Andy C. Kiser

Blunt tracheobronchial injuries: treatment and outcomes

BACKGROUND Tracheobronchial injury is a recognized, yet uncommon, result of blunt trauma to the thorax. Often the diagnosis and treatment are delayed, resulting in attempted surgical repair months or even years after the injury. This report is an extensive review of the literature on tracheobronchial ruptures that examines outcomes and their association with the time from injury to diagnosis. METHODS We reviewed all patients with blunt tracheobronchial injuries published in the literature to determine the anatomic location of the injury, mechanism of the injury, time until diagnosis and treatment, and outcome. Only patients with blunt intrathoracic tracheobronchial traumas were included. RESULTS We identified 265 patients reported between 1873 and 1996. Motor vehicle accidents were the most frequent mechanism of injury (59%). The overall mortality among reported patients has declined from 36% before 1950 to 9% since 1970. The injury occurred within 2 cm of the carina in 76% of patients, and 43% occurred within the first 2 cm of the right main bronchus. The proximity of the injury to the carina had no detectable effect on mortality. Injuries on the right side were treated sooner but were associated with a higher mortality than left-sided injuries. No association was detected between delay in treatment and successful repair of the injury; ninety percent of patients undergoing treatment more than 1 year after injury were repaired successfully. CONCLUSIONS This review of patients with blunt tracheobronchial injuries represents the largest cohort studied to date. These data suggest an ability to repair tracheobronchial injuries successfully many months after they occur. We are also able to assess the mortality associated with the location and side of injury, examine the time from injury until diagnosis and treatment, and evaluate treatment outcome.

Hybrid epicardial-endocardial ablation using a pericardioscopic technique for the treatment of atrial fibrillation

BACKGROUND Catheter ablation is an effective treatment for medically refractory, disabling atrial fibrillation (AF). Ablation success may be limited in patients with persistent or long-standing persistent AF. A pericardioscopic, hybrid epicardial-endocardial technique for AF ablation may be a preferred approach for such patients. Limited data are available using such an approach. OBJECTIVE To evaluate 1-year outcomes of a hybrid technique for AF ablation. METHODS A cohort of 101 patients underwent AF ablation using a transdiaphragmatic pericardioscopic, hybrid epicardial-endocardial technique. Patients were followed with 24-hour Holter monitors at 3-, 6-, and 12-month intervals. Symptom severity was assessed at baseline and follow-up by using the Canadian Cardiovascular Society Severity of Atrial Fibrillation scale. RESULTS Mean AF duration was 5.9 years; 47% were persistent and 37% were long-standing persistent. Mean left atrial size was 5.1 cm (range 3.3-7 cm). Overall, 12-month arrhythmia-free survival was 66.3% after a single ablation procedure and 70.5% including repeat ablation. Repeat ablation was required in 6% of the patients and antiarrhythmic drug therapy in 37% of the patients. Quality of life improved significantly and was durable over 12-month follow-up. There were 2 deaths, which occurred in the early postoperative period: one due to atrioesophageal fistula and the second due to sudden cardiac death without apparent cause by autopsy. CONCLUSIONS We report the largest series to date of a hybrid epicardial-endocardial, stand-alone ablation procedure using a pericardioscopic technique for the treatment of AF. While respecting the identified complications, our results demonstrate a high potential for successful treatment in a challenging patient population with AF.

The Convergent Procedure: A Multidisciplinary Atrial Fibrillation Treatment

BACKGROUND Persistent atrial fibrillation (AF) and long-standing persistent AF (LSPAF) are difficult to treat. Epicardial surgical and percutaneous catheter ablations have lower success rates in these patients. The convergent procedure, an endoscopic transdiaphragmatic ablation procedure with conventional percutaneous endocardial ablation, is examined. METHODS Twenty-eight patients with persistent AF or LSPAF underwent the convergent procedure. All underwent combined surgical epicardial radiofrequency ablation and electrophysiological transseptal endocardial ablation to electrically isolate the 4 pulmonary veins, to exclude the posterior left atrium, to ablate the coronary sinus, and to confirm block at the cavotricuspid isthmus. Follow-up was with 24-hour Holter monitoring at 3 months, and 24-hour or 7-day monitoring at 6 and 12 months. RESULTS The mean duration of the procedure was 187 minutes (102 surgical ablation minutes; 85 endocardial ablation minutes). The mean total fluoroscopy time was 35.1 minutes. Two patients developed symptomatic pericardial effusions requiring percutaneous drainage, and 1 patient has demonstrated phrenic nerve paresis. There were no deaths. At 3 months, 87% were in sinus rhythm, and 43% were free of AF and antiarrhythmic medications (AADs). At 6 months, 76% were free from AF and AADs. CONCLUSION The convergent procedure effectively combines surgical and electrophysiological AF expertise to provide a viable treatment option to patients with persistent AF or LSPAF. Long-term follow-up is under way.

