Injury to Internal Thoracic Artery to Left Anterior Descending Artery Grafts in Cardiac Reoperations

Abstract

This case series examines experiences and outcomes associated cardiac reoperations with preexisting internal thoracic artery to left anterior descending artery grafts.

Long-term survival benefit of using an internal thoracic artery (ITA) to bypass a critically stenotic left anterior descending artery (LAD) during coronary artery bypass grafting (CABG) is well established.^1,2 However, this benefit can be severely compromised during reoperative cardiac surgery if the preexisting ITA-to-LAD graft is injured.^3,4 Reoperations have become safer with modern imaging and surgical strategies.⁵ Given limited data on managing injured ITA grafts during reoperations, we examined our institution’s experience and outcomes associated with this complication.

Methods

This case series assessed injuries in cardiac reoperations with preexisting ITA-to-LAD grafts performed at Cleveland Clinic from January 2008 to January 2018. Computed tomography (CT) was used for anatomic risk stratification and surgical planning as previously described.³ Operative reports were reviewed to identify ITA-to-LAD graft injury. Reoperations included isolated CABG, valve surgery, combined CABG and valve surgery, and thoracic aorta surgery. Excluded were reoperations for infective endocarditis, heart transplant, and prior cardiac operations without median sternotomy. This study was approved by the Cleveland Clinic institutional review board, with a waiver of informed consent for research. This study followed the STROBE reporting guideline. Data were analyzed from November 2023 to January 2024 using SAS, version 9.4 and R, version 4.3.1.

Results

In 2473 cardiac reoperations, 28 injuries (1.1%) were identified (Table). Median patient age was 73 years (15th-85th percentile, 51-90 years); 3 (10.7%) patients were female, and 25 (89.3%) were male. Three patients (10.7%) had their initial ITA-to-LAD grafting at our institution; these injuries occurred during adhesiolysis after resternotomy. Preoperative CT was accessible for 25 patients (89.3%), with 14 (50.0%) grafts found near the sternum (Figure). In 5 of 28 cases (17.9%), cardiopulmonary bypass (CPB) via peripheral cannulation (femoral in 1, axillary in 4) was established before sternotomy due to high-risk location of the ITA-to-LAD graft behind the sternum. In 7 cases (25.0%), sternotomy was followed by CPB (femoral in 1, axillary in 6) and mediastinal dissection, with CPB initiated after injury in all but 1 case.

Table. Reoperative Procedure Types and Associated ITA Injuries.

Reoperative procedure	Procedures, No.	ITA injuries, No. (%)
Isolated CABG	473	8 (1.7)
CABG and valve	657	10 (1.5)
Isolated valve	808	4 (0.5)
Aorta
Any	450	5 (1.1)
Plus CABG	29	1 (3.4)
Plus CABG and valve	158	2 (1.3)
Plus valve	221	1 (0.4)
Isolated	42	1 (2.4)
Other (no CABG)	85	1 (1.2)
Total	2473	28 (1.1)

Abbreviations: CABG, coronary artery bypass grafting; ITA, internal thoracic artery.

Figure. High-Risk Grafts Behind the Sternum.

Computed tomography images demonstrating trajectory of both a patent left internal thoracic artery (orange box) and a saphenous vein graft (blue box) coursing in close proximity to the sternum.

Twenty-five injuries (89.3%) involved left ITA grafts, and 3 (10.7%), right ITA grafts. Twenty injuries (71.4%) involved grafts crossing the midline. Five injuries (17.9%) occurred during resternotomy; 13 (46.4%), during mediastinal dissection; and 10 (35.7%), during chest wall dissection. Seventeen injuries (60.7%) occurred before CPB initiation.

Management included primary repair (8 [28.6%]), graft ligation with new bypass (8 [28.6%]), distal bypass (6 [21.4%]), vein patch (2 [7.1%]), and simple ligation (4 [14.3%]). The latter was possible for atretic ITAs with non–flow-limiting LAD lesions.

Operative mortality was 3.6% (n = 1) due to a complication requiring conversion to full median sternotomy. Two patients (7.1%) required postoperative intra-aortic balloon pump circulatory support.

Discussion

In this study, injuries to ITA-to-LAD grafts during reoperative cardiac surgery were less common than the 5.3% (35 of 655) reported in 1999 by Gillinov and colleagues⁶ from our institution. That study reported 3 deaths (8.6%) and 14 postoperative myocardial infarctions (40.0%) following injury. Improved perioperative planning with modern imaging and refined reoperative and salvage strategies, as described by Roselli and colleagues,³ has since reduced these risks.⁵ These measures allow for anticipating and avoiding complications. For instance, when prior grafts are near the sternum or cross the midline, early initiation of CPB via peripheral cannulation prior to sternotomy may be warranted despite the associated risks of bleeding and prolonged CPB.⁶

When ITA injuries occur, they may be addressed safely with various techniques depending on the nature and extent of the injury. Immediate strategies to protect the brain and heart include prompt initiation of CPB via peripheral or central cannulation, hypothermia with or without circulatory arrest, and cardioplegia. Subsequently, the repair of injured grafts can be facilitated. A study limitation is the single-center, observational, and descriptive design, which may limit the generalizability of findings. In this study, operative mortality after ITA-to-LAD injuries was lower than previously reported.⁶

Supplement.

Data Sharing Statement