Age: 17 years
Gender: Male
Occupation: Student
Working diagnosis: Subaortic stenosis
HISTORY
Neurofibromatosis type 1 (NF1) was diagnosed soon after birth. No other health issues were identified, however, and the patient grew up normally.
One year ago at a routine clinic visit he was noted to have a systolic murmur. An echocardiogram confirmed significant fibromuscular subaortic stenosis. He was asymptomatic.
He underwent resection of the subaortic obstruction and longitudinal myectomy via a median sternotomy and longitudinal pericardiotomy. The pericardium was completely closed at the end of the procedure. Postoperative recovery was uneventful apart from a persistent 8-mm pericardial effusion without hemodynamic compromise, treated with aspirin.
Two months later he was readmitted to the hospital with dyspnea. Echocardiography showed a minimal pericardial effusion, good LV function, no LVOT obstruction, and mild aortic regurgitation. However, he was very breathless with large bilateral pleural effusions of uncertain etiology. Bilateral chest drains were inserted. The pleural fluid was a transudate. There was continuous drainage from both sides of the chest. Various means were tried in an attempt to reduce the drainage, including albumin replacement, somatostatin infusions, and even total parenteral nutrition and a fat-free diet in case this was a chylothorax. He was also developing a large ascites. Despite these empiric remedies, recurrent pleural effusions remained a problem. Therefore, 5 months later, the patient underwent open thoracotomy, pleural biopsy, and right talc pleurodesis. Repeat echocardiography demonstrated a thickened pericardium, confirmed on CT scanning. He was transferred for further assessment.
Comments: NF1 is an autosomal dominant disease affecting 1 in 4000 births. The involvement of neurofibromin in cardiac development is strongly supported by NF1 “knockout” mouse models; thus there is a higher-than-expected frequency of congenital heart disease among NF1 patients, ranging from 0.4% to 6.4% in published series. Of congenital heart defects seen, valvular pulmonary stenosis predominates and is a recognized feature of three uncommon clinical subtypes: (1) NF1, Watson syndrome; (2) NF1, Noonan syndrome; and (3) individuals with large deletions of the NF1 gene.
Subvalvular aortic stenosis spans a spectrum of anomalies from a simple fibrous membrane to a tunnellike fibromuscular band. A small proportion present de novo and are often referred for investigation of an asymptomatic heart murmur as in this case, although others may have a recurrence of a previously resected subvalvular membrane. Subaortic stenosis tends to be progressive, and surgery is recommended for symptomatic patients. The management of asymptomatic individuals is not well defined. In the young adult, a resting LVOT peak pressure gradient of 50 mm Hg or higher has been used as a criterion for intervention. Surgical resection should also be considered in patients with lower gradients if there is LV systolic dysfunction, moderate/severe aortic regurgitation, or a VSD.
PHYSICAL EXAMINATION
BP 114/77 mm Hg, HR 110 bpm, oxygen saturation 98% on room air
Height 170 cm, weight 66.3 kg, BSA 1.77 m 2
Surgical scars: Median sternotomy, right thoracotomy
Neck veins: The neck veins were markedly distended. Examiners were unable to identify the top of the venous pulsation even with the patient upright. There were prominent X and Y descents.
Lungs/chest: There was dullness to percussion and reduced breath sounds at the right lung base.
Heart: The rhythm was regular. There were normal heart sounds, no murmurs heard, and no third heart sound or friction rub.
Abdomen: Significant ascites and hepatomegaly were appreciated.
Extremities: Mild ankle edema was present.
Comments: The patient has obvious elevation of the central venous pressure (CVP). Elevated JVP is the hallmark of constrictive pericarditis. The X and Y descents in systole and early diastole, respectively, are prominent.
Kussmaul’s sign (not noted in this patient) was first described in patients with constrictive pericarditis and denotes the abnormal inspiratory increase in venous pressure when the heart is unable to accept the increase in systemic venous return without a marked increase in the filling pressure.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 102 bpm
QRS axis: +74°
QRS duration: 76 msec
Sinus tachycardia, normal axis, widespread T-wave inversion
Comments: Voltage criteria for LV hypertrophy, although absent in this case, would be expected in 65% to 85% of patients with subaortic stenosis.
Generalized T-wave inversion is a common finding in constrictive pericarditis. Other recognized changes include low QRS voltage and LA abnormalities suggestive of “p mitrale.”
CHEST X-RAY
FINDINGS
Cardiothoracic ratio: 47%
Situs solitus, levocardia, left aortic arch.
Median sternotomy clips were present. The heart size was at the upper limit of normal. An elevated right hemidiaphragm was seen with a possible right pleural effusion.
Comments: There was no evidence of pericardial calcification, which would be suggestive of tuberculous or idiopathic constrictive pericarditis (see also Case 72 ).
ECHOCARDIOGRAM
FINDINGS
The ventricular chambers were normal in size. There was normal LV systolic function (LVEDd 45 mm, LVESd 35 mm). Peak LVOT velocity was 1.0 m/sec. The atria were dilated.
Comments: The systolic function is not impaired, but on cine imaging, limited diastolic expansion could be appreciated as a result of pericardial constriction. It is difficult to assess the pericardial thickness with echocardiography, but it appears thickened and bright in this window.
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