Anatomical variants and hemodynamic changes
From an anatomical standpoint, stenosis arteriae pulmonalis is most commonly valvular in nature. However, infundibular (subvalvular) and supravalvular forms of narrowing are also encountered in clinical practice. Frequently, this defect is not isolated and is combined with other cardiovascular anomalies.
The key link in pathogenesis is the emergence of a mechanical obstruction in the path of blood flow. The right ventricle (RV) has to perform excessive work to push blood through the narrowed orifice into the pulmonary trunk. This triggers the following cascade of hemodynamic reactions:
- Difficulty in ejecting blood from the RV cavity.
- Chronic hemodynamic pressure overload of the RV.
- Development of pronounced right ventricular hypertrophy as a compensatory mechanism.
Clinical presentation
In clinically significant, severe stenosis, patients present with complaints reflecting reduced cardiac output and tissue oxygen deprivation. First and foremost, attention is drawn to:
- Dyspnea upon exertion and at rest.
- Palpitations.
- Rapid fatigability and generalized weakness.
During visual inspection of the patient (assessment of appearance), a specific sign is the early appearance of acrocyanosis — a bluish discoloration of the distal parts of the body (fingertips, lips, nose).
Physical diagnostics of the defect
Data from physical examination and auscultation play a decisive role in the initial diagnosis.
Inspection and palpation of the chest: Long-standing right ventricular hypertrophy in children and adolescents leads to chest deformity — the formation of the so-called "cardiac hump". In addition, forceful contractions of the hypertrophied myocardium manifest as a visible and palpable cardiac impulse.
Palpatory and auscultatory phenomena (auscultation point — 2nd intercostal space to the left at the sternal border):
- Systolic thrill: the mechanical passage of blood through the narrowed orifice creates chest wall vibration, which is palpated as a "cat's purr".
- Murmur: auscultation at the same point reveals an intense, rough systolic ejection murmur.
Instrumental confirmation and prognosis
Although the propedeutic picture is quite specific, precise verification of the diagnosis and determination of management tactics (including surgery) require additional methods. The main instrumental studies include:
- Echocardiography (EchoCG): allows visualization of the valve and assessment of the pressure gradient.
- Cardiac catheterization: invasive assessment of pressure inside the right ventricle and pulmonary artery.
- Angiocardiography: contrast study of the defect's anatomy.
The prognosis in the natural course of the disease depends on the degree of narrowing. Inrelenting progression of the stenosis inevitably leads to the exhaustion of the compensatory reserves of the hypertrophied myocardium and the worsening of symptoms of severe right-sided heart failure.
Briefly: answers to topical questions
How does the second sound (S2) change upon auscultation over the pulmonary artery in pulmonary stenosis?
In pulmonary valve stenosis, a local attenuation of the second sound (S2) over the pulmonary artery is determined.
- Auscultation point — 2nd intercostal space to the left of the sternum.
- Associated phenomena — a rough systolic murmur and a systolic thrill ("cat's purr") may be auscultated and felt at this same point.
To remember the physical findings, use the mnemonic: "Pulmonary Stenosis — Strength on the Left." On the left in the 2nd intercostal space, a rough Systolic murmur is localized, a Systolic thrill is palpated there as well, and the cardiac hump indicates the Strength (hypertrophy) of the right ventricle.
Class and exam questions
Why does a "cardiac hump" occur in pulmonary stenosis?
It forms due to marked right ventricular hypertrophy, which arises in response to pressure overload and deforms the compliant chest wall over time.
What are the main auscultatory signs of this defect?
The main sign is a rough systolic murmur heard in the second intercostal space to the left of the sternum. It is often accompanied by its palpatory equivalent — a systolic "cat's purr".
What are the risks of omitting surgical treatment in severe stenosis?
Without correction, the defect progresses, the hypertrophied right ventricle becomes exhausted, leading to the development and worsening of severe heart failure.
What else to study on this topic
- Features of echocardiography in pulmonary stenosis
- Technique and parameters of cardiac catheterization
- Principles of angiocardiographic diagnosis of defects
- Surgical treatment: indications and types of surgery
- Combined heart defects involving the pulmonary artery
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