Rotator Cuff Repair With Autologous Tenocytes and Biodegradable Collagen Scaffold: A Histological and Biomechanical Study in Sheep

2019 ◽  
Vol 48 (2) ◽  
pp. 450-459 ◽  
Author(s):  
Björn P. Roßbach ◽  
Mehmet F. Gülecyüz ◽  
Lena Kempfert ◽  
Matthias F. Pietschmann ◽  
Tina Ullamann ◽  
...  

Background: Large rotator cuff tears still represent a challenging problem in orthopaedics. The use of tenocytes on biomaterials/scaffolds for the repair of large rotator cuff defects might be a promising approach in the field of tendon regeneration. Hypothesis: Cultivated autologous tenocytes seeded on a collagen scaffold lead to enhanced histological and biomechanical results after rotator cuff repair in a sheep model as compared with unseeded scaffolds in an acute setting. Study Design: Controlled laboratory study. Methods: At the tendon-bone junction of the infraspinatus tendon of the right foreleg of 24 sheep, a 3.5 × 1.5–cm tendon defect was created. Sheep were randomly allocated to group 1, a defect; group 2, where an unseeded collagen scaffold was implanted; or group 3, which received the implantation of a collagen scaffold seeded with autologous tenocytes. Twelve weeks postoperatively, tendon regeneration was examined histologically and biomechanically. Results: The histology of the neotendons of group 3 showed better fiber patterns, a higher production of proteoglycans, and an increased genesis of collagen III in contrast to groups 1 and 2. Immunostaining revealed less tissue dedifferentiation, a more structured cartilage layer, and homogeneous cartilage-bone transition in group 3 in comparison with groups 1 and 2. Biomechanically, the tensile strength of the reconstructed tendons in group 3 (mean load to failure, 2516 N; SD, 407.5 N) was approximately 84% that of the native tendons (mean load to failure, 2995 N; SD, 223.1 N) without statistical significance. A significant difference ( P = .0095) was registered between group 1 (66.9% with a mean load to failure of 2004 N; SD, 273.8 N) and the native tendons, as well as between group 2 (69.7% with a mean load to failure of 2088 N; SD, 675.4 N) and the native tendons for mean ultimate tensile strength. In breaking stress, a significant difference ( P = .0095) was seen between group 1 (mean breaking stress, 1335 N/mm2; SD, 182.7 N/mm2) and the native tendons, as well as between group 2 (breaking stress, 1392 N/mm2; SD, 450.2 N/mm2) and the native tendons (mean breaking stress, 1996 N/mm2; SD, 148.7 N/mm2). Again, there was no significant difference between group 3 (mean breaking stress, 1677 N/mm2; SD, 271.7 N/mm2) and the native tendons. Conclusion: Autologous tenocytes seeded on collagen scaffolds yield enhanced biomechanical results after tendon-bone reconstruction as compared with unseeded scaffolds in an acute setting. Biomechanical results and histological outcomes were promising, showing that the use of autologous tenocytes with specific carrier matrices could be a novel approach for repairing rotator cuff tears. Clinical Relevance: This study supports the use of tenocytes and scaffolds for improving the quality of tendon-bone regeneration.

2020 ◽  
Vol 8 (2) ◽  
pp. 232596712090401
Author(s):  
Jong-Ho Kim ◽  
Dong-Jin Kim ◽  
Hyo-Jin Lee ◽  
Baek-Kyu Kim ◽  
Yang-Soo Kim

