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Biomedical subjects

Peter Feindt

Publications and source records attributed to Peter Feindt.

14 recordsLinked to original sources
PubMed2006

Gene expression in acute Stanford type A dissection: a comparative microarray study.

BACKGROUND: We compared gene expression profiles in acutely dissected aorta with those in normal control aorta. MATERIALS AND METHODS: Ascending aorta specimen from patients with an acute Stanford A-dissection were taken during surgery and compared with those from normal ascending aorta from multiorgan donors using the BD Atlas Human1.2 Array I, BD Atlas Human Cardiovascular Array and the Affymetrix HG-U133A GeneChip. For analysis only genes with strong signals of more than 70 percent of the mean signal of all spots on the array were accepted as being expressed. Quantitative real-time polymerase chain reaction (RT-PCR) was used to confirm regulation of expression of a subset of 24 genes known to be involved in aortic structure and function. RESULTS: According to our definition expression profiling of aorta tissue specimens revealed an expression of 19.1% to 23.5% of the genes listed on the arrays. Of those 15.7% to 28.9% were differently expressed in dissected and control aorta specimens. Several genes that encode for extracellular matrix components such as collagen IV alpha2 and -alpha5, collagen VI alpha3, collagen XIV alpha1, collagen XVIII alpha1 and elastin were down-regulated in aortic dissection, whereas levels of matrix metalloproteinases-11, -14 and -19 were increased. Some genes coding for cell to cell adhesion, cell to matrix signaling (e.g., polycystin1 and -2), cytoskeleton, as well as several myofibrillar genes (e.g., alpha-actinin, tropomyosin, gelsolin) were found to be down-regulated. Not surprisingly, some genes associated with chronic inflammation such as interleukin -2, -6 and -8, were up-regulated in dissection. CONCLUSION: Our results demonstrate the complexity of the dissecting process on a molecular level. Genes coding for the integrity and strength of the aortic wall were down-regulated whereas components of inflammatory response were up-regulated. Altered patterns of gene expression indicate a pre-existing structural failure, which is probably a consequence of insufficient remodeling of the aortic wall resulting in further aortic dissection.

Journal Article↗
PubMed2006

Amiodarone prophylaxis for atrial fibrillation of high-risk patients after coronary bypass grafting: a prospective, double-blinded, placebo-controlled, randomized study.

AIMS: Atrial fibrillation (AF) occurs often in patients after coronary artery bypass grafting (CABG) and can result in increased morbidity and mortality. Previous studies using P-wave signal-averaged electrocardiogram (P-SAECG) have shown that patients with a longer filtered P-wave duration (FPD) have a high risk of AF after CABG. We have shown that patients with an FPD > or = 124 ms and a root-mean-square voltage of the last 20 ms of the P-wave 20 < or = 3.7 microV have an increased risk of AF after surgery. Accordingly, the aim of this study was to investigate whether or not prophylactic peri-operative administration of amiodarone could reduce the incidence of AF in this high-risk group undergoing CABG identified by P-SAECG. METHODS AND RESULTS: In this prospective, double-blinded, placebo-controlled, randomized study, 110 patients received either amiodarone (n = 55) or placebo (n = 55). During CABG, two patients of both groups died. Amiodarone was given as 600 mg oral single dose one day before and from days 2 through 7 after surgery. In addition, amiodarone was also administered intravenously during surgery in a 300-mg bolus for 1 h and as a total maintenance dose of 20 mg/kg weight over 24 h on the first day following surgery. The primary endpoint was the occurrence of AF after CABG. The secondary endpoint was the hospitalization length of stay after CABG. The baseline characteristics were similar in both treatment groups. The incidence of post-operative AF was significantly higher in the placebo group compared with the amiodarone group (85 vs. 34% of patients, P < 0.0001). The prophylactic therapy with amiodarone significantly reduced the intensive care (1.8 +/- 1.7 vs. 2.4 +/- 1.5 days, P = 0.001) and hospitalization length of stay (11.3 +/- 3.4 vs. 13.0 +/- 4.3 days, P = 0.03). In the amiodarone group, concentrations of amiodarone and desethylamiodarone differed significantly between patients with AF and sinus rhythm (amiodarone: 0.96 +/- 0.5 vs. 0.62 +/- 0.4 microg/mL, P = 0.02; desethylamiodarone: 0.65 +/- 0.2 vs. 0.48 +/- 0.1 microg/mL, P = 0.04). CONCLUSION: The incidence of post-operative AF among high-risk patients was significantly reduced by a prophylactic amiodarone treatment resulting in a shorter time of intensive care unit and hospital stay. Our data supports the prophylactic use of amiodarone in peri-operative period in patients at high risk for AF after CABG.

