Age: 39 years
Gender: Male
Occupation: Manufacturer
Working diagnosis: Heart murmur
HISTORY
The patient had been found to have a murmur at the age of 14. The character of the murmur was felt most compatible with a small, restrictive PDA. The patient felt well and was followed clinically for 25 years. The only advice he was given was endocarditis prophylaxis. He was asymptomatic and not limited with exertion.
Over the last 6 months, however, he began experiencing progressive exercise intolerance manifested as easy fatigability and exertional dyspnea. An echocardiogram failed to demonstrate the PDA, and the patient was referred for further evaluation.
He is a smoker, with mild hyperlipidemia and no other risk factors for coronary heart disease. There was no family history of congenital heart disease.
Comments: The typical murmur of a PDA is continuous and “machinery-like.” It is usually quite characteristic. Many patients with small PDAs will not need intervention. If the shunt is very large in a baby, pulmonary hypertension may develop, eventually leading to reversed shunt and differential cyanosis (bluer toes than fingers).
The lack of a demonstrable PDA by echo is somewhat surprising, since the lesion, especially if small and restrictive as presumed here, is usually seen on color Doppler. However, one must also consider that the childhood diagnosis was incorrect, and that other explanations for both a murmur and worsening dyspnea must be entertained.
There are only a few hemodynamically significant congenital heart lesions that may first be diagnosed during adult life, either incidentally or due to the appearance of symptoms. More common among these is an ASD or, less commonly, Ebstein anomaly or significant pulmonary stenosis.
CURRENT SYMPTOMS
Although the patient continues to work full time, he becomes tired easily and needs to take rests more frequently than in the past. He notes feeling breathless more easily with mild exertion such as climbing two flights of stairs. He denies chest pain, palpitations, or syncope. He has never noticed cyanosis or ankle swelling.
NYHA class: II
PHYSICAL EXAMINATION
BP 130/80 mm Hg, HR 90 bpm, oxygen saturation 97% on room air (right hand)
Weight 90 kg, height 180 cm, BSA 2.12 m 2
Surgical scars: None
Neck veins: There was a prominent jugular A-wave. The central venous pressure was mildly elevated.
Lungs/chest: Chest was clear.
Heart: There was an RV lift and a palpable systolic thrill at the second left intercostal space. The first heart sound was normal, the second heart sound was widely split at the second left intercostal space, and a right-sided (augmented by inspiration) fourth heart sound was audible. There was a loud and harsh ejection murmur peaking late in systole, heard all over the precordium with maximum intensity (4/6) at the second left intercostal space and radiating to the back. There was no ejection click.
Abdomen: There was no ascites or hepatomegaly.
Extremities: There was no lower extremity edema. The skin was warm and dry.
Comments: There is no cyanosis at rest. Isolated pulmonary stenosis is not a cyanotic lesion, per se. However, arterial desaturation and cyanosis are not uncommon in patients with severe pulmonary stenosis due to right-to-left shunting through a patent foramen ovale or a coexisting ASD at rest and or during exercise. Such patients may have a degree of secondary erythrocytosis, which in itself may suggest the presence of a right-to-left shunt.
A prominent A-wave is due to forceful right atrial contraction essential to fill a hypertrophied noncompliant RV due to increased RV afterload. A V-wave may be indicative of significant tricuspid regurgitation, which may appear late in the course of the disease, when a pressure overloaded RV decompensates and RV failure ensues. The murmur here is conspicuously not that of a PDA, and there were no signs of pulmonary hypertension. Instead, the systolic thrill at the second left intercostal space indicates turbulence in the RVOT. It is present in all but the mildest forms of pulmonary stenosis. In this case, the characteristics and site of maximal intensity of the murmur indicate valvular stenosis, whereas infundibular stenosis is typically heard best at the third or fourth intercostal space.
Several characteristics indicate severe pulmonary stenosis: (1) A right-sided fourth heart sound, indicative of a hypertrophied and noncompliant RV; (2) a splitting of the second heart sound, which becomes wider in severe pulmonary stenosis due to delayed contraction of the infundibulum resulting in high pressure that delays valve closure (the pulmonary component is often not audible, however); (3) the lack of a systolic ejection click (the systolic ejection click may diminish in severe pulmonary stenosis); and (4) the long and late-peaking systolic ejection murmur. In cases of mild or moderate pulmonary stenosis, a loud ejection click is heard as the valve opens to its domed position. It has been suggested that in severe pulmonary stenosis with a hypertrophied, noncompliant RV, atrial systole may open the pulmonary vein to its “domed” position, and hence the ejection click will no longer be present. Inspiration with its increased systemic venous return may have a similar effect.
ELECTROCARDIOGRAM
FINDINGS
Heart rate: 84 bpm
PR interval: 160 msec
QRS axis: +110°
QRS duration: 85 msec
Normal sinus rhythm. Right-axis deviation to +110°. First-degree AV block. Dominant R-wave in lead V1 compatible with RV hypertrophy. No RA overload.
