PDA

1
PDA
2
Review the physiology of arterio-venous fistulae,
including changes to cardiac output, mean
arterial pressure, peripheral vascular
resistance, heart rate, when flow begins through
a fistula and when the fistula is occluded.

• Cardiac output increased
• Mean arterial pressure decreased
• Peripheral vascular resistance decreased
• Heart rate increased

3
Review the physiology of arterio-venous fistulae,
including changes to extracellular fluid volume,
blood volume, angiotensin concentration and urine
output, when flow begins through a fistula and
when the fistula is occluded.

• Extracellular fluid volume increased
• Blood volume increased
• Angiotensin concentration increased
• Urine output decreased

4
Circulatory volume is increased in all parts of
the cardiovascular system included in the shunt
circulation. In the case of patent ductus
arteriosus (PDA), what are the involved parts of
the system?
5
How is left heart workload increased in a
left-to-right shunting PDA?

• Left ventricle must pump increased volume

6
What is the eventual consequence?

• Left ventricular hypertrophy and left heart
  failure

7
What causes early pulmonary edema in these
patients?

• Increased pressure and volume in pulmonary
  circulation

8
Can pulmonary edema precede heart failure?
9
Why does closure of a right-to-left shunting PDA
cause the death of the patient?
10
What is the cause of posterior cyanosis in these
patients?

• The subclavian separates before the venous blood
  enters the aorta

11
What is a secondary consequence of cyanosis?

• Polycythemia

12
What is necessary for preoperative management of
patients with PDA?

• Diuretics and digitalis ( to treat pulmonary
  edema, A fib or CHF)

13
What is the definitive treatment?

• Surgical or coil occlusion of the ductus

14
What drug should be given before surgery (and
sometimes during surgery as well)?

• Atropine

15
What are 2 indications for this drug in surgical
ligation of PDA?

• Retracting the vagus will cause bradycardia
• Closing the ductus will also cause bradycardia

16
What is the prognosis for the patient without
signs of heart failure

• Good- excellent

17
What is the prognosis for the patient with
secondary mitral insufficiency

• Good

18
What is the prognosis for the patient with
cardiac failure and ventricular hypertrophy

• Fair

19
What is the prognosis for the patient with A fib

• Guarded

20
What is the prognosis for the patient with
recanalization of the PDA?

• Guarded