Age: 28 years
Gender: Male
Occupation: Travel guide
Working diagnosis: Congenitally corrected transposition of the great arteries
HISTORY
The presence of a murmur at birth led to an echocardiogram, and the patient remembered being told by his parents that he had reversed heart chambers. However, he had never undergone any surgical interventions.
Recently, during routine evaluation, he was told he may need valve surgery and sought a second opinion.
Comments: TGA means that there is a discordant ventriculoarterial connection. The term congenitally corrected means there is also a discordant AV connection, which hemodynamically “corrects” the abnormal ventriculoarterial connection. Thus, systemic venous blood enters the RA, empties into the LV, and is pumped to the pulmonary artery (PA). Hence, blood travels through the two circulatory beds in the normal sequence (in the absence of septal defects), but the RV is the systemic ventricle. Unless there are associated anomalies, the patients are not cyanotic and no intervention is needed in childhood or early adulthood. Common associated lesions are pulmonary stenosis and VSD. The expected consequences of CCTGA itself are systemic ventricular dysfunction, systemic tricuspid regurgitation (often associated with an Ebsteinoid malformation of the tricuspid valve), and complete heart block. Complete heart block is most likely related to the abnormal course of the conduction bundle (more anterosuperior and longer than seen in the normal heart).
CURRENT SYMPTOMS
The patient was completely asymptomatic. He denied any shortness of breath on exertion and could run for 45 minutes without any problems. He had no orthopnea or nocturnal dyspnea. He also denied any palpitations, dizziness or syncope, chest pain, or leg swelling.
NYHA class: I
Comments: Patients even with mild to moderate systemic RV dysfunction will often be asymptomatic. Established moderate ventricular dysfunction will often precede the development of symptoms. Thus, when symptoms do develop, the patient’s mortality is much higher (47% after 15 years, compared to only 5% in asymptomatic patients).
CURRENT MEDICATIONS
Perindopril 4 mg daily
Comments: Although there is little evidence proving the benefit of ACE inhibitor in patients with systemic right ventricular dysfunction, data from studies of ACE inhibitors on systemic LV dysfunction in other forms of heart disease have been extrapolated to adults with systemic RVs. As a consequence, many adults with a systemic RV are empirically treated with such drugs, even without symptoms, unless contraindicated.
PHYSICAL EXAMINATION
BP 130/80 mm Hg, HR 64 bpm, oxygen saturation at rest 95%
Height 165 cm, weight 55 kg, BSA 1.59 m 2
Surgical scars: None
Neck veins: There was a normal waveform visible 3 cm above the sternal angle.
Lungs/chest: Clear to auscultation
Heart: The rhythm was regular. The apex beat was normal (palpable at 10 cm from the midsternal line in the fifth intercostal space). Heart sounds were also normal except for a single S2. No S3 or S4 was heard. There was a grade 3/4 systolic ejection murmur best heard at the second right intercostal space, and a 3/4 holosystolic murmur best heard at the apex radiating toward the left axilla. Peripheral pulses were normal.
Abdomen: There was no hepatosplenomegaly.
Extremities: Normal, no edema present, no clubbing
Comments: Unless the patient has severe pulmonary stenosis with a VSD, most patients with CCTGA will be acyanotic on examination.
The S2 is single, made of the A2 component. This is because the aorta is anterior and easily heard, whereas the pulmonary valve is posterior, which makes the P2 inaudible.
The murmur may be due to subpulmonary stenosis.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 68 bpm
QRS axis: −30°
QRS duration: 100 msec
Sinus rhythm with normal PR interval. The P-waves are broad and possibly notched in lead II. There are Q-waves in V2–3. Deep S-waves in V1–3. Tall peaked T-waves in the precordial leads.
Comments: These are typical ECG findings of a patient with CCTGA. Note the absence of Q-waves laterally in leads V5 and V6 as well as the presence of Q-waves anteriorly, in this case in V2 and V3 but more commonly found in V1 and V2. This pattern is due to ventricular inversion with the septum depolarizing from right to left as opposed to the usual left-to-right depolarization pattern. Note also the presence of probable LA enlargement (P-wave of 0.12 msec in lead II), which may suggest left AV valve regurgitation.
This patient does not have delta waves on his ECG, which should be sought since Wolff-Parkinson-White syndrome (accessory pathway) may be encountered in patients with CCTGA.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 43%
Situs solitus, levocardia, left-sided aortic arch. The cardiac silhouette was not enlarged, and the lung parenchyma appeared normal.
Comments: Because of the unusual position of the great vessels (a variable left anteroposterior relationship arrangement of the aorta and the pulmonary trunk), the pulmonary trunk is inconspicuous and the pedicle of the heart may be narrow because of the loss of the normal perpendicular relationship of the great vessels.
The patient has normal bronchial anatomy. The left bronchus (measured from the carina to its first branch) is nearly twice as long as the right bronchus. This finding indicates normal thoracic situs (situs solitus). Also, the gastric bubble is on the left, indicating normal abdominal situs. About a third of patients with CCTGA have dextrocardia (apex points to the right with most of the heart being located in the right hemithorax).
EXERCISE TESTING
| Exercise protocol: | Bruce |
|---|---|
| Duration (min:sec): | 12:00 |
| Reason for stopping: | Leg fatigue |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 64 | 175 |
| Percent of age-predicted max HR: | 91 | |
| O 2 saturation (%): | 97 | 97 |
| Blood pressure (mm Hg): | 130/80 | 155/90 |
| Peak V o 2 (mL/kg/min): | 34.2 | |
| Percent predicted (%): | 84 | |
| Metabolic equivalents: | 9.6 | |
Comments: Often, patients with systemic RVs will consider themselves “asymptomatic” but will perform poorly on an exercise capacity test compared to normal controls.
This was not the case for this patient, who performed at 84% of maximum predicted capacity for age, which is reassuring.
There is no evidence of chronotropic incompetence or exercise-induced AV block.
ECHOCARDIOGRAM
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