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Borut Gersak

Publications and source records attributed to Borut Gersak.

12 recordsLinked to original sources
PubMed2006

Assessment of cardiac autonomic regulation and ventricular repolarization after off-pump coronary artery bypass grafting.

BACKGROUND: Altered autonomic regulation precipitates cardiac arrhythmias and increases the risk of sudden cardiac death. This risk is further increased by changes in ventricular repolarization. Autonomic regulation is deranged in patients after myocardial on-pump revascularization. We aimed to clarify how off-pump coronary artery bypass grafting (CABG) affects postoperative cardiac autonomic regulation and ventricular repolarization within 4 weeks after CABG. METHODS: Forty-two patients (mean age, 61.9 +/- 9.3 years; mean EURO score 2.6 +/- 1.9) were electively admitted for off-pump CABG. The electrocardiographic and respiratory waveform recordings were performed in the afternoon in the supine position for 10 minutes. Autonomic modulation was assessed using heart rate variability analysis. Power spectra were computed from 5-minute stable RR intervals using Fourier Transform analysis. Total power of spectra was defined in the range of 0.01 to 0.40 Hz, high-frequency power within 0.15 to 0.40 Hz, and low-frequency power within 0.04 to 0.15 Hz. Normalized power was defined as a ratio of power in each band/total power. The high- and low-frequency power as well as their normalized values indicated cardiac vagal and sympathetic modulation, respectively. Ventricular repolarization was assessed using QT interval, QT interval variability, and QT-RR interdependence analysis. QT intervals were determined from the beginning of the 5-minute segments. QT interval variability was evaluated by a T-wave template-matching algorithm. Pearson correlation between length of RR and QT interval was applied to study QT-RR characteristics. The results were tested for significance using the Fisher exact test, nonpaired t test, and analysis of variance; a P <.05 was considered significant. RESULTS: The frequency of arrhythmic events and heart rate increased from the fourth to the seventh postoperative day and returned to preoperative levels 4 weeks after CABG. Heart rate variability measures indicating autonomic modulation remained depressed even 4 weeks after the procedure. QT variability index increased from -1.2 +/- 0.5 to -0.8 +/- 0.4 on the fourth day after the operation (P <.05) and returned to -1.0 +/- 0.5 4 weeks after CABG (P = not significant). QT-RR correlation decreased from 0.41 to 0.23 (P <.05) and remained significantly impaired as long as 4 weeks after CABG. CONCLUSIONS: Observed faster heart rates until 1 week after off-pump CABG imply excessive adrenergic activation, which is comparable to on-pump CABG procedure rates. The results indicate profound autonomic derangement and loss of rate-dependent regulation after off-pump CABG even 4 weeks after operation. Restituted repolarization as assessed by QT variability index 4 weeks postoperatively corresponded with decreased frequency of rhythm disturbances 4 weeks after CABG. The loss of coupling between QT and RR intervals shows increased electrical instability postoperatively, which may serve as an additional promoter for postoperative arrhythmias, especially at higher heart rates.

Aged↗
PubMed2004

Sympathetic reinnervation after heart transplantation, assessed by iodine-123 metaiodobenzylguanidine imaging, and heart rate variability.

OBJECTIVE: Complete allograft denervation occurs during heart transplantation. Partial ventricular sympathetic reinnervation may develop one year or later after transplantation and can be measured with iodine-123-meta-iodobenziylguanidine (MIBG) uptake. Aim of this study was to assess sinus node sympathetic reinnervation measured with heart rate variability and ventricular sympathetic reinnervation evaluated with MIBG. METHODS: Twelve patients and 14 healthy controls were included. In patients, MIBG scintigraphy with early and late imaging was performed. Heart to mediastinum ratio (HMR) was calculated and patients were divided in groups with (HMR>1.3) and without left ventricular reinnervation (HMR<1.3). Bipolar ECG with high sampling rate and resolution was recorded over 8.5 min in supine position and in upright position after 10 min interval. R-R intervals in time domain and heart rate variability in frequency domain through spectral power analysis of R-R intervals were analysed to evaluate sinus node reinnervation. Spectral power in low frequency range (0.04-0.15 Hz) above 4.5 ms(2) was considered as sinus node sympathetic reinnervation. RESULTS: Six (50%) patients had evidence of left ventricular sympathetic reinnervation on scintigraphy. Sinus node sympathetic reinnervation based on heart rate variability was detected in 6 (50%) patients in supine, and in 4 (33%) patients in upright body position. Four patients groups were discerned: (1) with ventricular and sinus node sympathetic reinnervation, (2) with sinus node sympathetic reinnervation, (3) with ventricular sympathetic reinnervation and (4) without atrial or ventricular sympathetic reinnervation. Ventricular reinnervation process was time dependent and sinus node reinnervation was not. CONCLUSIONS: Simultaneous ventricular sympathetic reinnervation assessed by MIBG and sinus node sympathetic reinnervation assessed by heart rate variability in supine as in upright position were detected only in two patients (17%). The results of our study show that eventual sinus node sympathetic reinnervation and left ventricular sympathetic reinnervation do not occur simultaneously.

