Peer Reviewed Content

TITLE: EFFECT OF ENDOSCOPIC RADIAL ARTERY HARVEST ON GRIP AND PINCH STRENGTH SHORT TITLE: ENDOSCOPIC RADIAL ARTERY HARVEST EFFECT ON GRIP STRENGTH

Jared Blackmore, PA-C1, Casey T. Walk, MD2, Ronald Markert, PhD3, Jose Rodriguez, MD1

1 Division of Cardiothoracic Surgery, Miami Valley Hospital, 30 E. Apple St., Suite 1480, Dayton, OH 45409

2 Wright State University Department of Surgery, Miami Valley Hospital, Weber Center for Health Education 7th Floor, 128 E. Apple St., Dayton, OH 45409

3 Wright State University Boonshoft School of Medicine, Professor and Vice Chairman for Research, Department of Internal Medicine, 128 E. Apple St., Dayton, OH 45409

Keywords: Endoscopic radial artery harvesting, CABG, pinch strength, grip strength

Abstract:

Background: Coronary artery bypass grafting (CABG) utilizes autologous conduits, preferentially the internal mammary artery followed by the greater saphenous vein (GSV). Studies have shown that radial artery (RA) conduits, when combined with appropriate protocols, have improved outcomes compared to GSV. Harvesting the RA prompted concern for prolonged weakness in the donor hand; literature search showed that this has not been evaluated to date. Objective of this study is to evaluate the effect of endoscopic RA harvesting on grip and pinch strength.

Methods: A retrospective chart review was performed. Patients undergoing CABG with planned RA harvest who had pre/post operative grip and pinch strength recorded since 2016 were included. Patients with incomplete data were excluded. A dynamometer and pinch gauge were utilized to evaluate grip, tip pinch, key pinch, and palmar pinch strength. Preoperative data was compared to data collected at three weeks and three months postoperative follow up.

Results: Population of study included 23 men (88%) and 3 women (12%), mean age 60 years old, range of 47-71. No statistically significant differences were found among all strength assessments by the three month follow up. There was a down trend in grip strength at 3 weeks, but this equilibrated by the 3 month follow up. There was minimal change in all pinch strength assessments.

Conclusion: Endoscopic RA harvesting does not have a significant effect on grip or pinch strength, although there is a down trend of grip strength at 3 weeks that appears to equilibrate by the 3 month follow up.

Background

Coronary artery bypass grafting (CABG) is performed using various conduits to provide blood flow beyond a coronary artery stenosis or occlusion. Across the United States, two vessels are predominantly utilized for the surgery: the Internal Mammary Artery (IMA) and the Greater Saphenous Vein (GSV). The Radial Artery (RA) was first used by Carpentier in 1971 but stopped shortly after due to a 35% rate of occlusion and narrowing of the artery1,2 . In 1976, Fisk et al. stated, "the radial artery should not be used for coronary bypass3.” In the early 1990's, Acar et al., re-established the RA as a suitable conduit after incidentally discovering previous RA grafts that remained patent, and subsequently modified the harvest techniques to avoid spasm and intimal hyperplasia4. These studies also utilized calcium channel blockers during and after surgery, which were not available during the early attempts at using the RA as a CABG conduit. More recent studies have noted the superiority of the RA as a second-line conduit compared to the GSV, noting the multi -artery approach to CABG resulting in a lower incidence of cardiac events, lower risk of graft occlusion, lower incidence of myocardial infarction, a lower incidence of repeat revascularization and an improved survival benefit of the RA compared to GSV in patients younger than 705,6 .

Despite these publications, the GSV remains in favor as the second conduit following the IMA, instead of the RA. There are risks associated with radial artery harvesting including limb ischemia, limb loss, nerve damage, vasospasm, poor cosmesis pen technique, compression syndrome, increased surgical time and concern for residual hand and grip weakness. As endoscopic vessel harvesting has evolved, the RA can be harvested endoscopically in the same technique as the GSV. Endoscopic RA harvesting has shown to have fewer complications compared to open RA harvesting7,8. When compared for graft quality, patency, overall mortality, Endoscopic RA harvest was found to be non-inferior to open technique9. For the same quality, patency, and mortality the patient receives less complications at harvest site and improved cosmesis.

The only remaining concern is the question of residual strength after RA harvest. There is a gap in the literature relating to this concerned risk of decrease in hand strength in the donor arm. Many patients requiring CABG are relatively young and have significant concerns with losing grip or pinch strength in a donor hand after RA harvest. We have hypothesized that there is no loss of function or strength in the hand from the donor arm following endoscopic RA harvesting.

