Angiographic changes in saphenous vein grafts and atherosclerosis risk factors. A 5-year study with serial measurements of serum lipids and lipoproteins

The Predictive Effects of Clinical Hematological Changes on Saphenous Graft Patency after Coronary Artery Surgery

Objectives

To investigate the association between clinical hematologic parameters and saphenous vein graft failure after on-pump coronary artery bypass surgery.

Methods

A total of 1950 consecutive patients underwent isolated on-pump coronary artery surgery between November 2010 and February 2013. Of these, 284 patients met our inclusion criteria; their preoperative clinical hematological parameters were retrospectively obtained for this cohort study. And of them, 109 patients underwent conventional coronary angiography after graft failure was revealed by coronary computed tomography angiography. The primary endpoint was to catch at least one saphenous vein graft stenosis or occlusion following the coronary angiogram. We then analyzed risk factors for graft failure. In sequential or T grafts, each segment was analyzed as a separate graft.

Results

In logistic regression analysis, older age, platelet distribution width, and diabetes mellitus were identified as independent predictors of saphenous vein graft failure (P<0.). In contrast, preserved ejection fraction value favored graft patency (P<0.001).

Conclusion

Increased platelet distribution width is easily measurable and can be used as a simple and valuable marker in the prediction of saphenous vein graft failure.

Serial quantitative coronary analyses for the evaluation of one-year change in saphenous vein grafts

BACKGROUND

A paucity of data exists with respect to changes in whole saphenous vein grafts (SVGs) despite accelerated atherosclerosis within grafted saphenous vein conduits. In the present study, we evaluated the one-year change in SVGs by means of quantitative coronary analysis.

METHODS

This study enrolled consecutive 52 patients with 109 SVGs, who underwent coronary artery bypass graft surgery successfully. A follow-up study was performed in 33 patients with 65 SVGs after one year because 16 SVGs were obstructed (baseline, 8; follow-up period, 8), and 15 patients with 28 SVGs dropped out within one year.

RESULTS

Both minimal and mean lumen diameters decreased significantly (3.17 +/- 0.64 mm vs 2.41 +/- 0.57 mm, p < 0.001; 3.70 +/- 0.69 mm vs 2.92 +/- 0.70 mm, p < 0.001; respectively). Graft length also decreased significantly (107.1 +/- 25.8 vs 100.6 +/- 25.2 mm, p < 0.001). The graft shortening rate (graft shortening length/baseline graft length x 100) was greater than 5% in 33 vessels (51%) and greater than 10% in 23 vessels (35%). Coronary risk factors (smoking, diabetes mellitus, hypertension, dyslipidemia) did not reveal significant relationship with late loss of minimal and mean lumen diameters.

CONCLUSIONS

The present study showed a considerable and uniform lumen loss of SVGs after one year, irrespective of coronary risk factors. Graft length shortening was seen more than elongation.

BIOMECHANICAL CONSIDERATIONS IN THE DESIGN OF GRAFT: THE HOMEOSTASIS HYPOTHESIS

Since its inception in the 1960s, coronary artery bypass graft (CABG) evolved as one of the most common, best documented, and most effective of all major surgical treatments for ischemic heart disease. Despite its widespread use, however, the outcome is not always completely satisfactory. The objective of this review is to highlight the physical determinants of biomechanical design of CABG so that future procedures would have prolonged patency and better outcome. Our central axiom postulates the existence of a mechanical homeostatic state of the blood vessel, i.e., the variation in vessel wall stresses and strains are relatively small under physiological conditions. Any perturbation of mechanical homeostasis leads to growth and remodeling. In this sense, stenosis and failure of a graft may be viewed as an adaptation process gone awry. We outline the principles of engineering design and discuss the biofluid and biosolid mechanics principles that may have the greatest bearing on mechanical homeostasis and the long-term outcome of CABG.

Randomized trial of endoscopic versus open vein harvest for coronary artery bypass grafting: Six-month patency rates

OBJECTIVE

We sought to compare the 6-month angiographic patency rates of greater saphenous veins removed during coronary artery bypass grafting with the endoscopic vein harvest or open vein harvest techniques.

METHODS

Two hundred patients undergoing nonemergency on-pump coronary artery bypass grafting were prospectively randomized to either endoscopic vein harvest or open vein harvest. Follow-up angiography of all vein grafts was scheduled at 6 months. Graft patency and disease grades were assigned independently by 2 interventional cardiologists. Leg wound healing was evaluated at discharge, 1 month, and 6 months for evidence of complications.

