Ultrasound-Guided Thoracic Paravertebral Nerve Block on Postoperative Pain, Quality of Life, and Recovery in Patients with Non-Small-Cell Lung Cancer.

OBJECTIVES: Our study will investigate the effect of ultrasound-guided thoracic paravertebral block (UG-TPVB) on postoperative pain, quality of life, and enhanced recovery in patients with non-small-cell lung cancer (NSCLC) undergoing lobectomy surgery. METHODS: Our study included 100 patients aged 52 to 75 years who underwent lobectomy surgery with pathological diagnosis of NSCLC. Patients received ultrasound-guided thoracic paravertebral block or general anesthesia with tracheal intubation. Patients' pain score was recorded on a numeric rating scale (NRS) 24 hours post operation. The total postoperative dosage of tramadol hydrochloride, length of hospitalization, quality of life (QoL), and inflammation levels were recorded. RESULTS: Compared with patients who received general anesthesia with tracheal intubation, patients in the UG-TPVB group had lower postoperative NRS scores at 24 h (1.8 vs. 3.5, P = 0.035); the average 24 h postoperative NRS score of the UG-TPVB group is lower than that of the general anesthesia with tracheal intubation (4.6 vs. 5.3, P = 0.012), thus receiving less dosage of tramadol hydrochloride (221 ± 45 vs. 250 ± 38 mg, P < 0.01). Patients in the UG-TPVB group had better EORTC QLQ-C30 scores compared with patients in the general anesthesia with tracheal intubation group. The difference of length of hospitalization, hs-CRP, and IL-6 between two groups did not reach statistical difference (length of hospitalization 6.2 vs. 6.9 days, P = 0.055; hs-CRP: 7.1 ± 1.9 vs. 10.4 ± 6.6, P = 0.095; and IL-6: 71.3 ± 7.2 vs. 68.9 ± 8.7, P = 0.529). Discussion. NSCLC patients undergoing lobectomy surgery who received UG-TPVB had less postoperative pain, used less dosage of tramadol hydrochloride, and had better QoL.

Cryoneurolysis in Patients with Dorsal Neuropathic Pain Secondary to Tumor Invasion.

PURPOSE: To evaluate the safety and efficacy of cryoneurolysis (CNL) in patients with refractory thoracic neuropathic pain related to tumor invasion. MATERIALS AND METHODS: Between January 2013 and May 2017, this single-center and retrospective study reviewed 27 computed tomography-guided CNLs performed on 26 patients for refractory thoracic neuropathic pain related to tumor invasion. Patients with cognitive impairment were excluded. Pain levels were recorded on a visual analog scale (VAS) before the procedure, on days 1, 7, 14, 28 and at each subsequent follow-up appointment. CNL was clinically successful if the postprocedural VAS decreased by 3 points or more. To determine the duration of clinical success, the end of pain relief was defined as either an increased VAS of 2 or more points, the introduction of a new analgesic treatment, a death with controlled pain, or for lost to follow-up patients, the latest follow-up appointment date with controlled pain. RESULTS: Technical success rate was 96.7% and clinical success rate was 100%. Mean preprocedural pain score was 6.4 ± 1.7 and decreased to 2.4 ± 2.4 at day 1; 1.8 ± 1.7 at day 7 (P < .001); 3.3 ± 2.5 at day 14; 3.4 ± 2.6 at day 28 (P < .05). The median duration of pain relief was 45 days (range 14-70). Two minor complications occurred. CONCLUSIONS: Cryoneurolysis is a safe procedure that significantly decreased pain scores in patients with thoracic neuropathic pain related to tumor invasion, with a median duration of clinical success of 45 days.

Ultrasound-guided Interfascial Plane Blocks for Non-anesthesiologists in Breast Cancer Surgery: Functional Outcomes and Benefits.

