PULMONARY HYPERTENSION DEFINITION
Pulmonary hypertension is defined as an elevation in pulmonary artery pressure, with pulmonary artery mean pressure greater than 25 mm Hg at rest and/or greater than 30 mm Hg with exercise. This classic definition applies to both adults and children. There are multiple etiologies of pulmonary hypertension, many of which are much more common in the adult than the pediatric population. Table 29.1 presents the WHO classification scheme for pulmonary hypertension.
The symptoms associated with pulmonary hypertension in children are variable with symptomatology depending on the etiology and severity of disease as well as the age of the patient. At critical levels of pulmonary artery hypertension, symptoms may be attributed to low cardiac output. Although these symptoms may be nonspecific, they are likely to be significant and may include poor appetite and poor growth in infants, while older children may present with nausea, vomiting, activity intolerance, lethargy, or overt syncope.
The true incidence of pulmonary hypertension is not entirely clear. In recent years, the diagnosis has become more common—most likely because of a greater awareness of the disease. This is likely associated with a better understanding of the classification and underlying pathophysiology, as well as increased accessibility of diagnostic modalities such as echocardiography. It does appear that the frequency of disease may vary by gender, perhaps more so in adults than in children. The gender ratio in adult women is 1.7:1 compared to men, but some have suggested an equal ratio in females and males before adolescence. The relatively newly recognized entity of familial pulmonary hypertension comprises anywhere from 6% to 12% of cases of “idiopathic” pulmonary hypertension. It has been suggested that the mode of inheritance is autosomal dominant with incomplete penetrance. In addition, a gene for familial idiopathic pulmonary hypertension has been identified on chromosome 2q33. This gene is also believed to cause defects in bone morphogenetic protein receptor 2 (BMPR-2) and may lead to abnormalities in vascular smooth muscle, including uncontrolled proliferation. Genetic screening for BMPR-2 is available and is recommended for first-degree relatives of patients with idiopathic pulmonary hypertension. As this test has become more easily obtainable, a higher incidence of familial pulmonary hypertension may become apparent.
The clinical evaluation of pulmonary hypertension should be directed at determining the etiology of the disease, as well as its severity, and should establish a baseline for clinical follow-up. Table 29.2 lists studies that are important in the evaluations of the patient with newly diagnosed or suspected pulmonary hypertension. Echocardiography is an essential diagnostic tool in the evaluation of pulmonary hypertension. Echocardiographic predictors of prognosis include pericardial effusion, indexed right atrial area, the degree of septal shift toward the left ventricle in diastole, tricuspid annular plane systolic excursion, pulmonary vascular capacitance, RV myocardial performance index and right ventricular systolic function. Noninvasive assessment of pulmonary arterial pressure is a routine component of a comprehensive echocardiographic evaluation. The two-dimensional scan may suggest elevation in right-sided pressures. Doppler is used both to confirm the presence of pulmonary hypertension and quantify its severity. As a result, the echocardiogram plays a pivotal role in the diagnosis, identification, and follow-up of patients with pulmonary hypertension.
Severe pulmonary hypertension can often be recognizable by routine two-dimensional echocardiography. In the normal heart, left ventricular pressure is greater than right ventricular pressure. Subsequently, parasternal short-axis imaging demonstrates a circular left ventricle with the septal curvature being convex toward the right ventricle and concave toward the left ventricle. During ventricular systole, the septum moves toward the center of the left ventricle. The septum retains its convex curvature toward the right ventricle and concave curvature toward the left ventricle throughout the cardiac cycle. Pulmonary hypertension results in right ventricular pressure that may equal or exceed left ventricular pressure, causing septal flattening or a reverse septal curvature during systole. This may result in left ventricular compression, best seen in both parasternal long- and short-axis imaging (Fig. 29.1, Video 29.1). The majority of patients with pulmonary hypertension will have significant right ventricular and right atrial dilatation. Right ventricular hypertrophy is also common (Fig. 29.2, Video 29.2). Additionally, right ventricular systolic and diastolic function may be impaired. Right ventricular systolic dysfunction can be suggested by visual estimates or quantitatively estimated as discussed elsewhere in this text. However, these clinical clues and findings may be subtle, particularly with mild or moderate elevation in pulmonary arterial pressures. Therefore, the echocardiographer must maintain a high level of suspicion during image acquisition and interpretation.
