Pulmonic Valvular Stenosis Workup

Updated: Dec 19, 2016
  • Author: Melanie A Loewenthal, MD; Chief Editor: Robert E O'Connor, MD, MPH  more...
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Workup

Laboratory Studies

Laboratory evaluation usually is not helpful.

Oximetry provides information on possible right-to-left shunting in borderline cyanotic lesions or in patients with anemia but does not identify the cause of the shunt (pulmonary, interatrial, interventricular, great arterial). [11]

Although arterial blood gases (ABG) analysis usually is not needed, one notable exception is the hyperoxia test in newborns with cyanosis of undetermined origin.

Administered 100% FIO2 generally does not increase the partial pressure of oxygen to levels much greater than 100 mm Hg in patients with a cyanotic congenital heart defect.

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Chest Radiography

Chest radiography may demonstrate a prominent main pulmonary artery segment but a normal heart size.

Pulmonary vascular markings are usually normal but may be decreased in severe pulmonic valvular stenosis. In severe valvular pulmonary stenosis, CHF presents as cardiomegaly with right ventricular and right atrial enlargement.

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Electrocardiography

ECG reflects the degree of right ventricular involvement.

Right axis deviation and right ventricular hypertrophy are seen in moderate valvular pulmonary stenosis.

Degree of right ventricular hypertrophy correlates with the severity of pulmonic valvular stenosis.

Tall R wave in V1 more than 10 mm suggests severe stenosis.

Incidences of arrhythmias are increased in patients with pulmonic valvular stenosis. [4, 22]

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Echocardiography

The transthoracic approach provides valuable information about the site of obstruction and other possible congenital abnormalities. [14, 23, 24, 25]

Valve surface area is not used to determine the severity of stenosis. Rather, the peak gradient across the pulmonic valve is used as an indicator of disease severity. [9] Doppler studies can accurately determine velocity of flow across the valve. The gradient is calculated from 4 times the peak systolic velocity squared: Pressure gradient = 4 X velocity squared

Multiple views and measurements increase the accuracy of the predicted peak systolic pressure gradient.

A thickened pulmonic valve with restricted systolic motion, called doming, in the parasternal short axis view is apparent.

Frequently, the main pulmonary artery is dilated distal to the stenotic orifice.

In a study that compared live/real-time three-dimensional transesophageal echocardiography (3D-TEE) with two-dimensional transesophageal echocardiography (2D-TEE) to determine whether there are advantages to using 3D-TEE on patients with pulmonary stenosis (PS), investigators prospectively enrolled 16 consecutive adult patients with PS and indications of TEE. They found evidence of the incremental value of using 3D-TEE instead of 2D-TEE during assessments of PS, specifically in cases where special conditions cause inaccuracy in recordings of the transvalvular peak gradient. The investigators concluded that during routine echocardiographic examinations, 3D-TEE should be used as a complementary imaging tool to 2D-TEE. [26]

Most children with pulmonary stenosis do not require further evaluation beyond echocardiography.

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CT Scanning and Magnetic Resonance Imaging

Modalities such as MRI and CT can show structural cardiac abnormalities. [27, 28]

One case report described the identification of a patient with isolated subvalvular pulmonary stenosis using whole-heart MRI. [29] This imaging tool is noninvasive and has the added benefit of creating a 3-dimensional representation of the heart and surrounding structures. Other reports have described the use of whole-heart MRI as a presurgical adjunct. [27]

Cardiac CT has been beneficial for noninvasive presurgical evaluation of someone with known coronary artery disease. The radiation exposure is minimal with cardiac CT, and the reconstructions of a 64-slice CT can yield very accurate images of myocardium changes associated with outflow tract obstruction. [28]

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Cardiac Catherization

Catheterization assesses the morphology of the right ventricle, pulmonary outflow tract, degree of tricuspid regurgitant flow, and pulmonary arteries. The technique for angioplasty was described in 1982. [30] This procedure is not indicated for mild pulmonic valvular stenosis, but it is essential in severe stenosis.

Cardiac catheterization is indicated when pulmonary stenosis is not adequately evaluated by echocardiography. When the peak systolic gradient is more than 36 mm Hg, then balloon valvuloplasty may be indicated. [11] Cardiac catheterization with balloon valvuloplasty is indicated if the gradient is more than 50 mm Hg. [4]

Patients with echocardiographic evidence of significant pulmonic valvular stenosis (>50 mm Hg) should undergo diagnostic and therapeutic cardiac catheterization. Percutaneous balloon dilatation, stenting, and pulmonic valve replacement [31] are increasingly being performed with high success rates. [32, 33, 34]

Findings from a retrospective Chinese study appear to indicate similar immediate and long-term results between single-balloon valvuloplasty in children and Inoue balloon valvuloplasty in adults with isolated pulmonary valve stenosis. [35] In the pediatric group (n=38), the right ventricular pulmonary artery systolic gradient decreased from a baseline of 52.79 +/- 35.08 mmHg to a postprocedure 22.55 +/- 12.92 mmHg (P < 0.001); in the adult group (n=42), the baseline gradient of 94.79 +/- 42.19 mmHg decreased to 34.02 +/- 15.00 mmHg (P < 0.001) following the Inoue balloon pulmonary valvuloplasty. At a median follow-up of 15 years, the investigators found no significant differences in gradients for both groups relative to those at 1-month follow-up. [35]

 

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Surgical Interventions

Patients with infundibular or supravalvular pulmonic stenosis, if severe, require operative and invasive surgical interventions.

A surgical approach is often preferred in patients with Noonan syndrome because of the degree of immobility that is often present. [36]

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