AIM: Acute post-operative pain following modified radical mastectomy (MRM) in patients with breast cancer is challenging for anesthesiologists. This study aimed to prospectively compare the quality outcome of interfascial plane blocks performed with ultrasound guidance, and evaluate the consequences of sharing tasks with the breast surgeon. PATIENTS AND METHODS: The study involved 255 patients scheduled for unilateral MRM, who were divided into two groups: Pecs group: General anesthesia plus ultrasound-guided modified pectoral nerves blocks type I and II, including serratus and parasternal infiltration according to surgical requirements; and Control group: general anesthesia only. Quality was evaluated based on perioperative opioid consumption, reported pain intensity, rescue analgesic requirement, side-effects and length of hospital stay. Moreover, a breast surgeon with expertise in ultrasound-guided breast biopsy was trained to perform the blocks. The patient benefits from regional anesthesia delivered by a non-anesthesiologist were assessed. RESULTS: Significant reductions were noted in all of the following: Intraoperative opioid consumption (p<0.001), Numerating Rating Scale pain scores taken 0 and 24 h after surgery (p<0.001), post-operative analgesic administration (p<0.001), nausea and vomiting at 0, 6, and 12-h intervals (p<0.05), and hospital stay (p<0.001) were observed in the Pecs group compared with the control group. Furthermore, data obtained from patients receiving the block from the surgeon showed comparable benefits with no complications. CONCLUSION: Interfascial plane blocks may be an important alternative protocol in MRM, enhancing patient safety and cost benefits. Improvements in cross-disciplinary expertise through flexibility in the training of professionals with other backgrounds may provide effective analgesia and favorable outcomes.

"Isolated long thoracic nerve palsy": More than meets the eye.

INTRODUCTION: Two main hypotheses have been proposed for the pathophysiology of long thoracic nerve (LTN) palsy: nerve compression and nerve inflammation. We hypothesized that critical reinterpretation of electrodiagnostic (EDX) studies and MRIs of patients with a diagnosis of non-traumatic isolated LTN palsy could provide insight into the pathophysiology and, potentially, the treatment. MATERIAL AND METHODS: A retrospective review was performed of all patients with a diagnosis of non-traumatic isolated LTN palsy and an EDX and brachial plexus or shoulder MRI studies performed at our institution. The original EDX studies and MR examinations were reinterpreted by a neuromuscular neurologist and musculoskeletal radiologist, respectively, both blinded to our hypothesis. RESULTS: Seven patients met the inclusion criteria as having a non-traumatic isolated LTN palsy. Upon reinterpretation, all of them were found to have findings not consistent with an isolated LTN. On physical examination, three of them (43%) presented with weakness in muscles not innervated by the LTN. Four of them (57%) had additional EDX abnormalities beyond the distribution of the LTN. Five of them (71%) had MRI evidence of enlargement of nerves or denervation atrophy of muscles outside the innervation of the LNT, without evidence of compression of the LTN in the middle scalene muscle. CONCLUSION: In our series, all 7 patients, originally diagnosed as having an isolated LTN, on reinterpretation, were found to have a more diffuse muscle/nerve involvement pattern, without MR findings to suggest nerve compression. These data strongly support an inflammatory pathophysiology.

Indirect transfer of the sternal head of the pectoralis major with autogenous semitendinosus augmentation to treat scapular winging secondary to long thoracic nerve palsy.