Background: Ongoing controversy surrounds the best treatment modality for partial-thickness rotator cuff tears. Purpose: To investigate the effects of atelocollagen injection in patients with small, symptomatic, intratendinous rotator cuff tears. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: From January 2014 to December 2017, 94 patients who had small, symptomatic, intratendinous rotator cuff tears were enrolled and randomly allocated to 1 of 3 groups: intratendinous injection with 0.5 mL of type I atelocollagen (group 1, n = 32), intratendinous injection with 1 mL of type I atelocollagen (group 2, n = 30), and no injection of type I atelocollagen (group 3, n = 32). American Shoulder and Elbow Surgeons score, Constant Shoulder Score, visual analog scale pain score, and range of motion were evaluated before injection; at 3, 6, and 12 months after injection; and at final follow-up. Magnetic resonance imaging (MRI) was performed at least 6 months after injection to evaluate rotator cuff integrity. Results: Demographic data did not differ significantly among the 3 groups before injection ( P > .05). The mean follow-up period was 24.7 months. The functional and pain scores in groups 1 and 2 were significantly improved at final follow-up ( P < .05). No significant improvement was seen in functional or pain scores at final follow-up in group 3 ( P > .05). Groups 1 and 2 had significantly better functional scores compared with group 3 at final follow-up ( P < .05). The proportion of patients with a decrease in size of the torn tendon on follow-up MRI at least 6 months after atelocollagen injection was significantly higher in group 1 (28.1%; P = .02) and group 2 (36.7%; P = .003) compared with group 3 (6.3%). Conclusion: Atelocollagen injection can improve the functional outcome and integrity of the tendon in intratendinous rotator cuff tears.


2021 ◽  
Vol 9 (12) ◽  
pp. 232596712110607
Author(s):  
Yang-Soo Kim ◽  
Yun-Gyoung Lee ◽  
Min-Tae Kim ◽  
Hyo-Jin Lee

Background: Apoptosis and autophagy are known to be correlated with the extent of damage in torn rotator cuffs, and there is no biological evidence for self-recovery or healing of the rotator cuff tear. Purpose: To establish in a rat model of partial- and full-thickness rotator cuff tears how a glycogen synthase kinase 3β (GSK-3β) inhibitor affects the expression of apoptotic and autophagic markers. Study Design: Controlled laboratory study. Methods: Twelve-week-old Sprague Dawley rats were divided into 3 groups (n = 16 per group). Group 1 acted as the control, with no treatment; group 2 received partial-thickness (right side) and full-thickness (left side) rotator cuff tears only; and group 3 received the same rotator cuff injuries, with GSK-3β inhibitor injected afterward. The tendons from each group were harvested 42 days after surgery. Evaluation of gene expression, immunohistochemistry, and TUNEL staining (terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling) were performed for the following markers: caspases 3, 8, and 9 as well as Bcl-2 (B-cell lymphoma 2); BAX (Bcl-2-associated X protein); beclin 1; p53; and GSK-3β; which represented apoptotic and autophagic reactions. Statistical analysis was performed using 1-way analysis of variance. Results: In the group 2 rats with partial- and full-thickness tears, there were significant increases in the mRNA levels (fold changes) of all 8 markers as compared with group 1 (control). All these increased markers showed significant downregulation by the GSK-3β inhibitor in partial-thickness tears. However, the response to the GSK-3β inhibitor in full-thickness tears was not as prominent as in partial-thickness tears. The number of TUNEL-positive cells in group 2 (partial, 35.08% ± 1.625% [mean ± SE]; full, 46.92% ± 1.319%) was significantly higher than in group 1 (18.02% ± 1.036%; P < .01) and group 3 (partial, 28.04% ± 2.607% [ P < .01]; full, 38.97% ± 2.772% [ P < .01]), and immunohistochemistry revealed increased expression of all the markers in group 2 as compared with control. Conclusion: The apoptotic and autophagic activity induced in a rat model of an acute rotator cuff tear was downregulated after treatment with a GSK-3β inhibitor, particularly with partial-thickness rotator cuff tears. Clinical Relevance: A GSK-3β inhibitor may be able to modulate deterioration in a torn rotator cuff.


