Home | | Clinical Cases in Anesthesia | What are the anesthetic implications of intracardiac lesions with left-to-right shunting?

Chapter: Clinical Cases in Anesthesia : Congenital Heart Disease

What are the anesthetic implications of intracardiac lesions with left-to-right shunting?

Lesions with left-to-right shunting include all forms of atrial septal defect (ASD) and ventricular septal defect (VSD), patent ductus arteriosus (PDA), and other large aorto-pulmonary connections.

What are the anesthetic implications of intracardiac lesions with left-to-right shunting?

 

Lesions with left-to-right shunting include all forms of atrial septal defect (ASD) and ventricular septal defect (VSD), patent ductus arteriosus (PDA), and other large aorto-pulmonary connections. The magnitude and direc-tion of the shunt depends on the difference between the outflow resistances of the two connections and the size of the defect. The exceptions are communications between the left ventricle and right atrium where obligatory shunting of blood occurs due to the large pressure difference between these two cardiac chambers.

 

A left-to-right shunt only minimally influences uptake of inhalation anesthetic agents, unless cardiac output is depressed, in which case induction is accelerated. Induction with intravenous agents is delayed, since much of the injected drug is recirculated into the lung. Agents that cause myocardial depression are poorly tolerated in infants with limited cardiac reserve. Ketamine, opioid/relaxant tech-niques, or low-dose inhalation anesthesia with isoflurane or sevoflurane are usually well tolerated.

 

Infants with large left-to-right shunts have chronically congested lungs with decreased compliance, increased clos-ing volume, and increased airway resistance. Therefore, they should have their airway secured and ventilation controlled during anesthesia. However, close attention needs to be paid to maintenance of a relatively high pul-monary vascular resistance (PVR) to avoid excessive perfu-sion of the lungs. This can be accomplished by using the minimal oxygen concentration necessary to maintain ade-quate oxygen saturation and by maintaining normocarbia to mild hypercarbia.


Although mild afterload reduction leads to increased systemic output and a reduction in left-to-right shunting, excessive systemic vasodilatation can lead to right-to-left shunting and cyanosis if the PVR is high.

 

Endocarditis prophylaxis is required for nonrepaired VSD and PDA, the first 6 months following repair, or after 6 months if there is a residual lesion present.

 

Prevention of paradoxical air embolism from IV lines is mandatory.


Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail
Clinical Cases in Anesthesia : Congenital Heart Disease : What are the anesthetic implications of intracardiac lesions with left-to-right shunting? |


Privacy Policy, Terms and Conditions, DMCA Policy and Compliant

Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.