Eva Berglin

Monitoring of Extracellular Aspartate Aminotransferase and Troponin T by Microdialysis during and after Cardioplegic Heart Arrest

This study aims at developing per- and postopertive surveillance of the myocardium and focuses on ischemic damage following cardioplegic heart arrest. Levels of troponin T and total aspartate aminotransferase (ASAT) were analyzed in the myocardial interstitium of 10 patients with ischemic heart disease (IHD) who underwent coronary bypass surgery and in 12 patients with nonischemic heart disease (N-IHD) who underwent valvular surgery. Fluid from the myocardial interstitium of the anterior and the lateral wall of the heart was sampled by microdialysis probes that were implanted during surgery and extracted percutaneously 70–100 h later. There were no adverse reactions, and the equipment did not interfere with the surgical procedures. The peak in troponin T serum levels that occurred 4 h after cardiac arrest was preceded by a peak in troponin T levels in the microdialysates from the interstitium that occurred 1 h earlier. The concentration of troponin T in the microdialysate peak was 300 times higher than in the serum peak. The increase in serum ASAT levels during the first 7 h after cardiac arrest corresponded in time with a decrease in interstitial ASAT levels, which had already reached a maximum during cardiac arrest. The microdialysate/serum concentration ratio was considerably smaller for ASAT than for troponin T. Interstitial peak levels of troponin T correlated positively and significantly with peak levels of ASAT. Of the 22 patients, 15 had no postoperative events according to clinical outcome, ECG and serum tests. Fourteen of these had low to normal levels of interstitial ASAT and troponin T. Conversely, atrial fibrillation and/or premature atrial contractions were recorded in 8/22 patients, 7 of whom had elevated interstitial ASAT and/or troponin T concentrations in one or both of the sampled heart regions. The N-IHD patients had higher levels of troponin T in the interstitium 20–70 h following cardioplegia, while the peak levels did not differ between the groups. In conclusion, microdialysis sampling of troponin T and ASAT is safe and allows a highly sensitive analysis of the ischemic trauma exerted by the cardioplegic arrest.

Extracellular Amino Acids as Markers of Myocardial Ischemia during Cardioplegic Heart Arrest

Extracellular levels of amino acids in the myocardial interstitium are sensitive indicators of myocyte function. Lowered ATP leads to a rapid extracellular appearance of amino acids with a high intra- to extracellular concentration ratio, such as taurine and glutamate. Nitrogen fluxes are reflected by glutamine, while alanine, glycine, serine and leucine are markers of proteolysis. In addition, degradation of membrane phospholipids is reflected by other primary amines, such as phosphoethanolamine. The time course of these changes was determined before, during and after cardioplegic heart arrest. Two regions of the heart were monitored in 20 patients by means of microdialysis sampling. After only 20 min of heart arrest, extracellular taurine, glutamate and phosphoethanolamine increased transiently up to 25 times the basal level. Ten–20 min later, glutamine increased by 6 times. A doubling of alanine, glycine, serine and leucine levels took place 30 min after release of the aortic cross-clamp. After 2 h, all were at levels similar to those recorded 15–30 h later. Levels of taurine and glutamate in the anterior wall of the heart correlated significantly with those of its lateral wall. The response to surgery and heart arrest was studied in a group of patients with ischemic heart disease as well as in another group of patients, who underwent heart surgery for nonischemic reasons. The response of taurine and glutamine was significantly higher for the patients with ischemic heart disease, in spite of a shorter mean time of heart arrest. No sex differences were recorded. High levels of amino acids coincided frequently with clinical events, which were suggestive of ischemia, but were also recorded in a few patients without diagnosed events. We conclude that monitoring of extracellular amino acids is valuable for evaluation and development of cardioprotective strategies.

Angiographic results after the use of a sutureless aortic connector for proximal vein graft anastomoses

The sutureless aortic connector system was recently developed to create anastomoses between the aorta and saphenous vein grafts for coronary artery bypass grafting. Ten consecutive patients scheduled for coronary artery bypass grafting were studied; in each patient one proximal anastomosis was performed using the aortic connector and another was sutured in the conventional manner to serve as the patients own control. One graft in the sutured group had a significant stenosis and one of the grafts in which the aortic connector was used, was occluded. In this limited study the use of the sutureless connector system for proximal anastomosis shows satisfactory early graft patency (90%).

