Correlation between kinesthetic motor imagery of an amputated limb and phantom limb pain.

BACKGROUND: Phantom limb pain (PLP) is a frequent painful sensation in amputees, and motor imagery (MI) is a useful approach for the treatment of this type of pain. However, it is not clear regarding the best MI modality for PLP. OBJECTIVES: The purpose of this study was to investigate the relationship between the PLP and MI modality in upper limb amputees. STUDY DESIGN: Observational study. METHODS: Eleven patients who underwent unilateral upper limb amputation participated in this study. The MI modality (kinesthetic and visual) and PLP intensity were evaluated using the Kinesthetic and Visual Imagery Questionnaire (KVIQ)-20 and a visual analog scale. MI ability was also assessed during the hand mental rotation task. We examined the correlation between MI modalities, ability, and pain intensity. RESULTS: The total KVIQ kinesthetic score was negatively correlated with pain intensity (r = -0.71, P < 0.01): the more vivid the kinesthetic imagery, the weaker the pain. In particular, the reduction in pain intensity was associated with strong kinesthetic imagery of opposing movements of the deficient thumb (r = -0.81, P < 0.01). The KVIQ visual score and MI ability were not associated with pain intensity. CONCLUSIONS: Our data showed that the reduction of PLP could be associated with the kinesthetic modality of MI but not with visual modality or MI ability. In other words, it was suggested that the more vivid the sensation of moving muscles and joints in the defect area, the lower the PLP intensity. To reduce PLP, clinicians may prefer interventions using the kinesthetic modality.

The Effect of Continuous Field Block through Intercostal Muscles after Atrial Septal Defect Closure via a Mini-Right Thoracotomy in Pediatric Patients.

BACKGROUND: Postoperative pain management in thoracotomy patients often is difficult. Furthermore, pediatric patients present more challenges because of their inability to effectively communicate their pain intensity. The purpose of this study was to evaluate the use of continuous field block through intercostal muscles as postoperative pain management in pediatric thoracotomy. METHODS: Between 2014 and 2018, 11 patients underwent an ASD closure using a cardiopulmonary bypass via a mini-right thoracotomy through the fourth intercostal space. At the time of chest closure, a single-shot field block via the fourth intercostal muscles was performed with levobupivacaine (0.6 mg/kg). The first five patients were only given the single-shot field block (Single group). The remaining six patients were given levobupivacaine continuously (0.1 mg/kg/hr) through an indwelling catheter until the chest tube removal (Continuous group). The groups' vital signs, total amounts of acetaminophen used, postoperative courses were compared. RESULTS: Although the heart rate did not differ between the groups, the respiratory rate was significantly higher in the Single group versus the Continuous group at 16 and 32 hr post-surgery (35.6 ± 9.7/min vs. 18.5 ± 4.7/min; p=0.007, 43.0 ± 10.4 vs. 25.3 ± 3.1; p=0.042, respectively). The accumulated dosage of acetaminophen given by postoperative day 2 was significantly higher in the Single group versus the Continuous group (55.3 ± 22.1 mg/kg vs. 7.8 ± 17.4 mg/kg; p=0.012). CONCLUSIONS: Continuous field block via intercostal muscles after ASD closure via a mini-right thoracotomy in children was effective to stabilize the vital signs and reduce the analgesic medication use.

Postoperative atrial fibrillation: The role of the inflammatory response.

OBJECTIVE: Abnormal atrial conduction has been shown to be a substrate for postoperative atrial fibrillation (POAF). This study aimed to determine the relationship between the location of the atrial reentry responsible for POAF, and degree of atrial inflammation. METHODS: Normal mongrel dogs (n = 18) were divided into 3 groups: anesthesia alone (anesthesia), lateral right atriotomy (atriotomy), and lateral right atriotomy with anti-inflammatory therapy (steroid). Conduction properties of the right and left atria (RA and LA) were examined 3 days postoperatively by mapping. Activation was observed during burst pacing-induced AF. The RA and LA myeloperoxidase activity was measured to quantitate the degree of inflammation. RESULTS: Sustained AF (>2 minutes) was induced in 5 of 6 animals in the atriotomy group, but in none in the anesthesia or steroid groups. All sustained AF originated from around the RA incision. Three of these animals had an incisional reentrant tachycardia around the right atriotomy and 2 had a focal activation arising from the RA during AF. The LA activations in these animals were passive from the RA activation. The RA activation of the atriotomy group was more inhomogeneous than that of the anesthesia group (inhomogeneity index: 2.0 ± 0.2 vs 1.0 ± 0.1, P < .01). Steroid therapy significantly normalized the RA activation after the atriotomy (1.2 ± 0.1, P < .01). The inhomogeneity of the atrial conduction correlated with the myeloperoxidase activity (r = 0.774, P < .001). CONCLUSIONS: Reentrant circuits responsible for POAF are dependent on the degree of inflammation and rotate around the atriotomy. Anti-inflammatory therapy decreased the risk of postoperative AF.