Myocardial electrical impedance as a predictor of the quality of RF-induced linear lesions

Production of complete (i.e. continuous and transmural) cardiac lesions by radiofrequency (RF) ablation can cure certain cardiac arrhythmias. However, a predictor of lesion completeness that is reliable and can be measured intraoperatively is needed in order to maximize effectiveness of ablation therapy. Predictors that require membrane excitation or response to stimulation are not always practical. This study tested whether changes of myocardial impedance across the lesion can predict completeness. RF energy was applied epicardially on perfused rabbit ventricles to produce linear lesions that were complete (n = 25) or incomplete (noncontinuous or nontransmural, n = 25). Before and after creation of each lesion, the magnitude and phase of impedance at 1 kHz were measured with a four-electrode epicardial array across the lesion. For 16 of the lesions, the translesion stimulus-excitation delay was also measured. Lesion completeness was evaluated with 2,3,5-triphenyltetrazolium chloride stain. Complete lesions increased resistivity by 26 Omega cm (21% of the preablation value, p = 0.0007, n = 17) when the inactive RF electrode remained on the epicardium during impedance measurements. When the RF electrode was removed during measurements, the rise of resistivity by complete lesions increased to 58 Omega cm (30% of the preablation value, p = 0.022, n = 8). For incomplete lesions, resistivity did not change significantly. Ablation did not significantly alter the phase of impedance. Accuracies of predictions of lesion completeness by the change in resistivity or the change in translesion stimulus-excitation delay were comparable (Youdens index 0.75 and 0.625, respectively, n = 16). Thus, RF ablation increases myocardial resistivity. The resistivity can predict lesion completeness and may provide an alternative to predictors based on excitation.

Translesion stimulus-excitation delay indicates quality of linear lesions produced by radiofrequency ablation in rabbit hearts.

Failure of cardiac antiarrhythmic ablation to block action potential conduction produces poor outcomes which lead to repeat procedures. To overcome this, an intraoperative index of the quality of an ablation lesion is needed. We hypothesized that a rise in the translesion stimulus-excitation delay (TED) can indicate a continuous, transmural, linear lesion, and that the TED is related to the path length in the viable tissue around the lesion. Rabbit hearts were isolated, perfused with a warm physiological solution and stained with transmembrane potential-sensitive fluorescent dye. Radiofrequency (RF) ablation was performed on ventricular epicardium with a vacuum-assisted coagulation device to produce either a complete or incomplete lesion. Complete lesions were both transmural and continuous. Incomplete lesions were noncontinuous or nontransmural. The TED was determined with bipolar stimulation at one side of the lesion and either a bipolar electrogram at the other side or optical mapping on both sides. Hearts were then stained with tetrazolium chloride and examined histologically to estimate minimum path lengths of viable tissue from the stimulation site to the recording site. Complete lesions increased the TED by factors of 2.6-3.1 (p < 0.05), whereas incomplete lesions did not significantly increase the TED. Larger minimum path lengths were found for cases that had an increased TED. The TED was quantitatively predictable based on a conduction velocity of 0.38-0.49 m s(-1), which is typical of rabbit hearts. The TED significantly increases when a linear lesion is complete, suggesting that an intraoperative measurement of the TED may help to improve ablation lesions and outcomes. Predictability of the TED based on the viable tissue path suggests that quantitative TEDs for clinical lesions may be anticipated provided that the conduction velocity is considered.

Primary percutaneous endoscopic button gastrostomy: a modification of the "push" technique.

Percutaneous endoscopic gastrostomy (PEG) in children has important advantages over an open procedure. Since the original description by Gauderer and associates, there have been several modifications to the procedure. These have included laparoscopyassisted percutaneous gastrostomy, fluoroscopically guided percutaneous gastrostomy, and primary placement of a button gastrostomy. One of the most important modifications of PEG placement has been the “push” technique. This technique reduces the incidence of wound infections and esophageal injuries because the gastrostomy is not pulled through the oral cavity and the esophagus is instrumented only once. Additionally, by primarily placing the MIC-KEY gastrostomy (Ballard Medical Products, Draper, UT), a second procedure to replace a tube gastrostomy with a more permanent MIC-KEY is unnecessary. We report a modification of the techniques described by Stylianos and Flanigan and by Robertson and colleagues. We have performed primary placement of MIC-KEY gastrostomies using the “push” technique in six patients without perioperative complications.

