Richard B. Chard

Thoracic epidural anesthesia for cardiac surgery: the effects on tracheal intubation time and length of hospital stay.

UNLABELLED Improvements in analgesia after major surgery may allow a more rapid recovery and shorter hospital stay. We performed a prospective randomized trial to study the effects of epidural analgesia on the length of hospital stay after coronary artery surgery. The anesthetic technique and postoperative mobilization were altered to facilitate early intensive care discharge and hospital discharge. Fifty patients received high (T1 to T4) thoracic epidural anesthesia (TEA) with ropivacaine 1% (4-mL bolus, 3-5 mL/h infusion), with fentanyl (100-microg bolus, 15-25 microg/h infusion) and a propofol infusion (6 mg x kg(-1) x h(-1)). Another 50 patients (the General Anesthesia group) received fentanyl 15 microg/kg and propofol (5 mg x kg(-1) x h(-1)), followed by IV morphine patient-controlled analgesia. The TEA group had lower visual analog scores with coughing postextubation (median, 0 vs 26 mm; P < 0.0001) and were extubated earlier (median hours [interquartile range], 3.2 [2.1-4.6] vs 6.7 [3.3-13.2]; P < 0.0001). More than half of all patients were discharged home on Postoperative Day 4 (24%) or 5 (33%), but there was no difference in the length of stay between the TEA group (median [interquartile range], Day 5 [5-6]) and the General Anesthesia group (median [interquartile range], Day 5 [4-7]). There were no differences in postoperative spirometry or chest radiograph changes or in markers for postoperative myocardial ischemia or infarction. No significant TEA-related complications occurred. In summary, TEA provided better analgesia and allowed earlier tracheal extubation but did not reduce the length of hospital stay after coronary artery surgery. IMPLICATIONS We found that epidural analgesia was more effective than IV morphine for cardiac surgery. Epidural anesthesia also allowed earlier weaning from mechanical ventilation, but it did not affect hospital discharge time.

Comparison of epicardial and endocardial linear ablation using handheld probes.

BACKGROUND The optimal technique for producing linear radiofrequency thermal lesions in myocardial tissue is unclear. We compared epicardial ablation on the beating heart with endocardial ablation after cardioplegia. METHODS Radiofrequency lesions were produced using a multielectrode malleable handheld probe in ovine myocardium with three wall thicknesses. Detailed analysis of lesion dimensions was used to assess the effects of site of ablation, muscle thickness, and duration of ablation. RESULTS After epicardial atrial ablation, myocardial lesions were detected in all sections without macroscopically visible epicardial fat (n = 10), but only 43% (6/14) of sections with epicardial fat. Three of 24 atrial epicardial sections (13%) and 92% (23/25) of endocardial atrial lesion sections were clearly transmural. In thicker tissues lesion depth was independent of endocardial (right ventricle: 3.9 +/- 1.1 mm, left ventricle: 3.8 +/- 0.7 mm) or epicardial (right ventricle: 3.4 +/- 0.6 mm, left ventricle: 4.3 +/- 0.9 mm) ablation site. Epicardial lesions are less deep in thinner areas of myocardium (p = 0.003). Lesions were all wider than they were deep. There was no significant increase in lesion depth with the increase in ablation duration from 1 to 2 minutes. CONCLUSIONS Lesions were unlikely to be transmural with either technique when the wall thickness was greater than about 4 mm. Epicardial fat has an important negative effect on epicardial lesion formation. Where epicardial fat is absent epicardially produced lesions penetrate less deeply when the wall thickness is small, possibly due to endocardial cooling by circulating blood. Prolongation of the duration of ablation from 1 to 2 minutes does not significantly increase lesion depth.

Mechanism, localization and cure of atrial arrhythmias occurring after a new intraoperative endocardial radiofrequency ablation procedure for atrial fibrillation

OBJECTIVES The purpose of this study was to test a new pattern of radiofrequency ablation for atrial fibrillation (AFib) intended to optimize atrial activation, and to demonstrate the usefulness of catheter techniques for mapping and ablation of postoperative atrial arrhythmias. BACKGROUND Linear radiofrequency lesions have been used to cure AFib, but the optimal pattern of lesions is unknown and postoperative tachyarrhythmias are common. METHODS A radial pattern of linear radiofrequency lesions (Star) was made using an endocardial open surgical approach in 25 patients. Postoperative arrhythmias were induced and characterized during electrophysiological studies in 15 patients. RESULTS The AFib was abolished in most patients (91%), but atrial flutter (AFlut) occurred in 96% of patients postoperatively. At postoperative electrophysiological studies, 37 flutter morphologies were studied in 15 patients (46% spontaneous, cycle length [CL] 223 +/- 25 ms). Seven mechanisms (lesions discontinuity, n = 6; focal mechanism, n = 1) of AFlut were characterized in six patients. In these cases, flutter was abolished using further catheter radiofrequency ablation. In the remaining cases, flutter was usually localized to an area involving the interatrial septum, but no critical isthmus was identified for ablation. After 16 +/-10 months, 15 patients (65%) were asymptomatic with (n = 3) or without (n = 12) antiarrhythmic medications. Eight (35%) patients had persistent arrhythmias. Postoperative atrial electrical activation was near physiological. CONCLUSIONS The AFib maybe abolished using a radial pattern of linear endocardial radiofrequency lesions, but postoperative AFlut is common even when lesions are made under optimal conditions. Endocardial mapping techniques can be used to characterize the flutter mechanisms, thus enabling subsequent successful catheter ablation.