Surgery for atrial fibrillation: recent progress and future perspective.

Development and introduction of radiofrequency ablation devices allowed the maze procedures to be performed safely and easily, further enabling off-pump pulmonary vein isolation through a mini-thoracotomy or thoracoscope. The effects of the maze procedure include prevention of stroke and other complications related to atrial fibrillation, improved cardiac performance, and relief of symptoms. Indications for the maze procedure have been discussed on the basis of the evidence. Pulmonary vein isolation has been shown to be effective in most patients with paroxysmal atrial fibrillation and can be performed with endocardial catheter ablation and minimally invasive epicardial ablation. These two modalities should be compared in terms of the success rate, occurrence of cerebral microembolic signals, capability of additional lesions indicated for persistent or long-standing persistent atrial fibrillation, and closure of the left atrial appendage. Noncontinuous or nontransmural lines of conduction block as a result of incomplete ablation can result in recurrence of atrial fibrillation and induction of atrial tachycardia. Intraoperative verification of conduction block across the ablation lines is recommended to prevent these complications. Volume reduction of the enlarged left atrium or a boxlesion to isolate the entire posterior left atrium may be effective in patients with a dilated left atrium, but the potentially impaired atrial transport function should be considered. Mapping of active ganglionated plexi and their ablation may improve the outcome of the procedure, but the long-term effect on atrial fibrillation and autonomic nerve activities should be examined.

The effects of inflammation on heart rate and rhythm in a canine model of cardiac surgery.

BACKGROUND: Heart rate (HR) and rhythm disturbances are common after cardiac surgery. This study tests the hypothesis that the inflammation caused by cardiac surgery is an underlying mechanism for postoperative changes in HR, rhythm, and HR variability (HRV). METHOD AND RESULTS: Normal canines (n = 6 per group) were divided into 4 groups: (1) anesthesia, (2) sternotomy and pericardiotomy, (3) atriotomy, and (4) corticosteroids combined with an atriotomy. Continuous electrocardiographic recordings were done preoperatively and for 3 postoperative days. Electrophysiologic testing was done at the initial and terminal surgeries. C-reactive protein level was assessed at each study day, and tissue myeloperoxidase activity was assessed at the terminal study. Measurements of HRV were determined daily to detect changes in autonomic tone. Postoperatively, the HR increased in the pericardiotomy (P = .0005) and atriotomy (P = .001) groups and HRV decreased in both the groups. No significant change occurred in either the HR or HRV in the anesthesia (P = .52) and steroid (P = .16) groups. HRV (triangular index) on postoperative day 3 was correlated with the tissue myeloperoxidase levels (r = -.83; P = .0004). Autonomic blockade with atropine and esmolol resulted in an HR and HRV that were not significantly different between groups. Atrial premature beats occurred postoperatively in the all the groups except the anesthesia group and were independent of the degree of inflammation. CONCLUSION: Cardiac surgery increases the postoperative HR by reducing HRV, mostly because of a reduction in vagal tone. Furthermore, the magnitude of these changes is dependent on the degree of inflammation and is normalized by corticosteroids.

Double potential mapping: a novel technique for locating the site of incomplete ablation.

OBJECTIVE: Double potential mapping using bipolar electrodes that straddle the ablation line should identify the site of incomplete ablation as a conduction gap without constructing the activation maps. METHODS: Bipolar electrograms were recorded during pacing using 11 custom-made bipolar electrodes straddling the ablation line created by a bipolar radiofrequency ablation device on the lateral right atrium in seven canines. A linear ablation was made with an ablation device, of which one jaw was inserted into the atrium through a purse-string suture. A 3-mm-wide tape was placed on both jaws 10 mm from the tip of the ablation electrode to intentionally create an incomplete ablation lesion. The activation times at each dipole across the ablation line were defined as the times of the maximum positive and negative derivatives of the double potentials, and the site of conduction gap was determined as the site of the earliest activation across the linear ablation. The lateral right atrium was mapped simultaneously with 45 different bipolar electrodes to construct the activation maps and the earliest activation site across the ablation line was determined. RESULTS: The double potential mapping located the conduction gap on a real-time basis without displaying any maps. There was no significant change in the accuracy between the different times after ablation and different pacing cycle lengths. CONCLUSIONS: Double potential mapping locates the conduction gap on a real-time basis and would be useful in beating-heart epicardial ablation in off-pump setting.

Interatrial electrical connections: the precise location and preferential conduction.

