Age: 32 years
Gender: Female
Occupation: Retail manager
Working diagnosis: Noonan syndrome
HISTORY
The patient was diagnosed with pulmonary stenosis and Noonan syndrome at birth in 1972 and underwent open pulmonary valvotomy at the age of 11 months. Her childhood and adolescent development were relatively normal, with the expected manifestations of Noonan syndrome. Her level of physical activity was not limited by shortness of breath, and she performed well academically at school. Her social development and interactions were normal.
In her early 20s, she noticed increasing shortness of breath with less exertion. Workup showed progressive pulmonary stenosis, and she underwent balloon valvuloplasty with a good result.
Since then she had no further dyspnea. She underwent a sterilization procedure at the time of her marriage, 4 years ago, without complication. Her career progressed and she held a number of posts in middle-level retail management.
Apart from hypothyroidism she has had no other medical problems. She is a nonsmoker and drinks alcohol only occasionally.
Two months ago the patient began to experience nonexertional dizziness and lightheadedness on occasion. She had two brief syncopal episodes with minimal exertion, which she recovered from spontaneously. At the same time, she noted some limitation in pursuing activities of daily living and was short of breath on minimal exertion. She presented for further workup.
Comments: Noonan syndrome is a common autosomal dominant condition characterized by dysmorphic facies, short stature, and congenital heart disease. Most commonly, the patients have pulmonary stenosis. The incidence is estimated at between 1 in 1000 and 1 in 2000 live births.
Up to three quarters of male infants with Noonan syndrome may have undescended testes. Cryptorchidism, in turn, may adversely affect fertility. In the presence of normally descended testes, men with Noonan syndrome are likely to be fertile. Pubertal development is delayed is both sexes, and fertility does not appear to be affected in females.
PHYSICAL EXAMINATION
Pink, comfortable at rest, characteristic facies of Noonan syndrome
BP 115/75 mm Hg, HR 75 bpm, oxygen saturation 96%
Height 135 cm, weight 50 kg, BSA 1.37 m 2
General: The patient had a webbed neck, low-set ears, and low hairline.
Surgical scars: Midline sternotomy scar
Neck veins: JVP was not elevated and was normal in character.
Lungs/chest: Chest was clear.
Heart: A grade 3 ejection systolic murmur was audible in the aortic area, radiating to the carotids, and a grade 3 ejection systolic murmur was also heard in the pulmonary area radiating to the back.
Abdomen: Soft with no palpable organs
Extremities: Warm and well perfused. The patient was not clubbed.
Comments: The normal jugular venous contour is notable in any patient with suspected right heart abnormalities.
It can be difficult to distinguish a murmur of aortic stenosis from pulmonary stenosis, particularly if both are loud. Position of the murmur differs, as well as duration of the murmur relative to the second heart sound. While right-sided heart murmurs and sounds typically may be augmented by inspiration, this may be difficult to appreciate when the murmur is loud. Murmurs due to pulmonary stenosis radiate more to the back than murmurs due to aortic stenosis, because of the more anteroposterior direction of the main pulmonary artery, compared to the ascending aorta.
LABORATORY DATA
| Hemoglobin | 13.7 g/dL (11.5–15.0) |
| Hematocrit/PCV | 40% (36–46) |
| MCV | 88 fL (83–99) |
| Platelet count | 251 × 10 9 /L (150–400) |
| Sodium | 139 mmol/L (134–145) |
| Potassium | 3.8 mmol/L (3.5–5.2) |
| Creatinine | 0.6 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 4.0 mmol/L (2.5–6.5) |
Comments: The patient was not anemic or erythrocytotic.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 77 bpm
QRS axis: −95°
QRS duration: 80 msec
Normal sinus rhythm, indeterminate axis, tall R-wave in V1
Comments: The dominant R-wave in V1 and deep S-wave in V6 are consistent with RV hypertrophy due to pressure overload. There are no signs of LV hypertrophy. The superior axis is characteristic of patients with Noonan syndrome.
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 49%
Sternal wiring indicated a previous median sternotomy. There is no significant cardiomegaly, and the pulmonary vascular markings were normal.
Comments: Findings on CXR in a patient with Noonan syndrome depend on associated lesions. Significant pulmonary stenosis with severe RV hypertrophy, AVSDs, and hypertrophic cardiomyopathy can all give cardiomegaly, while coarctation of the aorta will produce characteristic findings of the aortic knuckle (see Case 24 ).
ECHOCARDIOGRAM