BACKGROUND: Scapular winging resulting from long thoracic nerve palsy is uncommon but debilitating, and the choice of surgical treatment is inconsistent. The autogenous semitendinosus tendon plays a key role as an interposed tendon graft, although its use in the indirect transfer of the sternal head of the pectoralis major during the treatment of scapular winging has rarely been reported. MATERIALS AND METHODS: A retrospective review was performed during a 9-year period from the clinical data of 26 cases (28 shoulders) with indirect transfer of the sternal head of the pectoralis major with the interposition of an autogenous semitendinosus tendon graft for dynamic stabilization of the scapula. The range of active movement (forward elevation, abduction, and external rotation), American Shoulder and Elbow Surgeons score, visual analog scale score, and complications were evaluated with a mean of 47 months of clinical follow-up. RESULTS: Patients' active shoulder movements (forward elevation, abduction, and external rotation), American Shoulder and Elbow Surgeons score, and visual analog scale score showed significant improvements (P < .01). One seroma developed and resolved with extraction. Four shoulders had adhesive capsulitis and recovered after physiotherapy. There was no recurrence of scapular winging in any patient. CONCLUSION: Timely treatment, often surgical, is vital to the recovery of scapular winging secondary to long thoracic nerve palsy. Our results suggest that indirect transfer of the sternal head of the pectoralis major with interposition of the autogenous semitendinosus tendon can effectively treat scapular winging due to long thoracic nerve palsy with limited sequelae. Widespread use of this technique is recommended.

Isolated Peripheral Nerve Palsies in Thoracic Outlet Syndrome.

Thoracic outlet syndrome (TOS) poses a difficult diagnostic entity with varied etiology and clinical presentation. We present a 35-year-old gentleman with unilateral long thoracic nerve palsy and contralateral subscapular paralysis caused by aberrant scalenus medius anatomy. TOS ought to be considered in patients presenting with isolated nerve palsies.

Influence of Body Mass Index on Compensatory Sweating in Patients after Thoracic Sympathectomy due to Palmar Hyperhidrosis.

Background Thoracic sympathectomy (TS) is one of the most effective methods of treatment of primary hyperhidrosis. One of the side effects of this procedure is compensatory sweating (CS). Objective The aim of our study was to evaluate the influence of body mass index (BMI) on CS in patients after TS due to palmar hyperhidrosis. Methods Data from 157 patients with palmar hyperhidrosis who underwent TS were collected. The patients were subsequently divided in two groups according to their initial BMI: group A, BMI < 25 kg/m2, and group B, BMI ≥ 25 kg/m2. Objective (gravimetry) and subjective (VAS) measurements of the intensity of hyperhidrosis were taken from the patients' bodies prior to surgery, as well as 3 and 12 months after TS. Results Average palmar hyperhidrosis levels before the surgery did not differ significantly between the two groups (238.65 vs. 190.15; p = 0.053). A statistically significant decrease in palmar hyperhidrosis was noted in both groups, both 3 and 12 months after surgery (238.65 vs. 11.86 vs. 13.5; p < 0.05, and 190.15 vs. 16.67 vs. 11.81; p < 0.05, respectively). The intensity of sweating over the abdomino-lumbar area differed significantly between the groups before the surgery, both in subjective (1.71 vs. 3.61; p < 0.05) and objective (13.57 vs. 35.95; p < 0.05) evaluations. Three months after surgical intervention, an intensification of CS was observed in both the groups; however, no statistically significant differences were observed between the two sets of patients (VAS: 4.58 vs. 5.16; p = 0.38; gravimetry: 33.87 vs. 53.89; p = 0.12). Twelve months after TS, CS was higher in the group with an initial BMI ≥ 25 kg/m2, both in subjective and objective evaluations (3.23 vs. 4.94; p = 0.03 and 18.08 vs. 80.21; p = 0.026, respectively). Conclusion Patients with a BMI ≥ 25 kg/m2 experience more severe CS after TS, both in subjective and objective evaluations.

Plantar Sweating as an Indicator of Lower Risk of Compensatory Sweating after Thoracic Sympathectomy.

