Age: 29 years
Gender: Male
Occupation: College instructor
Working diagnosis: Mustard repair of transposition of the great arteries
HISTORY
The diagnosis of TGA was made postnatally, and the patient underwent a balloon atrial septostomy (Rashkind procedure) followed by a Mustard operation at 2 years of age. He did well after the procedure and had a normal childhood.
He had been well until 6 months prior to his presentation (29 years old) when he developed a rapid and significant decline in his functional status. Exertional dyspnea prevented him from walking more than a block on flat ground, and he was not able to climb a flight of steps.
He was seen and started on diuretics. Soon the patient was able to return to his usual activities. He then underwent further evaluation.
Comments: The atrial redirection, or “switch,” operations, as described by Mustard and Senning were the first definitive operations for TGA. These operations involved redirecting blood flow at the atrial level. However, these operations leave the RV and the tricuspid valve in the systemic (subaortic) position. They have now been largely replaced by the arterial switch operation.
CURRENT SYMPTOMS
On diuretics, he was able to walk up several flights of stairs and felt that he had no functional limitation. His main recreational activity was dancing, which he had resumed.
NYHA class: I
Comments: After an atrial switch operation, potential cardiovascular causes of functional decline include systemic ventricular dysfunction, AV valve regurgitation, sustained arrhythmias, baffle obstruction and leaks, and pulmonary hypertension.
PHYSICAL EXAMINATION
BP 110/75 mm Hg, HR 70 bpm, oxygen saturation 99% on room air
Height 176 cm, weight 76 kg, BSA 1.93 m 2
Surgical scars: Midline sternotomy scar
Neck veins: JVP was normal.
Lungs/chest: Lungs were clear to auscultation.
Heart: There was no cyanosis or clubbing. There was a thrill at the left sternal border. The first heart sound was normal, and the second heart sound was loud and single. There was a grade 4/6 pan-systolic murmur heard best at the lower left sternal border.
Abdomen: No clinical hepatosplenomegaly
Extremities: No peripheral edema, and the peripheral pulses were normal.
Comments: Normal arterial saturations indicate that there is no significant right-to-left shunt through a baffle leak, although baffle leaks typically shunt left to right like other ASDs.
In atrial switch patients, the JVP reflects filling of the LV through the mitral valve.
The second heart sound is usually single in patients with TGA. This is because the aortic valve is located anteriorly, and the softer pulmonary sound is more posterior and less audible. Splitting of the second heart sound may indicate the development of pulmonary hypertension, when the normally soft posteriorly placed pulmonary closure sound becomes accentuated and thus audible.
The presence of a loud pan-systolic murmur suggests significant tricuspid regurgitation in this context. If this patient had a VSD, the murmur intensity would not be in the usual location since the shunt would be from RV to LV. Dynamic LVOT obstruction can also result in a systolic ejection murmur, but this was a not present in this patient.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 75 bpm
QRS axis: +140°
QRS duration: 122 msec
Normal sinus rhythm, normal P-wave morphology, right-axis deviation, and voltage criteria for RV hypertrophy with RV strain or repolarization abnormalities.
24-hour Holter ECG monitor: There was sinus rhythm throughout the study with an average heart rate of 75 bpm. There were rare, isolated ventricular and atrial premature complexes.
Comments: There is mandatory hypertrophy of the systemic RV, which is almost always obvious on the ECG.
Arrhythmias are common in patients after an atrial switch operation, and loss of sinus rhythm may precipitate functional deterioration. Arrhythmias that may develop include bradyarrhythmias, especially sinus bradycardia with junctional escape rhythms; intra-atrial reentry tachyarrhythmias (mainly atrial flutter variants); ventricular tachycardia; and sudden death. Arrhythmias are associated with cardiac morbidity and mortality.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 47%
The cardiac silhouette is at the upper limits of normal. There was a narrow vascular pedicle, with absence of the main pulmonary artery along the left heart border. There was no evidence of pulmonary venous hypertension or pulmonary edema. Sternal wires were present.
Comments: The narrow vascular pedicle is often (but not always) seen in TGA because of the parallel anteroposterior or side-by-side (as opposed to the normal crossed) relationship of the great vessels. The cardiac silhouette should be normal in size unless there is atrial or ventricular dilation.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