Once pulmonary hypertension has been suggested by clinical examination or initial echocardiographic imaging, a comprehensive, detailed examination should be undertaken to evaluate for congenital heart disease that may lead to pulmonary hypertension. The segmental approach using a complete two-dimensional assessment should be carried out with the goal of identifying potential sources of pulmonary hypertension including left-to-right shunts and obstructive lesions. Since many of the two-dimensional echocardiographic features as well as Doppler gradients actually predict right ventricular systolic pressure and not pulmonary artery pressure, one must take particular care to exclude obstructive lesions such as pulmonary stenosis and branch pulmonary artery stenosis (Fig. 29.3). Once right ventricular outflow tract obstruction has been excluded, right ventricular pressure can be considered as a surrogate of pulmonary artery pressure.
An intracardiac shunt can be found at any level: atrial, ventricular, or great arteries. Mean pulmonary artery pressure is derived by the product of pulmonary vascular resistance and pulmonary blood flow, which both can be affected by left-to-right intracardiac shunts. Early in the disease course, significant left-to-right shunt lesions result in increased flow to the pulmonary vascular bed. The increased flow results in increased mean arterial pulmonary pressure. Over time, increased pulmonary flow results in a progressive increase in pulmonary resistance with a concomitant increase in pulmonary artery pressure. As the pulmonary pressure approaches systemic pressure, as a result of either increased flow or resistance, care must be taken to not rely on color Doppler to identify these intracardiac shunts since low-velocity shunting is often present because of equalization of systemic and pulmonary arterial pressure.
Although qualitative data can be obtained by two-dimensional echocardiography, actual hemodynamic data is best estimated by Doppler echocardiography.
Tricuspid regurgitation is common in patients with and without pulmonary hypertension. Doppler measurement of tricuspid regurgitation velocity accurately predicts right ventricular systolic pressure in patients with a wide spectrum of both acquired and congenital heart disease. The maximal right ventricular to right atrial systolic velocity via continuous-wave Doppler interrogation of the tricuspid regurgitation jet is utilized. Typically, the apical four-chamber view and parasternal short- and long-axis planes allow for optimal alignment of continuous-wave Doppler using either an imaging or a non-imaging transducer. However, nonstandard “off-axis” views may be needed to achieve optimal alignment with the tricuspid regurgitant jet.
With careful adjustment of the transducer orientation with color Doppler guidance to ensure an optimal incident angle, Doppler echocardiography offers an accurate, noninvasive approach to determining right ventricular systolic pressure (RVSP). Currie et al. confirmed this with simultaneous continuous-wave Doppler echocardiography and invasive right-sided cardiac pressure measurements (Fig. 29.4). The tricuspid regurgitant velocity (TRV) reflects the peak right ventricular–to–right atrial pressure (RA) difference, as stated by the modified Bernoulli equation:
RVSP – RA = 4 (TRV)2
RVSP = 4 (TRV)2 + RA
Right atrial pressure can be estimated via several techniques. If a central venous catheter is present, direct right atrial pressure measurements can be obtained. The right atrial pressure can be estimated clinically by evaluating the jugular venous distention; however, this is difficult in children and impractical in a busy echocardiography laboratory. Kirchner et al. demonstrated that two-dimensional echocardiographic estimates of right atrial pressure can be obtained by evaluating the inferior vena cava. Subcostal imaging of inferior vena caval collapse within 2 cm of the right atrium correlates with right atrial pressure. Patients with an inspiratory collapse of the inferior vena cava greater than 50% tend to have a right atrial pressure less than 10 mm Hg, while those having less than 50% collapse tend to have right atrial pressure greater than 10 mm Hg. Ommen et al. suggested that a combination of hepatic venous Doppler evaluation in addition to inferior vena cava diameter changes with respiration can further predict right atrial pressure. In adults, if the inferior vena caval diameter is less than 15 mm Hg and the systolic forward flow Doppler velocity is greater than the velocity of atrial reversal in the hepatic vein, an estimated right atrial pressure of 5 mm Hg can be used. Alternately, if the inferior vena cava diameter is greater than 20 mm and systolic forward flow is less than the velocity at atrial reversal, an estimated right atrial pressure of 25 mm Hg can be used. All other patients can be assumed to have a right atrial pressure of 14 mm Hg.
