[GSTCVS certificate for cardiac pacemaker, ICD and CRT therapy]. / DGTHG-Zertifizierung zur Herzschrittmacher-, ICD- und CRT-Therapie.

Medical qualifications to perform operations with cardiac electronic implantable devices as well as for preoperative and postoperative therapy, including follow-up in this patient population are not well defined. Based on recommendations which have been worked out and published by an interdisciplinary consensus of cardiac surgeons, cardiologists and electrophysiologists, a certificate with three modules has been developed by the Working Group for Electrophysiologic Surgery of the German Society for Thoracic and Cardiovascular Surgery (GSTCVS, Deutsche Gesellschaft für Thorax-, Herz- und Gefäßchirurgie, DGTHG). First examinations for this certificate will be held in 2013 and transitional regulations apply until 1st April 2014. Further details are available on the homepage of the GSTCVS.

Comparison of sequential left internal thoracic artery grafting and separate left internal thoracic artery and venous grafting : A 5-year follow-up.

OBJECTIVES: The superiority of left internal thoracic artery (LITA) grafting to the left anterior descending artery (LAD) is well established. Patency rates of 80%-90% have been reported at 10-year follow-up. However, the superiority of sequential LITA grafting has not been proven. Our aim was to compare patency rates after sequential LITA grafting to a diagonal branch and the LAD with patency rates of LITA grafting to the LAD and separate vein grafting to a diagonal branch. METHODS: A total of 58 coronary artery bypass graft (CABG) patients, operated on between 01/2000 and 12/2002, underwent multi-slice computed tomography (MSCT) between 2006 and 2008. Of these patients, 29 had undergone sequential LITA grafting to a diagonal branch and to the LAD ("Sequential" Group), while in 29 the LAD and a diagonal branch were separately grafted with LITA and vein ("Separate" Group). Patencies of all anastomoses were investigated. RESULTS: Mean follow-up was 1958±208 days. The patency rate of the LAD anastomosis was 100% in the Sequential Group and 93% in the Separate Group (p=0.04). The patency rate of the diagonal branch anastomosis was 100% in the Sequential Group and 89% in the Separate Group (p=0.04). Mean intraoperative flow on LITA graft was not different between groups (69±8ml/min in the Sequential Group and 68±9ml/min in the Separate Group, p=n.s.). CONCLUSION: Patency rates of both the LAD and the diagonal branch anastomoses were higher after sequential arterial grafting compared with separate arterial and venous grafting at 5-year follow-up. This indicates that, with regard to the antero-lateral wall of the left ventricle, there is an advantage to sequential arterial grafting compared with separate arterial and venous grafting.

EuroSCORE overestimates the risk of cardiac surgery: results from the national registry of the German Society of Thoracic and Cardiovascular Surgery.

OBJECTIVE: The EuroSCORE risk stratification model has been developed in 1995 and is still widely used to assess individual patient risk prior to cardiac surgery. Furthermore, the score advanced to a decision tool to determine so-called "high-risk patients" and in consequence serves as an important selection criterion in new technologies, such as the catheter-based aortic valve replacement. Several studies with relatively small patient numbers showed a substantial overestimation of risk by the EuroSCORE. The aim of our study was to evaluate whether the nationwide data support this finding. METHODS: A subgroup of the registry of the German Society of Thoracic and Cardiovascular Surgery from 2006 and 2007, with 32,806 patients undergoing isolated coronary surgery and isolated aortic valve replacement was investigated. RESULTS: The overall hospital mortality in isolated coronary surgery in this patient cohort (n = 26,501 patients) was 2.6% (n = 695). The overall hospital mortality in isolated aortic valve replacement in this patient cohort (n = 6,305 patients) was 3.9% (n = 245). The logistic EuroSCORE predicted a proportion of 5.2% for patients with isolated CABG and 7.3% for patients with isolated aortic valve replacement. The area under the receiver operating characteristic curve was 0.77 for isolated CABG procedures and 0.69 for isolated valve procedures, supporting the substantial lack of predictive value of the EuroSCORE. CONCLUSION: The logistic EuroSCORE insufficiently evaluates the risk of the current patient population and therefore should be carefully used as a tool for important therapeutic decision-making.