Comments: A QRS axis of 110 degrees or more, an R/S ratio greater than 1 in lead V1 or V3R, an S-wave less than 2 mm in lead V1, and onset of intrisicoid deflection in V1 35 to 55 msec—all features of the current ECG—are considered to be indicative of RV hypertrophy. The Sokolow-Lyon criteria of RV hypertrophy (R in V1 + S in V5 or V6 > 10.5 mm) are less specific. The first two criteria mentioned on the current ECG (the QRS axis and R/S in V1) have an accuracy of 78% for RV hypertrophy.
There is a correlation between the ECG findings and the degree of pressure overload of the RV in patients with pulmonary stenosis. More specifically, with peak Doppler gradients less than 60 mm Hg, the ECG may be entirely normal in 50% of cases. With more severe pulmonary stenosis, most ECGs show signs of RV hypertrophy. Patients with R-waves in lead V1 greater than 20 mm almost always demonstrate gradients greater than 100 mm Hg and vice versa. However, the ECG is only indicative of the degree of pressure overload of the RV. This correlation is even less satisfactory in other types of congenital lesions. P-waves may be tall in inferior leads denoting RA hypertrophy.
CHEST X-RAY
FINDINGS
Situs solitus, levocardia, left aortic arch, marked enlargement of the main and left pulmonary arteries, normal cardiothoracic ratio, normal peripheral pulmonary vascular markings.
Comments: The rather prominent main pulmonary artery (PA) and the dilated left PA (perhaps due to preferential turbulent flow toward the latter through the stenotic pulmonary valve orifice) are the main features of the frontal chest radiograph in patients with pulmonary stenosis. The normal heart size is consistent with the absence of RV failure. However, RV enlargement may be evident in the lateral film. Pulmonary vascularity is also normal, which precludes pulmonary oligemia as happens in patients with a right-to-left shunt through an ASD, or in patients with severely reduced RV cardiac output or RV failure.
LABORATORY FINDINGS
| Hemoglobin | 15 g/dL (13.0–17.0) |
| Hematocrit/PCV | 48% (41–51) |
| MCV | 90 fL (83–99) |
| Platelet count | 300 × 10 9 /L (150–400) |
| Sodium | 139 mmol/L (134–145) |
| Potassium | 3.7 mmol/L (3.5–5.2) |
| Creatinine | 0.9 mg/dL (0.6–1.2) |
| Blood urea nitrogen | 5.0 mmol/L (2.5–6.5) |
Comments: Most patients have normal blood chemistry. Secondary erythrocytosis may be present in patients with a right-to-left shunt through an ASD.
EXERCISE TESTING
| Exercise protocol: | Modified Bruce |
|---|---|
| Duration (min : sec): | 8 : 00 |
| Reason for stopping: | Dyspnea and chest pain |
| ECG changes: | None |
| Rest | Peak | |
|---|---|---|
| Heart rate (bpm): | 90 | 160 |
| Percent of age-predicted max HR: | 88 | |
| O 2 saturation (%): | 97 | 99 |
| Blood pressure (mm Hg): | 130/80 | 175/85 |
Comments: Exercise capacity may be reduced in patients with significant RVOT obstruction, due to a fixed RV stroke volume and inadequate cardiac output (stroke volume × heart rate) during exercise. Relief of the obstruction can be expected to lead to a significant improvement in cardiopulmonary performance.
ECHOCARDIOGRAM
OVERALL FINDINGS
There was severe RV hypertrophy but maintained RV systolic function. The LV was normal. Mild tricuspid regurgitation was present with an estimated RV systolic pressure of 65 mm Hg. There was significant flow acceleration across the RVOT (Vmax = 4.7 m/sec). The RA was mildly dilated. The LA was normal. The aortic and mitral valves were normal. There were no signs of a PDA. An ostium secundum ASD was suspected (faint jet of left-to-right shunting on subcostal interrogation of the interatrial septum with color Doppler) but not clearly demonstrated.
FINDINGS
The RVOT is superior with the main pulmonary trunk to the right of the image and the Doppler jet seen from top to bottom.
There is turbulent flow (color aliasing) across the RVOT, mainly at the level of the pulmonary vein. The valve itself, however, was difficult to visualize.
Comments: Transthoracic echocardiography suggests the presence of a significant obstruction at the level of the RVOT. However, the poor echocardiographic window here did not allow for a clear assessment of the nature of the obstruction and the anatomy of the pulmonary vein and pulmonary arteries.
FINDINGS
Peak velocity through the RVOT is 4.7 m/sec (under the curve, as the direction of flow is from top to bottom), suggesting an estimated peak pressure gradient between the RV and the main PA of approximately 88 mm Hg.
Comments: Pulmonary stenosis is confirmed. Subvalvar stenosis is seen in approximately 40% of cases of valvar pulmonary stenosis due to infundibular hypertrophy. Ventricular “crosstalk” via altered RV geometry or bowing of the ventricular septum may also be evident, with resultant LV dysfunction or LV outflow obstruction, although uncommon.
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