Difficulties in the interpretation of coronary angiogram early after coronary artery bypass surgery on the beating heart

OBJECTIVE The major objective of this study was to evaluate the findings in early postoperative coronary angiography in patients who underwent coronary revascularization on the beating heart without cardiopulmonary bypass. METHODS Eighty-four consecutive patients receiving 113 grafts were studied. A coronary angiography was performed 0 to 5 days postoperatively. All the grafts were reviewed and classified in the following way: grade A (unimpaired run-off); grade B1 (<50 stenosis); grade B2 (>50% stenosis); grade O (occlusion). A second coronary angiography was performed in patients with a stenosis grade B2, 4 to 30 months postoperatively. An exercise test was performed by patients with B1 stenosis. RESULTS Overall graft patency was 96% in the 113 grafts. None of the 14 patients with B1 stenosis in the early coronary angiography had any clinical signs of ischemia. Eight of the 12 patients who exhibited B2 stenosis either at the anastomotic site, in the graft or in the distal coronary artery at the first coronary angiography had a normal angiogram at the re-angiography. CONCLUSION A majority of stenoses visualized at the early coronary angiography could not be seen at a later coronary angiography, which makes the interpretation of the angiogram unreliable as a tool for the decision as to redo-procedure in the early postoperative period.

Inflammatory response and platelet activation after off-pump coronary artery bypass surgery

Background. Cardiac surgery induces a systemic inflammatory activation and alterations in the hemostatic cascade. The responses contribute to postoperative complications but may also have protective effects. We investigated the relationship between inflammation, hemostasis and bleeding after off-pump coronary artery bypass surgery (OPCAB). Methods. Ten OPCAB patients were included in a prospective descriptive study. Selected markers of inflammation (IL-6, IL-8, PMN-elastase, C3a, and SC5b-9), and hemostasis (platelet count, β-thromboglobulin, anti-thrombin, D-dimer and fibrinogen) were measured before and immediately after surgery. Postoperative bleeding was registered. Results. Inflammatory variables did not alter significantly during surgery while β-thromboglobulin concentrations increased and anti-thrombin and fibrinogen decreased. There were significant postoperative correlations between PMN-elastase and β-thromboglobulin (r = 0.82, p = 0.004), between PMN-elastase and fibrinogen (r = 0.69, p = 0.03) and between C3a and β-thromboglobulin (r = 0.71, p = 0.02). In addition, there were significant inverse correlations between postoperative bleeding and pre- and postoperative fibrinogen levels (r = − 0.76, p = 0.011 and r = − 0.84, p = 0.002 respectively), between bleeding and postoperative β-thromboglobulin levels (r = − 0.66, p = 0.04) and between bleeding and postoperative PMN-elastase (r = − 0.75, p = 0.01). Conclusions. The results give further evidence for an association between the inflammatory response and hemostasis after cardiac surgery.

Microdialysis for myocardial metabolic surveillance: developing a clinical technique

Metabolic surveillance of the myocardium is of great interest in cardiac surgery. Microdialysis allows sampling of chemical substances from the interstitial fluid for immediate analysis. The two objectives of this study were to develop a technique for simple and safe implantation of a commercially available microdialysis probe (CMA‐70) into the myocardium and to obtain reference data for further use and metabolic control. Eighteen pigs were used in an experimental ischaemic heart model where the left anterior descending coronary artery was occluded for 20 min. Microdialysis was performed proximally as well as distally to the arterial occlusion site corresponding to a control and an ischaemic area in the heart. Two techniques were tried for probe implantation, using either a pacemaker wire attached to the probe tip or a needle introducer. Metabolic substrates (glucose, lactate, glycerol and pyruvate) were collected before, during and after ischaemia, for up to 6 h. Both techniques were highly effective in registering metabolic changes due to ischaemia with sharp time resolution, but the needle introducer was superior regarding probe durability. It is concluded that the CMA‐70 microdialysis probe implanted with the needle introducer allows for an accurate monitoring of myocardial metabolism during a prolonged period of time. Future studies in the human heart are warranted to further validate the technique.