Aged↗
PubMed2006

Prediction of atrial fibrillation after coronary artery bypass grafting: the role of chemoreflex-sensitivity and P wave signal averaged ECG.

Atrial fibrillation (AF) after coronary artery bypass grafting (CABG) results in a prolonged hospital stay associated with higher costs. In our study P wave triggered P wave signal averaged ECG and chemoreflex-sensitivity (CHRS) was performed on 101 consecutive patients with sinus rhythm before CABG in order to evaluate the utility of these methods to predict AF. A CHRS below 3.0 ms/mm Hg was predefined as a pathological CHRS. Postoperative AF was observed in 37 (37%) of 101 patients. Patients with AF were older (68.4+/-6.9 vs. 63.8+/-9.4 years, p<0.01), had a longer filtered P-wave duration (FPD) (133.6+/-10.2 vs. 123.6+/-14.9 ms, p<0.0001), a lower root mean square voltage of the last 20 ms of the P wave (RMS 20) (2.86+/-0.88 vs. 5.10+/-2.73 microV, p<0.0001) and a significantly lower CHRS (3.32+/-1.83 vs. 4.17+/-2.19 ms/mm Hg, p<0.05). A cut-off point (COP) of FPD> or =124 ms and RMS 20< or =3.7 microV achieved a specificity of 75%, a sensitivity of 78%, a negative predictive value of 86%, a positive predictive value of 64% and an accuracy of 76% for prediction of AF. The predictive power was lower for a pathological CHRS which achieved a specificity of 63%, a sensitivity of 60%, a negative predictive value of 73%, a positive predictive value of 48% and an accuracy of 61%. A stepwise logistic regression analysis of all preoperative variables identified COP (odds ratio 8.21; 95% CI, 2.02-33.37, p<0.003) as independent predictor. Patients with postoperative AF stayed longer in the intensive care unit (2.9+/-1.7 vs. 1.3+/-0.5 days, p<0.0001) and in hospital (13.5+/-4.3 vs. 11.4+/-1.1 days, p<0.0004). The results of our study show that the risk for AF after CABG could preoperatively be predicted with P wave signal averaged ECG and an analysis of CHRS. The predictive power of the COP could be used for a preoperative risk stratification and a corresponding prophylactic therapy in order to reduce costs.

Aged↗
PubMed2006

Delayed preconditioning via Angiotensin-converting enzyme inhibition: pros and cons from an experimental study.

1. Bradykinin B(2) receptor activation confers preconditioning from ischaemic injury. In the present study, we tested whether an angiotensin-converting enzyme (ACE) inhibitor (captopril) could mediate delayed preconditioning and, thus, cardioprotection. 2. New Zealand white rabbits received 15 mL infusion of either saline (control group; n = 7) or drugs (0.3 mg/kg captopril (CAP group; n = 7) or 0.3 mg/kg captopril + 0.1 mg/kg HOE 140 (CAPHOE group; n = 7)) via a marginal ear vein over 30 min. After 24 h, hearts were connected to a Langendorff apparatus and buffer perfused. The experimental protocol consisted of 20 min global normothermic hypoxia, followed by 120 min reperfusion. 3. Compared with baseline, the mean (SEM) contractile state (= dP/dt(max)) at 120 min reperfusion was decreased to 42 +/- ;23, 72 +/- ;16 (*P < 0.05 vs control) and 49 +/- ;22% in the control, CAP and CAPHOE groups, respectively. Early relaxation (= dP/dt(min)) was reduced to 55 +/- ;28, 73 +/- ;15 (*P < 0.05 vs control) and 52 +/- ;19% in the control, CAP and CAPHOE groups, respectively. The estimate for myocardial oxygen consumption (MVO(2)= rate-pressure product) was decreased to 52 +/- ;15, 69 +/- ;24 (*P < 0.05 vs control) and 56 +/- ;15% in the control, CAP and CAPHOE groups, respectively. Similarly, coronary flow was decreased in the control, CAP and CAPHOE groups to 49 +/- ;20, 67 +/- ;18 and 46 +/- ;19%, respectively. In contrast, ventricular extrasystoles during reperfusion were significantly elevated in both the CAP and CAPHOE groups (1.3 +/- ;0.2 and 1.1 +/- ;0.3 /min, respectively) compared with control (0.4 +/- ;0.2 /min). 4. Captopril confers delayed preconditioning against stunning via a B(2) receptor-mediated pathway. This pharmacological preconditioning protects against systolic and diastolic stunning, against vascular stunning and preserves cardiac metabolism. In addition to its accepted cardioprotective effects in early preconditioning, captopril should induce delayed preconditioning (e.g. for routine interventional cardiology or in elective cardiac surgery).