Figure 29.1. Severe right ventricular (RV) hypertension resulting in septal flattening and reverse septal curvature bowing toward the left ventricle (LV). Also note the RV dilation and RV hypertrophy. A: Parasternal long-axis imaging of severe RV hypertension resulting in compression of the LV. B:Parasternal short-axis imaging demonstrating the D-shaped LV.
Practically, the importance of accurate right atrial pressure is greatest at intermediate tricuspid regurgitant Doppler velocities. For example, a tricuspid regurgitation velocity of 2.5 m/s with a right atrial pressure of 5 mm Hg results in a calculated systolic pulmonary pressure of 30 mm Hg. However, if the right atrial pressure is 20 mm Hg, the same 2.5 m/s Doppler velocity would estimate a pulmonary pressure of 45 mm Hg. In contrast, if the tricuspid regurgitant velocity is 5 m/s, the error associated with accurate right atrial pressure estimation is of little clinical importance (105 mm Hg versus 120 mm Hg) since both values suggest severe pulmonary hypertension.
Figure 29.2. RV dilation and hypertrophy in pulmonary hypertension. A: Apical four-chamber imaging will typically demonstrate right ventricular (RV) dilation with significant pulmonary hypertension. This may often be the first echocardiographic sign of elevated pulmonary pressures. B: Also, with longstanding hypertension, there will be significant RV hypertrophy (arrows). RA, right atrium; LV, left ventricle; LA, left atrium.
Figure 29.3. The presence of severe right ventricular hypertension was suggested by right-to-left shunting through a ventricular septal defect. A: Suprasternal notch imaging revealed bilateral branch pulmonary artery hypoplasia (arrows). LPA, left pulmonary artery; MPA, main pulmonary artery; RPA, right pulmonary artery. B: Color Doppler imaging demonstrates marked flow acceleration. C: PAH is confirmed by continuous-wave Doppler interrogation calculating a gradient of 127 mm Hg. The patient was found to have Williams Syndrome. D: Angiography demonstrated severe branch pulmonary artery hypoplasia with multiple areas of segmental stenosis (arrows).
Pulmonary regurgitation is present in many normal individuals as well as in a large percentage of patients with congenital heart disease and nearly all patients with pulmonary hypertension. Pulmonary artery diastolic pressure can be estimated from the end-diastolic velocity of pulmonary regurgitation Doppler signal (Fig. 29.5). At end-diastole, the pulmonary regurgitation end-diastolic velocity (PREDV) jet represents the pressure difference between the pulmonary artery end-diastolic pressure and the right ventricular end-diastolic pressure. In the absence of tricuspid stenosis, the right ventricular end-diastolic pressure can be assumed to be equal to right atrial pressure (RAP). Therefore, pulmonary artery end-diastolic pressure (PAEDP) can be estimated using the modified Bernoulli equation:
PAEDP = 4 (PREDV)2 + RAP
Underestimation of the pressure gradient by the Doppler method may be caused in part by the inability to align the Doppler angle of interrogation parallel to the direction of the pulmonary regurgitant jet. Therefore, color Doppler should be used to guide the incident angle since the direction of the regurgitant jet is not predictable from the anatomy of the surrounding anatomic structures.
