Cardiology&Hemodynamics

Question 1

What is the most common type of vascular ring presenting in the newborn period?

(December 2021)

Answer 1

Double aortic arch (50%) followed by R aortic arch with aberrant L subclavian (~30%). Vascular rings are 2x more likely in males.

Question 2

What are the 3 types of interrupted aortic arch?

(January 2022)

Answer 2

IAA is a structural heart defect characterized by interruption or discontinuity along the aortic arch.

A (30-45%): disruption is distal to the L subclavian artery, around the same location as CoA occurs

B (50-70%): most common form of IAA more proximal between the L subclavian and the L carotid aa

C (rare): IAA occurs more proximal still between the brachiocephalic and common carotid aa

Question 3

Pathologic vs innocent murmurs

(January 2022)

Answer 3

Pathologic murmurs are:
-grade 3 intensity or more
-holosystolic
-diastolic
-loudest at the LUSB
-worsen with upright positioning
-harsh/blowing quality

None of these are perfect and all subjective and operator-experience dependent!

Question 4

Post-Ligation Cardiac Syndrome (PLCS):

-Clinical definition
-Risk factors
-Pathophysiology
-Differential for post-ligation decompensation and management based on timing
-perioperative optimization (3 major things)

Answer 4

• Hypotension requiring inotropic support and failure of oxygenation and ventilation usually 6-12 hours following ligation due to LV systolic and diastolic dysfunction, respectively. Primarily driven by afterload.

-Younger neonates (<28 days postnatal age), weight<1kg. Theoretically, neonates with high PAP from intrinsic PAH or chronic exposure to high-volume shunt, may have lower risk of PLCS as lesser change in afterload may protect the LV from failure. With TnECHO LVO <200mL/kg/min 1 hour post-ligation is sensitive for PLCS.

-Following ligation, there is an increase in LV Exposed Afterload > systolic impairment 2/2 decreased contractility > decreased LVO > decreased SAP & shock
Diastolic impairment (decreased relaxation) > increased LA pressure > increased pulmonary vv pressure > pulmonary edema & decreased compliance > hypoxia & impaired ventilation

-0-2h CXR to rule out pneumothorax/hyperinflation. Reassess ventilation and reduce MAP. TnECHO to assess LVO +/- start milrinone (isotropy, afterload reduction, lusitropy)
2-4h SBP or DBP less than 3rd %ile think adrenals first line hydrocortisone 2nd line dobutamine if SBP still low vs volume if diastolic BP still low
4-12h hypotension and oxygenation/ventilation failure. SBP low dobutamine, epi. Both SBP and DBP then epi. Refractory or worsening add hydrocortisone. For oxygenation/ventilation increase MAP, treat LV dysfunction, consider diuretics/milrinone if BP is normal/high

-Euvolemia, stable ventilation/oxygenation x 6-8 hours pre-op, and support the adrenals as needed

Question 5

Third degree AV block:

-aka?

-what is happening?

-what dictates hemodynamic stability/instability in infants with third degree AV block

-most common cause? dx?

-alternative causes?

-indications for pacemaker placement?

(June 2022)

Answer 5

-complete heart block (CHB)

-failure of atrial conduction down the AV node, resulting in complete dissociation between the atrial and ventricular rates. The atrial rate (P waves) is noted to be greater than the rate of QRS complexes.

-the strength of ventricular contraction (depolarization) and the rate of the ventricular escape rhythm

-60-90% of cases caused by neonatal lupus with placental crossing of maternal auto-antibodies causing range of cardiac, cutaneous, and systemic manifestations in neonate. Dx made by high maternal/neonatal levels of anti-Ro and anti-La Abs or characteristic rash, hematologic, or hepatic involvement. Tx w IVIG or steroids not shown to help in CHB.

-CHD, such as congenitally corrected transposition of the great arteries) or double-inlet left ventricle, in which the ventricle is L-looped, predispose neonates to conduction abnormalities, including neonatal complete heart block

-advanced 2nd or 3rd degree heart block a/w symptomatic bradycardia, HR < 55 bpm regardless of etiology and the presence of ventricular dysfunction, low cardiac output, or wide complex ventricular escape rhythm

Question 6

Neonates born to mothers treated with beta-blockers at the time of delivery are at increased risk for?

Appropriate postnatal care for neonate born to mother treated during pregnancy with nadolol?

(September 2022)

Answer 6

-bradycardia and hypoglycemia

-because nadolol has a long half-life, they should be monitored for bradycardia and hypoglycemia for 5 days