“Other” Neurologic Complications After Cardiac Surgery

Compared to the neurologic morbidity of stroke and cognitive dysfunction, “other” neurologic complications involving injuries to the brachial plexus, phrenic nerve, cranial nerves, other peripheral nerves, as well as the visual pathways, have been disproportionately underrepresented in the cardiac surgery and anesthesiology literature. These injuries are often missed in the early postoperative period when attention is focused principally on recovery from the acute trespass of cardiac surgery and cardiopulmonary bypass. However, when these problems do become apparent, they can cause considerable discomfort and morbidity. An overview of the current concepts of injury mechanisms/etiology, diagnosis, prognosis, and when possible, prevention of these injuries is presented.

Incidence and Predictors of Complications During Cryoballoon Pulmonary Vein Isolation for Atrial Fibrillation

BACKGROUND

Cryoballoon pulmonary vein isolation (PVI) has emerged as an alternative to radiofrequency PVI for atrial fibrillation (AF). Data are lacking to define the rates and predictors of complications, particularly phrenic nerve injury (PNI).

METHODS AND RESULTS

We evaluated a single-center prospective registry of 450 consecutive patients undergoing cryoballoon PVI between 2011 and 2015. Patients were 59±10 years old, 26% were women, 58% had hypertension, their mean CHA2DS2VASc score was 1.7±1.3, 30% had persistent atrial fibrillation, and 92% received a second-generation 28-mm balloon. Predefined major complications were persistent PNI, pericardial effusion, deep vein thrombosis, arteriovenous fistula, atrioesophageal fistula, bleeding requiring transfusion, stroke, and death. PNI was categorized as persistent if it persisted after discharge from the laboratory. Logistic regression was performed to identify predictors of complications and specifically PNI. We identified a major complication in 10 (2.2%) patients. In 49 (10.8%) patients, at least transient PNI was observed; only 5 persisted beyond the procedure (1.1%). All cases of PNI resolved eventually, with the longest time to resolution being 48 days. We also describe 2 cases of PNI manifesting after the index hospitalization. Regression analysis identified 23-mm balloon use (16.3% versus 5.2%, odds ratio 2.94, P=0.011) and increased age (62.8±7.7 versus 58.7±0.12 years, odds ratio 1.058, P=0.014) as independent significant predictors of PNI. There were no significant predictors of major complications.

CONCLUSIONS

In a large contemporary cohort, cryoballoon PVI is associated with low procedural risk, including lower rates of PNI than previously reported. Older age and 23-mm balloon use were associated with PNI. Our low rate of PNI may reflect more sensitive detection methods, including compound motor action potential monitoring and forced double-deflation.

[APPLICATION OF RECONSTRUCTIVE SURGICAL TECHNIQUES FOR THE PERIPHERAL NERVE TO INJURED PHRENIC NERVE TO RESTORE THE PARALYZED DIAPHRAGM]

Phrenic nerve injury often causes diaphragmatic dysfunction. Damage to the phrenic nerve may be caused by iatrogenic injury such as transection or crush during thoracic or neck surgery to treat bronchogenic, mediastinal, or neck tumors. Plication of the diaphragm is a procedure in which the flaccid hemidiaphragm is tautened by oversuturing it. Although it has been offered to patients with unilateral diaphragmatic paralysis who have severe dyspnea and other symptoms, the essential treatment should be restoration of the function to the paralyzed diaphragm. Established reconstructive techniques for peripheral nerves are indicated to treat some phrenic nerve injury cases. Muscle contraction and diaphragmatic function following nerve reconduction is recovered in many clinical cases, and favorable experimental results were seen in animal models. Reconstructive nerve procedures such as repair, graft, or transfer may be indicated in more cases of phrenic nerve injury to improve prognostic outcomes of surgery to treat locally advanced malignancies.

