Age: 33 years
Gender: Male
Occupation: Musician
Working diagnosis: Transposition of the great arteries
HISTORY
The patient was diagnosed with D-TGA at birth and underwent an atrial septostomy. Subsequently, a Mustard atrial redirection procedure was performed, and the patient did well.
Three years ago he was noted to have a junctional rhythm with bradycardia. He was not willing to consider insertion of a permanent pacemaker. Soon afterward he was found to have episodes of intra-atrial reentrant tachycardia (atypical atrial flutter) and junctional bradycardia. Beta-blockers to treat the tachyarrhythmia were contraindicated due to bradycardia. In view of this, the issue of insertion of a permanent pacemaker was again raised, and the patient consented to it.
Comments: Sinus node dysfunction is common in patients with transposition of the great arteries and prior atrial redirection surgery. The risk is due to a combination of both extensive atrial surgical scar formation and associated hemodynamic abnormalities.
PHYSICAL EXAMINATION
Pink
BP 100/80 mm Hg, HR 72 bpm, oxygen saturation 97%
Height 173 cm, weight 64 kg, BSA 1.75 m 2
Surgical scars: Median sternotomy scar
Neck veins: V-waves seen 3 cm above the sternal angle
Lungs/chest: Clear to auscultation
Heart: The rhythm was irregular. There were no palpable thrills. There was a normal first heart sound and a single second heart sound. A grade 1 systolic murmur was heard at the lower left sternal edge.
Abdomen: The liver was not palpable; there was no ascites.
Extremities: No edema was present, and the skin was warm.
PERTINENT NEGATIVES
There were no signs of SVC obstruction such as facial puffiness, swelling of the arms, or dilation of veins over the upper thorax.
Comments: The single second heart sound is due to the anterior position of the aortic valve, which is audible, whereas the more posteriorly located pulmonic valve is often not.
Patients with prior atrial redirection surgery are at risk of obstruction of the venous pathways. Fullness of the face and fluid retention, such as ascites or edema of the upper or lower extremities, may be evidence of obstruction, but its absence does not exclude the problem.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: ∼75 bpm
QRS axis: +165°
QRS duration: 106 msec
Atrial flutter at a rate of ∼250 bpm with a controlled ventricular response
Marked RV hypertrophy with right-axis deviation
Comments: RV hypertrophy is universal in patients with a Mustard or Senning repair of transposition of the great arteries. This is due to the hypertrophy of the RV in response to systemic arterial pressures. The right-axis deviation is due to the dominant forces produced by the systemic RV. Arrhythmias (especially atrial flutter variants) are common in these patients.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 47%
Normal heart size. There were prominent vascular markings with probably upper lobe distribution flow. There were no Kerley B lines and no clear evidence of interstitial edema.
Comments: There is no cardiomegaly and no evidence of overt heart failure in this patient. There is no appreciable dilatation of the azygos vein or SVC to suggest venous pathway obstruction.
EXERCISE TESTING
| Exercise protocol: | Bicycle ergometer starting at 12 W and increasing 10 W every min |
|---|---|
| Duration (min:sec): | 11:00 |
| Reason for stopping: | Sense of choking |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 72 | 147 |
| Percent of age-predicted max HR: | 79 | |
| O 2 saturation (%): | 97 | 90 |
| Blood pressure (mm Hg): | 100/80 | 120/80 |
| Peak V o 2 (mL/kg/min): | 24 | |
| Percent predicted (%): | 48 | |
| Ve/V co 2 : | 48 | |
| Metabolic equivalents: | 7.0 | |
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