Myocardial infarction: an important factor for surgical decision making?

BACKGROUND: Recent myocardial infarction has been identified as a risk factor and is currently used as a strong predictor in different scores. The aim of our study was to determine whether the impact of myocardial infarction, especially acute myocardial infarction, is still strong enough to justify a restrictive indication for isolated CABG procedure in patients with significant coronary artery disease. METHODS: 10 272 patients underwent isolated CABG at a single institution. A 10-year follow-up was performed with a completeness of 97.2 %. RESULTS: 6 107 (59.5 %) of the patients had a history of myocardial infarction. A stratified Kaplan-Meier analysis demonstrates a significantly worse survival for patients with myocardial infarction (chi-square value: 36.7, P < 0.0001). At a further differentiation for no myocardial infarction (n = 4 165), myocardial infarction > 90 days (n = 4 578), myocardial infarction up to 90 days (recent myocardial infarction) (n = 1 266) and ongoing acute myocardial infarction up to 15 days (n = 263), indicated a higher mortality for the more recent infarction in the univariate analysis. However, if patients with acute myocardial infarction in the past 6 years were analyzed separately, their risk remained at the same level as patients with non-acute myocardial infarction over the total observation period. Furthermore, propensity score matching revealed no statistical significant difference in the outcome of the patients. CONCLUSIONS: Structural myocardial damage represents a risk factor for survival after isolated CABG in univariate analysis. More appropriate statistical methods indicate a time-dependent loss of statistically relevant differences between patients with or without myocardial infarction prior to CABG. This is also true for "recent" myocardial infarction which is still part of current scores.

Preexisting atrial fibrillation as predictor for late-time mortality in patients with end-stage renal disease undergoing cardiac surgery--a multicenter study.

BACKGROUND: Although patients with end-stage renal disease (ESRD) are considered to be high-risk patients in cardiac surgery, the reported studies are rather small, resulting in unsatisfactory analyses of outcome determinants. Therefore, we aimed to identify possible risk factors, with a particular focus on the impact of pre-existing atrial fibrillation (AF) on the postoperative short-term and long-term mortality of ESRD patients undergoing cardiac surgery. METHODS: In a multicenter study 522 patients with ESRD undergoing CABG only (62.9 %), valve surgery only (17.2 %), or both (19.9 %) with comparable demographic and other cardiac risk factor characteristics were investigated retrospectively over a period of 10 years. The outcome was divided into perioperative (within 30 days) and late morbidity and mortality, and multivariate analysis was performed for both. RESULTS: The mean perioperative mortality was 11.5 % and the 5-year survival rate was 42 %. Emergency surgery, insulin-dependent diabetes mellitus, the number of vein grafts and age were identified as risk factors whereas complete revascularization, the use of an internal thoracic artery and the presence of sinus rhythm were identified as beneficial factors for long-term survival. 14.1 % of all patients had pre-existing AF. Although AF was not identified as an independent risk factor for perioperative mortality ( P = 0.59), it was identified as an independent predictor for late mortality ( P < 0.001). Median survival of patients without AF was 1816 days, while for patients with AF it was only 715 days. CONCLUSIONS: AF does represent an independent predictor for long-term but not perioperative mortality in patients with ESRD. However, effective treatment of AF is controversially discussed. Anticoagulation therapy or perioperative ablation of the arrhythmia should be considered in order to improve the survival of these patients.

Long-term results after coronary artery reconstructive surgery.

