Should angiographically disease-free saphenous vein grafts be replaced at the time of redo coronary artery bypass grafting?

Speculative Considerations about Some Cardiology Enigmas

Background:

Enigmas often lead to hypotheses and speculations. For this reason, especially for the sake of the reader’s motivation, we opted for the plain discussion of some cardiology enigmas.

Objective:

The present text was aimed to discuss speculatively some cardiology enigmas.

Method:

Text was freely designed in the context of coronary artery and heart valve diseases.

Results:

The results were presented as the combination enigma/hypothesis. 1) The absence of arteriosclerosis in intramyocardial coronary arteries/ endothelium-myocardial interaction (crosstalk); 2) The unique and always confirmed superior evolution of the internal thoracic artery as coronary graft/ higher NO basal release 3) The prophylactic left internal thoracic artery graft in mildly-stenosed coronary lesions/need of more accurate functional imaging techniques; 4) The high incidence of perioperative atrial fibrillation in patients with coronary artery disease/atrial ischemia associated to left circumflex coronary lesions; 5) The handling of disease-free saphenous vein grafts at the time of re-operation/biological serendipity with graft vein segments; 6) The possible aortic stenosis protection against coronary artery disease/ endothelium myocardium interaction (crosstalk) improving NO release.

Conclusion:

The discussed topics associated with their respective speculative hypothesis remain as enigmas, but would become motivations for investigations

A New Anatomic Score for Prognosis After Cardiac Catheterization in Patients with Previous Bypass Surgery

OBJECTIVES

The purpose of this study was to determine the value of a new anatomic score for prognosis after diagnostic catheterization in patients with previous coronary artery bypass grafting (CABG).

BACKGROUND

Previous CABG patients comprise a growing proportion of patients with coronary artery disease (CAD). Whereas prognostic scores are available to adjust for native CAD, there are no comparable scores for patients with previous CABG.

METHODS

We studied 3,178 previous CABG patients (2,729 in a training set) who underwent cardiac catheterization. With a Cox model to develop relative weights in the training set, we created a graft index that adjusted native anatomy for territories with grafts free of significant (> or =75%) stenoses. Scaling the regression coefficients by the maximum coefficient created an index ranging from 0 to 100, where 100 was three-vessel CAD with no patent grafts.

RESULTS

The graft index was significantly associated with all-cause death (chi-square = 121.9, p < 0.001). In combined models, the index was more strongly associated with all-cause death than either number of diseased vessels (chi-square = 68.0 and 1.7, respectively) or the Duke CAD index (chi-square = 54.3 and 9.5, respectively). In models for death using an independent validation set, the index was also associated more strongly than either native disease descriptors. In a model including other clinical variables, the graft index remained significantly associated with all-cause death (chi-square = 40.1, p < 0.001).

CONCLUSIONS

For previous CABG patients, the Duke graft index was significantly more associated with prognosis than native anatomy alone and quantifies the effect of patent grafts on survival. This tool has the potential to help determine prognosis and inform the referral of post-CABG patients to repeat revascularization procedures.

Functional assessment of disease-free saphenous vein grafts at redo coronary artery bypass grafting

BACKGROUND

Reoperations for coronary artery bypass grafting are on the rise. The general rule of replacing all saphenous vein grafts (SVGs) older than 5 years of age at the time of reoperation has recently been challenged on clinical grounds. This study provides functional data of endothelial behavior in long-term vein grafts.

METHODS

Previously placed SVGs were removed at the time of redo operations. Nitric oxide (NO) measurements in real time were carried out before and after stimulation with morphine. The measurements were compared to the angiographic appearance of the grafts obtained prior to operation. Grafts were categorized into 3 groups: disease-free, moderately diseased, and severely diseased.

RESULTS

Sixteen grafts were analyzed. Five were angiographically disease-free, 4 had moderate, and 7 severe disease. In the disease-free group, peak NO production after 10(-6) mol/L morphine stimulation was 35 mol/L, equivalent to the production of native saphenous vein. The severely diseased group did not demonstrate an increase in NO production, and the moderately diseased group produced a small rise in production.

CONCLUSIONS

Measurement of NO release of old SVGs, when angiographically pristine, equals that of native saphenous vein. These findings support the recent clinical observations that long-term angiographically disease-free vein grafts are biologically privileged.

Coronary artery surgery: the end of the beginning

In each of the first three decades of myocardial revascularization, conventional treatment has been revised completely. This lecture comments on three areas of discovery that have shaped the evolution of myocardial revascularization: science, technology development, and revascularization. The discoveries in all three areas are inexorably interrelated. The single greatest lesson learned so far is that conduit performance carries more prognostic weight than any other factor. We have observed that vein graft atherosclerosis is predictable, and that the first-generation lipid lowering drugs have a favorable effect in patients who achieve marked LDL reduction. Biologically better revascularization begins with use of the internal thoracic artery for grafting to the anterior descending coronary artery. As the results of internal thoracic artery grafting are widely reported, arterial bypass revascularization has expanded, notably by radial and gastroepiploic arteries. The results of bilateral internal thoracic artery grafting are discussed, including large-scale registry results of internal thoracic artery usage in the United States. The internal thoracic artery is significantly underutilized. Diabetes affects both endoluminal and surgical revascularization. The new pharmacology in cardiology interventions shows promise in diminishing restenosis and thrombosis even in diabetic patients. Conversely, extended internal thoracic artery grafting may also benefit diabetic patients. Now we are entering a new age of minimally invasive coronary surgery. We have passed through the early stages of mini-thoracotomy, and we are moving on to access through 1-cm ports, intrathoracic cannulation, antegrade and retrograde myocardial protection, and computer guided three-dimensional vision and instrumentation. The potential for robotic control adds greater precision, ease of use, and safety. This new technology will be integrated with diagnostic information, intraoperative monitoring, anesthesia and perfusion data, cost accounting, and surgical note transcription. The operating room of the future will package intraoperative information and is adaptable to all surgical specialties. The future of coronary artery surgery will depend on minimally invasive techniques, all-arterial grafting, and selective lipid modification to reduce progressive atherosclerosis. The conclusion of this decade marks the end of the beginning. The new generation of cardiothoracic surgeons will share in an array of technology and research unmatched in previous decades.