical of patients with D-TGA and Mustard repair, which is related to the presence of the systemic RV. The loud aortic component of S2 is due to the anteriorly positioned aorta.
A pulsatile liver would not be expected, as tricuspid regurgitation is related to the systemic ventricle.
The elevated JVP and dependent edema attest to the presence of heart failure.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 77 bpm
QRS axis: +153°
QRS duration: 122 msec
Sinus rhythm with first-degree AV block and RV hypertrophy (marked right-axis deviation of initial QRS forces and R’ of 17 mm in V1).
Comments: RV hypertrophy is an expected finding in patients with D-TGA after Mustard or Senning repair, reflecting systemic RV pressure.
Simus node dysfunction and junctional rhythms are common in patients with D-TGA status after the Mustard procedure, although this is not seen in this ECG.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 58%
There was evidence of cardiac enlargement with pulmonary vascular congestion. A permanent pacemaker was in place. There were no pleural effusions.
Comments: Note the position of the ventricular pacemaker lead, which courses through the systemic venous pathway to the LV apex.
Comments: The lateral view also demonstrates transvenous pacing leads in the anatomic LA and LV consistent with a patient who has undergone an atrial switch operation for D-TGA.
EXERCISE TESTING
Cardiopulmonary Exercise Stress Test Performed 5 Months Postpartum
| Exercise protocol: | Modified Bruce |
|---|---|
| Duration (min : sec): | 13 : 50 |
| Reason for stopping: | Fatigue |
| ECG changes: | None |
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