Postlobectomy Early Complications

Immediate postoperative complications are common after lobectomy. The most effective management of postoperative crises is prevention, which starts with preoperative preparation and patient screening. There are many factors that can be controlled and improved by the patient. Equally important is patient selection, which is influenced by pulmonary function tests, cardiopulmonary reserve, and preexisting comorbidities. After the operation, the care team can also greatly improve outcomes with aggressive cardiopulmonary therapies, ambulation, vigilant monitoring, and frequent assessments of the patient. Prevention strategies can minimize risks; however, when they occur, a proactive approach may minimize the long-term sequelae.

Comparison of pulmonary vein isolation using cryoballoon versus conventional radiofrequency for paroxysmal atrial fibrillation

The aim of this study was to compare the results of pulmonary vein isolation using conventional irrigated radiofrequency (RF) approach versus the cryoballoon (CB) ablation. From January 2008 to December 2011, a total of 426 patients with drug-resistant symptomatic paroxysmal atrial fibrillation underwent pulmonary vein isolation as the index procedure by conventional manual RF or CB ablation at our center. A final population of 396 patients was considered for analysis and divided into 2 groups: conventional RF ablation (n = 260) and CB ablation (n = 136). At a mean follow-up of 23 ± 13 months (median 27, range 4 to 68), the success rate for RF ablation group was 57.3% (149 patients) and was 63.2% (86 patients) for cryoablation group (p = 0.25). Procedural times were significantly shorter in the cryoablation group (192 ± 49 vs 112 ± 58 minutes, p <0.000001) but not fluoroscopy times (36 ± 14 vs 31 ± 17 minutes, p = 0.45). No clinical predictors were found to predict atrial fibrillation recurrences. Complication rates were similar in both groups except for phrenic nerve palsy that was uniquely observed in the CB group (8.1%, p <0.00001). All phrenic nerve palsies resolved during follow-up. In conclusion, on a medium-term follow-up, conventional point-by-point RF ablation and CB ablation showed similar success rates. Procedural times were significantly shorter in the CB approach. The most frequent complication during CB procedures was phrenic nerve palsy, which occurred in 8.1% of patients and resolved in all during the follow-up period.

[Complications after lung transplantation in chronic obstructive pulmonary disease]

BACKGROUND AND OBJECTIVE

Lung transplantation (LT) in chronic obstructive pulmonary disease (COPD) is a procedure with a high rate of morbimortality. The aim of this paper is to analyze the early and late rates of complications and mortality in COPD patients undergoing LT.

PATIENTS AND METHOD

Retrospective study of 107 COPD patients transplanted in the Hospital Universitario La Fe, between 1991 and 2008. Preoperative variables were collected as well as all the complications, medical and surgical, occurred in the follow-up, which are expressed as mean or percentage as appropriate. The 30-day mortality and long term survival were established.

RESULTS

A total of 94 men (87.9%) and 13 women (12.1%) were transplanted with a mean age (SD) of 52.58 (8.05) years with 71% of double-lung LT. BODE score was 7.24 (1.28). The rate of primary graft dysfunction was 39.3%. The most common surgical complications were phrenic paralysis (16.8%), hemothorax (17.8%) and pleural effusion (30.8%). There was a high number of postoperative hospitalization (30%) and medical complications such as hypertension (36%), diabetes mellitus (16.7%) and renal failure (40%), secondary to treatment. Perioperative mortality was 14% and 34.5% after a year, being the most frequent causes infections (34.6%) and chronic rejection (BOS) (17.8%). Five-year survival was 40.9% with bronchiectasis and smoking history being the risk factors.

CONCLUSIONS

LT is a procedure with a high early mortality rate associated with high medical and surgical complications that affect the outcome.

Neonatal phrenic nerve injury due to traumatic delivery

AIMS

To describe the clinical course of infants recovering spontaneously from diaphragmatic paralysis due to perinatal phrenic nerve injury as well as those that underwent plication of the diaphragm.

METHODS

Between 1990 and 2006, 14 newborns admitted to the Neonatal Intensive Care Unit (NICU) of the Wilhelmina Children's Hospital in Utrecht, The Netherlands, were diagnosed with diaphragmatic paralysis due to obstetric phrenic nerve injury. The clinical and follow-up data were studied retrospectively.