Plasmapheresis as a rescue therapy to resolve cardiac rejection with vasculitis and severe heart failure. A report of five cases

The predominant causes of late graft loss and death after cardiac transplantation are graft rejection and infection. The histopathological classification of acute rejection is based on cellular phenomena such as lymphocytic infiltration and myocyte damage. The adverse prognostic importance of vascular or humoral rejection has been reported, but there is no well-documented treatment available. In our experience, comprising 151 orthotopic transplants, five patients presented with graft rejection characterized by a lymphocytic vasculitis that did not respond to conventional therapy. Because of a deteriorating condition, in spite of vigorous antirejection treatment that included inotropic drugs and circulatory support, plasmapheresis was tried as a last, desperate means to stop the process from developing further. The clinical symptoms rapidly subsided in all five patients after the first couple of plasma exchanges. All of the patients are alive and well after 2–3.5 years of follow-up. Although the mechanism of action is unclear, plasmapheresis was beneficial in these critically ill patients.

Temporary circulatory support with extra corporeal membrane oxygenation in adults with refractory cardiogenic shock

Objective. Early and long-term survival in patients suffering from cardiogenic shock is poor. Treatment with mechanical assist devices is complicated and expensive but claim to improve survival. We reviewed our experience of venoarterial extracorporeal membrane oxygenation (ECMO) in patients with acute cardiogenic shock. Design. ECMO was used in 52 patients with cardiogenic shock. They were divided into those not operated upon previously (n=19) and those having had cardiac surgery prior to circulatory collapse (n=33). Results. Twenty-six patients were weaned from ECMO. Early mortality for all patients was 48%. Mortality beyond 30 days was 5.8%, with no mortality in the non-cardiotomy group. Long-term survival for patients in the non-cardiotomy group was 63%, as compared to 33% in post-cardiotomy patients (p=0.07). Age over 55 years, female gender or cannulation site did not appear to influence survival. Conclusion. Mortality for patients in cardiogenic shock is very high. Treatment with ECMO in patients with refractory cardiogenic shock can be performed with good survival especially in non-surgical patients.

Tricuspid valve insufficiency as a complication of endomyocardial biopsy

The purpose of this study was to investigate the occurrence of major tricuspid insufficiency caused by endomyocardial biopsy in heart transplant recipients. Endomyocardial biopsy was used for the detection of rejection and Doppler echocardiography was performed at regular intervals. Six of 96 heart transplant patients (6.3%) had sudden appearance of large tricuspid regurgitation, all of which were directly related to a preceding biopsy. Chordal tissue was identified histologically in biopsy samples of all six patients. All patients developed symptoms of right ventricular failure which was confirmed by right heart catheterization. Three patients subsequently underwent valvuloplasty for ruptured chordae tendineae of either of the three leaflets. Two of these three patients were free from symptoms during follow-up, but the third patient developed moderate tricuspid regurgitation and clinical symptoms. It is concluded that endomyocardial biopsy, although it is the most useful tool for detection of rejection, should be used with caution with regard to anatomical structures and the risk of damage to the tricuspid valve must not be neglected. It is also concluded that valvuloplasty of the tricuspid valve can be successfully performed in a transplanted heart.

Short-term sinus rhythm predicts long-term sinus rhythm and clinical improvement after intraoperative ablation of atrial fibrillation

AIMS Our aim was to compare the long-term effects on rhythm and quality of life (QoL) after left atrial epicardial radiofrequency (RF) ablation vs. no ablation in patients undergoing cardiac surgery. METHODS AND RESULTS Thirty-nine patients with ECG documented atrial fibrillation (AF) scheduled for coronary artery bypass grafting (CABG) with or without concomitant valve surgery were consecutively elected for epicardial RF ablation. Thirty-nine age- and gender-matched patients scheduled for CABG with or without concomitant valve surgery only and with documented AF served as controls. The follow-up after ablation was 32 +/- 11 months. The percentage of patients in sinus rhythm (SR) at long-term follow-up was 62 vs. 33% (P = 0.03) after ablation and no ablation, respectively. SR at 3 months was highly predictive of that at 32 months (sensitivity 95%, positive predictive value 86%). Long-term SR was associated with better QoL, fewer symptoms, higher ejection fraction, and smaller left and right atria than AF. CONCLUSION SR at 3 months was highly predictive of long-term SR that was associated with clinical improvement when compared with patients still in AF. AF at 3 months did not preclude a later stabilization to SR.