3-Iodobenzylguanidine↗
PubMed2003

A technique for aortic valve replacement on the beating heart with continuous retrograde coronary sinus perfusion with warm oxygenated blood.

The protection of ventricular myocardium in aortic valve operations is always an issue because those hearts do not tolerate global ischemia well. A technique of aortic valve replacement is described involving continuous retrograde coronary sinus perfusion with warm oxygenated blood used in 34 patients to date without any complications. This technique maintains a beating heart throughout the procedure.

Aortic Valve↗
PubMed2003

Topical cardiac cooling--computer simulation of myocardial temperature changes.

Topical cardiac cooling (TC) is often used in cardiac surgery. We used a computer simulation to study temperature changes in the heart, especially in the right ventricular wall. A three-dimensional computer heart model, derived from Visible Human Data set, National Library of Medicine was used. The model is made from cubes, with spatial resolution of 1mm. Explicit Finite Different method and temperature diffusion equation were used to calculate new temperatures. Three different simulations were performed and simulated temperatures were drawn on a cross-section of heart model in different colors. The results show that areas not immersed into TC solution are less protected against ischemia. It is important not to rely solely on topical cooling but use appropriate method of myocardial protection technique.

Anatomy, Cross-Sectional↗
PubMed2003

Body surface mapping of cardiac activity after partial left ventriculectomy.

MECG measurements were performed using 35 electrodes in 10 patients operated with partial left ventriculectomy (PLV). Body surface ECG signals were recorded and five measurements were done: prior to PLV, second, third, fourth and fifth postoperative day. This work was concentrated on the following mapping methods: average isopotential ST segment maps (STM), QRS interval isointegral maps (QRM) and isochronal activation maps (IAM). STMs of the patients show a great positive area (elevation) over the anterior aspect of the heart and a great negative area (depression) over the lateral and posterior aspect of the heart before the operation. After the operation, the ST elevation over the anterior, lateral and posterior aspect of the heart was reduced. A substantial positive value over the excised area of the heart was present also on the end of the postoperative monitoring interval. Minimal and maximal values of the QRMs were smaller and also show some kind of normalisation. The area of the left ventricle, where PLV was performed, was carefully analysed for any changes of activation time for different heart regions. IAMs indicate that the start of the first activation was quite stable and in accordance with the position of the QRMs minimum.

Body Surface Potential Mapping↗
PubMed2003

Breathing rates and heart rate spectrograms regarding body position in normal subjects.

The right lateral body position has been proposed as an effective vagal enhancer. However, the possibility of breathing affecting heart rate power spectra in different body positions has not been assessed. The level of vagal modulation in various body positions in normal subjects was estimated by calculating heart rate power spectra. The results suggest that the levels of vagal modulation do not necessarily reflect a change due to assuming different body position, but might be the consequence of changed breathing patterns. Before adopting the right lateral body position as vagal enhancing, the contribution of varying breathing pattern should be eliminated.

Adult↗
PubMed2003

Endoscopic aortic valve replacement.

During the last 8 years, many different approaches for minimally invasive aortic valve surgery have emerged. We have developed a technique that enables total endoscopic aortic valve replacement with port access, via a small right lateral thoracotomy with only soft tissue retraction and minimally invasive aortic crossclamping. The operation is performed under video guidance, since no direct eye vision is possible. We believe this is the first such operation performed in cardiac surgery and that it mak es possible broadening of indications for nonsternotomy-video-directed surgery in the future.

Adult↗
PubMed2002

Right ventricular metastatic choriocarcinoma obstructing inflow and outflow tract.

We operated on a 34-year-old man with a metastatic tumor that extended from the tricuspid valve to the pulmonary valve and obstructed the right ventricle inflow and outflow tracts. The tumor was removed with preservation of the tricuspid valve. Additional chemotherapy was carried out according to the BEPO (etoposid, eisplatin, bleomycin, vincritin) scheme. Histology revealed metastasis of a choriocarcinoma originating from the right testis. Computed tomography performed after 6 months detected no metastases in the lungs. Magnetic resonance imaging showed a thickened right ventricle free wall and apex. The patient is doing well 18 months postoperatively.