RESULTS

Four infants recovered spontaneously and could be weaned from mechanical ventilation within nine days without further treatment. Plication of the diaphragm was performed in 10 infants because of failure to wean from ventilatory support or serious persistent respiratory distress. Time between birth and plication ranged from 10 to 51 days, with a median of 19 days. Satisfactory respiratory outcome was achieved in 86% of the cases.

CONCLUSIONS

The minority of infants suffering from diaphragmatic paralysis due to perinatal phrenic nerve injury recovers spontaneously. Infants who fail to wean from ventilatory support and undergo early plication have a quick recovery and can be extubated successfully within a few days.

Recurrent lung collapse due to unidentified phrenic nerve injury after cardiac surgery

Partial or complete recurrent lung collapse after cardiac surgery is one cause of failure to wean from ventilator support, and frequently leads to multiple reintubations and prolonging intensive care unit and hospital stays. A 79-year-old female underwent uneventful coronary artery bypass surgery and was extubated on the first postoperative day (POD). On POD 2, a routine portable chest X-ray (CXR) revealed complete opacification of the left hemithorax. The patient was readmitted to the Cardiovascular Intensive Care Unit (CVICU) and electively intubated, and bronchoscopy revealed a left mainstem bronchus mucous plug. The patient was extubated uneventfully the same day. A CXR on the next day revealed recurrent total collapse of the left lung, which this time was successfully treated non-invasively with intermittent CPAP mask, percussive therapy, and respiratory treatments using acetylcysteine solution. After several days, the left lung collapsed again, necessitating reintubation and repeat bronchoscopy. With Pulmonary medicine present, the patient was subsequently extubated so that bronchoscopy could be performed while the patient was breathing spontaneously. This examination revealed dynamic collapse of the left lower lobe bronchus. A sniff test was performed and revealed an immobile left hemi-diaphragm. The patient gradually became stronger, and as the airway edema subsided, she was able to be managed on the regular nursing floor with intermittent CPAP mask treatments and mucolytics. Although uncommon, one documented cause of failure to wean from mechanical ventilation is diaphragmatic dysfunction. This finding is often delayed because it requires a sniff test in an extubated patient to make the diagnosis.

[Phrenic nerve paralysis following lung transplantation]

Phrenic nerve paralysis is a well-documented complication of cardiac operation, but there is less commonly reported after lung transplantation. A retrospective study of 49 lung transplantation was done at Okayama University Hospital. Phrenic nerve paralysis (unilateral in 3 patients and bilateral in 1) was found in 4 patients (8.2%). All of these paralyses were transiently recovered. The average length of ventilation, intensive care unit stay and hospitalization for recipients with phrenic nerve paralysis was not significantly longer than the other (no diaphragmatic paralysis) recipients, but there was a tendency to be longer. Diaphragmatic paralysis is most likely related to difficulty in detecting the phrenic nerve caused by adhesions, injury due to dissection, thermal injury by electrocartery, or local topical hypothermia using ice-slush. Therefore, it is important to take care of avoiding the injury of the nerve during the operation.

Satisfactory Results of Diaphragmatic Plication for Bilateral Phrenic Nerve Paralysis

Bilateral diaphragmatic plication was performed in a 44-year-old man who underwent complete resection of a thymoma infiltrating the right lung, bilateral brachiocephalic vein, pericardium, and bilateral phrenic nerves. The plication procedure allowed him to be weaned from the ventilator on postoperative day 4. He demonstrated no restrictive or obstructive pattern of lung function, and after respiratory rehabilitation he returned to work full time 5 weeks after the operation. The present results indicate that ventilatory movement of the thoracic cage can compensate for loss of bilateral diaphragmatic ventilation for at least 18 months.