Tunnelling versus open harvest technique in obtaining venous conduits for coronary bypass surgery

BACKGROUND The tunnelling as opposed to the open harvest technique for harvesting long saphenous vein for coronary artery bypass procedures is a less frequently used technique as it requires more handling of the vein and this may induce trauma. This study aims to compare the degree of endothelial denudation and donor site morbidity between the two different harvest techniques. METHODS Saphenous vein segments in 78 patients (45 in tunnelling versus 33 in open harvest group) undergoing coronary artery bypass procedures were examined by light microscopy and graded according to the extent of endothelial denudation varying from grade 1 (most preserved) to grade 6 (>90% endothelial denudation). Clinical parameters relating to donor site morbidity including leg wound pain and infection were also assessed. RESULTS There was no statistical difference in the age, sex, macroscopic vein quality, length and time taken to harvest the veins between the two groups. The tunnelling technique always used thigh saphenous vein whereas nearly a third of veins harvested by the open harvest technique were lower leg veins (P=0.001). The tunnelling technique resulted in an endothelial score of 2.5 compared with 3.3 for the open harvest technique (P < 0.001). In addition, saphenous vein tunnelling resulted in significantly less leg wound pain (1.2 vs. 1.8, P=0.001), no leg wound infection (compared with 12.2% in open harvest group, P=0.02) and produced cosmetically more acceptable scars. Furthermore, length of hospital stay was significantly prolonged to 19.3 days in those with leg wound infection compared to 8.7 days in those without leg wound infection (P < 0.001). CONCLUSIONS These results show that saphenous vein tunnelling is an attractive alternative to the open harvest technique in obtaining venous conduits for coronary artery bypass procedures.

Surgical procedure for the cure of atrioventricular junctional (“AV node”) reentrant tachycardia: Anatomic and electrophysiologic effects of dissection of the anterior atrionodal connections in a canine model

OBJECTIVES This study was undertaken to examine the electrophysiologic and anatomic effects of a surgical procedure that cures the anterior (common) type of atrioventricular (AV) junctional reentrant tachycardia. BACKGROUND The procedure was designed to interrupt the reentrant circuit at the point of earliest atrial activation during AV junctional reentrant tachycardia, the anterior atrionodal connections. METHODS Atrioventricular node function and the sequence of electrical excitation of Kochs triangle were examined in 18 dogs. Excitation of Kochs triangle was mapped using a 60-channel mapping system. Surgical dissection was performed in 10 dogs and a sham procedure in 8. After 28 to 35 days, AV node function and the atrial excitation pattern were reassessed. The AV junction was examined using light microscopy. RESULTS Some degree of AV node damage was visible in all dogs in the dissection group, but it was minor in 40% of cases. The anterior part of the AV node was disconnected from the anterior atrionodal connections in all cases. Anterograde AV node function was mildly impaired. The median AH interval was increased (62 vs. 76 ms [interquartile ranges 48 to 72 and 64 to 104, respectively], p = 0.05), and the AV Wenckebach cycle length was increased (210 vs. 245 ms [interquartile ranges 200 to 230 and 210 to 260, respectively], p = 0.02). The degree of impairment of conduction was directly proportional to the length of dissection (p < 0.05) but not to the degree of damage to the AV node. Ventriculoatrial (VA) conduction was destroyed in 50% of dogs undergoing dissection but in none of those with a sham operation (p < 0.04). The AV node remained responsive to autonomic blocking drugs, and atrial mapping during ventricular pacing revealed that the site of exit from the AV node had been altered. CONCLUSIONS The atrionodal connections closest to the His bundle are the preferred route of conduction through the AV node during normal AV or VA conduction. Destruction of these connections modifies AV node conduction. The surgical procedure selectively interrupts these connections, and this interruption is likely to be the mechanism of cure.

Outcomes for Surgical Treatment of Atrial Fibrillation Using Cryoablation During Concomitant Cardiac Procedures