BACKGROUND: Diffuse coronary artery disease, multiple consecutive stenoses and complex lesions are a common finding in coronary surgery. Coronary reconstructive surgery in terms of extended anastomoses with or without thromboendarterectomy is still controversially discussed. The aim of this study was to evaluate the long-term results of patients who underwent coronary reconstruction. METHODS: Between January 1995 and June 2004, 640 consecutive, unselected patients underwent isolated CABG with coronary reconstructive surgery of the LAD at a single institution. A cross-sectional long-term follow-up was performed with a completeness of 99.2 %. Questionnaires were sent to all patients with a response rate of 83.2 % (n = 533). RESULTS: 147 of the 640 patients (22.9 %) died during up the follow-up period which was up to 10 years. Of the 371 patients who responded to the questionnaires, the status of 54 patients (15.9 %), predominantly those with a preoperative lower NYHA class, remained unchanged, while 294 patients (79.2 %) improved by at least one NYHA class. Repeat angiography was performed in 80 patients (15.7 %). Indications for percutaneous coronary intervention for the LAD arose in 4 cases (0.8 %); the interventions were performed in the proximal (n = 2) or distal (n = 1) LAD and one intervention affected the anastomotic area. Redo CABG was necessary in 3 patients (0.5 %). CONCLUSIONS: Coronary reconstruction in patients with complex coronary morphology and advanced diffuse CAD is in an additionally investigated subgroup of patients associated with a satisfying graft patency and excellent long-term results in terms of survival, NYHA class and reintervention rate.

Coronary reconstructive surgery versus coronary artery bypass grafting--a documentation gap.

OBJECTIVE: Over the last years, there has been a clear trend that an increasing number of patients are admitted for CABG with advanced disease, complex pathomorphological alterations and impaired left ventricular function. The necessity of performing extensive reconstructive coronary surgery rather than coronary bypass grafting, in its original sense, is not appropriately documented by the current version of the German Documentation System for Cardiac Surgery, nor in other national and international documentation systems. PATIENTS AND METHODS: 5821 consecutive, unselected patients underwent isolated CABG from 7/1995 through 12/2003 at a single institution. A closing date follow-up procedure up to 8 years postoperatively was performed with a completeness of 98.8%. RESULTS: The need for reconstructive surgery in terms of extended anastomoses with or without coronary endarterectomy has doubled in our patients since 1995 and is steadily increasing with 15.7 % (n=102) of these patients requiring such surgery in 2003. Current documentation does not allow any prediction of complex coronary morphology. The Kaplan-Meier survival curve reveals no substantial difference between patients with and without coronary reconstructive surgery up to 8 years after CABG. CONCLUSION: The increase of complexity in CABG procedures currently remains undetected, since preoperative imaging methods often fail to predict complex coronary morphology. Survival after coronary reconstructive surgery is comparable to that of "classical" CABG. Therefore, a standardized documentation is required to evaluate surgical results and to contribute to the improvement of medical decision-making which presupposes valid data.

Minimal early mortality in CABG--simply a question of surgical quality?

BACKGROUND: The increasing number of risk scores and models for the evaluation of the early risk after cardiac surgery reflects the interest in 'calculating' the risk of adverse events. Different time intervals, but also different 'types' of death are generally accepted in the evaluation of early mortality. The aim of this study was to focus on the differences in the calculation of early mortality and to focus on their potentially misleading impact on risk stratification. METHODS: We investigated 7,436 patients who underwent coronary artery bypass grafting from June 30, 1988 through June 30, 2001. A follow-up was performed 180 days after operation (98.7 % complete). RESULTS: According to the definition of 30-day mortality to represent the total time interval between an intervention and the 30th postoperative day, the 30-day mortality was 5.92 % (n = 440 patients). Hospital mortality reflects the number of deaths from the day of intervention through the patient's individual discharge, independent of any fixed time interval. Hospital mortality was 5.86 % (n = 436 patients) in our patient group. 30-day hospital mortality requires the investigation of hospital mortality until the 30th postoperative day; in-hospital and general mortality after the 30th postoperative day remained excluded from the analysis; 30-day hospital mortality was 5.19 % (n = 386 patients). Assuming a maximum hospital stay of 5 days, hospital mortality would decrease to 2.64 % (n = 196 patients). CONCLUSIONS: 30-day mortality, hospital mortality and 30-day hospital mortality are used to determine early outcome. The present data indicate the vulnerability of non-standardized time intervals to discharge policy. However, both hospital mortality and 30-day hospital mortality are predominantly used in current risk scores and models. In view of the comparability and meaning of data, the methodology for the evaluation of early risk should be reconsidered.