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Abdominal complications following open-heart surgery: a report of 12 cases and review of the literature.

INTRODUCTION: Abdominal complications following open-heart surgery remain serious events as the mortality is reported to be tremendously high. The clinical presentation, the diagnostic strategy and the therapeutic management varies. We reviewed all records of those patients who developed abdominal complications with surgical consequences during the last five years, recorded a complete follow-up and compared the findings to a current view of the literature. PATIENTS AND METHODS: Altogether 5720 patients underwent open-heart surgery at our institution between 1/98 and 12/02. Out of these 12 (10 men, 2 women) developed severe gastrointestinal complications with surgical consequences. The mean age was 73.17 +/- 8.1 I1 years. Seven patients underwent isolated coronary artery bypass grafting (CABG), two patients combined aortic valve replacement (AVR) and CABG, one isolated AVR, one mitral valve replacement (MVR) and yet another one combined MVR and CABG. The clinical records of all these patients were examined and a complete follow-up was recorded. RESULTS: The duration of the entire cardiac operation was a mean of 212.67 +/- 36.97 min, perfusion time 103 +/- 29.32 min and myocardial ischaemic time 52.25 +/- 24.56 min. Length of ICU-stay was between I and 5 days after cardiac surgery. Concerning gastrointestinal complications nine patients suffered from ischaemic intestinal disease, two from gastrointestinal ulcer bleeding and one from a preoperatively unknown bowel tumour with subsequent ileus. Four patients died in the immediate postoperative course, one patient within two years and seven patients show a satisfactory status at follow-up. CONCLUSIONS: A review from the literature shows an enormous mortality from abdominal complications following open-heart surgery. This was also found in our series. As many of these patients have a history of abdominal disease more attention should be paid to such anamnestic hints in the preparation before cardiac surgery. Hence we recommend early diagnostic measures and explorative laparotomy in doubtful situations in patients with positive anamnesis.

Aged↗
PubMed2005

Risk factors of ventricular tachyarrhythmias after coronary artery bypass grafting.

BACKGROUND: Ventricular arrhythmias are rare and represent the most serious arrhythmic complication after coronary artery bypass grafting (CABG). METHODS: The present retrospective study was conducted for identifying patients at risk of ventricular arrhythmias with ventricular signal averaged ECG, standard deviation of all normal RR intervals (SDNN), angiographic and echocardiographic data. We defined ventricular arrhythmias as sustained ventricular fibrillation and ventricular tachycardia. The study population consisted of 209 consecutive patients with sinus rhythm undergoing CABG. The primary endpoint was the occurrence of VA after CABG. The secondary endpoints were hospital length of stay after CABG and the occurrence of VA after hospital discharge. RESULTS: During the postoperative follow-up ventricular arrhythmias were observed in 11 patients (5%). Patients with ventricular arrhythmias showed a higher incidence of ventricular late potentials (91 vs. 9% of patients, p<0.0001) than patients without ventricular arrhythmias. In addition patients with ventricular arrhythmias had a lower left ventricular ejection fraction (44.2+/-15.2 vs. 60.1+/-13.1%, p<0.0001) and a SDNN (22.4+/-8.8 vs. 34.4+/-16.1 ms, p<0.02). A stepwise logistic regression analysis of all variables identified the combination of ventricular late potentials, ejection fraction < or = 38% and SDNN < or = 28 ms (odds rate 26.00; 95% CI, 3.44-196.67, p<0.002) as an independent predictor of ventricular arrhythmias. CONCLUSIONS: The results of our study suggest that the probability of ventricular arrhythmias could be predicted after CABG by a combination of low left ventricular ejection fraction and a measurement of ventricular signal averaged ECG and standard deviation of all normal RR intervals. Patients who can be identified as having a high risk of ventricular arrhythmias should be observed carefully after surgery.

Aged↗
PubMed2005

Anticoagulation during extracorporeal circulation under conditions of an ongoing systemic inflammatory response syndrome: effects of heparin.

