Age: 22 years
Gender: Female
Occupation: Mother
Working diagnosis: Ebstein anomaly of the tricuspid valve
HISTORY
The patient was diagnosed early in infancy with Ebstein anomaly of the tricuspid valve, ASD, and RVOT obstruction. At 1 year of age she underwent a successful balloon dilatation of the obstructed RVOT.
She remained well and asymptomatic until 2 years ago (20 years old) when she had a successful pregnancy but suffered a stroke after delivery, from which she fully recovered. Following this she underwent a successful device closure of the ASD, which was thought to have been the cause of a paradoxical embolus.
Her exercise tolerance remained normal up until 6 months prior to presentation. During this time her major complaint was shortness of breath on mild to moderate exertion. She was referred for further evaluation.
Comments: Ebstein anomaly has a prevalence of 5 per 100,000 live births (0.5% of congenital heart disease). Most cases are sporadic, although familial cases have been reported. A predisposing factor may be maternal use of lithium carbonate during pregnancy.
Ebstein anomaly is defined as apical displacement of the septal and often mural leaflets of the tricuspid valve. Associated abnormalities include the presence of an ASD or stretched PFO, conduction system abnormalities, RVOT obstruction, and other cardiac defects.
Pregnancy in women with Ebstein anomaly can be well tolerated in the absence of significant cyanosis, arrhythmia, and/or heart failure.
As patients become older, tachyarrhythmia becomes a frequent and often disabling complication. Arrhythmia is usually supraventricular but can also be ventricular in origin and may lead to sudden cardiac death.
CURRENT SYMPTOMS
Shortness of breath on exertion is the patient’s primary complaint. For example, she was unable to run after her 2-year-old son. The patient also described sporadic episodes of dizzy spells associated with palpitations. She denied chest pain or syncope.
NYHA class: II–III
Comments: Despite the risk of arrhythmia, heart failure, and cyanosis, many patients with Ebstein anomaly surviving to adulthood maintain a good NYHA class I–II for many years.
PHYSICAL EXAMINATION
Looking healthy, pink, and well perfused
BP 110/70 mm Hg, HR 78 bpm, oxygen saturation 98% on room air
Height 165 cm, weight 67 kg, BSA 1.75 m 2
Neck veins: 3–4 cm above the sternal angle
Lungs/chest: Clear lung sounds
Heart: The rhythm was regular. A mild RV lift was present. Normal first and second heart sounds were heard, with a 3/6 pan-systolic murmur at the lower left sternal edge. A soft ejection systolic murmur was also heard.
Abdomen: Normal
Extremities: Normal palpable peripheral pulses, with no radiofemoral delay detected. There was no edema.
PERTINENT NEGATIVES
None
Comments: The JVP can remain low or normal despite severe tricuspid regurgitation due to severe enlargement of the very compliant RA.
Typical auscultatory findings in Ebstein anomaly include wide splitting of the first (the second portion sometimes referred to as a sail-like sound) and second sounds (due to RBBB), a gallop rhythm, and a holosystolic murmur.
The systolic ejection murmur was probably due to mild residual RVOT obstruction.
LABORATORY DATA
| Hemoglobin | 13.9 g/dL (11.5–15.0) |
| Hematocrit/PCV | 39% (36–46) |
| MCV | 89 fL (83–99) |
| MCHC | 34 g/dL (31–35) |
| Platelet count | 210 × 10 9 /L (150–400) |
| Sodium | 141 mmol/L (134–145) |
| Potassium | 3.6 mmol/L (3.5–5.2) |
| Creatinine | 0.91 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 4.7 mmol/L (2.5–6.5) |
| ALP | 53 U/L (38–126) |
| ALT | 9 IU/L (8–40) |
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 80 bpm
QRS axis: +131°
QRS duration: 113 msec
Sinus rhythm with borderline first-degree heart block
Right bundle branch block. Poor R progression. Unusual Q-waves V2–3. No frank RA overload. Generally low-voltage ECG.
24-hour Holter ECG: Sinus rhythm with sinus arrhythmia, and occasional supraventricular and ventricular ectopics.
Comments: The ECG in Ebstein anomaly is highly variable. The most common findings are first-degree block, RBBB, low voltage, and RA overload.
The apical displacement of the septal tricuspid valve leaflet is associated with discontinuity of the central fibrous body, creating a potential substrate for multiple accessory AV pathways invariably located in the atrialized portion of the RV. If an accessory pathway is present, it is usually mapped and obliterated either surgically or preoperatively using percutaneous radiofrequency ablation techniques. On this occasion there was no evidence of pre-excitation.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 60%
Cardiomegaly with RA enlargement. There is no evidence of pulmonary hypertension. The lung fields are normal.
Comments: The prominent bulging of the right cardiac border indicates right atrial enlargement, as is often seen in Ebstein patients.
The findings largely depend on the severity of the disease. The cardiac silhouette may vary but is generally of a globular shape due to RA enlargement and dilatation of the RV infundibulum. The aortic knuckle is often small, reflecting the chronically low cardiac output in many of these patients.
EXERCISE TESTING
Treadmill Stress Test
| Exercise protocol: | Modified Bruce |
|---|---|
| Duration (min : sec): | 9 : 12 |
| Reason for stopping: | Dyspnea |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 78 | 165 |
| Percent of age-predicted max HR: | 83 | |
| O 2 saturation (%): | 98 | 81 |
| Blood pressure (mm Hg): | 110/40 | 145/70 |
| Peak V o 2 (mL/kg/min): | 14 | |
| Percent predicted (%): | 43 | |
| Ve/V co 2 : | 31 | |
| Metabolic equivalents: | 4.7 | |
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