BACKGROUND: The atria are assumed to be connected electrically to each other at the level of the Bachmann's bundle, coronary sinus (CS) musculature, and interatrial septum, and these connections may have an important role in the interatrial conduction and perpetuation of various types of atrial tachyarrhythmias. However, the number, location, and preferential connections of the interatrial conduction related to the site of activation have not been examined yet. METHODS: The endocardium of both atria and the CS were mapped during continuous pacing from the left superior and inferior pulmonary veins, right pulmonary veins, upper and lower right atrium, or right atrial septum at various paced cycle lengths in 14 canines. The electrograms were recorded by custom-made form-fitted electrodes mounted on a specially designed device that allowed the septal aspects of the electrode forms to be spatially fixed to each other accurately. RESULTS: Four distinct interatrial electrical connections were identified at the Bachmann's bundle, CS, and antero-superior and postero-inferior septa. Decremental conduction was not seen in any of the connections. Bachmann's bundle was the most preferential connection during pacing from any epicardial site. The transseptal connections were evident only during pacing from the interatrial septum. The preference among the four connections was determined by the site of stimulation and the propagation of the activation related to the myocardial architecture. CONCLUSION: These unique preferential connections may play a significant role in the interatrial conduction and perpetuation of atrial tachyarrhythmias.

Concurrent multiple left atrial focal activations with fibrillatory conduction and right atrial focal or reentrant activation as the mechanism in atrial fibrillation.

OBJECTIVE: We examined the atrial activation during atrial fibrillation to validate the rationale behind simplified surgical procedures. METHODS: Intraoperative mapping of the entire atrial epicardium was performed in 21 patients with permanent atrial fibrillation and mitral valve disease using a 256-channel, 3-dimensional dynamic mapping system. RESULTS: Concurrent multiple repetitive activations arose from the posterior left atrium adjacent to the pulmonary veins or the left atrial appendage in all patients. The fastest activation propagated toward the right atrium conducting through Bachmann's bundle, leaving the other activations confined to a small atrial region. As the activation propagated toward the right atrium, there was a progressive conduction delay or block in the pathway. As a result, the activation in the right atrium desynchronized with the left atrial activation and became irregular and complex. The average cycle length measured at the right atrial appendage was significantly longer than that at the left atrial foci (206 +/- 32 milliseconds vs 175 +/- 23 milliseconds, P <.001). In addition to the passive activation, a focal activation and reentrant activation were also observed in the right atrium in 5 and 6 patients, respectively. The number of wave fronts in the right atrium was significantly greater than that in the left atrium (2.9 +/- 0.8 vs 0.6 +/- 0.7, P <.001). CONCLUSIONS: Multiple left atrial focal activations with fibrillatory conduction and right atrial focal or reentrant activations are the mechanism in permanent atrial fibrillation associated with mitral valve disease. Intraoperative mapping would facilitate the indication for simplified procedures confined to the left atrium or the pulmonary veins.

Incisional atrial reentrant tachycardia: experimental study on the conduction property through the isthmus.

BACKGROUND: Incisional atrial reentrant tachycardia is a life-threatening tachyarrhythmia after surgery for congenital heart disease. Slow conduction through an isthmus between anatomical barriers, such as a right atriotomy or the sites for cannulation, has been shown to be a prerequisite for perpetuation of the incisional atrial reentrant tachycardia. However, the conduction property through the isthmus has not been examined in detail. METHODS: To examine the conduction property, 2 tandem incisions were made on the lateral right atrium with various distances (3 to 20 mm) between the incisions in 16 canines. Four weeks after the surgery, the lateral right atrium was mapped epicardially during pacing to examine the conduction property through the isthmus. The conduction property was characterized by approximated curves of the conduction velocity through the isthmus in accordance with the pacing cycle lengths. The atrial tissue at the isthmus was examined microscopically. RESULTS: The approximated curves of the conduction velocity were classified into 3 different types. Decremental conduction was observed only in the isthmi between 5 and 15 mm in width. A small amount of surviving myocardium between the scars formed the critical isthmus microscopically (decremental type). In the isthmi wider than 15 mm in width, slow conduction was not seen at any paced cycle length (nondecremental type). In the extremely narrow isthmi less than 5 mm in width, all of the atrial myocardium at the isthmus was replaced by fibrous tissue. Conduction was blocked at the isthmus and the activation detoured around the incisions (block type). There was a statistically significant difference in the approximated curves between the 3 different types of conduction properties (P <.01). CONCLUSION: The width of the isthmus determines the conduction property through the isthmus that contributes to the development of the incisional atrial reentrant tachycardia. Thus, the incisional atrial reentrant tachycardia may be preventable by leaving a sufficient amount of surviving myocardium between the incisions or by connecting the incisions by an ablative procedure.