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

Potential Immunoregulatory and Antiviral/SARS-CoV-2 Activities of Nitric Oxide

Nitric oxide (NO) represents a key signaling molecule in multiple regulatory pathways underlying vascular, metabolic, immune, and neurological function across animal phyla. Our brief critical discussion is focused on the multiple roles of the NO signaling pathways in the maintenance of basal physiological states of readiness in diverse cell types mediating innate immunological functions and in the facilitation of proinflammatory-mediated adaptive immunological responses associated with viral infections. Prior studies have reinforced the critical importance of constitutive NO signaling pathways in the homeostatic maintenance of the vascular endothelium, and state-dependent changes in innate immunological responses have been associated with a functional override of NO-mediated inhibitory tone. Accordingly, convergent lines of evidence suggest that dysregulation of NO signaling pathways, as well as canonical oxidative effects of inducible NO, may provide a permissive cellular environment for viral entry and replication. In immunologically compromised individuals, functional override and chronic rundown of inhibitory NO signaling systems promote aberrant expression of unregulated proinflammatory pathways resulting in widespread metabolic insufficiencies and structural damage to autonomous cellular and organ structures. We contend that restoration of normative NO tone via combined pharmaceutical, dietary, or complex behavioral interventions may partially reverse deleterious physiological conditions brought about by viral infection linked to unregulated adaptive immune responses.

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

Endogenous morphine signaling via nitric oxide regulates the expression of CYP2D6 and COMT: autocrine/paracrine feedback inhibition

We determined changes in mRNA expression in specific enzymes involved in the biosynthesis of morphine in human white blood cells via microarray. Leukocyte exposure to morphine down-regulated catechol-O-methyl transferase (COMT) and CYP2D6 by approximately 50% compared with control values. The treatment did not alter DOPA decarboxylase and dopamine beta-hydroxylase expression, demonstrating the specificity of morphine actions. The verification of the microarray data was accomplished via real-time Taqman reverse transcriptase polymerase chain reaction (RT-PCR) focused on CYP2D6 and COMT expression in different blood samples treated with morphine. The analysis showed similar changes in the expression of CYP2D6 and COMT mRNA. The expression was reduced by 47 +/- 7% for CYP2D6, substantiating the microarray finding of a 54% reduction. Furthermore, exposure of white blood cells to 10(-6) M S-nitroso-N-acetyl-DL-penicillamine (SNAP), a nitric oxide (NO) donor, reduced the expression of CYP2D6 and COMT. Prior naloxone (10(-6) M) or N-nitro-L-arginine methyl ester (L-NAME) (10(-4) M) addition abrogated morphine's down-regulating activity, demonstrating morphine was initiating its actions via stimulating constitutive NO synthase derived NO release via the mu3 opiate receptor splice variant. In the past we demonstrated that UDP-glucurosyltransferase is involved in metabolizing morphine to morphine 6-glucuronide in adrenal chromaffin cells. In the present study its expression was not found in controls and morphine-treated cells, suggesting that morphine 6-glucuronide may not be synthesized in white blood cells. Taken together, it appears that morphine has the ability to modulate its own synthesis via autocrine and paracrine signaling.

Early results of off-pump coronary artery bypass grafting for patients on chronic renal dialysis

OBJECTIVE

Renal dialysis is one of the independent risk factors for coronary artery bypass graft surgery. Off-pump coronary artery bypass grafting (OPCAB) may become a good option for these patients. In this study, early results as well as surgical techniques of OPCAB in dialysis patients were analyzed compared with non-dialysis patients.

METHODS

Between July 1997 and December 2002, 471 consecutive patients who underwent OPCAB were enrolled in this study. Among them, 20 patients (4.2%) had received hemodialysis regularly for more than 3 months until the operation. Severity of coronary artery disease or clinical presentations had no significant difference, however, left ventricular function was significantly impaired in dialysis patients.

RESULTS

The average number of anastomosis was 2.8 +/- 1.0 in the dialysis group and 3.2 +/- 1.0 in the non-dialysis group (p=0.056). Twelve patients (60.0%) received 3 or more bypass grafts in the dialysis group. Among them, 6 patients were revascularized only by in-situ or composite arterial conduits using bilateral internal thoracic arteries with or without the gastroepiploic artery. No patients required aortic clamping in the dialysis group. There was no mortality or morbidity in dialysis patients. Perioperaitve bleeding and mechanical ventilation time in the intensive care unit was similar in both groups. No dialysis patients required prolonged mechanical ventilation and hemodialysis from the beginning of the operation to extubation.

CONCLUSION

The rationale for OPCAB for dialysis patients has been established. Total arterial revascularization without aortic clamping is applicable for dialysis patients who require multivessel bypass grafts.

[Morphological changes in aorto-coronary vein graft--the analysis of autopsy and biopsy material]

BACKGROUND

Patients with implanted aortic coronary grafts have different survival time, which raises the question why the efficacy of graft implants is so poor. The aim of this study was to present the results of the analysis of morphological changes in the vein grafts taken after the death of patients who died after surgery in different time intervals, as well to present the analysis of the grafts obtained after surgical reintervention.