2017 ◽  
Vol 5 (2_suppl2) ◽  
pp. 2325967117S0005
Author(s):  
Hakan Tırın ◽  
Murat Gülçek

Background: Rotator cuff tears have an adverse effect on daily activities in personal disability and functional restriction. A few clinical studies have demonstrated the structural superiority of the double row technique. The aim of our study 3 cm below and the top of the rotator cuff tears and a double row repair technique with the results of the retrospectively our patients treated by comparing the results of double row repair techniques to understand the relationship between the tear size. Methods: In this retrospective study, and the data of patients who underwent arthroscopic rotator cuff repair in the years 2011-2014 were scanned as a single center. Inclusion criteria:1)3 cm above and below the rotator cuff tear preoperative identified by MRI imaging and confirmed by arthroscopy,2)which is operated by a double row repair techniques 3)do not benefit from conservative treatment 4)before patients are no operation history. Exclusion criteria: 1)partial tears, 2)irrepereabl tears, 3)arthritis in the shoulder x-ray, 4)are the follow-up of the patients over 2 years ago. In our study, patients under 3 cm (small and medium) and 3 cm above (large and massive) as we group. Tears under 3 cm was named as group 1, 3 cm above the tears were classified as group 2. 33 patients in group 1, 31 patients group 2 were classified. The patients preoperatively, postoperatively at 6 months, 12 months and finally at 24 months VAS scores, joint ROMs, Constant and UCLA scores were evaluated. At the end of 2 years, patients MRI taken as a result of rupture rates and functional outcomes were compared. Results: Between the groups; age, sex, side, AC joint pathology and the dominant limb with respect was found that no statistically significant difference (p>0.05). According to MRI results rupture rate of 33.3% in group 1, group 2 was found to be 19.4%. The comparison between groups; Constant score at all measurement values were found to be statistically significant difference (p<0.05). 3 cm below the rotator cuff tear time of four measurements was found to be higher than the constant score. The comparison between groups; VAS and UCLA scores in all measured time was found that no statistically significant difference (p>0.05). Conclusions: Double row repair technique is a safe surgical technique that can be applied regardless of the size of the tear. 3 cm above the rotator cuff tear in functional outcomes are worse, rupture rate is higher.


2016 ◽  
Vol 45 (1) ◽  
pp. 157-166 ◽  
Author(s):  
Hyun Soo Ok ◽  
Byung Guk Kim ◽  
Won Chul Choi ◽  
Chul Gie Hong ◽  
Jee Woong Kim ◽  
...  

Background: Studies on the results of arthroscopic repair of massive rotator cuff tears have reported widely varied prognoses. Among other factors, the sizable discrepancy can be attributable to the fact that the current definition of massive rotator cuff tears covers an extensive area of tendons. Hypothesis: Functional and radiological results according to subgroups would show significant inter-subgroup differences preoperatively and postoperatively. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 104 patients who required arthroscopic repair for massive rotator cuff tears were prospectively evaluated. The patients were allocated into 3 groups according to tendon involvement as diagnosed by preoperative magnetic resonance imaging: group 1 (anterosuperior type involving the subscapularis and supraspinatus), group 2 (posterosuperior type involving the infraspinatus and supraspinatus), and group 3 (anteroposterior type involving the subscapularis, supraspinatus, and infraspinatus). We compared functional results (at 2 years postoperatively) and radiological findings (at 1 year postoperatively) for each group. Results: There were 34 patients in group 1, 54 in group 2, and 16 in group 3. In all 3 groups, functional results significantly improved after surgery. There were no statistically significant intergroup differences in functional results among the 3 groups. On the radiological evaluations, each group (groups 1, 2, and 3) showed a significantly different result in the preoperative acromiohumeral distance (AHD) (7.19, 5.44, and 5.22 mm, respectively), tear size (38.8, 39.3, and 46.4 mm, respectively), extent of retraction (33.9, 40.0, and 41.4 mm, respectively), postoperative AHD (8.92, 7.37, and 6.71 mm, respectively), and retear rate (23.5%, 51.9%, and 56.2%, respectively) ( P < .001 for all). Conclusion: Massive rotator cuff tears can be divided into 3 types: anterosuperior (group 1), posterosuperior (group 2), and anteroposterior (group 3). Each group has distinctive characteristics and shows different results in the preoperative AHD, tear size, extent of retraction, postoperative AHD, and retear rate, which provide a reasonable basis for categorization. So far, massive rotator cuff tears have only been broadly defined, consequently being understood as a single category by many. However, to clearly understand and evaluate this injury, we suggest identifying differences within the category through proper subclassification.


VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.


2021 ◽  
Vol 28 (3) ◽  
pp. 328-338
Author(s):  
Ogbutor Udoji Godsday ◽  
Nwangwa Eze Kingsley ◽  
Nwogueze Bartholomew Chukwuebuka ◽  
Chukwuemeka Ephraim ◽  
Ezunu Emmanuel ◽  
...  

Decline in normal physiological pulmonary function has been attributed to premorbid conditions such as prehypertension. Research evidence suggests that physical activity reduces age-related decline in pulmonary function and improves the efficiency of the lungs in prehypertensive patients. However, there is a scarcity of data evidence relating to isometric exercise and pulmonary function. Furthermore, the interrelationship between the intensity and duration of isometric exercise and pulmonary function in these patients is still uncertain. Therefore, this study was undertaken to investigate the effect of isometric handgrip exercise on pulmonary function capacity in adults with prehypertension. To determine the effectiveness of isometric handgrip exercise on pulmonary function capacity in adults with prehypertension. A quasi experiment using a pre- and post-exercise method was carried out in two out-patients hospital settings. The sample comprised 192 sedentary pre-hypertensive subjects, aged between 30–50 years, that were randomly distributed into three groups of 64 participants each. The subjects performed, for 24 consecutive days, an isometric handgrip exercise at 30% Maximum Voluntary Contraction (M.V.C.). At the end of the 24 days, group one (GP1) discontinued, while group two (GP2) continued the exercise protocol for another 24 consecutive days and group three (GP3) continued with the exercise protocol for another 24 consecutive days but at 50% M.V.C. Determinants of lung function (outcomes) were Forced Expiratory Volume in 1 s (FEV1), Forced Vital Capacity (FVC), FEV1/FVC Ratio and Peak Expiratory Flow Rate (PEFR). The study shows that there was no statistically significant difference in the pre- and post-exercise outcomes for FEV1, FVC, FEV1/FVC Ratio and PEFR after 24 days for group 1. In group 2, there was a statistically significant difference in the FVC [(mean = 0.12 ± 0.12), (p = 0.002)], FEV1 [(mean = 0.15 ± 0.17), (p = 0.003)] and PEF [(mean = 0.85 ± 0.35), (p = 0.001)] after 48 days. In group 3, there was a statistically significant difference (p = 0.001) in all the outcomes assessed after 48 days. There was a between groups difference in favour of group 2 compared with group 1 for outcomes of FEV1 [(mean = 0.142 ± 0.68), (p = 0.005)] and PEF [(mean = 0.83 ± 0.19), (p = 0.0031)]. There was statistically significant difference in favour of group 3 compared to group 2, by increasing the exercise intensity from 30% to 50% M.V.C., for outcomes of FVC [mean change = 0.10 ± 0.052), (p = 0.005)], FEV1/FVC [mean change = 3.18 ± 0.75), (p = 0.017)] and PEF [(mean change = 0.86 ± 0.35), (p = 0.001)] after 48 days. Isometric handgrip exercise (after 48 days at 30% to 50% M.V.C.) improves outcomes of pulmonary function capacity in adults with prehypertension. Meanwhile, duration and/or increase in intensity of the isometric effort significantly contributed to the affects attained.


Arthroplasty ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhijie Chen ◽  
Kaizhe Chen ◽  
Yufei Yan ◽  
Jianmin Feng ◽  
Yi Wang ◽  
...  