Ventricular Septal Defect
The presence of a ventricular septal defect affords an additional opportunity to noninvasively estimate right ventricular pressure. A moderate sized VSD results in the best correlation between Doppler assessment and absolute pressure measured via catheter. A small defect may be difficult to accurately align with the Doppler beam, resulting in underestimation of the LV–to–RV gradient (and overestimation of RVSP). Meanwhile, large defects may result in an overestimation of the actual measured pressure drop across the ventricular septum. Continuous-wave Doppler can accurately measure the instantaneous pressure gradient across the ventricular septal defect and thereby can be used to estimate right ventricular systolic pressure. In the absence of left ventricular outflow tract obstruction, the left ventricular systolic pressure (LVSP) is essentially equal to the systemic systolic blood pressure (SBP). By once again applying the modified Bernoulli equation, the right ventricular systolic pressure (RVSP) can be estimated by using the ventricular septal defect Doppler velocity (VSDV):
Figure 29.4. Quantitation of RV systolic pressure. A: Diagram demonstrating how to measure systolic right ventricular (RV) pressure from the tricuspid regurgitation (TR) continuous-wave Doppler velocity. The peak systolic tricuspid pressure gradient from the RV to the right atrium (RA) is represented by 4(peak TR velocity)2. Therefore, systolic RV pressure is estimated by adding an estimated or measured RA pressure to the pressure derived from the TR velocity. LA, left atrium; LV, left ventricle; RAP, right atrial pressure; RVP, right ventricle pressure. B: Simultaneous RV and RA pressure tracings and TR velocity recording by continuous-wave Doppler echocardiography. Pressure gradients (36, 31, and 29 mm Hg, respectively) derived from the peak Doppler velocities of the second, third, and fourth beats (3.0, 2.8, and 2.7 m/s, respectively) are similar to the catheter-derived RV–to–RA gradients (arrows, 33, 28, and 26 mm Hg). (From Oh JK, Seward JB, Tajik AJ, eds. The Echo Manual. 3rd ed. Philadelphia: Lippincott Williams & Wilkins. © 2006 Mayo Foundation for Medical Education and Research.)
Figure 29.5. Quantitation of PA end-diastolic pressure. A: Diagram of continuous-wave Doppler interrogation of pulmonary regurgitation (PR) from the left parasternal window. If end-diastolic pulmonary velocity is 3 m/s, end-diastolic pulmonary artery (PA) pressure = 4(3)2+ 14 = 50 mm Hg, assuming a right atrial (RA) pressure of 14 mm Hg. LA, left atrium; RV, right ventricle. B: Continuous-wave Doppler demonstrating a PR velocity in a patient with normal PA pressure. Because the pressure difference between the PA and right ventricle is small during diastole, contraction of the right atrium decreases the PA–RV pressure gradient, resulting in a dip in pulmonary regurgitation velocity. C: When pulmonary pressure is high, RA contraction typically does not make a notable change in the PA–RV pressure gradient—hence, no dip in the continuous-wave Doppler signal of pulmonary regurgitation. (From Oh JK, Seward JB, Tajik AJ, eds. The Echo Manual. 3rd ed. Philadelphia: Lippincott Williams & Wilkins. © 2006 Mayo Foundation for Medical Education and Research.)
RVSP = SBP – 4 (VSDV)2
In general, when appropriately aligning the Doppler beam, the jet through a perimembranous ventricular septal defect is directed anteriorly and rightward. Often, adequate alignment can be obtained from the left parasternal view. However, alternative views, such as a subcostal view or a modified apical view, where the transducer is positioned toward the right ventricle, may be needed (Fig. 29.6).