OBJECTIVE: Open-heart surgery with cardiopulmonary bypass (CPB) causes changes in haemostasis. Artificial surfaces are bioincompatible and, thus, may initiate a reaction similar to an acute inflammation. In some patients, this 'postperfusion syndrome' (PPS), which includes changes in haemostasis, is the beginning of a systemic inflammatory response syndrome (SIRS). However, it is not clear whether the changes in coagulation represent a consequence or a main cause of the inflammatory reaction. Thus, the aim of our study was to investigate the cascade of coagulation and the effects of heparin under special circumstances of an ongoing SIRS. METHODS: In a prospective evaluation using standardized operative procedures with CPB, we compared Group A (control group with normal postoperative course, n =20) with Group B (patients with postoperative SIRS, n =12). At six time points beginning before and ending two days after surgery, we measured platelet counts, leucocyte counts and plasma levels of fibrinogen, factor XII and antithrombin III (ATIII), in addition to standard coagulation tests (PTT, TT and ACT). Furthermore, we determined parameters of inflammation, such as C-reactive protein, PCT, IL-6, IL-8, IL-10 and TNF-alpha. RESULTS: In Group B (SIRS), we found a reduced anticoagulation during CPB with significantly lower values for PTT (60+/-7 versus 160+/-11 s), ACT (270+/-33 versus 532+/-44 s) TT (40+/-3 versus 150+/-15 s) compared to the control Group A. Simultaneously, we found a significant increase of factor XII in the SIRS group (191+/-16 versus 10+/-2%). There were no significant differences concerning the preoperative ATIII levels and the intraoperative dosage of heparin; the intraoperative decrease of fibrinogen, ATIII and platelets was comparable in both groups. Furthermore, we could see that significant changes of inflammatory parameters in the SIRS group (increasing levels of TNF-alpha, Il-6, IL-8 and IL-10) occurred at least 30 min after the observed reduction of anticoagulatory effect. CONCLUSIONS: With our results, it could be demonstrated that the development of inflammatory complications after CPB is correlated to a significantly reduced intraoperative effect of heparin. As this reduction of anticoagulation significantly preceded the changes of inflammatory parameters in SIRS patients, we think that a hypercoagulatory state, especially in cases of ongoing inflammation, is an additional trigger of SIRS.

Aged↗
PubMed2003

Norepinephrine-induced delayed cardioprotection against stunning is at the expense of a higher postischemic arrhythmia rate.

OBJECTIVE: alpha(1)-adrenoceptor activation confers myocardial protection from ischemic injury. We tested whether norepinephrine mediates delayed cardioprotection against stunning and whether this alters postischemic arrhythmias. METHODS: New Zealand White rabbits were assigned to three groups: Control-group (n=7): no drugs. Norepinephrine-group (n=7): 75 microg norepinephrine/kg bodyweight (bw). Norepinephrine/prazosin-group (n=7):75 microg norepinephrine and 15 microg prazosin/kg bw. After 24 h, hearts were excised, perfused with buffer and subjected to 20 min of ischemia followed by 120 min of reperfusion. RESULTS: (a) Developed pressures (dP) (P(syst)-P(diast)) at the end of reperfusion: C: 51.2+/-5.0%, NE: 71.7+/-5.1% (p<0.05 vs. C), NEP: 50.7+/-5.0%. (b) Ventricular extra beats (vebs) were detected throughout the experiments. C: 0.41+/-0.15 vebs/min, NE: 1.06+/-0.18 vebs/min (p<0.05 vs. C), NEP: 1.17+/-0.3 vebs/min. CONCLUSION: Norepinephrine confers delayed preconditioning against myocardial stunning via an alpha(1)-adrenoceptor mediated pathway. Norepinephrine-mediated preconditioning involves a beneficial effect towards stunning, but at the expense of a higher rate of postischemic ventricular arrhythmia.

Adrenergic alpha-Agonists↗
PubMed2003

Effects of direct mechanical ventricular assistance on regional myocardial function in an animal model of acute heart failure.