Background Hyperhidrosis is a dysfunction of the autonomic nervous system that results in regional excessive sweating, mostly in the hands, armpits, and feet. A permanent and effective treatment of hyperhidrosis can be achieved by interruption of the thoracic sympathetic chain with endoscopic thoracic sympathectomy (ETS). However, some side effects, particularly compensatory sweating (CS), are the limitations of this procedure. The mechanism of CS and the associated risk factors are still controversial. The aim of this retrospective study was to determine the relationship with various parameters associated with CS in patients undergoing ETS. Materials and Methods ETS was performed on a total of 95 patients for palmar hyperhidrosis, axillary hyperhidrosis and facial blushing by the same surgeon. The mean age of the patients was 26.41 (± 7) years, and 54 (56.8%) were males. Palmar hyperhidrosis was present in 54 (56.8%) patients, axillary hyperhidrosis in 33 (34.7%) patients, and facial blushing in 8 (8.5%) patients. Moreover, 38 (40%) patients also had plantar sweating. The severity of CS was rated into three scales as less, moderate, and severe. Results Regarding the severity of CS, 55 (57.9%) patients had no or less CS, 28 (29.5%) had moderate CS, and 12 (12.6%) patients had severe CS. Higher age group had a significant increased risk of severe CS (p = 0.03) (r = 0.262). Patients with body mass index (BMI) > 25 kg/m2 had a statistically significantly increased risk of severe CS (p = 0.016). Facial blushing resulted in severe CS in a significantly higher proportion of patients than by palmar and axillary hyperhidrosis (p = 0.001). The level of surgery was another important risk factor for CS, with the T2 level showing an increased risk of severe CS compared with T3 level (p < 0.001). Furthermore, plantar sweating was inversely and significantly related to the development of CS. Patients with plantar sweating had a significantly decreased incidence of developing CS (p = 0.015). Conclusion CS after thoracic sympathectomy for primary hyperhidrosis is the most displeasing and restrictive side effect. This study demonstrates that older age, operation level, facial blushing, and high BMI are risk factors for CS, as have been shown in several similar studies. An interesting finding of the present study is that there was a decreased incidence of CS among patients with plantar sweating. This situation may help us to distinguish high risk for CS before ETS operation.

The Erector Spinae Plane Block: A Novel Analgesic Technique in Thoracic Neuropathic Pain.

Thoracic neuropathic pain is a debilitating condition that is often poorly responsive to oral and topical pharmacotherapy. The benefit of interventional nerve block procedures is unclear due to a paucity of evidence and the invasiveness of the described techniques. In this report, we describe a novel interfascial plane block, the erector spinae plane (ESP) block, and its successful application in 2 cases of severe neuropathic pain (the first resulting from metastatic disease of the ribs, and the second from malunion of multiple rib fractures). In both cases, the ESP block also produced an extensive multidermatomal sensory block. Anatomical and radiological investigation in fresh cadavers indicates that its likely site of action is at the dorsal and ventral rami of the thoracic spinal nerves. The ESP block holds promise as a simple and safe technique for thoracic analgesia in both chronic neuropathic pain as well as acute postsurgical or posttraumatic pain.

The Cardioprotective Effects of Late-Phase Remote Preconditioning of Trauma Depends on Neurogenic Pathways and the Activation of PKC and NF-κB (But Not iNOS) in Mice.

BACKGROUND: A superficial abdominal surgical incision elicits cardioprotection against cardiac ischemia-reperfusion (I/R) injury in mice. This process, called remote preconditioning of trauma (RPCT), has both an early and a late phase. Previous investigations have demonstrated that early RPCT reduces cardiac infarct size by 80% to 85%. We evaluated the cardioprotective and molecular mechanisms of late-phase RPCT in a murine I/R injury model. METHODS: Wild-type mice, bradykinin (BK) 2 receptor knockout mice, 3M transgenic mice (nuclear factor κB [NF-κb] repressor inhibitor of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha [IκBα((S32A, S36A, Y42F))]), and inducible nitric oxide synthase (iNOS) knockout mice were analyzed using a previously established I/R injury model. A noninvasive abdominal surgical incision was made 24 hours prior to I/R injury and the infarct size was determined at 24 hours post-I/R injury. RESULTS: The results indicated that a strong cardioprotective effect occurred during late-phase RPCT (58.42% ± 1.89% sham vs 29.41% ± 4.00% late RPCT, mean area of the infarct divided by the mean area of the risk region; P ≤ .05; n = 10). Furthermore, pharmacological intervention revealed the involvement of neurogenic signaling in the beneficial effects of late RPCT via sensory and sympathetic thoracic nerves. Pharmacological experiments in transgenic mice-implicated BK receptors, ß-adrenergic receptors, protein kinase C, and NF-κB but not iNOS signaling in the cardioprotective effects of late RPCT. CONCLUSION: Late RPCT significantly decreased myocardial infarct size via neurogenic transmission and various other signaling pathways. This protective mechanism differentiates late and early RPCT. This study describes a new cardiac I/R injury prevention method and refines the concept of RPCT.