Abstract Objective To evaluate the effect of medial posterior tibial slope (PTS) on mid-term postoperative range of motion (ROM) and functional improvement of the knee after medial unicompartmental knee arthroplasty (UKA). Methods Medical records of 113 patients who had undergone 124 medial UKAs between April 2009 through April 2014 were reviewed retrospectively. The mean follow-up lasted 7.6 years (range, 6.2–11.2 years). Collected were demographic data, including gender, age, height, weight of the patients. Anteroposterior (AP) and lateral knee radiographs of the operated knees were available in all patients. The knee function was evaluated during office follow-up or hospital stay. Meanwhile, postoperative PTS, ROM, maximal knee flexion and Hospital for Special Surgery (HSS) knee score (pre−/postoperative) of the operated side were measured and assessed. According to the size of the PTS, patients were divided into 3 groups: group 1 (<4°), group 2 (4° ~ 7°) and group 3 (>7°). The association between PTS and the knee function was investigated. Results In our cohort, the average PTS was 2.7° ± 0.6° in group 1, 5.6° ± 0.9° in group 2 and 8.7° ± 1.2° in group 3. Pairwise comparisons showed significant differences among them (p < 0.01). The average maximal flexion range of postoperative knees in each group was 112.4° ± 5.6°, 116.4° ± 7.2°, and 117.5° ± 6.1°, respectively, with significant difference found between group 1 and group 2 (p < 0.05), and between group 1 and group 3 (p < 0.05). However, the gender, age, and body mass index (BMI) did not differ between three groups and there was no significant difference between groups in terms of pre−/postoperative HSS scores or postoperative knee ROM. Conclusion A mid-term follow-up showed that an appropriate PTS (4° ~ 7°) can help improve the postoperative flexion of knee. On the other hand, too small a PTS could lead to limited postoperative knee flexion. Therefore, the PTS less than 4° should be avoided during medial UKA.


2021 ◽  
pp. 1-7
Author(s):  
Emre Erdem ◽  
Ahmet Karatas ◽  
Tevfik Ecder

<b><i>Introduction:</i></b> The effect of high serum ferritin levels on long-term mortality in hemodialysis patients is unknown. The relationship between serum ferritin levels and 5-year all-cause mortality in hemodialysis patients was investigated in this study. <b><i>Methods:</i></b> A total of 173 prevalent hemodialysis patients were included in this study. The patients were followed for up to 5 years and divided into 3 groups according to time-averaged serum ferritin levels (group 1: serum ferritin &#x3c;800 ng/mL, group 2: serum ferritin 800–1,500 ng/mL, and group 3: serum ferritin &#x3e;1,500 ng/mL). Along with the serum ferritin levels, other clinical and laboratory variables that may affect mortality were also included in the Cox proportional-hazards regression analysis. <b><i>Results:</i></b> Eighty-one (47%) patients died during the 5-year follow-up period. The median follow-up time was 38 (17.5–60) months. The 5-year survival rates of groups 1, 2, and 3 were 44, 64, and 27%, respectively. In group 3, the survival was lower than in groups 1 and 2 (log-rank test, <i>p</i> = 0.002). In group 1, the mortality was significantly lower than in group 3 (HR [95% CI]: 0.16 [0.05–0.49]; <i>p</i> = 0.001). In group 2, the mortality was also lower than in group 3 (HR [95% CI]: 0.32 [0.12–0.88]; <i>p</i> = 0.026). No significant difference in mortality between groups 1 and 2 was found (HR [95% CI]: 0.49 [0.23–1.04]; <i>p</i> = 0.063). <b><i>Conclusion:</i></b> Time-averaged serum ferritin levels &#x3e;1,500 ng/mL in hemodialysis patients are associated with an increased 5-year all-cause mortality risk.


2021 ◽  
Vol 9 (4) ◽  
pp. 232596712110024
Author(s):  
Koray Şahin ◽  
Fatih Şentürk ◽  
Mehmet Ersin ◽  
Ufuk Arzu ◽  
Mechmet Chodza ◽  
...  