Doppler gradients across a ventricular septal defect predict peak instantaneous pressure gradients between the left and right ventricles. The majority of ventricular septal defect Doppler signals will have a plateau appearance, allowing for accurate estimation of the peak-to-peak gradient between the left and right ventricles. However, when interpreting these gradients when asynchronous peaking of left ventricle and right ventricle pressures is present, care must be taken not to underestimate the right ventricular pressure in this setting. In these patients, the ventricular septal defect Doppler signal will peak early in systole, creating a sloped appearance. The right ventricular peak pressure occurs later than the left ventricular peak pressure. The clinical consequence of using the instantaneous peak Doppler gradients is the underestimation of the right ventricular pressure by overestimating the true peak-to-peak gradient. In the presence of a sloped Doppler signal, using the end-systolic or the mean gradient across the ventricular septal defect may better predict the right ventricular systolic pressure.
Patent Ductus Arteriosus
The Doppler flow pattern and derived pressure gradient across a patent ductus arteriosus can also be used to predict pulmonary artery pressure. Optimal alignment is usually best achieved with the high left parasternal short-axis view. Continuous left-to-right ductal shunting is interrogated with continuous-wave or pulsed-wave Doppler. The peak systolic ductus arteriosus velocity (PDAV) can be used to estimate the pressure gradient between the aorta (Ao) and pulmonary artery. Therefore, with the modified Bernoulli equation, the pulmonary artery pressure (PAP) can be estimated as:
PAP = Ao – 4(PDAV)2
Aortic pressure is assumed to be equal to systolic pressure obtained by cuff or arterial line measurements.
Early systolic right-to-left shunting is associated with systemic or near systemic pulmonary pressures (Fig. 29.7). In patients with suprasystemic pulmonary pressure, a prolonged duration of right-to-left ductal flow may be observed. Severe pulmonary hypertension with a concomitant patent ductus arteriosus may result in reversal of transverse aortic arch flow because of the decrease in left ventricular cardiac output.
Pulmonary Artery Velocity Curve
The pulmonary artery Doppler velocity curve can be used to estimate pulmonary artery pressures in the absence of adequate tricuspid or pulmonary insufficiency, ventricular septal defect, or patent ductus arteriosus. With normal pulmonary pressure, the right ventricular ejection curve tends to have a longer time from onset of flow to peak flow, giving a “rounded” appearance. As pulmonary pressure increases, the curve more closely resembles the left ventricular ejection curve with very rapid acceleration and a short time period from flow onset to maximum velocity. Clearly, these patterns can be subtle and should be reserved for instances when all other methodologies just described are not available.
Figure 29.6. Utilization of VSD velocity to estimate RV systolic pressure. A: Continuous-wave Doppler image obtained from a subcostal imaging plane predicting normal right ventricular pressure in an infant with a small perimembranous ventricular septal defect. B:Alternatively, continuous-wave Doppler image obtained from a left parasternal position in a patient with a large ventricular septal defect demonstrating low-velocity (2 m/s) left-to-right shunting consistent with elevated right ventricular pressure. Both Doppler signals have a more typical plateau appearance.
Figure 29.7. Pulmonary artery hypertension is confirmed with pulsed-wave Doppler from high left parasternal imaging of a patent ductus arteriosus. There is diastolic left-to-right shunting (above baseline) and systolic right-to-left shunting predicting near systemic pulmonary artery pressure.
Management of pulmonary hypertension varies based on the specific etiology of the disease. For discussion purposes, management can be divided into general measures, as well as measures directed specifically at the pulmonary vascular bed. In any case, efficacy of therapy can be determined by a combination of symptoms, chemical measures such as BNP, noninvasive measures (echocardiography), and more invasive measures such as cardiac catheterization. In any case these studies are serially followed over time in order to determine disease progression/improvement as well as the response to therapy. Other functional studies such as the six-minute walk test or graded-treadmill study with measurement of oxygen consumption are also helpful in studying the disease progression as well as the response to therapy.