Can Thoracic Sympathetic Nerve Damage Be Reversed?

BACKGROUND: Function of the thoracic sympathetic chain (TSC) reportedly recovers after surgical clips are removed. Hence, this study was designed to study nerve regeneration after unclipping the TSC. METHODS: The bilateral TSCs of six goats were studied; the goats were separated into three groups (groups I, II, and III) during excision, clipping, and unclipping. During surgery, the TSCs were excised with a scalpel in group I and clipped in groups II and III. In group III, the clips were removed 1 month postoperatively and observed for possible nerve healing for 1 month. All TSCs were examined histologically following en block resection at 1 month postoperatively in groups I and II and at 2 months postoperatively in group III. RESULTS: Inflammation in nerve sections was noted following clip removal. Furthermore, there was significant degeneration and cell infiltration in the nerve fibers of the clipped regions. The Schwann cells around the peripheral nerve endings in the unclipped regions facilitated nerve transmission by reconstitution of myelin. CONCLUSION: Clipping the TSC can cause histologic degeneration; however, histologic nerve regeneration occurs after unclipping.

Repair of intra-thoracic autonomic nerves using chitosan tubes.

We investigated the safety and usefulness of chitosan nano/microfiber mesh tubes (C-tubes) in regenerating damaged thoracic autonomic nerves. Animal experiments were performed in six dogs. The right thoracic sympathetic nerve (Experiment 1, n=3) and phrenic nerve (Experiment 2, n=3) were resected and sutured with C-tubes. After surgery, in Experiment 1, Horner's syndrome was observed. In Experiment 2, mobility of diaphragm was assessed by chest X-ray imaging. Nerve regeneration was assessed pathologically in both experiments. All six dogs survived without complication throughout the observational period. In Experiment 1, sympathetic nerve began to regenerate inside the C-tube at three months. At 7 and 12 months after surgery, the sympathetic nerves were connected. Though all three dogs had right Horner's syndrome after surgery, it improved at 12 months. In Experiment 2, at 12 months, the phrenic nerves were connected in two of the three dogs. In X-ray imaging, though all three dogs had eventration of the diaphragm, the right diaphragm moved in response to breathing in the dogs in which phrenic nerve regenerated. C-tubes can be safely used to facilitate the regeneration of damaged sympathetic and phrenic nerves and the restoration of their lost functions.

Pulse-train stimulation for detecting medial malpositioning of thoracic pedicle screws.

