Ferdinand Waldenberger

Cardiac Troponin T: A New Marker of Myocardial Tissue Damage in Bypass Surgery

The purpose of this study was to evaluate cardiac troponin T (TnT) in the diagnosis of minor perioperative myocardial tissue damage and small myocardial infarctions during aortocoronary bypass surgery. In 15 patients without enzymatic or electrocardiographic signs of perioperative myocardial ischemia (group 1, uncomplicated bypass surgery), TnT did not exceed 3.55 micrograms/L. In 3 patients with perioperative non-Q-wave infarctions (group 2), TnT was significantly higher than in group 1 patients. In all 3 patients, TnT peak concentrations exceeded 3.5 micrograms/L. Thirteen patients (group 3, borderline cases) showed either signs of perioperative myocardial ischemia by creatine kinase isoenzyme MB (CKMB) activity levels (CKMB > 20 U/L on the first postoperative day, 3 patients) or by electrocardiography (new ST-T segment alterations, 10 patients). TnT concentrations were comparable to group 1 patients and indicated uncomplicated bypass surgery in all 3 patients with solely elevated CKMB activities. On the other hand, TnT concentrations in 3 patients with electrocardiographic signs of perioperative myocardial ischemia were significantly higher than in uncomplicated patients (group 1) with peak values exceeding 3.5 micrograms/L. Thus, TnT indicated perioperative non-Q-wave infarctions not detected by CKMB activity in these 3 patients. These results are in accordance with findings in nonsurgical patients. They suggest a higher sensitivity and specificity of cardiac TnT compared to CKMB activity in the diagnosis of small perioperative myocardial infarctions after bypass surgery.

Aortic arch surgery using bilateral antegrade selective cerebral perfusion in combination with near-infrared spectroscopy

OBJECTIVE Near-infrared spectroscopy (NIRS) complements online monitoring of cerebral oxygenation during aortic arch surgery. Its addition targets at an increase of safety of a complex procedure employing bilateral antegrade cerebral perfusion (BACP) and circulatory arrest under tepid blood temperatures. We report the outcome of NIRS-guided aortic arch surgery using BACP with moderate hypothermic circulatory arrest (MHCA). METHODS Between December 2006 and December 2008, NIRS was used in 13 patients (mean age: 67.5 ± 11.3 years) undergoing aortic arch repair using BACP combined with MHCA. The diagnosis was atherosclerotic thoracic aneurysms in eight and acute aortic dissection in five patients. Seven patients had a hemi-arch replacement, six underwent frozen stent-graft arch replacement and four patients had concomitant procedures such as coronary artery bypass grafting (CABG) or aortic valve surgery. Our regimen of employing an algorithm for adaptation of perfusion modalities included the threshold of the drop in regional cerebral oxygen saturation <55% and/or a drop in the total oxygen index (TOI) of 15-20% assessed by the means of NIRS. RESULTS The mean MHCA was 35 ± 16min and lowest bladder temperature was 26 ± 1.2°C. The mean TOI pre-MHCA was 66 ± 6.5%. Twelve out of 13 patients underwent bilateral perfusion because of unilateral drops below the threshold level of TOI (mean: 44±7.9%). In three patients, an organic psychosyndrome was observed. No patient developed permanent neurological dysfunction. CONCLUSION NIRS-guided BACP during MHCA allows a safe approach to complex aortic arch surgery. The drop of brain oxygenation values in the contralateral hemisphere during unilateral ACP strongly suggests the routine use of BACP, when circulatory arrest under tepid temperatures is used.

Repair of stent graft-induced retrograde type A aortic dissection using the E-vita open prosthesis †

