Age: 46 years
Gender: Male
Occupation: Accountant
Working diagnosis: Repaired tetralogy of Fallot
HISTORY
The patient had a primary repair of TOF when he was 8 years old. Following this he remained well under occasional follow-up for the following 28 years.
He then complained of palpitations at age 36. He was started on sotalol. Echocardiography demonstrated severe pulmonary regurgitation. Though occasional palpitations persisted, these were tolerated well, and no further evaluation was pursued.
Eight years later, at age 44, he presented with atrial reentrant tachycardia requiring direct current cardioversion. Sotalol was discontinued and amiodarone commenced. A workup confirmed his severe pulmonary regurgitation. After case discussion, pulmonary valve replacement was deferred and electrophysiology study with a view to ablation was planned. Mapping confirmed atrial reentrant tachycardia around a scar, and he underwent successful ablation of the likely pathway. He was symptom free for 6 months, but atrial reentrant tachycardia continued to recur despite amiodarone, and repeated direct current cardioversion at his local hospital was required. He presented for further management.
Comments: Pulmonary regurgitation is a common finding 20 to 30 years after repair of TOF; it has been associated with an increased risk of both atrial and ventricular arrhythmia, late RV dysfunction, and sudden cardiac death. To address legitimate concerns that untreated pulmonary regurgitation may lead to irreversible RV dysfunction, pulmonary valve implantation needs to be considered. However, these issues must be balanced with both the fact that pulmonary regurgitation in some patients is well tolerated for decades and the fact that currently available bioprosthetic valves have a finite lifespan. The timing of pulmonary valve surgery, therefore, remains a challenging clinical decision.
The onset of arrhythmia in the context of pulmonary regurgitation after repair of TOF is an indication to assess the degree of pulmonary regurgitation and ventricular function. Arrhythmia may be considered as an indication for valve replacement. According to the principles of mechanoelectric interaction, arrhythmias may reflect hemodynamic abnormalities, with both components requiring attention.
PHYSICAL EXAMINATION
BP 125/86 mm Hg, HR 64 bpm, oxygen saturation 99%
Height 182 cm, weight 62 kg, BSA 1.77 m 2
Surgical scars: Midline sternotomy scar
Neck veins: The JVP was not elevated, and the waveform was normal.
Lungs/chest: Clear to auscultation and percussion
Heart: The heart rate was regular. There was an RV heave. Auscultation revealed a normal first heart sound and an ejection systolic murmur followed by a single second heart sound with absent pulmonary component. There was a short, early diastolic murmur at the right sternal edge. Peripheral pulses were palpable and equal.
Abdomen: No abnormality detected
Extremities: No clubbing or swelling of ankles
Comments: This patient had classic features of significant pulmonary regurgitation. The short, early diastolic murmur is in keeping with severe pulmonary regurgitation, as is the RV heave. Bear in mind that the clinician may be surprised that in severe pulmonary regurgitation with no turbulence, the murmur may not be heard at all.
LABORATORY DATA
| Hemoglobin | 14.7 g/dL (13.0–17.0) |
| Hematocrit/PCV | 45% (41–51) |
| MCV | 96 fL (83–99) |
| Platelet count | 183 × 10 9 /L (150–400) |
| Sodium | 138 mmol/L (134–145) |
| Potassium | 3.9 mmol/L (3.5–5.2) |
| Creatinine | 0.8 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 6.3 mmol/L (2.5–6.5) |
OTHER RELEVANT LAB RESULTS
| T4 | 15.7 pmol/L (7.5–21) |
| TSH | 2.39 IU/L (0.32–5.0) |
| Calcium (corr) | 2.35 mmol/L (2.20–2.62) |
| Inorganic phosphate | 1.09 mmol/L (0.8–1.40) |
| Magnesium | 0.81 mmol/L (0.7–1.0) |
| INR (on warfarin) | 2.5 |
Comments: It is important to remember thyroid dysfunction both as a cause of arrhythmia and as a consequence of amiodarone therapy. In this case, thyroid function was normal.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 66 bpm
QRS axis: +85°
QRS duration: 144 msec
Sinus rhythm with RBBB. There is voltage evidence for LV hypertrophy (R1 + S3 > 25; raVL > 11 mm).
Comments: RBBB is a typical finding after repair of the TOF, particularly in older adults who had a right ventriculotomy at the time of surgery. The QRS duration in this context may nevertheless additionally change over time reflecting volume dilatation of the right side of the heart. Prolonged QRS duration greater than 180 msec is regarded as a risk factor for sudden cardiac death. Given the history and examination findings one may have expected the QRS duration to have been longer in this patient.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 50%
Borderline cardiomegaly, prominent main and left pulmonary arteries, normal pulmonary vascular markings, no evidence of thoracotomy.
Comments: Despite clinical evidence of significant pulmonary regurgitation , the heart is not significantly enlarged in this patient. This is in keeping with the modest prolongation of QRS duration.
There is no evidence of ascending aortopathy; the aortic knuckle is not enlarged.
EXERCISE TESTING
| Exercise protocol: | Modified Bruce |
|---|---|
| Duration (min:sec): | 10:38 |
| Reason for stopping: | Dyspnea |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 64 | 157 |
| Percent of age-predicted max HR: | 90 | |
| O 2 saturation (%): | 99 | 98 |
| Blood pressure (mm Hg): | 125/86 | 140/90 |
| Peak V o 2 (mL/kg/min): | 28.5 | |
| Percent predicted (%): | 78 | |
| Ve/V co 2 : | 35 | |
| Metabolic equivalents: | 8.4 | |
Comments: Maximal V o 2 and Ve/V co 2 values are abnormal with respect to age and sex-matched controls, but are relatively preserved with respect to other repaired TOF patients with pulmonary regurgitation (see Case 41 ), though this patient exercised for a shorter duration than average.
ECHOCARDIOGRAM
OVERALL FINDINGS
Normal LV size and systolic function were seen. The RV was moderately dilated with normal systolic function. There was mild tricuspid regurgitation with mild to moderate RA dilatation. Severe pulmonary regurgitation was demonstrated with no functioning pulmonary valve tissue.
There was normal LV size and function. The RVOT was dilated. The aortic root measured 38 mm. A small residual VSD (5 mm) with left-to-right shunt was demonstrated with a gradient of 80 mm Hg.
Comments: Aortic regurgitation from aortic root dilatation must be excluded in any patient with TOF (see Case 45 ).
FINDINGS
There was severe dilatation of the RV with normal systolic function. The tricuspid valve was mildly regurgitant with RA enlargement also present.
Comments: Atrial enlargement augments the risk of atrial arrhythmia.
FINDINGS
There was no residual stenosis through the RVOT. The regurgitation ends well before the completion of diastole, consistent with severe regurgitation.
Comments: Note the antegrade flow in end diastole; the A-wave, suggesting the RV is already filled to capacity in mid diastole such that atrial contraction results in forward flow to the pulmonary artery (PA). This flow pattern tends to be more noticeable in ventricles without severe dilatation (see Case 41 ), although it can occur in the latter.
For the aortic valve, Doppler traces can be used to calculate a pressure half-time to gauge the severity of regurgitation. No such guidelines have been worked out for pulmonary valve severity, though the general concept is the same. The velocity will fall at a faster rate in the setting of more severe regurgitation, because the pressure difference between the PA and RV will equalize much faster (albeit the pressure difference in diastole between PA and RV is normally much smaller compared to the aorta and the LV).
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