Angioplasty of the internal thoracic artery bypass-graft an alternative to reoperation

The impact of advances in percutaneous catheter interventions on redo cardiac surgery

Toward the end of the twentieth century, redo cardiac surgery accounted for approximately 15-20% of total cardiac surgical volume. Major risk factors for redo cardiac surgery include young age at time of the first operation, progression of native coronary artery disease (CAD), vein graft atherosclerosis, bioprosthetic valve failure and endocarditis, and transplantation for end stage heart failure. Historically, redo coronary artery bypass grafting (CABG) alone carried a mortality risk of around 4%. Factors such as older age, female sex, comorbidities, combined procedures, hemodynamic instability, and emergency procedures contributed to even higher mortality and morbidity. These poor outcomes made it necessary to look for less invasive alternate methods of treatment. Advances in catheter-based interventions have made a major impact on redo cardiac surgeries, making it no longer the first option in a majority of cases. Percutaneous interventions for recurrence following CABG, transcutaneous aortic valve replacement (TAVR) for calcific aortic stenosis, valve in valve (VIV) implantations, device closure of paravalvular leaks (PVL), and thoracic endovascular aortic repair (TEVAR) for residual and recurrent aneurysms and mitral clip to correct mitral regurgitation (MR) in heart failure are rapidly developing or developed, obviating the need for redo cardiac surgery. Our intent is to review these advances and their impact on redo cardiac surgery.

Resistance of the Internal Mammary Artery to Restenosis: A Histomorphologic Study of Various Porcine Arteries

BACKGROUND/AIMS

Restenosis after percutaneous transluminal angioplasty (PTA) of the internal mammary artery (IMA) grafts is much less pronounced than in other arteries and venous grafts. The aim of the study was to test whether various arteries respond differently to dilatation.

METHODS

PTA of the IMA, carotid, renal and circumflex coronary (RCx) arteries was performed in 9 pigs (balloon to artery ratio of 1:1.5). After 8 weeks, angiography was repeated and vessels prepared for histological analysis. Immunohistochemical staining was done to examine proliferative activity (Ki67) and to identify the vasa vasorum of the adventitia (F VIII-RA).

RESULTS

The intima-media ratio after PTA was lowest in the IMA (0.06), followed by the carotid (0.27) and renal arteries (0.49) and the RCx (0.69). Proliferation of the intima was seen at 287 degrees of the vessel circumference in the RCx, at 286 degrees in the renal and at 166 degrees in the carotid artery. No proliferative activity was seen in the IMA. The intima-adventitia ratio was lower in the IMA than in the RCx and renal arteries (p < 0.05).

CONCLUSION

Intima proliferation after PTA varies between the different vessels, with best results seen in the IMA. There are differences in remodeling after PTA between muscular, muscular/elastic and elastic arteries.

"Backdoor" Alternative Approach to Stenting of a Post-Anastomotic Coronary Artery Lesion via a Chronically Obstructed Right Coronary Artery after Failure to Stent through a Tortuous Free Internal Mammary Graft

We describe the case of a patient who previously had coronary artery bypass grafting including a free right internal mammary artery graft anastomosed to a chronic totally occluded right coronary artery (RCA) proximally and distally and who presented with a high-risk acute coronary syndrome. Coronary angiography revealed the graft to be patent with a distal post-anastomotic culprit lesion within the posterolateral branch of the native RCA. Because of technical challenges, PCI could not be performed through the graft and the lesion was stented via the chronically occluded RCA instead, in a "backdoor" approach with a good final result.

Long drug-eluting stent implantation for a diffusely diseased right internal mammary artery

The frequent use of the internal mammary artery as a bypass graft has brought about an increasing need for angioplasty to treat stenotic arterial grafts. Percutaneous interventions of internal mammary artery grafts by balloon angioplasty or stenting with bare-metal stents have been described in the past. However, implantation of bare-metal stents was associated with high rates of restenosis. The introduction of drug-eluting stents for the treatment of diseased native coronary vessels has been associated with a reduced need for repeat intervention compared with bare-metal stents for both low-risk lesions and high-risk, complex lesions, including the 'long lesion' subset. We describe a case of long drug-eluting stent implantation for a diffusely diseased right internal mammary artery.