Critical medicine topic-CMT 015

PATENT DUCTUS ARTERIOSUS SIZE

AND PULMONARY-TO-SYSTEMIC VASCULAR

RESISTANCE (PVR/SVR)

 

 

1. Determinants of Pathophysiology

• Role of PDA size
• Importance of the PVR/SVR ratio

2. Hemodynamic Changes in a Large PDA

• Increased pulmonary blood flow
• Enlargement of the pulmonary arteries
• Left atrial and left ventricular enlargement
• Descending aortic dilatation
• Development of congestive heart failure

3. Pulmonary Hypertension and Eisenmenger Syndrome

• Development of pulmonary arterial hypertension
• Bidirectional or reversed ductal shunting
• Right-to-left shunt
• Differential cyanosis

4. Clinical Features

Peripheral Signs

• Bounding peripheral pulses
• Wide pulse pressure
• Hyperdynamic precordium

Cardiac Auscultation

• Continuous "machinery" murmur
• Mitral diastolic flow rumble in large shunts
• Changes in murmur with pulmonary hypertension
• Loud pulmonary component of the second heart sound (P2)

5. Electrocardiographic Findings (ECG)

• Normal ECG in small PDA
• Left ventricular hypertrophy with strain
• Right ventricular hypertrophy in pulmonary hypertension
• Sinus rhythm

6. Chest X-ray Findings

• Dilated proximal pulmonary arteries
• Pulmonary plethora
• Cardiomegaly in large shunts

7. Echocardiographic Evaluation

M-mode Echocardiography

• Left atrial enlargement
• Left ventricular enlargement
• Aortic enlargement

Two-dimensional Echocardiography

• Direct visualization of the ductus arteriosus

Doppler Echocardiography

• Quantification of left-to-right shunt
• Estimation of pulmonary artery pressure

8. Key Concept

The clinical manifestations and hemodynamic consequences of PDA are primarily determined by two factors:

• Size of the ductus arteriosus
• Ratio of pulmonary vascular resistance (PVR) to systemic vascular resistance (SVR)

DR.C.GANESAN M.D.,

PROFESSOR OF MEDICINE