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Published on: March 27, 2018
Pulmonary sequestration of cardioplegia administered via the aortic root during aortocoronary bypass surgery
Tamra McFarlane1, Robert Kleinloog, Margot Bennett
1Department of Surgery, Nelson Mandela School of Medicine, University of Kwa-Zulu Natal, South Africa. tamra@dbn.stormnet.co.za
Insights
A pulmonary artery vent effectively prevents cardioplegia solution from entering the lungs during coronary artery bypass graft surgery. This method ensures cardioplegia solution circulating in the lungs can be retrieved, safeguarding lung parenchyma.
Area of Science:
- Cardiovascular Surgery
- Nuclear Medicine
- Cardiopulmonary Bypass
Background:
- Cardiac surgeons have an accepted observation that cardioplegia solution may enter the lung parenchyma during cardiopulmonary bypass (CPB).
- Previous studies have not confirmed or disputed this observation regarding cardioplegia solution flow during CPB.
- This study addresses the efficacy of measures to prevent cardioplegia entering the lungs.
Purpose of the Study:
- To establish the efficacy of measures to prevent cardioplegia solution from entering the lungs during cardiac surgery.
- To determine if cardioplegia solution circulates through the lung parenchyma or merely pools.
- To investigate cardioplegia flow during coronary artery bypass graft (CABG) surgery.
Main Methods:
- A prospective study involving 20 consecutive patients undergoing CABG.
- Technetium (Tc-99m) radioactive isotope added to cardioplegia solution to trace flow.
- Radiation detection using a dose calibrator and well counter to quantify Tc-99m presence.
Main Results:
- The pulmonary artery (PA) vent demonstrated 90-100% effectiveness in retrieving cardioplegia solution.
- The PA vent successfully retrieved solution not drained by atriocaval cannulae.
- Confirmation of cardioplegia solution presence and quantity in lung parenchyma samples.
Conclusions:
- The PA vent is effective in preventing cold blood cardioplegia solution from entering the lungs.
- Cardioplegia entering the lung parenchyma during CPB circulates and can be retrieved by a left atrial vent.
- The described method offers a useful approach for future investigations of cardioplegia flow.
Unlabelled:
A semi-quantitative method was devised of tracing blood flow through the heart and lungs at the time of cardioplegia delivery and circulatory arrest of the heart during coronary artery bypass graft surgery (CABG). There were no previous studies confirming or disputing an accepted 'observation' by cardiac surgeons that cardioplegia solution does enter the lung parenchyma during cardiopulmonary bypass (CPB). This study was conducted as part of a larger (n = 142) double-blind, randomised, controlled, clinical research study.
Objective:
The objective was initially to establish the efficacy of measures to prevent cardioplegia entering the lungs and, subsequently, to determine whether cardioplegia indeed circulates through the lung parenchyma or merely accumulates and 'pools'.
Method:
A prospective study on 20 consecutive patients (5 per group) admitted for CABG was made. Technetium (Tc-99m), a radioactive isotope, was added to the cold blood cardioplegia solution prior to cardioplegia delivery in order to track flow of cardioplegia solution. An independent nuclear medicine radiographer measured the samples with the use of a 'Curimentor' dose calibrator for presence and quantity of radiation in the samples. Decay was factored into the results. The Tc-99m tracer samples were also analysed using Gamma Acquisition and Analysis on the Genie 2000vdm Well Counter to confirm the presence and quantity of Tc-99m.
Results:
In the four groups, it was confirmed that the pulmonary artery (PA) vent is 90-100% effective in retrieving any cardioplegia solution not drained by the atriocaval cannulae.
Conclusions:
The PA vent is effective in preventing cold blood cardioplegia solution from entering the lungs. Any cardioplegia that does enter the lung parenchyma during CPB circulates through the lungs and can be retrieved by a vent in the left atrium. This method may be useful in other studies that require investigation.