[Stability of the Euro-score as an identification tool for patient risk groups -- dependency of the applied documentation system]. / Stabilität des Euro-Score als Instrument zur Identifikation von Patientenrisikogruppen--Abhängigkeit des verwendeten Dokumentationssystems.

From the different methods for risk adjustment, scores allow a rough classification of the patients. The Euroscore represents one of the most modern scores. The most recent version of the documentation system of the German Society for Thoracic and Cardiovascular Surgery may be used without extended extra-work to evaluate the Euroscore despite the presence of various limitations. The investigation of the scores with nearly complete adaptation of the variables of the quality assurance documentation to the original definition showed no substantial differences between the score groups. However, many methodological implications favor the development of self-evaluated models to obtain a most recent weight for each risk factor and to be able to take into account new therapeutical options. These models can be evaluated by the existing database and extended by the most recent data.

[Not Available]. / Stabilität des Euro-Score als Instrument zur Identifikation von Patientenrisikogruppen - Abhängigkeit des verwendeten Dokumentationssystems.

From the different methods for risk adjustment, scores allow a rough classification of the patients. The Euroscore represents one of the most modern scores. The most recent version of the documentation system of the German Society for Thoracic and Cardiovascular Surgery may be used without extended extra-work to evaluate the Euroscore despite the presence of various limitations. The investigation of the scores with nearly complete adaptation of the variables of the quality assurance documentation to the original definition showed no substantial differences between the score groups. However, many methodological implications favor the development of self-evaluated models to obtain a most recent weight for each risk factor and to be able to take into account new therapeutical options. These models can be evaluated by the existing database and extended by the most recent data.

Does the completeness of revascularization contribute to an improved early survival in patients up to 70 years of age?

OBJECTIVE: In the era of a renewal of incomplete revascularization approaches, the controversy reappears as to whether the approach for complete revascularization is of prognostic value. The clear advantage of complete revascularization in elderly patients has recently been published. However, for the younger patient group, there is no conclusive information available so far. The aim of our study was to investigate the effect of complete vs. incomplete revascularization in patients up to 70 years of age. PATIENTS AND METHODS: 6531 patients underwent isolated CABG. 5003 of these patients were aged up to 70 years at the time of operation. RESULTS: Incomplete revascularization was performed in 534 (10.7 %) patients. The most common reasons for incomplete revascularization were small vessels and massive calcification. The differences in mortality up to the 180(th) day after CABG are statistically significant. By Kaplan-Meier analysis, the time relationship between incomplete revascularization and death affects predominantly the very early period after CABG. By logistical regression, incomplete revascularization was found to be an independent risk factor for death after CABG. CONCLUSION: Incomplete revascularization affects the early outcome after CABG in patients up to 70 years of age as an independent risk factor for death. In view of recent approaches for primarily incomplete CABG, our results indicate the necessity to reconsider the advantages of complete revascularization.

Does the completeness of revascularization affect early survival after coronary artery bypass grafting in elderly patients?