Adult↗
PubMed2002

Aortic and mitral valve surgery on the beating heart is lowering cardiopulmonary bypass and aortic cross clamp time.

OBJECTIVE: The concept of cardiac surgery on the beating heart is acceptable rationale for the cardiac surgery in the next millenium. Beating heart (off-pump) coronary artery bypass grafting (CABG) techniques have led us to consider the possibility for performing the aortic and mitral valve surgery (mitral valve repairs and replacements - with or without CABG) on the beating heart with the technique of retrograde oxygenated coronary sinus perfusion. METHODS: We used the technique of retrograde oxygenated blood coronary sinus perfusion in 78 patients (Group All) - (36 patients were with extremely low ejection fraction (Group X) - 62% of whom were in New York Heart Association (NYHA) class 4 and 34% of whom were in NYHA class 3). The procedures for the patients were: aortic, mitral and tricuspid valve surgery, in combination with CABG in ischemic patients. CABG was done in all the cases off-pump. In addition, we performed a case match study for 37 patients with good ejection fraction (51.65 +/- 11.88) (Beating Heart Group) operated on the beating heart with most appropriate group of patients (No. 37) operated in our institutions on arrested heart (ejection fraction 51.07 +/- 12.93) (Arrested Heart Group). The case match selection criteria were: gender, left ventricular ejection fraction, atrial fibrillation, hypertension, pulmonary hypertension, and diabetes. The selected beating heart group and selected arrested heart groups were without statistically significant differences for the mentioned criteria. RESULTS: There were statistically significant differences between Beating Heart Group and Arrested Heart Group in the duration of Cardiopulmonary Bypass Time (69.35 +/- 13.52 min. versus 93.59 +/- 28.54 min.), p<0.001, and statistically significant differences in Aortic Cross Clamp Time (46.5 +/- 8.95 min. versus 61.5 +/- 18.34 min.), p<0.001. The values for Creatinin Kinase (CK) and LDH were not statistically different, however the absolute values for Beating Heart Group were lower. There was no statistical difference in complication rate for both the groups for: sternal infection, bleeding, death, atrial fibrillation, AV block and neurological complications. The total early mortality for all the patients was 5.1% (4 out of 78) - for the group X 8.3 % (3 of 36 patients). Two were in-hospital deaths. One patient with triple-vessel disease and acute mitral insufficiency on intra aortic balloon pump (IABP) had been operated on 6 days after acute myocardial infarction (AMI). The cause of the death was systemic meticillin resistant staphylococus aureus (MRSA) infection - (eight days prior to our operation, arthrodesis of the talocrural joint was performed by an orthopedic surgeon). The other death was a female patient who was operated on after previous multiple cerebrovascular infarctions (CVI) (cause of the death was CVI). In addition, one patient died one month after the operation because of prosthetic valve endocarditis (PVE) on aortic and mitral valves (silver-coated silzone aortic and mitral valves were implanted because of chronic latent asymptomatic tibial osteitis). None of these deaths were cardiac related. CONCLUSIONS: We conclude that beating heart valve surgery (any combination) with or without CABG significantly lower the cardiopulmonary bypass and aortic cross clamp time. In addition, the advantages of beating-heart surgery are 1) the perfused myocardial muscle, 2) the heart is not doing any work, 3) no reperfusion injury, 4) the possibility for ablation of atrial fibrillation on the beating heart, and 5) testing of the mitral valve repair is done in real physiologic conditions in the state of left ventricle beating tonus. The procedure could be the procedure of choice for the valve operation or combined operations (valve operation and CABG) in high-risk patients with low ejection fractions. There is no doubt that at present day in cardiac surgery exist at least two major factors for mortality and morbidity after cardiac surgery, which are operation - related, namely cardiopulmonary bypass time and its duration and aortic cross clamp time (ischemic time of myocardium). In the last few years a number of different techniques emerged in the field of cardiac surgery, which were directed toward better results in the selected high risk patients or to minimize the deleterious effects of cardiopulmonary bypass (CPB) on the overall postoperative performance [Calafiore 1996, Tasdemir 1998]. Due to the fact, that the cardiac muscle should be protected at most during the cardiac arrest, retrograde blood cardioplegia was successfully introduced [Buckberg 1990], and more - the warm cardioplegia is being used recently [Kawasuji 1997]. The natural status of the human heart is the beating status, so it is reasonable to try to perform the operations on the beating heart. This has been done recently with the MID - CAB and OP - CAB (off-pump CABG) operations [Tasdemir 1998]. The retrograde warm blood cardioplegia has therefore led us to the premise, that with retrograde oxygenated blood perfusion it would be possible to achieve the operations on the beating heart even in the open heart surgery, such as aortic and/or mitral valve surgery. All will agree that the most damaging effect of the cardioplegia is the reperfusion injury [Allen 1997], and it is obvious that with the technique of retrograde continuous oxygenated blood perfusion this effect will be canceled. In this article, we would like to show the how-to technique for the operations on the beating heart in the case of operations on the aortic valve replacement (AVR) with mitral valve repair (MVR) or replacement MVR and with/without concomitant coronary artery bypass (CABG) surgery. The tricuspid valve repair (PTV) is normally done on the beating heart and there it is realized what problems or technical difficulties may arise during procedures on the mitral valve: the walls of the ventricles are not flattened and the exposure of the mitral valve is challenging task. Furthermore, the free walls of the ventricles with interventricular septum are in the state of the tonus, so every force applied to better expose the aortic or mitral valve is not acceptable

