Age: 33 years
Gender: Male
Occupation: Salesman
Working diagnosis: Large ventricular septal defect
HISTORY
During infancy, the patient was diagnosed with a large VSD and underwent pulmonary artery (PA) banding through a left thoracotomy at the age of 5 months.
At the time of PA banding for this patient, two-dimensional echocardiography and MRI were not yet available, and the complex anatomy could not be detected as easily as it can be today.
When he was 4 years old, he underwent a sternotomy to close the VSD. However, after direct inspection of the anatomic setting, the VSD appeared unsuitable for closure. The chest was, thus, closed without any intracardiac repair.
The possibility of a Fontan circulation was discussed at the age of 16 years, but it was felt better to be postponed at the time.
Over the ensuing years the patient remained well without any particular shortness of breath on exertion and without any report of cyanosis. He returned for routine follow-up.
Comments: A large VSD will allow for a pronounced interventricular left-to-right shunt as the pulmonary vascular resistance falls soon after birth. The consequent volume overload of the LV in infancy may then give rise to heart failure. PA banding is performed to decrease pulmonary blood flow, thereby preventing or alleviating ventricular failure and—more importantly—preventing the development of PA occlusive disease.
A Fontan circulation would be an option in which systemic venous return could be directed to the PA without passing through an RV. This would normally involve proximal PA ligation as well. Due to the large interventricular communication, both ventricles would then have acted as a “single” systemic ventricle.
Lack of notable cyanosis in this situation suggests an optimally balanced VSD shunt, namely adequate PA banding without excessive pulmonary flow and without substantial right-to-left shunting, at least at rest. The degree of secondary erythrocytosis in such a patient, when present—provided there is no iron deficiency—indicates indirectly the magnitude of right-to-left shunting at rest and/or during exercise.
CURRENT SYMPTOMS
The patient remains essentially asymptomatic without any history of exercise-induced dyspnea, cyanosis, or angina. On average he has one or two episodes of palpitations per year, always short lived, with no associated syncope or any other symptoms. He is fit, can climb several flights of stairs, and exercises several times a week.
NYHA class: I
Comments: The history suggests the VSD shunt to be appropriately balanced by the PA banding also during exercise, with no symptoms indicating inadequate pulmonary blood flow, significant hypoxemia, or LV dysfunction precipitated by exertion. The episodes of palpitation might represent transient atrial tachyarrhythmia although they also might be explained by ectopic beats.
PHYSICAL EXAMINATION
BP 130/80 mm Hg, HR 67 bpm, oxygen saturation 93% on room air
Height 165 cm, weight 70 kg, BSA 1.79 m 2
Surgical scars: There was a left thoracotomy and a median sternotomy scar.
Neck veins: JVP was not elevated.
Lungs/chest: Chest was clear.
Heart: There was an RV lift and a faint precordial thrill. Moreover, there was a normal first and a split second heart sound with a soft pulmonary component to it, and a grade 4/6 systolic ejection murmur at the upper left sternal edge, which radiated well to the back.
Abdomen: Soft and normal to palpation
Extremities: There was no evidence of clubbing or peripheral edema.
Comments: The scars originated from the PA banding during infancy and the intended VSD closure in childhood, respectively.
The RV heave suggests marked hypertrophy, presumably due to increased intraventricular pressure. Since the large VSD is not restrictive, the pronounced systolic murmur is therefore attributed to the impeded flow through the PA band rather than to the VSD, as is also indicated by its ejection character. This is supported by the radiation to the back, a finding more common in murmurs due to obstruction of intrathoracic vessels than in those of intracardiac origin.
These findings add to the other evidence suggesting no significant interventricular right-to-left shunting or any sign of heart failure.
LABORATORY DATA
| Hemoglobin | 16.1 g/dL (13.0–17.0) |
| Hematocrit/PCV | 46% (41–51) |
| MCV | 91 fL (84–98) |
| Platelet count | 205 × 10 9 /L (136–343) |
| Sodium | 138 mmol/L (134–145) |
| Potassium | 4.0 mmol/L (3.5–5.2) |
| Creatinine | 0.72 mg/dL (0.60–1.2) |
| Blood urea nitrogen | 3.8 mmol/L (2.5–6.5) |
| Ferritin | 237 µg/L (32–284) |
| Transferrin | 2.5 g/L (2.0–3.2) |
Comments: A significantly increased hemoglobin and hematocrit would reflect right-to-left shunting. The opposite is not always true: An apparently normal hemoglobin/hematocrit may be present with cyanosis if the patient has concomitant iron deficiency or other cause of anemia.
In this case, the hemoglobin and hematocrit values are not elevated and there is no evidence of iron deficiency. The laboratory findings therefore indicate that there has been no significant secondary erythrocytosis. This supports the clinical impression of no significant right to left shunting.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 67 bpm
PR interval: 220 msec
QRS axis deviation: +254°
QRS duration: 129 msec
Sinus rhythm with one ventricular ectopic beat, first-degree heart block, extreme axis deviation, RBBB.
Comments: The marked QRS axis deviation is similar to that usually associated with AVSDs or tricuspid atresia, and is not a typical finding in patients with VSD. The depolarization pattern might therefore suggest an unusual topographical arrangement of the ventricular myocardium.
The diagnosis of RV hypertrophy is difficult in the presence of RBBB.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 52%
The cardiac silhouette was mildly enlarged with evidence of RA dilatation. The central pulmonary arteries were dilated while the peripheral vascular markings were not definitely increased.
Comments: Central PA dilation is consistent with PA banding and enlargement of the vessel distal to the narrowing from poststenotic dilatation as well. RV hypertrophy resulting from PA banding may impair ventricular filling, thereby explaining the enlarged atrium. The lack of overtly increased vascular markings suggests there is no hemodynamically important excess pulmonary blood flow.
EXERCISE TESTING
| Exercise protocol: | Modified Bruce |
|---|---|
| Duration (min:sec): | 11:13 |
| Reason for stopping: | Dyspnea |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 67 | 125 |
| O 2 saturation (%): | 93 | 87 |
| Blood pressure (mm Hg): | 130/80 | 170/90 |
| Double product: | 21,250 | |
| Peak V o 2 (mL/kg/min): | 22.8 | |
| Percent predicted (%): | 67 | |
| Ve/V co 2 : | 68 | |
| Metabolic equivalents: | 4 |
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