General therapeutic measures have included anticoagulation with warfarin. This has been based on adult studies prior to the historical advent of vasodilator therapy. These studies suggested a survival benefit in patients who received warfarin therapy. The rationale for this therapy is supported by the observed presence of microthrombi in the pulmonary vasculature of patients with pulmonary hypertension discovered at either lung biopsy or autopsy. It is unclear if this is a primary or a secondary finding. There are no data to suggest that the use of warfarin is an effective therapy for children with pulmonary hypertension.
Digoxin has also been traditionally used for the treatment of pulmonary hypertension, especially in the face of right ventricular dysfunction. Similarly, no data exist to demonstrate the efficacy of this therapy.
Pulmonary vasodilator therapy has been a major advancement in patients with pulmonary hypertension. Table 29.3 represents a vasodilator treatment protocol for patients with pulmonary hypertension. Many believe that patients with newly diagnosed pulmonary hypertension should undergo acute drug testing in the cardiac catheterization laboratory to determine reactivity and allow for a rational approach to therapy. Pulmonary vascular reactivity is defined as a 20% or greater decrease in pulmonary vascular resistance and/or increased cardiac output with acute drug testing in the catheterization laboratory. This evaluation is typically performed with a combination of inhaled nitric oxide, intravenous prostacyclin, and oxygen. It is recommended by some that patients who demonstrate pulmonary vascular reactivity have therapy with an oral calcium channel blocker, such as nifedipine. In the absence of reactivity, and in the presence of systemic or suprasystemic pulmonary artery pressure, symptoms of low cardiac output, or right ventricular dysfunction as demonstrated by echocardiography, therapy with continuous intravenous prostacyclin is recommended. This implies the need for long-term central venous access. As depicted in Table 29.3, therapy with oral agents such as endothelin inhibitors and/or sildenafil may be used as an adjunctive therapy to prostacyclin or an initial therapy in the patient with subsystemic pulmonary artery pressure and good right ventricular function. Studies assessing oral prostacyclin derivatives are ongoing; their use may soon be approved in the United States.
An exhaustive review of the efficacies of therapies and multiple agents available for the treatment of pulmonary hypertension is beyond the scope of this chapter. By way of a very brief summary, it should be noted that therapy with intravenous prostacyclin has resulted in significant improvement in outcomes for patients with pulmonary hypertension, with most studies suggesting a 5-year survival of nearly 95% in children treated with continuous intravenous prostacyclin therapy. There are different forms of intravenous prostacyclin including a shorter acting form (epoprostenol) as well a longer acting form (treprostinil). Additional forms of prostacyclin (subcutaneous and inhaled), as well as other agents, such as the endothelin receptor blockers (bosentan, sitaxsentan, etc.) and phosphodiesterase-5 inhibitors (sildenafil, tadalafil), are currently being widely used, with evidence suggesting very good efficacy. The particular agent or agents that are used in any particular patient depend upon the severity of the disease, as suggested above, as well as upon the experience and preference of the practitioner. Nonetheless, further studies are on the horizon detailing the efficacy of the above drugs as well as combination drug therapy targeted at forms of pulmonary hypertension in specific etiologic groups. Additional pulmonary vasodilator agents are continually being developed and tested. These include agents in the categories described above as well as agents in new categories that may have a favorable effect on the pulmonary vasculature.
Finally, much work continues with regard to the use of additional heretofore-untapped medical therapies for pulmonary hypertension. The genomic approach, including further identification of candidate genes, may allow for manipulation of selected genes as well as for a further understanding of the pathobiology and genetics of pulmonary hypertension. Perhaps this approach will someday allow for the prevention of this potentially devastating disease.
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1.What are the symptoms associated with pulmonary hypertension in children?