Methods

An IRB was obtained, and a retrospective chart review was performed. Patients undergoing CABG with planned RA harvest who had pre/post operative grip and pinch strength recorded since 2016 were included. Exclusion criteria for the study was previous cerebrovascular accident with residual deficit of the upper extremity and insufficient data for analysis.

A dynamometer and pinch gauge were used to assess the patient's grip and pinch strength prior to surgery, and then approximately three weeks and three months postoperatively. The dynamometer assesses the grip strength of the hand. The pinch gauge is used to assess the tip pinch, key pinch, and palmar pinch – all various techniques to test pinch strength. Tip pinch is when then thumb opposes the pad of the index finger. Key pinch is when the thumb opposes the side of the index finger. Palmar pinch is when the thumb, index, and middle finger all assert a force on an object. Each test is performed three times on each hand for an accurate mean. The non-donor arm was tested to use as the control.

Data analysis was performed using the statistical software program, SPSS. A p value of less than 0.05 was considered significant. All radial arteries were harvested using the endoscopic technique, as described by Dr. Navia, et al., with a minor difference of a more distal incision10. The procedure was performed using the Vasoview Hemopro 2 Endoscopic Vessel Harvesting System (Getinge US Sales, LLC, Wayne, NJ). Average tourniquet time of our procedure was 22 minutes. The patients were started on a diltiazem drip of 2.5mg/hr intraoperatively and this was continued until postoperative day 1, if tolerated. On postoperative day 1, the patients were started on amlodipine 5mg PO QD and continued upon discharge.

Results

The patients were 23 men (88%) and 3 women (12%). The mean age was 60 years old, with a range of 42-71. Two patients were excluded from final data calculations as they were found to have chronic unilateral weakness from previous CVAs. Two patients did not receive testing at their first post-op visit but did receive testing at the three-month follow-up visit. Three patients did not show up to their three-month follow-up visit, but their first post-op visit results were included in the statistical analysis. Mean first and second visit post op day were 21.5 and 94.17 days. Grip and pinch strength compared to control are outlined in Table 2. One patient did not receive pre-operative grip strength testing but was tested with the pinch gauge; for this patient, only the pinch gauge was used at follow-up visits.

Compared to First Follow Up Evaluation

Strength Assess-

Preoperative Evaluation Compared to Second Follow Up Evaluation

Discussion

This study followed grip and pinch strengths of 24 patients from preoperative to postoperative settings after endoscopic RA harvesting and noted no statistical difference over time compared to preoperative assessments. There is a down trend in strength when compared to the control (nondonor arm), noted mostly at grip strength at first follow up. This notes approximately a 5.7 lb. difference between the donor and control arms at this time interval, that we found to be on average of 21.5 days. This difference was noted to be equilibrating at the second follow up (avg. 94.17 days) as the grip strength difference was 2.9 lbs. All other pinch grip strength assessments had no statistical difference with observed minimal change throughout the entirety of the study.

While no statistical significance was noted, this change in grip strength demonstrates a clinical change to the patients, bringing into question how to determine clinical significance. Studies on the minimal clinically important difference in grip strength have noted that any change greater than 6.5 kg (14.33 lbs) are clinically significant11,12. While there was a demonstrated decrease in grip strength post op, it not only was statistically insignificant, but clinically insignificant as well. Also, it equilibrated over time to within 3 lbs of preoperative testing. Long term studies could be performed to ensure this trend continues.

The literature supports the RA to be the preferred second choice conduit over the GSV when utilized in appropriate scenarios and has noted multiple benefits including overall survival5,6. There is a concern for risks and complications associated with harvesting the RA 1-3. However, endoscopic harvesting of RA is much preferred over open approach as it has been shown to be non-inferior in overall mortality, fewer complications, non-inferior conduit quality, as well as overall improved cosmesis 7-9 .

This study is not without limitations. The data collection is not randomized, but this is unable to be designed in this fashion due to the nature of the procedures. Another limitation is the overall number of patients; a better analysis could be completed with a larger population. Larger studies at longer intervals would improve understanding of the complete effect of endoscopic RA harvesting on grip strength. However, our study was sufficiently powered with the number of patients used, therefore we stopped further data collection.

Conclusions

Our study has shown no significant decrease in grip or pinch strength in the short- or longterm settings. Following cessation of data collection, we have applied the results of the study to our practice and have endoscopically harvested over 250 radial arteries without complication, regardless of hand dominance. Our criteria for use of RA in CABG are as follows; complete palmar arch with a RA diameter of at least 2mm per ultrasound measurement, left sided lesions of at least 70%, right sided lesions of at least 90%, adequately sized coronary with good runoff per subjective discretion. Exclusion criteria includes incomplete palmar arch, RA measuring less than 2mm, atherosclerotic disease of the RA, End Stage Renal Disease requiring hemodialysis, subclavian stenosis, Raynaud