Suprasternal direct aortic approach transcatheter aortic valve replacement avoids sternotomy and thoracotomy: first-in-man experience

OBJECTIVES Direct aortic deployment of a transcatheter aortic valve eliminates the need to traverse the aortic arch with the valve delivery system, enables placement of large sheaths in the aorta and innominate artery, provides maximal precision during deployment and ensures a safe, conventional surgical aortotomy closure. We describe the initial experience with the Suprasternal Aortic Access System (SuprAA System, Aegis Surgical Ltd, Dublin, Ireland) for direct transaortic/innominate valve delivery. METHODS Patients with severe, symptomatic aortic stenosis who were candidates for transcatheter aortic valve replacement (TAVR) via a direct transaortic approach were enrolled in the SuprAA-TAVR First-in-Man Study. Under general anaesthesia, the innominate artery and aortic arch were exposed in each patient, using the SuprAA System via a 2.5-cm incision directly above the sternal notch. The TAVR delivery sheath was positioned and the transcatheter valve deployed routinely under fluoroscopic guidance. Upon sheath removal, haemostasis at the aortotomy site was confidently secured using a double purse-string suture closure. All were extubated immediately. A meta-analysis of the direct aortic approach was done for comparison. RESULTS Four male patients (mean 82.5 years) underwent SuprAA-TAVR (2 CoreValve; 2 SAPIEN). Anatomical visualization was excellent and suprasternal valve deployment was accurate regardless of sheath size with 100% Valve Academic Research Consortium-2 procedural success. The average total procedure time was 109.5 min without perioperative wound or vascular complications. CONCLUSIONS The SuprAA System provides direct aortic/innominate access without sternal or thoracotomy incision. Patient recovery to normal activity is maximized, sheath size limitations are eliminated and valve deployment is precise. This innovative system creates a new and exciting minimally invasive approach for high-risk patients with aortic stenosis.

Hybrid treatment of atrial fibrillation.

Endocardial catheter ablation (CA) and surgical Maze-like procedures have become mainstays of interventional treatment for atrial fibrillation (AF). However, CA has limited efficacy particularly in patients with persistent AF who have a high risk of recurrent AF. Epicardial CA in conjunction with endocardial CA, a hybrid CA, offers the potential advantage for robust lesion formation, left atrial debulking, and mapping and CA of residual arrhythmia circuits. Hybrid CA procedures may improve the success rate of an ablation procedure for AF, particularly in those with persistent or long-standing persistent AF and those with significant structural heart disease. However, the ideal patient populations who may benefit from hybrid AF ablation and the ideal tools and techniques for hybrid AF ablation have yet to be determined. In this review, we discuss the hybrid CA procedure including motivation for and methods of hybrid CA, available tools, and reported efficacy of the procedure.

Challenges and Outcomes of Posterior Wall Isolation for Ablation of Atrial Fibrillation

Background The left atrial posterior wall (PW) often contains sites required for maintenance of atrial fibrillation (AF). Electrical isolation of the PW is an important feature of all open surgeries for AF. This study assessed the ability of current ablation techniques to achieve PW isolation (PWI) and its effect on recurrent AF. Methods and Results Fifty‐seven consecutive patients with persistent or high‐burden paroxysmal AF underwent catheter ablation, which was performed using an endocardial‐only (30) or a hybrid endocardial–epicardial procedure (27). The catheter ablation lesion set included pulmonary vein antral isolation and a box lesion on the PW (roof and posterior lines). Success in creating the box lesion was assessed as electrical silence of the PW (voltage <0.1 mV) and exit block in the PW with electrical capture. Cox proportional hazards models were used for analysis of AF recurrence. PWI was achieved in 21 patients (36.8%), more often in patients undergoing hybrid ablation than endocardial ablation alone (51.9% versus 23.3%, P=0.05). Twelve patients underwent redo ablation. Five of 12 had a successful procedural PWI, but all had PW reconnection at the redo procedure. Over a median follow‐up of 302 days, 56.1% of the patients were free of atrial arrhythmias. No parameter including procedural PWI was a statistically significant predictor of recurrent atrial arrhythmias. Conclusions PWI during catheter ablation for AF is difficult to achieve, especially with endocardial ablation alone. Procedural achievement of PWI in this group of patients was not associated with a reduction in recurrent atrial arrhythmias, but reconnection of the PW was common.

Effect of ablation on local activation intervals and dominant frequencies of fibrillation

Activation frequencies of tachyarrhythmias may guide production of high-quality ablation lesions. To examine this in rabbit ventricles, frequencies from bipolar potentials adjacent to a continuous and transmural lesion were analyzed with a time-domain algorithm and FFT. Time-domain analysis produced greater variability among frequencies compared with dominant frequencies from the FFT. With either time-domain or FFT, frequency distributions were different after vs. before ablation. Means of frequencies had equal probability to increase or decrease, while standard deviations decreased after production of a continuous and transmural lesion. Thus, both the time-domain method and FFTs indicate reduced variation of activation frequencies by ablation.