RESULTS

There were 3 conversions from endoscopic vein harvest to open vein harvest because of vein factors. Leg wound complications were significantly lower in the endoscopic vein harvest group (7.4% vs 19.4%, P = .014). On multivariable analysis, endoscopic vein harvest emerged as the only factor affecting wound complications (odds ratio, 0.33). Three deaths (2 perioperative and 1 late) occurred in the endoscopic vein harvest group that were unrelated to vein graft closure. Twenty-four and 29 patients in the endoscopic vein harvest and open vein harvest cohorts, respectively, refused the follow-up 6-month angiography. Therefore a total of 144 angiograms (73 endoscopic vein harvests and 71 open vein harvests) and 336 vein grafts (166 endoscopic vein harvests and 170 open vein harvests) were available for analysis. The overall occlusion rates at 6 months were 21.7% for endoscopic vein harvest and 17.6% for open vein harvest. Additionally, there was evidence of significant disease (>50% stenosis) in 10.2% and 12.4% of endoscopic vein harvest and open vein harvest grafts, respectively. By means of ordinal hierarchic logistic regression, endoscopic vein harvest was not found to be a risk factor for vein graft occlusion or disease (odds ratio, 1.15). Significant predictors were congestive heart failure (odds ratio, 2.87), graft to the diagonal artery territory (odds ratio, 1.76), larger vein conduit size (odds ratio, 1.32), and graft flow (odds ratio, 0.90).

CONCLUSION

Endoscopic vein harvest reduces leg wound complications compared with open vein harvest without compromising the 6-month patency rate. The overall patency rate depends on target and vein-related variables and patient characteristics rather than the method of vein harvesting.

Factors affecting saphenous vein graft patency: clinical and angiographic study in 1402 symptomatic patients operated on between 1977 and 1999

BACKGROUND

The purpose of this study was to find the preoperative and intraoperative factors that affect vein graft patency.

METHODS

A total of 3715 graft angiograms in 1607 patients were studied for recurrence of angina. The preoperative patient characteristics and intraoperative variables were prospectively collected from patients who had primary coronary artery bypass grafting during the period from 1977 to 1999. A total of 1339 (83%) patients were male, with a mean age of 59 years. The mean period from operation to reangiogram was 99 months. The saphenous vein was grafted to the left anterior descending artery in 557 (15%), to the diagonal artery in 669 (18%), to the obtuse marginal artery in 1300 (35%), to the right coronary artery in 409 (11%), and to the posterior descending artery in 780 (21%) cases. Graft failure was defined as >or=80% stenosis.

RESULTS

During the course of the study, 2266 (61%) grafts were patent, and 1449 (39%) had failed. The patient variables that significantly reduced graft patency were a younger age (P <.001) and an ejection fraction <30% (P =.047). Operative variables associated with reduced graft patency were small coronary artery diameter (P <.001), large conduit diameter (P =.001), and the coronary artery grafted (lowest patency in the right coronary artery and maximum patency in the left anterior descending artery territory; P =.002). The interval from operation to repeat angiogram (P <.001, with 78% patent at 1 year, 78% at 5 years, 60% at 10 years, and 50% at 15 years) and the year in which the operation was performed (more recent operations had better patency; P <.001) significantly affected graft patency.

CONCLUSIONS

Saphenous vein graft patency improved over the course of the study. The best results were obtained in older patients with good left ventricular function. Large-caliber arteries on the left system, when grafted with a small-diameter vein, were associated with the best outcome.

Association of lipoprotein(a) excess with early vein graft occlusions in middle-aged men undergoing coronary artery bypass surgery

OBJECTIVE

To assess the relationship of lipoprotein(a) to early vein graft occlusions in patients after coronary artery bypass grafting.

METHODS

We studied 102 male patients (mean age 52.3 +/- 8.6 years) with chest pain occurrence during the first year (mean time 5.3 +/- 3.0 months) after surgical myocardial revascularization. Graft patency was examined by electron-beam computed tomography (n = 102) and quantitative coronary angiography (n = 31).

RESULTS

Patients were divided into 2 groups according to graft patency data: 66 (65%) with occlusions and 36 (35%) without occlusions at follow-up. No significant differences were found between the groups concerning age, smoking, family history of coronary heart disease, previous myocardial infarction, hypertension, serum lipids, and apolipoprotein B. Lipoprotein(a) level was significantly higher in patients with occluded grafts with a median (95% confidence intervals) of 24 mg/dL (17-42 mg/dL) versus 12 mg/dL (6-24 mg/dL) in patients with patent grafts, P <.01. More patients with nonoccluded grafts were taking statins postoperatively: 42% versus 18% of patients with occluded grafts, P <.05. The sensitivity and specificity of electron-beam computed tomography in revealing vein graft occlusion was close to 100%.