STUDY DESIGN: Thoracic pedicle screw location and the current needed to stimulate adjacent neural tissue was evaluated using brief, high-frequency pulse trains and monitoring electromyography (EMG) from muscles in the lower limbs. OBJECTIVE: To establish a safe and reliable method for detecting medial malpositioning of pedicle screws placed in the thoracic spine during instrumentation and fusion. SUMMARY OF BACKGROUND DATA: Neurophysiologic studies for testing thoracic pedicle screw placement used single-pulse stimulation and monitored EMG from thoracic-innervated muscles. We propose that with this approach, stimulation fails to activate lower motor neurons innervated by spinal cord axons, such that medial malplacement of screws will go largely undetected. METHODS: EMG was monitored from multiple lower-limb muscles. Pedicle tracks were created free-hand, using a curved pedicle finder. A ball-tipped probe-insulated along its shaft-was used to palpate the walls of the pedicle tracks. During probing, constant-current, high-frequency 4-pulse stimulus trains were delivered through the ball tip, and the minimum current (i.e., threshold) needed to evoke EMG was determined for each pedicle track. The threshold current for stimulation through each screw was also determined. Postoperative serial computed tomography scans of all implanted thoracic and L1 screws were rated with respect to screw position and the pedicle wall. RESULTS: A total of 116 screws were implanted in 7 subjects. Two pedicle tracks were redirected during surgery because of particularly low thresholds to stimulation. Definite medial defects were found in 19 screws, 18 of which were detected by the experimental technique. For these screws, the average threshold to probe stimulation of their associated pedicle tracks was 7.9 +/- 4.6 mA, much lower than current thresholds for less medially placed pedicle tracks. Stimulation of these screws resulted in high thresholds (19.8 +/- 5.3 mA) when a response was evoked at all; stimulating 8 of these 19 medially malpositioned screws failed to elicit any lower-limb EMG at considerably higher (25 or 30 mA) stimulus intensities. CONCLUSION: This preliminary study supports the hypothesis that high-frequency stimulus pulse trains areeffective at detecting defects in the medial wall of pedicles in the thoracic spine during instrumentation, thereby improving on techniques using single-pulse stimulus protocols.

Restoration of elbow flexion by performing contralateral lateral thoracic and thoracodorsal nerve transfers after experimental musculocutaneous nerve transection.

OBJECT: The immediate transfer of the right lateral thoracic nerve (LTN) and the thoracodorsal nerve (TDN) to the transected left musculocutaneous nerve (MCN), leading to nerve cross-neurotization, was performed in cats to evaluate reinnervation of the biceps brachii muscle (BBM). METHODS: Surgery to produce cross-neurotization of the MCN was performed in 12 cats (treatment group). Transection of the MCN was performed without attempts at neurotization in three cats (control group). Reinnervation of the BBM was assessed by performing electromyography (EMG) 6 months (14 cats) and 26 months (one cat) postsurgery. True Blue retrograde axonal tracing studies, tensile force measurements (muscle extensometry), and histopathological analyses were performed. All cats in the treatment group recovered voluntary contraction of the BBM and regained elbow flexion. Electromyography revealed no abnormal spontaneous activity in the BBM. Muscle evoked potentials were recorded in that muscle after right C-8 ventral branch stimulation. The muscle contraction strength in the left BBM varied from 108 to 557 g. The BBMs regained their normal appearances. The region of the MCN distal to the anastomosis displayed a normal histological appearance. Fluorescence was detected in the ventral horn of the spinal cord in the right C-8 and T-1 segments. In contrast, in all cats in the control group there was atrophy of the BBM, no EMG signal, and no clinical sign of recovery. There was no contraction of the BBM, no labeled neuron in the spinal cord, and the MCN displayed major degenerative changes. CONCLUSIONS: These findings demonstrate that the LTN and TDN can be used to neurotize injured contralateral brachial plexus nerves and obtain successful reinnervation in cats.

Efficient reinnervation of hindlimb muscles by thoracic motor neurons after nerve cross-anastomosis in rats.

