Both skeletonized and pedicled internal thoracic arteries supply adequate graft flow after coronary artery bypass grafting even during intense sympathoexcitation

Up-to-Date, Skeletonized or Pedicle Bilateral Internal Mammary Artery; Does It Matter?

PURPOSE

In this article, we reported on the up-to-date literature regarding skeletonized bilateral internal mammary artery (BIMA) flow and the effect on sternal perfusion. We also reviewed the pros and cons of the skeletonization technique versus the conventional pedicle technique for harvesting the BIMA.

METHODS

We performed an up-to-date review using the PubMed database, with a specific focus on the contemporary published literature.

RESULTS

BIMA skeletonization can preserve the sternal microcirculation, minimize tissue damage, and maintain blood supply to the chest wall at the tissue level. This effect is also apparent in diabetics. Deep sternal wound infection (DSWI) rates are significantly less with skeletonization versus the conventional pedicle technique and are comparable to single internal mammary artery harvesting.

CONCLUSIONS

Contemporary large-scale studies demonstrate that skeletonization of the BIMA increases conduit length, provides superior flow, reduces the incidence of DSWIs, and improves late survival. Hopefully, this review will increase awareness of the compelling evidence in favor of using skeletonized internal mammary arteries and stimulate increased uptake of BIMA revascularization surgery.

Physiological insights of recent clinical diagnostic and therapeutic technologies for cardiovascular diseases

Diagnostic and therapeutic methods for cardiovascular diseases continue to be developed in the 21st century. Clinicians should consider the physiological characteristics of the cardiovascular system to ensure successful diagnosis and treatment. In this review, we focus on the roles of cardiovascular physiology in recent diagnostic and therapeutic technologies for cardiovascular diseases. In the first section, we discuss how to evaluate and utilize left ventricular arterial coupling in the clinical settings. In the second section, we review unique characteristics of pulmonary circulation in the diagnosis and treatment of pulmonary hypertension. In the third section, we discuss physiological and anatomical factors associated with graft patency after coronary artery bypass grafting. In the last section, we discuss the usefulness of mechanical ventricular unloading after acute myocardial infarction. Clinical development of diagnostic methods and therapies for cardiovascular diseases should be based on physiological insights of the cardiovascular system.

Off-pump Skeletonized Versus Pedicled Left Internal Mammary Artery Grafting: Mid-term Results

BACKGROUND

Skeletonization of the internal mammary artery for single left internal mammary artery (LIMA) use remains controversial. We sought to elucidate the effect of different harvesting techniques applied in single LIMA grafting.

METHOD

Between January 2006 and January 2012, 982 patients undergoing off-pump coronary artery bypass with pedicled LIMA conduits (P Group) and 928 patients undergoing the same operation with skeletonized LIMA conduits (S Group) were enrolled. The length and blood flow of the conduits, and in-hospital and mid-term outcomes with one-year postoperative graft angiographic results were analyzed and compared between groups.

RESULTS

Twenty-five (2.7%) patients in the S group died in hospital, compared with 26 (2.6%) in the P group, with similar rates of sternal wound infection, chest wall pain, and low-output syndrome. Although the length and blood flow of conduits were increased in the S Group, postoperative conduit patency was similar between groups (p = 0.470). During a median follow-up of 32.2 months, the groups showed similar total survival (88.3 ± 3.2%, S Group; 85.5 ± 2.0%, P Group; p = 0.118) and cardiac event-free survival (82.7 ± 3.3%, S Group; 80.3 ± 2.0%; P Group; p = 0.129), with similar postoperative complications.

CONCLUSIONS

Skeletonization of single LIMA has no extra benefit in early or mid-term outcomes, suggesting no advantage over the pedicled technique.

Endothelial and neural factors functionally involved in the modulation of noradrenergic vasoconstriction in healthy pig internal mammary artery

The role of endothelial and neural factors as modulators of neurogenic- and noradrenaline-induced vasoconstriction was examined in healthy pig internal mammary artery (IMA). Tetrodotoxin-, guanethidine-sensitive electrical field stimulation (EFS)-, and noradrenaline-elicited contractions were significantly diminished by prazosin (n=8, P<0.001) and less so by rauwolscine, indicating functional α₁- and α₂-adrenoceptor-mediated noradrenergic innervation of the IMA. Endothelium removal reduced neurogenic (n=8, P<0.01) but augmented noradrenaline responses (n=8, P<0.01), suggesting the release of two endothelium-dependent factors with opposite effects. In the presence of endothelium, neurogenic and exogenous noradrenaline vasoconstrictions were enhanced by L-NOArg (n=7, P<0.05 and P<0.01 respectively) and ODQ (n=7, both P<0.05); in denuded arteries, nNOS inhibition with N(ω)-propyl-L-arginine increased neurogenic contraction (n=7, P<0.05). Western blotting indicated the presence of neural and endothelial origin NO (n=6, P<0.001). Tetraethylammonium (n=9, P<0.001), iberiotoxin (n=7, P<0.001) and 4-aminopyridine (n=8, P<0.01) enhanced vasoconstrictions revealing a modulatory role of big conductance Ca²⁺-activated K⁺ (BK(Ca)) and voltage-dependent K⁺ (K(v)) channels in noradrenergic responses. Bosentan pretreatment (n=8, P<0.05) suggested endothelin-1 as the inferred contractile neurogenic endothelial-dependent factor. Indomethacin-induced inhibition involved a muscular prostanoid (n=9, P<0.05), functionally and immunologically localized, and derived from cyclooxygenase (COX)-1 and COX-2, as revealed by Western blots (n=5, P=0.1267). Thus, noradrenergic IMA contractions are controlled by contractile prostanoid activation and endothelin-1 release, and offset by BK(Ca) and K(v) channels and neural and endothelial NO. These results help clarify the mechanisms of vasospasm in IMA, as the preferred vessel for coronary bypass.

Human internal thoracic artery grafts exhibit severe morphological and functional damage and spasmic vasomotion due to oxidative stress

Background

The internal thoracic artery (ITA) is the first choice for myocardial revascularization, but atherosclerotic lesions and perioperative vasospasm may still limit its functionality. Oxidative stress via the peroxynitrite – poly-(ADP-ribose) polymerase (PARP) cascade plays an important role in the pathogenesis of impaired vascular tone via endothelial injury. We aimed to investigate and describe the histology, PARP activation and functionality of ITA grafts and to assess the possible beneficial effect of PARP-inhibition.

Material/Methods

ITA specimens from 47 patients (26 men, mean age 66.2±1.7 years) who underwent coronary bypass surgery were processed for histological and immunohistochemical studies for oxidative stress and PARP activation, and were functionally tested with acetylcholine (ACh) and sodium nitroprusside (SNP) with or without PARP inhibition.

Results

The sections showed atherosclerotic alterations and oxidative and nitrosative stress were evidenced by positive 3-nitrotyrosine, 4-hydroxynonenal and PAR stainings. Functionally, 88.1% reacted to K-Krebs, 68.7% exhibited contraction after 1 μM phenylephrine, 29.9% exhibited relaxation to 30 μM Ach, and all precontracted segments relaxed to 30 μM SNP. High amplitude vasomotion was observed in 47.8% of the segments, which could be abolished by the application of 10 μM SNP. Incubation of the preparations with PJ34 did not improve endothelium-dependent vasodilation.

Conclusions

ITA grafts are severely damaged both morphologically and functionally in patients undergoing coronary artery bypass surgery, but PARP inhibition cannot improve their functional characteristics. The topical use of SNP to the ITA during the operation may improve vascular functions by dilating the vessels and eliminating the eventual spasmic vasomotion.