The Use Of Intraoperative Transit Time Flow Measurement Can Reduce
Preoperative Myocardial Injury
Zheng Quan MD,1,3,4 Xiaoyu Zhang MD,2,4, Xueyu Song MD,1,3 Pengyu Chen
MD,1,3 Qiyong Wu MD,1,*
Department of Thoracic and Cardiovascular Surgery, Changzhou No. 2
People’s Hospital, Affiliated with Nanjing Medical University,
Changzhou, Jiangsu, China 2. Heart Center, Northwest Women and
Children’s Hospital, Xi’an, Shaanxi, China 3. Dalian Medical
University, Dalian, Liaoning, China 4. These authors contributed
equally to this study *
Correspondence: Qiyong Wu, MD, Department of Thoracic and
Cardiovascular Surgery, Changzhou No. 2 People’s Hospital, Affiliated
with Nanjing Medical University, Changzhou, Jiangsu, China. Email:wqyxycxy@aliyun.com.
In the work by Zheng Quan MD et al. about the Use of Intraoperative
Transit Time Flow Measurement Can Reduce Preoperative Myocardial Injury
(1), the authors did a retrospective, observational study of the effects
of exposure to the TTFM procedure. They collected patient data from the
Second People’s Hospital of Changzhou, affiliated with Nanjing Medical
University, from June 2016 to June 2021; patients undergoing off-pump
coronary artery bypass grafting surgical procedures with general
anesthesia were eligible. If they met one of the following criteria,
patients were excluded: postoperative troponin did not reach normal
value; combined with other valve surgery and significant liver
dysfunction; died within 1 week after surgery. And after excluding 30
patients who did not meet the criteria, 146 patients were eventually
included in the trial. In these studies, postoperative myocardial injury
was defined as an independent rise in cardiac troponin (from baseline)
70 times the upper reference limit (URL) according to ARC-2 criteria10,
regardless of the symptoms of ischemia and electrocardiogram changes,
within this study, specifically 2380ng/L. All data entered into EpiData
Version 2.1 (EpiData Association) was reviewed manually to ensure
accuracy. After the coronary vessel bypass is completed, the heart is
restored to its anatomic position, attachments are removed, and blood
flow is measured immediately using the TTFM. In general, a 3 mm size
probe is used for the internal mammary artery and a 4 mm or 5 mm probe
for the radial artery or cavernous vein, as appropriate. The decision to
review the graft is based on the TTFM flow, along with the specific
clinical situation and an assessment of the target vessel. Blood samples
were collected immediately postoperatively, 4 hours postoperatively, 12
hours postoperatively, 24 hours postoperatively, and 48 hours
postoperatively and tested for cTNI within 1 hour using a VITROS
immunoassay analyzer (Ortho Clinical Diagnostics, Raritan, USA).
According to the manufacturer’s instructions, the lower limit of cTNI
using the Immunodiagnostic Troponin I ES test kit was 12 ng/L. The
99th percentile upper reference limit was 34 ng/L,
Therefore, they set the standard for significant myocardial injury at
2380 ng/L. This association between the use of TTFM and myocardial
injury was robust in the multivariate regression models (in all models,
p 0.05). Multiple logistic regression models were fit to estimate the
relationship between the use of TTFM and myocardial events while
adjusting for other independent variables. They performed three model
fittings on the use of TTFM to confirm its stability, and the results
indicated that the association between the use of TTFM and myocardial
injury was still independently predicted. Fifty-nine people received
TTFM, while 47 did not. In total, 7 (6.6%) had at least one grafting
vessel obstruction. Only 1 patient where the TTFM was used had an
occlusion graft vs. 6 patients where the TTFM was not used and had
postoperative injury. In 2001, the use of TTFM techniques for assessing
the quality of grafts intraoperatively, on the basis of the presence and
volume of flow were clearly described (2).
Many years ago, in our initial experience in OPCAB in acute AMI, we
learned the important role that plays the spread of a thrombus in
relation to the recovery of the cardiac muscle, sometimes independent of
the time; in those years, we didn’t have any possibility to mesa sure
the flow and the quantification of the myocardial damage immediately
(3–4) Using TTFM we can reconsider the most common use of OPCAB in
situations of acute AMI where we can give the patient a better long-term
survival, such as a Lima to Lad or arterial conduits in a young patient,
or situations where we can do a MIDCAB and the variables, MINI OPCAB
(lower middle incisions), or ROBOTIC operations (,5, 6.7, 8,9,10). .a
systematic review of the evidence and expert opinion statements, (11)
concluded that although TTFM use may increase the cost and duration of
the procedure and requires a learning curve, its cost/benefit ratio
seems largely favorable, in view of the potential clinical consequences
of graft dysfunction. These consensus statements will help to
standardize the use of TTFM in clinical practice and provide guidance in
clinical decision-making. Although the use of TTFM is around 30% of
coronary operations, it is clear that there are different situations
where the use is fundamental. For example, when you don’t have total
control of the graft because of the incision; or situations like the
MINI OPCAB operation where the dissection of the mammary is limited (12)
In conclusion, the work of Zheng Quan MD et al. (1) remarks the
importance of the use of TTFM to reduce the incidence of preoperative
myocardial injury during off-pump coronary bypass surgery. Support of,
in some ways, the recent expert opinion to promote the use of TTFM (10).
References
1 Zheng Quan, MD et al. The Use of Intraoperative Transit Time Flow
Measurement Can Reduce Preoperative Myocardial Injury
JOCS-2022-ORIG-1076
2 Denton A. Cooley, MD, reviewed No. 2.Giuseppe D’Ancona, Hratch L.
Karamanoukian, Marco Ricci, Tomas A. Salerno, Jacob Bergsland, editors,
Intraoperative Graft Patency Verification in Cardiac and Vascular Surge
PMC101218 Tex Heart Inst v.28 (4), 2001