OBJECTIVES Stent graft-induced retrograde type A dissection is a life-threatening complication after endovascular treatment of acute aortic type B dissections. METHODS From August 2005 to February 2011, retrograde aortic dissection occurred in 4 of 29 patients (13.8%) undergoing thoracic endovascular aortic repair (TEVAR) for acute complicated aortic type B dissection. Three patients underwent emergent surgical conversion immediately after TEVAR. The operative strategy was a combined surgical and endovascular approach (frozen elephant trunk technique) using a specially designed hybrid prosthesis (Jotec E-vita open). All operations were performed under moderate hypothermia (25-28°C) and selective bilateral antegrade cerebral perfusion. The mean duration of circulatory arrest was 56 ± 7 min. Operative data and the outcome of surgery were analysed retrospectively. Data were analysed retrospectively in the limited number of patients. RESULTS All patients survived the surgical procedure. No stroke, paraplegia, renal failure or other major complications occurred. Postoperative CT scans revealed perigraft thrombus formation and stable aortic dimensions in all patients after 6 months. In one patient, the retrograde dissection remained primarily undetected and untreated. The patient died suddenly, with no clinical signs, within 7 days after stent graft implantation. Autopsy revealed cardiac tamponade due to retrograde type A aortic dissection. CONCLUSIONS Retrograde aortic dissection type A is a serious complication of thoracic endovascular repair of acute aortic type B dissection. Despite the small number of patients investigated in this study, the frozen elephant trunk technique appears to be a feasible bail-out strategy for the treatment of these acute aortic events.

Fate of the False Lumen After Combined Surgical and Endovascular Repair Treating Stanford Type A Aortic Dissections

BACKGROUND The purpose of this study was to evaluate the alterations of the aorta by using a new combined surgical and endovascular technique for the treatment of aortic type A dissections. The diameter of the descending aorta, the implanted stent graft, and the false lumen were evaluated. METHODS Between August 2005 and February 2009, 14 patients (aged 49 +/- 13 years; 11 men, 3 women) with type A dissection in the aorta were operated on the thoracic aorta by the frozen elephant trunk technique. The size dynamics of the false lumen were analyzed by deducting the diameter of the stent graft obtained on computed tomography from the maximum dimension of the aorta. RESULTS The technical success rate was 100%. All patients survived during the follow-up period. The mean follow-up period was 21.4 months. No redisection or aortic rupture occurred during the follow-up period. Postoperative computed tomography scans showed complete thrombus formation of the false lumen in the perigraft space within the entire zone of the stented segment of the hybrid prosthesis during the first 2 weeks after surgery in 12 patients (86%), whereas all patients showed complete obliteration of the false lumen at the 3-month control. The follow-up computed tomography scan obtained after 12 months revealed shrinkage of the false lumen in 9 patients (64%). CONCLUSIONS The combined surgical and endovascular technique described in this report proved effective for the treatment of extended aortic lesions. The perigraft space thrombosed completely and had shrunken after successful placement of the stent graft.

Protective effects of various preservation solutions on cultured endothelial cells.

Vascular endothelium represents the first target in organ preservation and plays an important role in reperfusion injury. Bovine aortic endothelial cells were cultivated and the most commonly used preservation solutions, such as University of Wisconsin HTK (Brettschneiders histidine-tryptophane-ketoglutarate), and Euro-Collins solutions were tested on the endothelial monolayer. In addition, one group of cultivated cells was preserved with cold saline solution, and endothelial monolayers grown in culture medium were used as controls. The quality of preservation was assessed after 24, 48, and 72 hours of cold storage. Reperfusion was simulated and its effects were observed by reincubation in culture medium at 37 degrees C for 6 hours. The total number of cells, cell viability (determined using trypan blue exclusion), and morphologic alterations were determined. Prostacyclin release was evaluated as a biochemical marker. University of Wisconsin solution maintains more than 99% cell viability after rewarming after both 24 and 48 hours of cold storage. After 72 hours, 86.7% of cells were still viable. Preservation with HTK and Euro-Collins solution allowed cell survival for only 24 hours (96.7%, HTK; 49.9%, Euro-Collins), with no viable cells seen after 48 hours. The cold saline-preserved sample showed 57.8% viable cells after 24 hours and 29.7% after 48 hours. No viable cells were detectable after 72 hours. Light microscopy revealed several patterns of both structural damage and intracellular change (nucleus and cytoplasm) in the endothelial monolayer after preservation with HTK, Euro-Collins solution, and cold saline solution. No morphologic alterations were seen in the University of Wisconsin solution group for as long as 72 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Reperfusion after cardioplegic cardiac arrest--effects on intracoronary leucocyte elastase release and oxygen free radical mediated lipid peroxidation.

