Considering milk price volatility for investment decisions on the farm level after European milk quota abolition.

After the abolition of the milk quota in the European Union, milk price volatility is expected to increase because of the liberalized market conditions. At the same time, investment appraisal methods have not been updated to capture the increased uncertainty. Therefore, the objective of this paper is to assess the effect of changing price volatility due to quota abolition on investment decisions at the dairy farm level. To contribute to the objective and to approximate milk price volatility after the European milk quota abolition, the risk-adjusted discount rate for risk-averse dairy farmers is derived based on the milk price volatility of a milk price series from New Zealand. New Zealand dairy farmers have faced liberalized market conditions for more than 3 decades. Afterward, the risk-adjusted discount rate is applied to appraise milking technology investments for an average German dairy farmer. The results show that it is still more reasonable to invest in a parlor system than an automated milking system, although the net present value of the parlor system investment varies between €191,723 for risk-neutral dairy farmers and €100,094 for modestly risk-averse dairy farmers. For the automated milking system investment, the same calculations lead to €132,702 for risk-neutral dairy farmers and €31,635 for risk-averse dairy farmers. According to higher levels of milk price volatility after milk quota abolition, the reduction of the expected utility of the underlying investment decision for modest risk-averse dairy farmers is almost similar to a milk price decrease of 5% for risk-neutral dairy farmers. Therefore, the findings urge finance providers and extension services to consider the change of increasing milk price volatility after dairy quota abolition when giving dairy farmers financial advice. The risk-adjusted discount rate is a flexible tool to do so.

Prediction of the site and severity of obstruction in hypertrophic cardiomyopathy by color flow mapping and continuous wave Doppler echocardiography.

OBJECTIVE: We investigated whether the site and severity of an obstruction in hypertrophic cardiomyopathy can be accurately predicted by the combined use of color-coded and continuous wave Doppler echocardiography. BACKGROUND: Predicting the site of obstruction by end-systolic cavity shape is not reliable. Therefore, hemodynamic localization of the obstruction is required before surgery is performed. Such localization should be possible with color flow imaging, which provides two-dimensional velocity mapping reflecting the distribution of pressures within the left ventricle. Discrepancies in assessment of the pressure gradient by Doppler echocardiography and cardiac catheterization (which are usually not performed simultaneously) may be due to spontaneous variation of the dynamic obstruction in addition to technical factors related to both methods. METHODS: Twenty consecutive patients with hypertrophic cardiomyopathy were examined 1 day before transseptal left heart catheterization. The obstruction site was defined by color flow mapping. The pressure gradient was determined by continuous wave Doppler echocardiography. Measurements were also performed simultaneously in 10 patients during cardiac catheterization. RESULTS: Midventricular obstruction was correctly identified in 4 patients and subvalvular obstruction in 15 patients. One patient had no obstruction at rest. Invasively and noninvasively determined pressure gradients correlated well (r = 0.89, SEE = 16.3 mm Hg). Multiple single-beat analysis in 10 patients, also simultaneously examined with Doppler echocardiography and catheterization, yielded an excellent correlation (r = 0.97, SEE = 13.1 mm Hg). Comparing the simultaneous (r = 0.96, SEE = 12.5 mm Hg) and nonsimultaneous (r = 0.81, SEE = 23.8 mm Hg) recordings in these patients, we found that the spontaneous variation of the dynamic obstruction mainly accounted for discrepancies (p less than 0.05). CONCLUSION: The combined use of color-coded and continuous wave Doppler echocardiography provides the relevant hemodynamic information required for decision-making in patients with hypertrophic cardiomyopathy who are considered for transaortic myectomy.

Guidelines for management of left-sided prosthetic valve thrombosis: a role for thrombolytic therapy. Consensus Conference on Prosthetic Valve Thrombosis.

OBJECTIVES: We sought to form a consensus recommendation for management of prosthetic valve thrombosis (PVT) from previous case and uncontrolled reports from a consensus of international specialists. BACKGROUND: PVT and thromboembolism relate to inadequate anticoagulation and valve type and location. PVT is suspected by history (dyspnea) and auscultation (muffled valve sounds or new murmurs) and confirmed by Doppler echocardiography showing a marked valve gradient. METHODS: A consensus conference was held to recommend management of left-sided PVT. RESULTS: Transesophageal Doppler echocardiography is used to visualize abnormal leaflet motion and the size, location and mobility of thrombus. Thrombolysis is used for high risk surgical candidates with left-sided PVT (New York Heart Association functional class III or IV) because cerebral thromboembolism may occur in 12% of patients. Duration of thrombolysis depends on resolution of pressure gradients and valve areas to near normal by Doppler echocardiography performed every few hours. Lysis is stopped after 72 or 24 h if there is no hemodynamic improvement (operation indicated). Heparin infusion with frequent measurement of activated partial thromboplastin time (aPTT) begins when aPTT is more than twice control levels and can be converted to warfarin (international normalized ratio [INR] 2.5 to 3.5) plus aspirin (81 to 100 mg/day). Patients in functional class I or II have lower surgical mortality, and those with large immobile thrombi on the prosthetic valve or left atrium have responded to endogenous lysis with combined subcutaneous heparin every 12 h (aPTT 55 to 80 s) plus warfarin (INR 2.5 to 3.5) for 1 to 6 months. Operation is advised for nonresponders or patients with mobile thrombi. CONCLUSIONS: Thrombolysis, followed by heparin, warfarin and aspirin, is advised for high risk surgical candidates with left-sided PVT.

Expression of calcium channel subunits in the normal and diseased human myocardium.