Background: Knot-tying suture-bridge (SB) rotator cuff repair may compromise the vascularity of the repaired tendon, causing tendon strangulation and medial repair failure. The knotless SB repair technique has been proposed to overcome this possibility and decrease retear rates. Purpose: To compare clinical and structural outcomes and retear patterns between the knot-tying and knotless SB techniques. We hypothesized that the knotless technique would result in lower retear rates owing to the preservation of intratendinous vascularity. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 104 patients with full-thickness rotator cuff tears were randomly and prospectively allocated to undergo knot-tying (group 1) or knotless (group 2) SB repair. Clinical outcome measures included range of motion, the visual analog scale (VAS) for pain, and the Constant score for function. Repair integrity was evaluated on magnetic resonance imaging scans using the Sugaya classification. Retears were also classified according to their pattern as type 1 (lateral) or type 2 (medial). Results: Overall, 88 patients (group 1: n = 42 [mean ± SD age, 54.3 ± 9.8 years]; group 2: n = 46 [mean ± SD age, 55.8 ± 8.2 years]) were included in the final analysis. The mean ± SD follow-up period was 25.4 ± 8.3 and 23.3 ± 7.2 months for groups 1 and 2, respectively. From preoperatively to postoperatively, the mean VAS pain score improved significantly in both groups (group 1: from 7.4 ± 1.7 to 1.0 ± 1.7; group 2: from 7.1 ± 1.9 to 1.3 ± 2.0; P < .0001 for both), as did the mean ± SD Constant score (group 1: from 51.7 ± 13.4 to 86.0 ± 11.5; group 2: from 49.4 ± 18.4 to 87.2 ± 14.8; P < .0001 for both). There was no significant difference between the groups for the postoperative VAS or Constant score. The retear rate was not significantly different between the groups (19.0% [8/42] in group 1 and 28.3% [13/46] in group 2; P > .05). There was a significant difference in the type 2 failure rate (75.0% [6/8] in group 1 and 23.1% [3/13] in group 2; P = .03). Conclusion: Both techniques showed excellent improvement and comparable clinical outcomes, and there was no significant difference in retear rates. Consistent with previously published data, the type 2 failure rate was significantly higher with the knot-tying technique. Registration: NCT03982108 ( ClinicalTrials.gov identifier).


2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Mohamed MesbahTahaHassanin ◽  
Ahmad ShafieAmmar ◽  
Radwa M. Abdullah ◽  
Mohammad Hassan Khedr

Abstract Background Right ventricular apical pacing with the resultant left ventricular dyssynchrony often leads to depressed systolic function and heart failure. This study aimed at investigating the relation between various septal locations guided by ECG and fluoroscopy and the intermediate term functional capacity of the patients. Results Fifty patients who received a single lead pacemaker with assumed > 90% pacemaker dependency. Patients were randomized according to RV pacing site RV into group 1 “high septum” (n = 15), group 2 “mid septum” (n = 25), and group 3 “low septum” (n = 10) using QRS vector and duration as well as fluoroscopic parameters. Their clinical status was assessed 6 months after device implementation using 6-min walk test (6MWT). The study showed that paced QRS complex duration itself has no significant difference between the different septal pacing locations (P-value 0.675), although its combination with the paced QRS complex vector can signify the optimal pacing site and 6MWT showed a significant difference among the groups in favor of group 1; group 1 (413.3 ± 148.5), group 2 (359.8 ± 124.6), and group 3 (276.0 ± 98.5) P value 0.04. Conclusion There was a significant difference found between the three septal pacing sites concerning the patient functional capacity with superiority of high septal location. By contrast, different septal sites showed no significant difference of the paced QRS complex duration. To optimize the pacing site in the septum, assessment of the paced QRS vector in leads I and III is of a great benefit especially when combined with paced QRS complex duration assessment.


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