OBJECT: Peripheral motor axons can regenerate through motor endoneurial tubes of foreign nerves to reinnervate different target muscles. This regenerative capacity has been brought to clinical applications for restorative surgery after nerve or root injury. In this study the authors explore the extent to which nerve cross-anastomosis between lower intercostal nerves and lumbar ventral roots would be effective in inducing reinnervation of paralyzed hindlimb muscles after spinal cord hemisection at the thoracolumbar boundary in rats. METHODS: The proximal extremities of sectioned intercostal nerves T10-12 were surgically connected to the distal extremities of sectioned ipsilateral lumbar ventral roots L3-5, respectively. Motor activity reappeared 2 months postsurgery; however, locomotion was not restored and inappropriate motor patterns persisted at 9 months postsurgery. At that time, data from electrophysiological and histological studies and horseradish peroxidase retrograde labeling demonstrated efficient regrowth of thoracic motor neuron axons that reached hindlimb muscles. They also revealed a persistent maturation defect of regrown fibers, as shown by size heterogeneity and presumable extensive axonal branching. These features are consistent with reduced neural activity subsequent to continuing inappropriate motor patterns. CONCLUSIONS: These results indicate that cross-anastomosis of intercostal nerves with lumbar ventral roots allows efficient reinnervation of paralyzed hindlimb muscles after spinal cord hemisection in rats. Stimulating the reorganization of the neuronal circuitry in the central nervous system by locomotion training or other methods would presumably result in both functional and anatomical improvements. This experimental setting provides a convenient animal model to investigate these processes.

Isolated serratus anterior paralysis: a simple surgical procedure to reestablish scapulo-humeral dynamics.

We present an original surgical technique for the treatment of an isolated paralysis of the serratus anterior muscle. We used this technique on six patients in whom nonoperative treatment failed. We fixed the inferior angle of the scapula at approximately 35 degrees of lateral position with synthetic ribbon: not to the rib behind the inferior scapular angle but to the next lower rib, usually the eighth. Therefore the scapula was not fixed directly to the pectoral cage, but over a loop of 2-2.5 cm in length. This is the crux of the procedure, because this "loose" fixation enables lateral movement of the scapula and complete painless arm elevation without scapular winging. The follow-up period was 1-7 years (mean, 4 years and 9 months). The clinical results were "excellent" for five patients and "very good" in one patient. We recommend this procedure for its excellent restoration of shoulder function.

Associated movement as a sequel to thoracotomy: aberrant regeneration to the latissimus dorsi muscle.

We describe two patients with unusual associated movements as a sequel to thoracotomy. The two patients developed involuntary twitchings of the latissimus dorsi, which were induced by contractions of the adjacent muscles, the serratus anterior muscle in patient 1 and the external intercostal muscle in patient 2, after lobectomy for lung cancer. Electrophysiological and radiological studies showed that aberrant regeneration from the adjacent nerves to the denervated latissimus dorsi could be responsible for the associated movements.

Chronic stimulation enhances extramyocardial collateral blood flow after a cardiomyoplasty.

We have previously demonstrated that collateral blood flow can be established between skeletal muscle and myocardium in animals that have undergone a latissimus dorsi cardiomyoplasty. We have also shown that 5 minutes after the thoracodorsal nerve is electrically stimulated at 1.25 Hz, there is a sixfold increase in the collateral blood flow between the latissimus dorsi and the heart. In this experiment, we hypothesized that chronic stimulation of a latissimus dorsi cardiomyoplasty would result in a sustained increase in the latissimus-derived collateral blood flow. In 24 adult male goats, an ameroid constrictor was placed around a branch of the circumflex coronary artery, and a latissimus dorsi cardiomyoplasty was performed. After a rest period of about 1 week, the latissimus dorsi cardiomyoplasties were stimulated continuously at a 2-Hz frequency for 6 weeks. Collateral blood flow between the muscle and the heart was then measured with colored microspheres. Sixteen animals survived to the final experiment, and collaterals developed in 10. In these 10 animals, the latissimus collaterals continuously delivered 0.17 +/- 0.03 mL.g-1 x min-1 (mean +/- the standard error) of blood to ischemic myocardium. This flow represents 24.0% +/- 3.9% of the flow measured to normal myocardium. These results demonstrate that in an animal model of coronary artery disease, chronic electrical stimulation of a latissimus dorsi cardiomyoplasty maintains an elevated level of latissimus-derived collateral blood flow to the myocardium.