Experimental repair of phrenic nerve using a polyglycolic acid and collagen tube

OBJECTIVE

The feasibility of a nerve guide tube for regeneration of the phrenic nerve with the aim of restoring diaphragmatic function was evaluated in a canine model.

METHODS

The nerve tube, made of woven polyglycolic acid mesh, had a diameter of 3 mm and was filled with collagen sponge. This polyglycolic acid-collagen tube was implanted into a 10-mm gap created by transection of the right phrenic nerve in 9 beagle dogs. The tubes were implanted without a tissue covering in 5 of the 9 dogs (group I), and the tubes were covered with a pedicled pericardial fat pad in 4 dogs (group II). Chest x-ray films, muscle action potentials, and histologic samples were examined 4 to 12 months after implantation.

RESULTS

All of the dogs survived without any complications. x-ray film examination showed that the right diaphragm was paralyzed and elevated in all dogs until 3 months after implantation. At 4 months, movement of the diaphragm in the implanted side was observed during spontaneous breathing in 1 dog of group I and in 3 dogs of group II. In the dogs showing diaphragm movement, muscle action potentials were evoked in the diaphragm muscle, indicating restoration of nerve function. Regeneration of the phrenic nerve structure was also examined on the reconstructed site using electron microscopy.

CONCLUSION

The polyglycolic acid-collagen tube induced functional recovery of the injured phrenic nerve and was aided by coverage with a pedicled pericardial fat pad.

Diaphragm paralysis definitively diagnosed by ultrasonography and postural dependence of dynamic lung volumes after seven decades of dysfunction

Unilateral diaphragm paralysis is an important and often unrecognized cause of dyspnea. In patients with appropriate risk factors, such as prior head and neck surgery and presentation of positional dyspnea or dyspnea on submersion, unilateral diaphragmatic paralysis should be considered. We present our approach to the diagnosis of diaphragm paralysis and demonstrate the utility of upright/supine spirometry and M-mode ultrasonography in these patients' evaluation.

Initial Experience Using a Forward Directed, High-Intensity Focused Ultrasound Balloon Catheter for Pulmonary Vein Antrum Isolation in Patients with Atrial Fibrillation

BACKGROUND

A high-intensity-focused ultrasound balloon catheter (HIFU-BC) is designed to isolate pulmonary veins (PV) outside the ostia (PV antrum). This catheter uses a parabolic CO2 balloon (behind water balloon) to focus a 20-, 25-, or 30-mm diameter ring of ultrasound forward of the balloon (parallel to catheter shaft). The purpose of this study is to test the safety and efficacy of the HIFU-BC for PV antrum isolation in patients with atrial fibrillation (AF).

METHODS AND RESULTS

Twenty-seven patients with paroxysmal (19 patients) or persistent (8 patients) AF were studied. Double transseptal puncture was performed for left atrial deployment of a Lasso catheter (for PV mapping) and the 14 Fr HIFU-BC. The HIFU-BC was positioned outside the PV orifice over a guidewire. HIFU energy (acoustic power 45 watts) was applied for 40 seconds with a 20-mm sonicating ring and 40 or 60 seconds with a 25-mm or 30-mm sonicating ring. No other ablation system was utilized. PV antrum isolation was attempted using HIFU-BC in 78 of 104 PVs (25/27 RSPVs, all 23 LSPVs, all 23 LIPVs, all four left common trunks and 3/27 RIPVs). HIFU-BC successfully isolated 68 (87%) of the 78PV antra with 1-26 (median 3) HIFU applications. The complications include transient bleeding from a distal branch of the left superior PV resulting from guidewire manipulation in one patient and right phrenic nerve injury in another patient. No PV stenosis (>50% narrowing) and no LA-esophageal fistula occurred. At the 12-month follow-up, 16 (59%) of the 27 patients were free of symptomatic episodes of AF (only 3 of the 16 patients were receiving antiarrhythmic medications).

CONCLUSIONS

Forward-focused HIFU applications isolated PVs outside the PV ostium with elimination of AF in 16 (59%) of the 27 patients at 12 months following the single ablation procedure.