Chronic left heart catheterization for microvascular blood flow determination in the rabbit: a minimally invasive technique using specially designed port devices.

BACKGROUND: This study describes a modified catheterization technique with subcutaneously implanted port catheters to be inserted in a retrograde manner across the aortic valve into the left heart ventricle through the right carotid artery to measure organ perfusion. MATERIALS AND METHODS: The specially designed arterial port catheters were implanted in New Zealand rabbits (n = 11, 3.7 +/- 0.1 kg [mean +/- SEM]) under iv anesthesia (medetomidine/ketamine) and single-shot perioperative antibiotic therapy. Hemodynamics were registered continuously during the operation via an ear artery catheter. RESULTS: Implantation of ports was performed in all animals (11/11) without major complications (mean operation time: 70 +/- 3 min). We did not observe catheter-associated arrhythmia, fall in mean arterial pressure (MAP before and post OP: 70 +/- 2 and 68 +/- 2 Torr, respectively), or change in arterial oxygen saturation (SaO2 before and post OP: 89 +/- 3 and 95 +/- 2%, respectively). With a specifically modified microsurgical insertion technique, cerebral blood supply was effectively preserved as evidenced from postmortem histological examinations, cerebral blood flow determination with fluorescent microspheres, and measurement of S-100b protein serum concentrations, a specific marker of neuronal damage. The positioning of the catheter tip in the left ventricle was found to be correct in 10/11 animals. CONCLUSIONS: Repeated and atraumatic microsphere injections into the left ventricle have become feasible by transcutaneous puncture of subcutaneous port systems over several weeks under light sedation. Hence, this new approach (i) avoids the necessity of repeated intracardiac injections and port insertions via thoracotomy, thus reducing the perioperative stress for the animals, and (ii) allows for the first time minimally invasive repetitive and chronic measurements of regional organ blood flow under various experimental settings.     

A comparison between forefoot plaster and wooden soled shoes following Mitchell's osteotomy for hallux valgus

Between 1 October 1997 and 1 November 1998, 43 patients (59 feet) were treated with a standard Mitchell's osteotomy for hallux valgus. Of these, 26 patients (36 feet) were treated postoperatively in a forefoot plaster. The other 17 patients (23 feet) were treated with a wooden soled shoe. There was no significant difference between the 2 groups for age, indication for surgery, pre-operative deformity or grade of the operating surgeon. There was no significant difference in the mean time immobilised, mean time to union or complications. The patients were interviewed by telephone after a mean follow-up of 9.4 months. There was no significant difference in results between the 2 groups. This suggests that a forefoot plaster following Mitchell's osteotomy is unnecessary. Postoperative mobilisation in a wooden soled shoe can be used as an alternative.     

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

BACKGROUND: Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome. METHODS: Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively. RESULTS: In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B. CONCLUSIONS: The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.     

Revascularization during acute myocardial infarction: risks and benefits revisited

BACKGROUND: Indication for immediate revascularization during acute myocardial infarction (MI) is debated. Drug-resistant crescendo angina, as well as hemodynamic compromise, however, often requires acute operation. In this study the differential risks of acute coronary artery bypass grafting with and without MI were stratified. METHODS: Five hundred eighteen patients undergoing isolated coronary artery bypass grafting were investigated. Thirty-nine patients underwent acute revascularization because of enzyme-proven or electrocardiogram-proven MI accompanied by crescendo angina, hemodynamic compromise, or both. They were compared with 33 emergent, 63 urgent, and 383 elective patients without MI. Preoperative risk factors for early mortality and necessity of continuous venovenous hemofiltration were analyzed by means of logistical regression analysis. Perioperative data were compared. RESULTS: Early mortality of the MI cohort was 15.4%, in contrast to 15.2% in emergent, none in urgent, and 2.1% in elective patients. Left internal thoracic artery was used in 87% of MI, 97% of emergent, 94% of urgent, and 97% of elective patients. Intraaortic balloon pump was necessary in 50% of MI patients, 27% of emergent, 6.3% of urgent, and 3.1% of elective cases. Continuous venovenous hemofiltration was performed in 29% of MI patients, 15% of emergent, 4.9% of urgent, and 3.4% of elective patients. Hemodynamic instability significantly increased the odds ratio for early mortality and continuous venovenous hemofiltration. CONCLUSIONS: Patients undergoing acute revascularization carried an elevated risk to die early notwithstanding the presence or absence of acute MI. Liberal use of left internal thoracic artery grafts was not detrimental in acute patients whereas liberal use of intraaortic balloon pump was beneficial. In almost 30% of MI patients, continuous venovenous hemofiltration was not necessary, implying a severely impaired perioperative hemodynamic condition. Immediate revascularization in the presence of acute MI is therefore indicated although it may be addressed as a separate high-risk group.     

Factors influencing intensive care unit length of stay after surgery for acute aortic dissection type A

BACKGROUND: Operative mortality after acute aortic dissection type A is still high, and prolonged stay at the intensive care unit is common. Little has been documented about factors influencing the intensive care unit length of stay. The aim of this study was to determine such variables. METHODS: During a 10-year period, 67 patients (47 male, 20 female) were operated on for acute aortic dissection type A. In 42 patients (63%), an ascending aortic replacement was performed, 23 patients (34%) underwent a Bentall procedure, and 2 patients (3%) received a valve-sparing David type of operation. In 14 of these cases (20%), an additional partial or total arch replacement was performed. RESULTS: Hospital mortality was 9 of 67 (14%). Median postoperative intensive care unit length of stay was 5 days (range, 1 to 72 days). Intensive care unit stay was in univariate analysis significantly influenced by the following factors: age (p = 0.008), body mass index (p = 0.039), cardiopulmonary bypass time (p = 0.018), aortic cross-clamp time (p = 0.031), postoperative low cardiac output syndrome (p < 0.001), and postoperative lactate levels (p = 0.01). By multivariate analysis, age (p = 0.012), cardiopulmonary bypass time (p = 0.037), and the presence of a postoperative low cardiac output syndrome (p < 0.001) significantly influenced intensive care unit stay. CONCLUSIONS: Stay in the intensive care unit after operation for acute aortic dissection type A seems to be determined by age, cardiopulmonary bypass time, and the postoperative presence of a low cardiac output syndrome.     