OBJECTIVE: Usefulness and risks of incomplete versus complete revascularization are still matters of ongoing discussions. Because an increasing number of elderly patients are undergoing coronary artery bypass grafting (CABG), the question arises whether a less extensive surgical approach is more prudent than complete revascularization. METHODS: Of 6531 patients undergoing isolated CABG, 859 were 75 and older at the time of operation. Mean age of the 859 patients was 77+/-2.7 years (median: 76 years); 65% were men. Follow-up enquiry by questionnaire was performed at the 180th postoperative day with a completeness of 95.6%. Assessment of the impact of incomplete revascularization utilized both multivariable analysis and propensity score matching to account for selection factors. RESULTS: Incomplete revascularization was performed in 133 patients (16%). The most common reasons for incomplete revascularization were small vessels (55%) and massive calcification (32%). Mortality until 180 days after CABG was higher (n=32; 24%) after incomplete than after complete revascularization (n=105; 15%; P=0.005). By logistic multivariable regression, incomplete revascularization was identified as an independent risk factor for death (Odds ratio, 1.8; P=0.015). By time-related analysis, incomplete revascularization predominantly affected the early period after CABG (P=0.001). Aortic cross clamping time was only slightly shorter for the group with incomplete (59+/-27 min (median: 55 min) vs. 63+/-26 min (median: 58 min); P=0.1). CONCLUSIONS: Incomplete revascularization increases the early risk of death after CABG in patients aged 75 years and older. The potential compensating benefit of the shorter aortic cross clamping time does not outweigh the advantages of complete revascularization. Thus, in the era of high-volume interventional approaches and minimally invasive techniques, the advantages of complete revascularization need to be considered.

Target, application, and interpretation of scores and alternative methods for risk assessment in cardiac surgery.

BACKGROUND: The more popular the use of different methods for risk adjustment becomes, the more often data are applied without any regard about the primary target and/or about important assumptions. Furthermore, risk adjustment is no longer restricted for quality assurance purposes, but became a "tool" of health policy. Few working groups currently use risk adjustment for the development of new therapeutic concepts. The aim of our study is to clarify possibilities and limitations of popular risk adjustment methods. PATIENTS AND METHODS: 4985 Patients underwent isolated CABG. Statistics was performed by calculating descriptive statistics, Parsonnet, and Higginsscores. Furthermore, the parametric, time-adjusted hazard function by Blackstone was used. RESULTS: Descriptive statistics allows intra-, and interinstitutional comparisons of single items to identify "outlying" results. Risk scores aim to predict preoperatively the risk category of the patient who undergoes cardiac surgery. However, since different scores are based on a score-specific combination of variables, and different definitions of the investigation interval, different results may occur, when different scores are calculated for a single patient. However, the use for example, of scores in patient groups allows description of changing risk structures. Most of the scores derive from univariate analyses and monophasic functions. However, survival curves are predominantly multiphasic and require a consideration of the time-dependency of "risk factors". DISCUSSION: An increasing number of patients with severe comorbidity undergoes cardiac surgery. To evaluate reliably present and futurous therapeutic options, risk adjustment is necessary. Since various tools for risk-adjustment are available, a serious discussion about reliability and application is necessary.

The meaning of early mortality after CABG.

OBJECTIVE: Investigations of early mortality after coronary artery bypass grafting (CABG) are predominantly based on 30-day mortality or hospital mortality. The advantages, disadvantages, and usefulness of hospital mortality and 30-day mortality analyses to investigate the early risk after CABG are evaluated. METHODS: A total of 4985 patients underwent isolated CABG from June 1988 to June 1997. A follow-up was performed 180 days after CABG (response rate: 98.6%). RESULTS: The mean hospital stay was 13.5+/-9.6 days, the range was 0 to 142 days (25% quartile, 9 days; median, 12 days; 75% quartile, 15 days). The hospital mortality was 5.3%. The 30-day mortality was 5.6%. The non-parametric Kaplan-Meier curve of the time interval 0-180 days postoperatively proves the persistence of the still decreasing behaviour of the survival curve beyond the 30th day until about the 60th postoperative day. Stratified by era of operation, the 'early phase' after CABG seems to be prolonged beyond 30 days at least for the more recent operation era since 1991. Risk stratification proves that the higher the risk group, the more the early phase tends towards a prolongation. CONCLUSIONS: The hospital mortality reflects institutional habits concerning postoperative patient care. Therefore, a systematic underestimation of early mortality is likely. In contrast to hospital stay, the evaluation of 30-day mortality requires a follow-up procedure but allows interinstitutional comparisons. Nevertheless, 30-day mortality systematically underestimates the early risk, at least in the more recent CABG period. So, a standardized evaluation of a longer time period (p.e. 180 days) is recommended.