A.Usually quite severe and very difficult to treat because children with pulmonary hypertension have significant pulmonary bed hypoplasia
B.Tend to be mild but are progressive with growth
C.Variable and depend on the etiology and severity of the underlying cause
D.Usually do not require therapy since the symptoms are usually mild and self-limited
E.At critical levels, which is usually related to high left ventricular end diastolic pressure and the accompanying hemodynamic embarrassment
2.Which of the following is true with regard to the etiologies of pulmonary hypertension in children?
A.The most common etiology in children are the disorders related to thrombotic obstruction of the pulmonary arteries.
B.Chronic lung disease in the premature infant is an ever increasing etiology in the pediatric population.
C.Portal hypertension and liver disease associated pulmonary hypertension is almost never seen in children and is truly a disease of the adult population.
D.Persistent pulmonary hypertension of the newborn (PPHN) is a different disease and should not be included in the classification scheme of pulmonary hypertension.
E.Sarcoid as an etiology in children is underdiagnosed.
3.Which of the following studies should be part of the routine evaluation in the work up of pulmonary hypertension in children?
A.A liver biopsy
4.Which of the following is a part of the typical therapeutic regimen for children with pulmonary hypertension?
5.What additional typical therapeutic/interventional approaches with regard to pulmonary hypertension in children might be used?
A.Balloon atrial septostomy
C.A Blalock-Taussig shunt
6.A premature infant born at 27 weeks, who is now three months of age, is being assessed for pulmonary hypertension. Which of the following is most consistent with significant pulmonary hypertension?
A.Peak tricuspid regurgitation velocity of 2.5 m/sec
B.Patent ductus arteriosus which is shunting right-to-left during systole and left-to-right during diastole
C.Septal curvature being convex toward the right ventricle
D.Left-to-right ventricular septal defect Doppler gradient of 4 m/sec
E.Normal right ventricular size
7.A 16-year-old is being evaluated for suspected autoimmune disorder. A routine echocardiogram is obtained. The right atrial pressure is assumed to be 10 mmHg. The peak tricuspid regurgitation velocity is 3.5 m/sec. What is the estimated right ventricular pressure?
8.Which of the following makes accurate pulmonary artery pressure estimation difficult?
A.Severe tricuspid regurgitation
B.Elevated right atrial pressure
D.Pulmonary vein stenosis
E.A large atrial septal defect
9.How is right ventricular pressure best predicted?
A.Mean tricuspid regurgitation velocity plus right atrial pressure
B.4 (pulmonary regurgitation end-diastolic velocity)2 plus right atrial pressure
C.2 (tricuspid regurgitation velocity)4 plus right atrial pressure
D.4 (tricuspid regurgitation velocity)2 plus right atrial pressure
E.2 (pulmonary regurgitation end-diastolic velocity)4 plus right atrial pressure
10.A 32-year-old has a moderate-sized secundum atrial septal defect. A routine echocardiogram is obtained. The right atrial pressure assumed to be 10 mmHg. The peak tricuspid regurgitation velocity is 3.5 m/sec. The pulmonary regurgitation end-diastolic velocity is 0. 5 m/sec. What is the estimated pulmonary artery end-diastolic pressure?
1.Answer: C. Though pulmonary hypertension is less common in children, it is still quite variable and can be anywhere from mild (requiring no specific therapy) to severe. The variability in symptoms may be related to the underlying etiology as well as the severity itself.
2.Answer: B. The etiologies of pulmonary hypertension and their incidence in children are different than those in adults. For example, chronic thromboembolic disease as a cause of pulmonary hypertension is extremely uncommon in children. Similarly, sarcoid as a cause of PH is virtually unheard of in the pediatric population. Chronic lung disease is, in fact, an ever-increasing cause/association with PH in the premature infant. Finally, portal hypertension secondary to liver disease has been associated with PH in children. PPHN has always been in the spectrum and in the differential diagnosis of pulmonary hypertension.