In experimental animal models reperfusion of ischaemic myocardium causes sequestration of leucocytes within the coronary circulation. Leucocytes contribute to postischaemic myocardial injury by releasing proteolytic enzymes and by generating oxygen free radicals. The aim of this study was to investigate whether leucocytes also contribute to myocardial injury following ischaemia and reperfusion associated with cardioplegic cardiac arrest. Therefore, we studied the release of the proteolytic enzyme elastase and oxygen free radical initiated myocardial lipid peroxidation in coronary sinus blood during reperfusion after cardioplegic cardiac arrest. The elastase‐alpha‐1‐proteinase inhibitor complex and malondialdehyde (a byproduct of myocardial lipid peroxidation) were measured in arterial, central venous and coronary sinus blood samples in 19 patients undergoing elective coronary artery bypass grafting before aortic crossclamping and 1,5, 10 and 20 min after aortic declamping. Malondialdehyde concentrations did not increase significantly during the study period, whereas elastase concentrations showed a significant increase during cardiopulmonary bypass in arterial, central venous as well as coronary sinus blood. Neither elastase nor malondialhyde concentrations in coronary sinus blood differed significantly from arterial or central venous blood at any time point measured. Our data demonstrated increased elastase concentrations during cardiopulmonary bypass, but we did not find enhanced intracoronary elastase release or myocardial lipid peroxidation. Our data suggest that patients are sufficiently protected from leucocyte mediated ischaemia reperfusion injury during uncomplicated coronary artery bypass grafting with cardioplegic arrest.

Hybrid Treatment in a Patient With Acute Aortic Syndrome and an Aberrant Right Subclavian Artery

A 57-year-old man was admitted to our department with recent onset of chest pain. Computed tomography (CT) scans revealed an acute aortic syndrome manifested by a penetrating atherosclerotic ulcer and contained rupture at the level of origin of an aberrant right subclavian artery. A combined vascular and endovascular approach was selected. The entire arch was rerouted, a reversed bifurcated Dacron prosthesis was placed, and a bypass was created between the right common carotid artery and the lusorian artery, followed by thoracic endovascular aortic repair. The clinical course was uneventful. The CT scan obtained after the procedure revealed regular supra-aortic perfusion and complete exclusion of the complex lesion.

Frozen elephant trunk technique for acute type A aortic dissection

We present a case of a 59-year old male with a Stanford type A aortic dissection (DeBakey type I) extending from the sinotubular junction to the abdominal aorta. The patient was treated by a combined surgical and endovascular repair (frozen elephant trunk technique) using a specially designed hybrid prosthesis (E-vita open, Jotec GmbH). This onstage hybrid procedure enables simultaneous treatment of the ascending aorta, the aortic arch and the descending aorta.

Transvenous, intracardial cardioversion for the treatment of postoperative atrial fibrillation.

Atrial fibrillation (AF) following cardiac surgery is an important factor contributing to postoperative morbidity. Transvenous, intracardial cardioversion (TIC) has been shown to be effective in the treatment of chronic AF, but is an invasive and cost-intensive procedure. However, TIC would definitely be a beneficial approach if recurrence of AF following TIC is low and pharmacological treatment could be avoided. Thus, we hypothesised that TIC would be superior to conventional treatment with amiodarone with respect to the conversion rate and recurrence of AF. We compared TIC and conventional amiodarone therapy in a prospective, randomised and controlled trial in patients who developed AF following cardiac surgery. Twenty-three patients developed AF out of a total of 76 patients who gave written informed consent. Eighteen of these AF patients could be randomised into two equally sized groups to receive either an ALERT pulmonary artery catheter and TIC, or a standard pulmonary artery catheter and treatment with amiodarone. Haemodynamic parameters were registered before intervention to exclude pulmonary hypertension or fluid overload. Rates of cardioversion were compared by a Likelyhood ratio test. Out of the nine ALERT patients, AF in five cases converted to sinus rhythm (SR) with a median of two shocks (6 J). After 24 hours however, only two patients remained in sinus rhythm. On the other hand, six of the nine patients treated with amiodarone were still in SR after 24 hours. Whereas no difference was detectable in the conversion rate, persistence of SR following TIC was low. Thus, TIC without antiarrhythmic treatment is not recommendable for the treatment of postoperative AF.