Pulmonary HTN, HTN, HF, myocarditis/pericarditis (still to finish)

Question 1

What are the common causes of central cyanosis in neonates?

Answer 1

Three common causes of central cyanosis (or hypoxemia) are cardiac disease, pulmonary disease, and CNS depression. Clinical findings often direct physicians to the correct system
that causes cyanosis. Crying may improve the cyanosis caused by lung diseases or CNS depression; however, crying usually worsens cyanosis in patients with cyanotic heart defects.

Question 2

What are some tools used in the investigation of cyanotic newborns?

Answer 2

Question 3

Describe role of ECG and CXR in evaluation of cyanotic neonates

Answer 3

Although the routine tools of cardiac evaluation (physical examination, ECG, and chest radiography) are not very help-
ful in diagnosing a specific cyanotic heart defect, these tools are often useful in reducing the diagnostic possibilities. Besides being cyanotic, a neonate may have dyspnea, tachyp-
nea, abnormal heart sounds, heart murmurs, or abnormal peripheral pulses. A midline liver may be palpable (or seen on radiography). Chest radiography may show abnormal lung fields (e.g., increased vascularity, oligemic lung fields, or other abnormalities) and abnormal cardiac shadow (abnormal size or abnormal silhouette). The ECG findings may include abnormal rhythm and rate, abnormal QRS axis, atrial hypertrophy, or ven-
tricular hypertrophy. The more of these abnormalities the patient has, the greater the chance of having CHDs. Cardiology consult should be considered at this time.

Question 4

What is the hyperoxitest?

Answer 4

This test helps differentiate cyanosis caused by cardiac disease from that caused by pulmonary diseases. When central cyanosis has been confirmed by arterial Po 2 , one tests the response of arterial Po 2 to 100% oxygen inhalation (hyperoxitest). Oxygen should be administered through a plastic hood (e.g., an Oxyhood) for at least 10 minutes to completely fill the alveolar space with oxygen. With pulmonary disease, arterial Po 2 usually rises to greater than 100 mm Hg. When there is a significant intracardiac right-to-left shunt, the arterial Po 2 does not exceed 100 mm Hg, and the rise is usually not more than 10 to 30 mm Hg. Exceptions exist in patients with large pulmonary blood flow and those with severe lung pathology.

Question 5

Describe the role of arterial pO2 in preductal and postductal arteries in the work up of cyanotic neonates

Answer 5

It is important that one obtain arterial blood samples from the right upper body (right radial, brachial, or temporal artery), rather than from the descending aorta, to detect (true) cyanotic CHDs. If a low arterial Po 2 is obtained from an umbilical artery line (or from a lower extremity site), another sample from the right upper body should be obtained, and the Po 2 values from the two sites should be compared to see if there is a right-to-left ductal shunt. Arterial Po 2 from the right radial artery that is 10 to 15 mm Hg higher than that from an umbili-
cal artery catheter is significant. In severe cases of right-to-left ductal shunt, differential cyanosis may be noticeable, with a pink upper and a cyanotic lower body. Such a right to left ductal shunt is caused not only by persistent pulmonary hypertension of the newborn (PPHN) but also by other serious cardiovascular conditions, including severe obstructive lesions of the left ventricle (LV) (e.g., severe AS) or aortic obstructive lesions (e.g., interrupted aortic arch, COA)

Question 6

What is the role of PGE1 in cyanotic neonates?

What are some side effects of PGE1 infusion?

Answer 6

If a cyanotic CHD or a ductus-dependent cardiac defect (e.g., pulmonary atresia with or without ventricular septal defect [VSD], tricuspid atresia, HLHS, interrupted aortic arch, severe COA) is suspected or confirmed, a PGE 1 (Prostin VR Pediatric) intravenous (IV) infusion should be started. At the same time, cardiology consultation should be requested on an urgent basis. The starting dose of Prostin is 0.05 to 0.1 μ g/kg per minute administered in a continuous IV drip. When the desired effects (increased Po 2 , increased systemic blood pressure, improved pH) are achieved, the dose should be reduced step by step to 0.01 μg/kg per minute. When the initial starting dose has no effect, it may be increased up to 0.4 μg/kg per minute. Three common side effects of IV infusion of PGE 1 are apnea (12%), fever (14%), and flushing (10%). Less common side effects include tachycardia or bradycardia, hypotension, and cardiac arrest.

Question 7

What is the definition of Heart failure?

Answer 7

Congestive heart failure (CHF) is a clinical syndrome in which the heart is unable to pump enough blood to the body to meet its needs, to dispose of systemic or pulmonary venous return adequately, or a combination of the two