Direct mechanical ventricular assistance (DMVA) improves hemodynamics in failing hearts without complications associated with a blood/device interface. Epicardial Doppler displacement transducers provide exact measurements of tissue displacement and regional myocardial function (RMF). An in vivo porcine model of acute heart failure was used to examine the effects of DMVA on RMF, which have not been reported before. In 8 anesthetized pigs cardiac output (CO), left ventricular pressure (LVP), aortic blood pressure (BP), systolic contractility (dp/dt max), and systolic wall thickening fraction (WT%) were measured. A multichamber pump system (IMPS) surrounding the left ventricle was implanted and the measurements were repeated. Then acute heart failure was induced by beta-blockade, resulting in a decline of all measured parameters to more than 30% compared to baseline values. In the further course of the experiment, repeated measurements were taken at several intervals with and without DMVA by the implanted device. The IMPS implantation caused no significant hemodynamic changes. Under conditions of acute heart failure DMVA improved LVP (46 +/- 7 to 81 +/- 9 mm Hg), dp/dt max (532 +/- 207 to 744 +/- 361 mm Hg/s), CO (1.5 +/- 0.1 to 1.9 +/- 0.5 L/min) and WT% (19 +/- 7% to 32 +/- 8%). Left ventricular myocardium not directly assisted by external pressure application showed improved regional myocardial function during DMVA. We conclude that DMVA is capable of improving hemodynamics due to extrinsic compression. It also enhances the remaining myocardial function of the failing heart, which might lead to myocardial recovery. These synergistic effects are considered responsible for the high efficiency shown by the IMPS in previous investigations.

Acute Disease↗
PubMed2002

Clinical evaluation of reflectance spectrophotometry for the measurement of gastric microvascular oxygen saturation in patients undergoing cardiopulmonary bypass.

OBJECTIVE: To evaluate the impact of cardiopulmonary bypass (CPB) on gastric mucosal oxygen saturation assessed by reflectance spectrophotometry in patients undergoing coronary artery bypass graft surgery. DESIGN: Prospective, observational study. SETTING: A division of cardiothoracic anesthesia in a university hospital. PARTICIPANTS: Twelve consecutive patients undergoing CPB. INTERVENTIONS: Monitoring, anesthesia, surgical procedure, and CPB for the patients followed routine clinical protocol as established in the departments. Microvascular oxygen saturation in gastric mucosa was assessed by reflectance spectrophotometry before, during, and after CPB. MEASUREMENTS AND MAIN RESULTS: Gastric mucosal oxygen saturation averaged 65 +/- 7% (mean +/- SD) before CPB, decreased significantly to 57 +/- 9% during CPB (p < 0.01), and was 59 +/- 8% after CPB. These changes in regional oxygen saturation were not mirrored in variables of systemic oxygenation. Gastric mucosal oxygen saturation always showed instantaneous reactions to various surgical and pharmacologic interventions. CONCLUSION: Reflectance spectrophotometry allowed the authors to assess gastric mucosal oxygen saturation with a high repetition rate, regardless of spontaneous circulation with pulsatile flow or nonpulsatile flow during CPB. This technique provided the means to monitor on-line the course of tissue oxygen saturation throughout the operative procedure. Reflectance spectrophotometry is an appropriate and sensitive assessment tool to monitor gastric mucosal oxygen saturation in patients undergoing CPB.

Aged↗
PubMed2002

Cardiopulmonary bypass: Evidence or experience based?

OBJECTIVE: Evidence-based medicine is emerging as a new paradigm for medical practice. The purpose of this study was to evaluate the amount and quality of scientific evidence supporting principles that are currently applied for cardiopulmonary bypass performance. METHODS: A survey of all German departments of cardiac surgery regarding cardiopulmonary bypass performance disclosed major differences. Consequently, for 48 major principles of cardiopulmonary bypass performance, relevant Medical Subject Headings were identified, and a literature search of the Medline database was performed. Two sequentially applied sets of inclusion-exclusion criteria were selected to assess the best available evidence. RESULTS: Thirty-three thousand articles relating to the subject were identified. Among these, 1500 fulfilled the first set of inclusion criteria: meta-analysis of (randomized) controlled clinical trials and in vitro and animal studies. Rigorous methodological criteria were then applied to further select remaining publications. Ultimately, 225 articles referring to major cardiopulmonary bypass principles were identified as providing the best available evidence. These were graded according to their methodological rigor (susceptibility to bias). The scientific evidence on the investigated cardiopulmonary bypass principles did not prove to be of a high enough level to allow general recommendations to be made. CONCLUSIONS: The scientific data concerning the effectiveness and safety of key principles of cardiopulmonary bypass are insufficient in both amount and quality of scientific evidence to serve as a basis for practical, evidence-based guidelines.

Acid-Base Equilibrium↗