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