BACKGROUND Surgical treatment of atrial fibrillation (AF) with heat-based therapies has been associated with a high rate of arrhythmia recurrence. We studied the short-term to medium-term outcomes with a unique biatrial linear ablation procedure for AF treatment using an argon-based cryoablation device during concomitant cardiac operations. METHODS Between March 2005 and July 2008, 57 patients (47% men) with problematic AF underwent a linear endocardial ablation procedure (Star pattern) using the flexible argon-based cryoablation probe during concomitant cardiac operations. Procedures were performed with valve or coronary operations, including mitral valve replacement (25%), mitral valve repair (16%), coronary artery bypass grafts (21%), and congenital heart surgery (8%). Atrial fibrillation was persistent or long-standing persistent in 50.9% of patients. RESULTS Kaplan-Meier survival curves (with the standard error) demonstrated 91% (3.9%) of patients were still free of their first recurrence at 6 months, 81% (5.6%) at 12 months, and 70% (6.8%) at 24 months. Time to first recurrence was not significantly associated with age (p = 0.47), gender (p = 0.52), or type of AF (p = 0.69). There were no complications attributed to the cryoablation procedure. There was one in-hospital death and one death after discharge. Twelve patients (21%) required permanent pacemaker implantation postoperatively. There were no early or late thromboembolic events. CONCLUSIONS This study demonstrated the medium-term efficacy of cryoablation with a unique biatrial pattern of linear lesions for the treatment of AF during a concomitant cardiac operation. Short-term to medium-term outcomes were at least equivalent to those reported for other energy modalities.

Ebstein's Anomaly in Those Surviving to Adult Life - A Single Centre Experience

BACKGROUND Ebsteins anomaly (EA) occurs in about one to five per 200 000 live births. Long-term follow-up data of adults with EA is scarce due to the relatively low frequency of the disease and the variation of its anatomic and haemodynamic severity. METHODS Since 1995, in our adult congenital heart disease (ACHD) centre, we have practised a uniform approach to management of adults with EA, with surgery reserved for those with refractory arrhythmia (failed medical and/or catheter-based treatment) or worsening symptoms of breathlessness. A retrospective review of medical records of all such patients with EA and normal cardiac connections was performed. RESULTS Fifty-one EA patients (17 males) were identified. Mean age at diagnosis was 21+/-21 years and mean follow-up time at our centre was 21±14 years. During this time, 18 patients (35%) had documented supraventricular arrhythmia. Sixteen patients (30%) underwent ablation therapy with long-term relief from arrhythmia in nine (56%). Nine patients (18%) underwent tricuspid valve (TV) surgery (four repair and five replacement), with seven patients having undergone a tricuspid valve surgery prior to referral to our unit. Three patients died, one of cardiogenic shock after redo surgery (58 years), one of progressive heart failure (45 years) and one with malignancy. Overall survival was 100% to age 40 years, 95% to age 50 years and 81% to age 60 years. CONCLUSIONS Ebsteins Anomaly in adulthood often has severe morphological abnormalities but is compatible with good medium-term survival, with a generally symptom driven approach to the indications for interventions.

Fixed left ventricular outflow tract obstruction mimicking hypertrophic obstructive cardiomyopathy: pitfalls in diagnosis

We present a case series that highlights the diagnostic challenges with left ventricular hypertrophy (LVH) and left ventricular outflow tract obstruction (LVOTO). Fixed structural lesions causing LVOTO with secondary LVH may mimic hypertrophic obstructive cardiomyopathy (HOCM). Management of these two entities is critically different. Misdiagnosis and failure to recognize fixed left ventricular outflow tract (LVOT) lesions may result in morbidity as a result of inappropriate therapy and delay of definitive surgical treatment. It is thus necessary to identify the correct type and level of obstruction in the LVOT by careful correlation of clinical examination, Doppler evaluation, and advanced imaging findings.

Congenital heart surgery in adults: An Australian experience of 379 cases

Abstract Background: Congenital heart disease (CHD) may present for the first time in adult life and may require operative repair. Due to technical advances in CHD surgery, an increasing population of children with CHD are surviving into adult life, some of whom need further surgery for residual or complicating lesions. Little is known about the outcomes of CHD surgery in adult patients. Aim: To assess the frequency, types and outcomes of congenital heart surgery in adults. Methods: Retrospective review of hospital records. Long-term outcome data were obtained by questionnaires and from the State Registry of Births, Deaths and Marriages. Results: From 1982–1995, 379 adults aged 34±16 (range, 16–73) years, comprising 144 males and 235 females, were operated on for CHD. In 328 patients, this was their first operation: closure of atrial septal defect in 212 (64%, secundum type in 180, sinus venosus in 14, primum in 18); closure of a persistent ductus arteriosus in 30; repair of coarctation of the aorta in 30; closure of ventricular septal defects in 17; repair of tetralogy of Fallot in 10, and 29 others. Fifty-one cases were reoperations and included Fontan repair in 8, revision of coarctation of the aorta in 8, and complete repair of pulmonary atresia/ventricular septal defect after earlier palliation in 5 subjects. There were 7 perioperative deaths (2%) within 30 days of surgery. After median follow-up of 8 years, there were 27 late deaths (7%). Most survivors are in functional Class I. Conclusions: Congenital heart disease surgery is often required in adults, both for first operations and redo procedures, many of which are for complex heart disease. Despite this, good perioperative and long-term results may be obtained.

Establishment and First Audit of a New Perioperative Echocardiography Service

Intraoperative echocardiography has become an integral service for cardiothoracic surgery. Establishing a service requires new ultrasound technologies and a dedicated team prepared to be trained in this new discipline. The establishment of a new perioperative service at Westmead Hospital, Australia is outlined. Early experience, current practice, teaching and research programs are presented and the first audit is reported.