3.Answer: E. An echocardiogram is a critical study in the work-up of pulmonary hypertension. It is critical for the assessment of the degree/severity of pulmonary hypertension including the analysis of the right ventricular function. In addition, it is critical for ruling out congenital heart disease as a potential etiology of the PH. The other studies are not a part of the routing work-up of PH.
4.Answer: B. Coumadin has become a routine medication in the patients with PH. Although randomized controlled trials to prove its efficacy have not been done, previous studies in adults have suggested that there is a therapeutic benefit to anti-coagulation. It is believed that this is the case as autopsy or biopsy specimens have shown thromboses in small pulmonary vessels in patients with PH. Whether this finding is primary or secondary is not clear. The other medications may be used depending upon the complications of PH such as arrhythmias or right ventricular dysfunction, but are not a routine therapy for all patients with PH.
5.Answer: A. Balloon atrial septostomy is a potential therapeutic endeavor for patients with severe, symptomatic PH. Creation of an atrial level communication will allow a “pop-off” so that cardiac output may be preserved during a right heart hypertensive episode, at the expense of right-to-left shunting and desaturation. The need to do a balloon atrial septostomy implies the need to intensify therapy overall, including perhaps an evaluation for lung transplantation. Heart transplantation alone is not an appropriate therapy for pulmonary hypertension because a heart is unlikely to function in a milieu of elevated pulmonary vascular resistance. The other choices would not be appropriate choices in the typical setting of pulmonary hypertension.
6.Answer: B. Right-to-left shunting across a patent ductus arteriosus is consistent with systemic level pulmonary pressures and therefore consistent with significant pulmonary hypertension. A peak tricuspid regurgitation velocity of 2.5 m/sec would be consistent with a RVSP of 25 mmHg, which would be normal. Pulmonary hypertension results in right ventricular pressure that may equal or exceed left ventricular pressure, causing septal flattening or a reverse septal curvature during systole (convex toward the left ventricle). Left-to-right ventricular septal defect Doppler gradient of 4 m/sec would indicate that there is a significantly higher left ventricular pressure compared to the right ventricle. However, if there were significant left ventricular outflow obstruction, one may still have elevated pulmonary pressures. Additionally, with a right bundle branch block, there may be an initially elevated gradient in the face of pulmonary hypertension. Pulmonary hypertension typically results in right ventricular dilation and systolic dysfunction.
7.Answer: D. Doppler measurement of tricuspid regurgitation velocity accurately predicts right ventricular systolic pressure in patients with a wide spectrum of both acquired and congenital heart disease. The tricuspid regurgitant velocity (TRV) reflects the peak right ventricular–to–right atrial pressure (RA) difference, as stated by the modified Bernoulli equation: RVSP = 4 (TRV)2 + RA= 4 (3.5)2 + 10 = 59 mmHg.
8.Answer: C. Since many of the 2-D echocardiographic features, as well as Doppler gradients, actually predict right ventricular systolic pressure and not pulmonary artery pressure, one must take particular care to exclude obstructive lesions such as pulmonary stenosis and branch pulmonary artery stenosis.
9.Answer: D. The tricuspid regurgitant velocity (TRV) reflects the peak right ventricular-to-right atrial pressure (RA) difference, as stated by the modified Bernoulli equation: RVSP = 4(TRV)2 + RA.
10.Answer: C. Pulmonary artery diastolic pressure can be estimated from the end-diastolic velocity of pulmonary regurgitation Doppler signal. At end-diastole, the pulmonary regurgitation end-diastolic velocity (PREDV) jet represents the pressure difference between the pulmonary artery end diastolic pressure and the right ventricular end-diastolic pressure. In the absence of tricuspid stenosis, the right ventricular end-diastolic pressure can be assumed to be equal to right atrial pressure (RA). Therefore, pulmonary artery end-diastolic pressure (PAEDP) can be estimated using the modified Bernoulli equation: PAEDP = 4 (PREDV)2 + RA