Influence of follow-up response on risk-factor analysis.

BACKGROUND: Long-term analyses after coronary artery bypass grafting (CABG) are used to investigate therapeutical options and factors influencing the natural course of ischemic heart disease. In general, long-term studies require a follow-up. Dependent on the interval between the intervention and the follow-up procedure a certain amount of patients is lost to follow-up. The aim of the present study was to examine the influence of incomplete follow-up on conclusions regarding the postoperative patient outcome. For the investigation, the same statistical methods were applied to the data accumulated by the 70% and by the 90% responses. METHODS: 2012 patients underwent isolated CABG between June 1988 and December 1992. For data acquisition, tools of the HVMD (Heidelberger Verein für multizentrische Datenanalyse e.V.) were used. Analyses were performed using tools of SAS (Statistical Analysis Systems, Inc.). The parametric, time-adjusted hazard function method was employed. A first follow-up questionnaire, was distributed six months after operation with a 97.8% response. In February 1997 the same questionnaire was sent to patients and their general practioners. The primary response to that was 68.9% (approximately 70%). Then another mailing of the same questionnaire and phone calls to patients and their home doctors raised the response to 93.7% (approximately 90%). RESULTS: The mean follow-up was 1378 days in the group with 70% response and 1682 days in the group with 90% response. The parametric, time-adjusted hazard function showed a very similar pattern of factors in the early phase of both groups. In the 90% response group, the intermediate phase reached a higher relative influence than in the 70% response group. The relative influence of the late phase showed an inverse pattern. In the multivariate analysis most of the variables which had been identified by the 70% response model reappeared in the 90% response model. However, there were some potentially important and interesting differences. CONCLUSIONS: The results indicate the necessity to carefully consider the acceptance of incomplete follow-up for differentiated risk adjustment.

Successful revascularisation for unstable angina of a patient with asymptomatic bilateral internal carotid occlusion, 70% stenoses of the external carotid arteries, and other circulation disturbances.

Nowadays, advanced surgical and anaesthesiological techniques of coronary artery bypass grafting minimize the risk of severe complications in patients with advanced arteriosclerotic cerebrovascular disease. Nevertheless, in case of highly compromised cerebrovascular status, the decision whether to undertake coronary artery bypass grafting or not requires special patient-related consideration. A severe, unstable angina made it necessary to perform coronary bypass grafting in a patient with bilateral internal carotid occlusion, a bilateral mid-stage stenosis of both external carotid arteries, a diminished flow within the right vertebral artery, and a subsequently impaired intracranial blood flow. Intraoperatively, besides the usual hemodynamic measurements, laser-Doppler flow probes were placed on the left and right upper temple to monitor relative changes of the cerebral blood supply. Using an individual perioperative management, the patient experienced a normal postoperative course and was discharged in good condition.

[Internal quality assurance or Hawthorne effect?]. / Interne Qualitätssicherung oder Hawthorne-Effekt?

The tendency of study participation per se to affect outcome is described by the term Hawthorne effect. This process defines the first step for internal quality assurance. However, whenever an attempt is made to describe the effects of quality assurance in more detail specific mathematical tools are required, including a database system that allows the calculation of clinical profiles, problem profiles, time-related variance of variables, univariate and multivariate statistics, calculation of scores and application of the hazard function. However, it has to be considered that any mathematical model is a way to present a hypothesis and not a proof. Whenever a proof is required, one should not ask for internal quality assurance, but design a randomized study.