METHODS

The total number of 656 grafts of 308 dead patients was analyzed, as well as 76 grafts from 40 patients who underwent surgical reintervention. According to the duration of the graft since surgical intervention until death, all the analyzed changes were divided into two groups: a) early changes and complications, and b) late changes and complications in aorto-coronary vein grafts.

RESULTS

After the autopsy, 518 vein grafts from the first group were evaluated histopathologically. Changes were found in the form of small or large areas with peeled endothelium in 266 grafts, with the insudation of fibrin and thrombocytes in such places, subendothelial edema, and occlusive thrombosis of the graft lumen. Significant stenosis, which occurred distally from the anastomoses, was present in 118 grafts without changes in the walls of the graft, and there was significant narrowing of the graft lumen in 134 vein grafts due to intimal hyperplasia. In the second group, 138 grafts were histopathologically analyzed after autopsy. Significant hyperplasia was present in 117 grafts with the migration of smooth muscle cells from media into intima, and in 21 grafts there were atheromatous plaques. In 120 veins analyzed before the graft implantation, the lesion or the lack of endothelium was found, as well as the penetration of fibrin and blood elements and intimal hyperplasia. In 46 veins analyzed before the graft implantation, significant intimal hyperplasia with the elevated number of smooth muscle cells was found.

CONCLUSION

The most frequent lesions in the grafts were the lesions of the endothelium, which caused thrombosis formation and lumen occlusion. Intimal hyperplasia in patients with longer survival time occurred due to the migration of smooth muscle cells from the media, or due to the formation of atherosclerotic plaques, which caused graft lumen stenosis or thrombosis.

Accelerated graft disease in a composite saphenous vein with internal thoracic artery in a chronic renal dialysis patient

A 59-year-old man with 18-year history of renal dialysis due to chronic nephritis suffered coronary artery disease, which was complete occlusion of the right coronary artery and diffuse 90% stenosis of the proximal left anterior descending artery. Off-pump coronary artery bypass grafting was performed. Saphenous vein (SV) was anastomosed with left internal thoracic artery (ITA) as a T-graft. Left ITA was anastomosed to the left anterior descending artery. The end of SV was sewn on the posterior descending artery. Coronary and graft angiography performed 2 weeks after the operation showed good patency with good distal run-off of both left ITA and SV. Three months after the operation, he was admitted with unstable angina. Angiography revealed accelerated SV graft stenosis without any change of prior coronary disease. However, angiography 7 months after the operation revealed complete obstruction of the SV graft when he was admitted because of recurrent anginal pain.

The radial artery in coronary re-operations

OBJECTIVES

Vein graft (VG) failure often leads to coronary re-operation (re-do coronary artery bypass grafting (CABG)). As the internal thoracic artery (ITA(s)) and VG have often already been used and as the VG has usually failed, the radial artery (RA) is ideally suited for use in re-do CABG. We evaluated our experience where the RA(s) was a key conduit in re-do CABG to determine the safety and efficacy and compared this to re-operations where the RA was not used.

METHODS

Three hundred and fifty-two consecutive patients who had re-do CABG using the RA(s) from July 1995 to March 1999 were studied: mean age 67.3 years, 209 (60%) angina Class III or IV, past acute myocardial infarction (AMI) in 201 (57%), left ventricular ejection fraction <50% in 109 (31%). Five hundred and thirty-two RAs were used (bilateral in 180 (51%) patients). Additionally, 232 new left ITAs (66% of patients) and 71 new right ITAs (20% of patients) were placed. A total of 1022 distal anastomoses were performed (mean of 2.9 per patient). Follow-up was at 1 month, 3 months, and yearly. The results were also compared to 730 patients having re-do CABG without an RA (January 1990 to June 1995) using identical operative and myocardial protection techniques.

RESULTS

RA spasm was noted intra-operatively in four (1.1%) patients, operative mortality was noted in 14 (3.9%) patients, peri-operative myocardial infarction was noted in ten (2.8%) patients, intra-aortic balloon pump was used in nine (2.6%) patients, stroke was noted in six (1.7%) patients, deep sternal infection was noted in two (0.6%) patients, and re-operation for haemorrhage was performed in seven (2.0%) patients. There was only one (0.3%) forearm infection, and two (0.6%) forearm haematomas required drainage. There was no hand ischaemia. When compared to 730 re-do CABG patients without RA, there were significant differences in arterial grafts used (2.6 vs. 1.2, P=0.01), in deep sternal infection (0.6% vs. 2.6%, P=0.01) and donor site infection (0.3% vs. 2.7%, P=0.005) favouring the RA group. Three-year actuarial survival was 89.2% in the RA group and 88.5% in the non-RA group (P=1.0).

CONCLUSIONS

Use of the RA in re-do CABG is safe, effective, allows additional conduit choice, reduces donor site and sternal infections, and may avoid further late VG failure.