Cardiovascular Journal of Africa: Vol 27 No 3 (May/June 2016)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 3, May/June 2016

162

AFRICA

Perivascular administration of cyanoacrylate onto the saphenous

vein graft to prevent vascular injury due to extreme stress in

group 1 proved to be protective

in vitro

CABG remains the superior method for promoting quality

of life and lifespan in the treatment of coronary artery disease

affecting multiple vessels. Long-term success is determined by

graft success. Atherosclerosis and early occlusions may be seen in

a short period of time, particularly in venous grafts.

Increased rates of atherosclerosis and rapid neo-intimal

hyperplasia in venous grafts are described as endothelial injury

and endothelial dysfunction as a result of exposure of the vein

to the arterial system in peri-operative graft preparations.

3-5

recent years, pharmacological, genetic and physical protective

methods have been described to provide protection against early

injury to saphenous vein grafts.

3-15

et al

. classified coronary endothelial injury into three types

and reported that particularly type 3 injury may result in stenosis

and occlusion of the coronary artery.

Endothelial injury was

defined as: type 1 injury: normal morphology despite functional

changes in the endothelial layer; type 2 injury: maintenance

of internal elastic lamina and medial layer despite separation,

local peeling and intimal damage in the endothelial layer; type

3 damage: peeling of the endothelial layer and subsequent

formation of sub-endothelial tissue, and intimal and medial

damage in the respective classification.

Okazaki

et al

classified endothelial injury into five stages.

The classification includes stage 1: normal morphology; stages 2

and 3: minor or diffuse adhesion of blood cells (corresponding

to type 1 injury); stage 4: rare isolated separation in endothelial

cells (corresponding to type 2 injury); stage 5: generalised lack of

endothelial cells (corresponding to type 3 injury). In particular,

development of type 3 (stage 5) injury and widespread formation

of a sub-endothelial layer will lead to platelet aggregation and

the formation of thrombus as a result of contact between blood

components and this layer. This will trigger smooth muscle

proliferation and migration with mitogen factors; hence this may

result in early or late stenosis or occlusion in the anastomosis

area.

16-17

Stooker

et al

. exposed saphenous veins to an arterial system-

like pressure atmosphere using a non-pulsatile cardiopulmonary

device. The study indicated that endothelial injury of the

saphenous vein graft was prevented by fibrin glue.

Fibrin and fibrinogen degradation products proved to be

potent chemotactic agents for saphenous vein grafts.

However,

in a report by Nomura

et al.

regarding the use of perivascular

fibrin glue, they state it may direct the cellular stimulus and

migration to the adventitial level, preventing intimal thickening.

Perivascular fibrin glue and losartan administration were

demonstrated by Moon

et al

. to prevent neo-intimal hyperplasia

following saphenous vein graft angioplasty.

Absorbable (vicryl) and non-absorbable (polyester) loose

stents significantly reduced neo-intimal thickening, as shown

by the examination of saphenous vein grafts at one and six

months.

6,9

Looseness of the support was reported as the potential

reason.

However, the space between the graft and these loose

grafts was filled with fibrin after a short time and the loose

structure disappeared, stimulating new microvascular growth in

that area.

9,19

It has therefore been suggested to cause development

of the vasa vasorum and protection against vascular hypoxia,

not intimal thickening.

However, in an

in vivo

study by Wan

et al

., saphenous vein

graft intimal thickening could not be reduced by fibrin glue in

the long term.

The reason is that the chemotactic effects of

fibrin cannot be controlled and it will stimulate late intimal

thickening.

We did not discover any other studies on this topic, apart

from cyanoacrylate-related vascular embolism and arterial

intervention-site repair.

20,21

These resources specify the superior

adhesion characteristic of cyanoacrylate and its low fibrosis rate

during the follow-up period.

Dai

et al

. showed reduced intimal and medial thickening

of the vein graft and inflammatory responses in their rabbit

model study.

However, it is not known whether the use of

cyanoacrylate

in vivo

will cause graft restriction and related

problems. This is because previously used supportive stents were

loose or absorbable, whereas cyanoacrylate is a strong adhesive

expected to have long-term durability.

Conclusion

This study demonstrated that cyanoacrylate provided external

support to the graft without any chemotactic effect, and primary

protection of the graft against damage due to extreme stress.

However,

in vivo

studies are required to investigate the effects on

the graft in the long term.

References

Kajimoto K, Miyauchi K, Yamamoto T, Daida H, Amano A. Meta-

analysis of randomized controlled trials on the treatment of unprotected

left main coronary artery disease: one-year outcomes with coronary

artery bypass grafting versus percutaneous coronary artery intervention

with drug-eluting stent.

J Card Surg

2012;

(2): 152–157.

Oh EH, Imanaka Y, Hayashida K, Kobuse H. Meta-analysis compar-

ing clinical effectiveness of drug-eluting stents, bare metal stents and

coronary artery bypass surgery.

Int J Evid Based Healthc

are 2007;

(3):

296–304.

Motwani JG, Topol EJ. Aortocoronary saphenous vein graft disease:

pathogenesis, predisposition, and prevention.

Circulation

1998;

916–931.

Shah PJ, Gordon I, Fuller J, Seevanayagam S, Rosalion A, Tatoulis J,

et al

. Factors affecting saphenous vein graft patency: clinical and angio-

graphic study in 1402 symptomatic patients operated on between 1977

and 1999.

J Thorac Cardiovasc Surg

2003;

126

: 1972–1977.

Wan S, Arifi AA, Chan MC, Yip JH, Ng CS, Chow LT,

et al

. Differential,

time-dependent effects of perivenous application of fibrin glue on medial

thickening in porcine saphenous vein grafts.

Eur J Cardiothorac Surg

2006;

(5): 742–746.

Mehta D, George SJ, Jeremy JY, Izzat MB, Southgate KM, Bryan AJ,

. External stenting reduces long-term medial and neointimal thickening

and platelet derived growth factor expression in a pig model of arterio-

venous bypass grafting.

Nat Med

1998;

: 235–239.

Angelini GD, Lloyd C, Bush R, Johnson J, Newby AC. An external,

oversized, porous polyester stent reduces vein graft neointima formation,

cholesterol concentration, and vascular cell adhesion molecule 1 expres-

sion in cholesterol-fed pigs.

J Thorac Cardiovasc Surg

2002;

124

: 950–956.

Stooker W, Niessen HW, Baidoshvili A, Wildevuur WR, van Hinsbergh

VW, Fritz J,

et al

. Perivenous support reduces early changes in human

vein grafts: studies in whole blood perfused human vein segments.

Thorac Cardiovasc Surg

2001;

121

: 290–297.