[Quality assurance in heart surgery: 8 years experience with a "feedback-control" system in Heidelberg]. / Qualitätssicherung in der Herzchirurgie: Acht Jahre Erfahrung mit einem "Feedback-control"-System in Heidelberg.

An important aspect of quality assurance in cardiac surgery covers the epidemiological analysis of patient data. After an 8 year period of clinical experience with quality assurance, we summarize and evaluate current concepts and actual experiences regarding a special type of database application and organisation ("feedback-control-system") for quality assurance. It had been developed to meet and solve the problems related to the data acquisition process, that are typically present in the clinical routine of quality assurance. In 1988 the "feedback-control-system" was designed and implemented in the Department of Cardiac Surgery at Heidelberg University. Since then it had been continuously improved and adapted to satisfy current needs in cardiac surgery. More than 1500 items are now recorded routinely per patient. At present, detailed information of more than 10,000 patients is available for the specific methods of analysis in the field of quality assurance. The basic concept included 1. the integration of the data acquisition in the daily clinical routine, 2. the evaluation and improvement of collected data material by means of "output-functions", that require previously recorded reliable data (that is automatically computer generated operation reports, letters, statistics, accounting etc.), and 3. to ensure that the medical and non-medical staff members participate in the advantages and the responsibilities of the data-base system for quality assurance. Analyses of perioperative risks and results, early discovery of trends, identification of special subpopulations receiving special types of treatment in cardiac surgery etc. have now become a regularly performed tool in clinical routine. This includes the availability of "problem profiles", "trend analysis", the use of simple concluding statistics as well as the calculation of multivariable models. This internal quality assurance is completed by "multicentric" comparisons with further hospitals already using the same data-base system (external quality assurance). Within 8 years, the feedback-control-system has become a reliable and valuable tool for quality assurance in daily routine. The high acceptance of the database system is related to the advantages it provides for every participant. We conclude that the concept of data evaluation and improvement by means of "output functions" and "integration of data acquisition in clinical routines" has proved to be efficient in everyday practice. The sensitivity and specifity to such a feedback controlled system as a tool for measuring surgical quality, however, still remains a matter requiring further research.

Continuous measurement of porcine renal cortex microcirculation with enhanced thermal diffusion technology.

Continuous monitoring of renal cortical blood flow (RCBF) in the perioperative setting of aortic or renal vascular surgery could facilitate the early detection of vascular complications, possibly resulting in a reduction of postoperative renal failure. A new prototype system for measurement of parenchymous organ perfusion based on the principle of thermal diffusion ("TD"-Thermal Diffusion Electrode, Thermal Technologies Inc., Cambridge, MA, USA) was used for RCBF measurements in the outer cortex of the porcine kidney. We validated the sensitivity of the device to detect renal blood flow impairment, comparing TD flow data with renal artery blood flow values (RABF), measured by ultrasonic flow probes. The hypothesis was tested that acute disturbances of RCBF, induced by a variable degree of renal artery stenosis, can be immediately detected and continuously monitored by TD measurements in the porcine renal cortex. Mean baseline RCBF measured by TD electrodes was 68.1 +/- 25.0 ml/100 g/min. Mean baseline RABF was 102.1 +/- 26.6 ml/min. Controlled induction of a variable degree of renal arterial occlusion by implanted vascular balloon occluders was always followed by an immediate and proportional decline of RCBF, as measured by TD. Flow data obtained with both methods were significantly correlated by linear regression (r=.82, r2=.68; P < 0.0001). Dynamic changes of RABF in the time course of renal artery partial/total occlusion and arterial flow release could be continuously followed by detection of corresponding flow changes of RCBF. We conclude that the TD system investigated in the current study allows a continuous and sensitive determination of porcine renal cortex perfusion. A clinical evaluation of the method, e.g., in the perioperative setting of aortic or renal transplantation surgery, now appears to be justified.