Aortic Valve↗
PubMed2002

Body surface mapping after partial left ventriculotomy.

OBJECTIVE: To demonstrate cardiac electrophysiological changes in patients where partial left ventriculotomy was performed and multichannel electrocardiographical measurements and body surface potential mapping were used. METHODS: Body surface ECG signals were recorded during sinus rhythm for one minute. Six patients were operated on with partial left ventriculotomy were monitored. All patients had normal coronary angiography data. The data were acquired prior to the partial left ventriculotomy, and on the second, third, fourth, and fifth postoperative day using 32-body surface leads. The recorded data were analysed by determining ST-40 and QRS integral maps. The analysis was done on a set of selected beats during the sinus rhythm and on the averaged beats. RESULTS: Before the operation, ST-40 maps typically showed an area of strong positive potentials (elevation) over the anterior aspect of the torso and a region of strong negative potentials (depression) over the lateral, and posterior aspects of the torso. After the operation, the ST elevation over the anterior, lateral and posterior aspects of the torso was reduced. An area of marked positive potentials remained in the precordial area (overlying the excised area of the heart), even during the postoperative monitoring interval (day two through day five). We also noticed that the amplitude of cardiac signals decreased by approximately 30% after the partial left ventriculotomy. Qualitative map changes were substantiated by statistical parameters. CONCLUSIONS: Results of our study demonstrate that noninvasive acquisition of body-surface electrocardiographs may detect changes in the cardiac activity of patients undergoing partial left ventriculotomy. This finding suggests that body surface mapping may also be useful in assessing the arrhythmia vulnerability.

Adult↗
PubMedDate not supplied

Hypoxic and pharmacological preconditioning preserves vasomotor response of porcine coronary artery.

Vasomotor response of the coronary artery depends on both endothelial and smooth muscle cells. Response is altered by hypoxia-reoxygenation-induced damages. Hypoxic preconditioning and pharmacological preconditioning as well can prevent these alterations. We compared the effectiveness of both types of preconditioning against hypoxia-reoxygenation-induced changes in vasomotor response of the isolated artery. Porcine arterial rings (3-4 mm wide) were cut from the left anterior descending porcine coronary artery and placed in Krebs-Henseleit solution. In order to obtain control response of the arteries, we contracted arterial rings with 20 mM KCl before ("standard contraction") and after 60-min hypoxia and 30-min reoxygenation. In other groups, nitric oxide-synthase and cyclooxygenase were inhibited. Then, the rings were pre-contracted with U46619 and relaxed by cumulative addition of the substance P. Contractions and relaxations of non-preconditioned and hypoxically or pharmacologically preconditioned rings were compared. Hypoxic preconditioning was performed by two periods of 5-min hypoxia and 10-min reoxygenation. For pharmacological preconditioning, we used application of adenosine, adrenaline, acetylcholine and angiotensin II. Analysis was performed with one-way ANOVA, followed by Dunnett's Multiple Comparison Test. After hypoxia-reoxygenation, in non-preconditioned rings KCl-induced contractions were significantly increased compared to standard contraction. Relaxations of hypoxically and pharmacologically preconditioned rings (expressed as percentages of U46619-induced pre-contraction) were significantly decreased (p < 0.01) compared to hypoxic but not to normoxic rings. Hypoxic and pharmacological preconditioning may preserve contraction and endothelium-dependent relaxation of porcine coronary artery after long-lasting hypoxia-reoxygenation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