CONCLUSION

There is an association between high lipoprotein(a) level and vein graft occlusions in middle-aged men during the first year after coronary artery bypass grafting. Use of statins is associated with a lower rate of vein graft occlusion. Electron-beam tomography could be useful for assessing graft occlusions.

Improved patency in vein grafts harvested with surrounding tissue: results of a randomized study using three harvesting techniques

BACKGROUND

The technique of harvesting the saphenous vein for coronary artery bypass grafting influences the fate of vein grafts. The patency rate of a novel "no-touch" technique in which the vein is harvested with a pedicle of surrounding tissue and not distended was compared with two other techniques.

METHODS

One hundred fifty-six patients who underwent coronary artery bypass grafting were randomized to three saphenous vein harvesting groups: group C (conventional)--the vein was stripped, distended, and stored in saline; group I (intermediate)--the vein was stripped, local application of papaverine was used instead of distention, and the vessel was then stored in heparinized blood; and group NT (no-touch)--the vein was harvested with surrounding tissue, not distended, and stored in heparinized blood. Surgical and clinical factors that might influence graft occlusion were recorded. One hundred twenty-seven vein grafts in group C, 116 in group I, and 124 in group NT, as well as 118 left internal mammary artery grafts, were angiographically assessed at 18 months mean follow-up time.

RESULTS

The vein graft patency was 88.9% in group C, 86.2% in group I, and 95.4% in group NT. There was a statistically significant difference between the patency of the single-vein grafts in NT and the other two groups (p = 0.025). The higher the flow, the better the patency irrespective of the technique used. A higher attrition rate was found in vein segments taken from the knee area in group I. Poor vein quality affected patency in all groups. Forty-seven of all 51 sequential grafts (92.2%) were patent. The patency of left internal mammary artery grafts was 108 of 118 (91.5%).

CONCLUSIONS

We conclude that preservation of the surrounding tissue of the saphenous vein using this no-touch technique abolishes venospasm intraoperatively and plays an important role in maintaining vein graft function and patency.

Effects of preventive group education on the resistance of LDL against oxidation and risk factors for coronary heart disease in bypass surgery patients

BACKGROUND

Comprehensive preventive education for heart patients is effective in reducing cardiac events. However, very demanding counselling protocols cannot easily be implemented as an integral part of clinical practice in hospitals.

AIM

To evaluate whether recurrent preventive group education for coronary artery bypass grafting patients affects the resistance of LDL against oxidation and the classical risk factors for coronary heart disease.

METHODS

A prospective, controlled study with one-year follow-up was carried out in Southern Finland. Coronary artery bypass patients were allocated late (> or = 18 months) after the operation in the intervention and control groups.

RESULTS

Seventy two patients (65 men and 7 women) completed the study. Twelve-hour group education on healthy life-style had a significant (25%, P = 0.01) but transient positive effect on the resistance of LDL against oxidation. There was a trend towards increased physical activity in the intervention group. The impact of education on patients' weight was also more consistent (1.2 kg at 12 months, P < 0.05), whereas long-term effects on fibrinogen and serum lipids were small.

CONCLUSIONS

Repeated group education applied as an economically feasible part of specialist care had only small positive effects on patients' risk factors. There was a significant, but transient, increase in the resistance of LDL against oxidation. However, effective lipid lowering drug treatment is indicated for most coronary artery bypass patients rather than repeated health education alone.

Management of dyslipidemia after coronary artery bypass grafting

The results of serial angiographic studies and intervention trials in patients after coronary artery bypass artery grafting have provided ample evidence that abnormalities of the plasma lipoprotein system are one of the most significant risk factors for a rapid atherosclerotic attrition of saphenous vein grafts. In addition to confirming the well recognized role and contribution of cholesterol-rich LDL or lipoprotein B particles to the progression of atherosclerotic lesions, intervention trials have also provided strong evidence for the atherogenic capacity of some intact and partly delipidized triglyceride-rich very low density lipoprotein and intermediate density lipoprotein (lipoprotein B complex) particles, and the protective effect of some (high density lipoprotein 3) but not all high density lipoprotein particles. Most importantly, those studies have emphasized the need for an early, aggressive treatment of dyslipoproteinemias with pharmacological agents as the most efficient therapeutic approach to delaying, if not preventing, the detrimental effect of atherosclerosis on saphenous vein grafts.