Role of thoracic surgery and interventional bronchoscopy in Wegener's granulomatosis

BACKGROUND: Wegener's granulomatosis (WG) is defined as granulomatous vasculitis affecting small and medium-sized arteries and veins. Histologically, inflammatory changes with infiltration of the endothelium, fibrinoid necrosis, and formation of necrotizing granulomas are found. Pulmonary involvement is one of the cardinal features of WG and occurs in 85% of patients during the course of disease. Surgery is often required for both diagnosis and therapy. METHODS: Fifteen consecutive patients are presented to illustrate the spectrum of surgical interventions in WG. RESULTS: In 8 patients open lung biopsy, wedge resection, or segmental resection for hitherto undiagnosed infiltrate revealed WG. Eight patients presented with tracheal stenosis and all 8 underwent repetitive tracheoscopic dilation. Five patients presented with subglottic stenosis without any signs of pulmonary manifestation. All patients underwent tracheoscopic dilation, 3 in conjunction with glucocorticoid injection therapy. After multiple dilations, 1 patient still had destructing ulcerative tracheitis in which total stenting maintained airway patency. One patient received subglottic tracheal resection prior to multiple dilations; another patient, because of expiratory tracheal collapse, underwent stabilization of the membranous part of the trachea and the large bronchi with a polytetrafluoroethylene implant. CONCLUSIONS: Surgical lung biopsy in numerous patients established the final diagnosis. Thoracic surgery including bronchologic measures such as bouginage and stenting, however, also has a place in the long-term management of WG.     

The discovery of renal contrast media in Berlin

After X-rays were detected and cystoscopes had become available, progress in nephrology depended on the development of contrast media which would permit imaging of the kidneys and the urinary system. We describe how A. Binz and C. R?th, two chemists at the Agricultural Academy in Berlin, synthesized iodinated derivatives which were potent chemotherapeutics. Moses Swick tested the substances in the clinics of L. Lichtwitz (Hamburg) and A. von Lichtenberg (Berlin) and discovered a rapid renal excretion. He also observed that an iodinated N-acetylated derivative, later named Uro-Selectan, amplified X-ray contrast after intravenous application. With this substance and other derivatives which were produced by Schering-Kahlbaum AG, the door was open for excretion urography.     

Malignancy in a vestibular schwannoma. Report of a case with central neurofibromatosis,treated by both stereotactic radiosurgery and surgical excision,with a review of the literature

Malignant change in schwannoma is rare. Malignant change in a vestibular schwannoma (acoustic neuroma) is even more rare. This paper presents a case of rapidly growing vestibular schwannoma first treated by radiosurgery whose histopathology after surgical excision 42 months later showed malignant changes. Up to now, eight cases of malignancy in eighth nerve tumours have been reported, four of which, including the present case, had previously been treated with radiosurgery and four cases that had not received radiation. Thus, it would seem, the overall incidence is extremely low. Nevertheless, extreme vigilance and careful reporting continues to be necessary.     

Clinical role of flow velocity of left atrial auricle for prediction of short and long term success of cardioversion in patients with non-valvular atrial fibrillation

INTRODUCTION: Echocardiographic parameters for predicting cardioversion (CV) outcome and long-term sinus rhythm (SR) maintenance in patients with nonvalvular atrial fibrillation (AF) are not accurately defined. AIMS: The authors aim was to evaluate the role of left atrial appendage (LAA) flow velocity detected by transesophageal echocardiography before CV for prediction of short and long-term (1 year) outcome of CV in patients with nonvalvular AF. METHODS: One hundred and nine patients (66 males, mean age: 57 +/- 13 years) with nonvalvular AF lasting more than 48 hours but less than 1-year duration underwent transthoracic and transesophageal echocardiography before either electrical or pharmacological CV attempt. RESULTS: Cardioversion was successful in restoring SR rhythm in 83 (76%) and unsuccessful in patients 26 (24%). Mean LAA peak emptying flow was higher in patients with successful than in those with unsuccessful CV (36.7 +/- 14.7 vs 26.3 +/- 9.2 cm/sec; p < 0.01). At multivariate analysis the left LAA emptying velocity > 32 cm/sec was the only independent predictor of CV success. Seventy-four out of the 83 patients with successful CV had a complete follow-up of 1 year. At the end of the 1-year follow-up, 40 of the 74 (54%) patients who underwent successful CV preserved the SR. Mean LAA peak emptying velocity was higher in patients remaining in SR for 1 year than in those with AF relapse (40.3 +/- 15.6 vs 32.2 +/- 12.2 cm/sec cm/sec; p < 0.001). On multivariate analysis, only the mean LAA peak emptying velocity > 39 cm/sec and the use of preventive antiarrhythmic drug treatment predicted the continuous preservation of SR during 1 year. CONCLUSION: In patients with nonvalvular AF, measurement of precardioversion LAA flow velocity profile by transesophageal echo cardiography provides valuable information for prediction of both short and long-term success of CV.