We investigated the expression of alpha1 and beta subunits of the L-type Ca2+ channel on the protein level in cardiac preparations from normal human heart ventricles and from the hypertrophied septum of patients with hypertrophic obstructive cardiomyopathy (HOCM). 1,4-Dihydropyridine (DHP) binding and immunorecognition by polyclonal antibodies directed against the C-terminal amino acid sequences of the beta2 and beta3 subunits were used for detection and quantification of alpha1, beta2, and beta3 subunits. Bmax of high-affinity DHP binding was 35 +/- 2 fmol/mg protein in HOCM and 20 +/- 2 fmol/mg protein in normal human hearts (P<0.05). In rabbit hearts the anti-beta2 subunit antibody immunoprecipitated 80% of the total amount of DHP-labeled Ca2+ channels present in the assay. Under identical experimental conditions 25% of labeled Ca2+ channels were recovered in the immunoprecipitates of both normal and HOCM ventricles. A similar partial immunoprecipitation was observed in pig hearts. Immunoblot analysis demonstrated that the beta2 subunit was associated with the DHP receptor/Ca2+ channel in cardiac muscle of rabbit, pig, and human heart. In neither of these purified cardiac Ca2+ channels was the beta3 subunit isoform detected. Our results suggest that both alpha1 and beta2 subunit expression is upregulated in HOCM in a coordinate manner.

Expression of atrial myosin light chains but not alpha-myosin heavy chains is correlated in vivo with increased ventricular function in patients with hypertrophic obstructive cardiomyopathy.

The adult rodent heart adapts to increased work load by reexpression of its fetal genes, for example, beta-myosin heavy chain (MHC), in order to improve contractile function. However, the human ventricle regulates contractility by expression of atrial essential myosin light chain (ALC-1) rather than beta-MHC. We evaluated the impact of both mechanisms in patients with hypertrophic cardiomyopathy. MHC isoform expression was quantified at the mRNA and protein levels by reverse transcriptase polymerase chain reaction and immunoblotting, respectively. Although alpha-MHC mRNA was detected in control and hypertrophied human ventricular tissue, alpha-MHC protein was not observed. Similarly, we investigated the expression of ALC-1 by two-dimensional polyacrylamide gel electrophoresis and the clinical and hemodynamic parameters of the patients with hypertrophic cardiomyopathy. We found a significant positive correlation between ALC-1 protein expression and dP/dtmax in the hypertrophied human ventricle in vivo. Correlations between dP/dtmax and expression of protein for the ryanodine receptor and L-type Ca2+ channel were excluded. Our data suggest that reexpression of ALC-1 improves the contractile state of the adult human heart. We propose that two evolutionarily divergent compensatory mechanisms for increased work demand exist in the mammalian heart: MHC regulation in rodents and essential MLC regulation, of cardiac contractility, in humans.

Lower intensity anticoagulation therapy results in lower complication rates with the St. Jude Medical prosthesis.

Six hundred consecutive patients were operated on between September 1978 and October 1982 for isolated aortic (n = 298), mitral (n = 215), or multiple valve replacement (n = 87) with the St. Jude Medical bileaflet prosthesis. Mean age of the 303 female and 297 male patients was 50.7 +/- 9.6 (range 12 to 83) years. All patients were followed up prospectively; follow-up was complete and averaged 122.2 +/- 1.1 months for operative survivors. Total follow-up for aortic patients was 2904.1 patient-years, for mitral replacement 1859.5 patient-years, and for multiple valve replacement 736 patient-years. When the prothrombin times measured with different thromboplastins were converted into an international normalized ratio, four patient groups could be separated; that is, the groups comprised patients whose anticoagulation was maintained during the follow-up within an international normalized ratio corridor of 4.0 to 6.0, 3.0 to 4.5, 2.5 to 3.5, or 1.75 to 2.75. Less intensive anticoagulation in terms of the international normalized ratio values caused only a mild increase in the incidence of thromboembolic complications but a highly significant decrease in the rate of bleeding. Severe bleeding complications in the aortic valve group were highest with an international normalized ratio of 4.0 to 6.0 (1.15 per patient-year) and lowest with an international normalized ratio of 1.75 to 2.75 (0.24 per patient-year). The same held true for patients with single St. Jude Medical mitral valve replacement (2.09 per patient-year versus 0.72 per patient-year) and multiple valve replacements (4.45 per patient-year versus 1.20 per patient-year). These results suggest that the generally recommended international normalized ratio of 3.0 to 4.5 may be too high for patients with St. Jude Medical aortic valve replacement and also for patients with St. Jude Medical prostheses in the mitral position if, with respect to the thromboembolic hazard, there is not a predominating patient-related comorbidity. A large multicenter prospective randomized study is therefore proposed to establish the safe international normalized ratio levels accompanied by the lowest complication rates for both bleeding and thromboembolic events after St. Jude Medical prosthesis implantation (German experience with low intensity anticoagulation study).

Prognosis of patients with hypertrophic obstructive cardiomyopathy after transaortic myectomy. Late results up to twenty-five years.

A complete clinical study was performed for 364 patients with hypertrophic obstructive cardiomyopathy who were operated on in the years 1963 to 1991 (217 male, 146 female, mean age 40 years, range 5 months to 76 years). Transaortic subvalvular myectomy was performed in 272 patients (hospital mortality 2.9%), and 92 patients needed additional cardiac procedures simultaneously (hospital mortality 10.9%). A complete follow-up study (100%) included 346 patients who survived the operation. The shortest follow-up time was 2 months and the longest 25.2 years (mean 8.2 years). Most of the patients improved clinically by one to three classes (New York Heart Association). During the observation period 38 patients (10.4%) died. The death of 17 patients was closely related to the original disease (4.9%). Other causes, unrelated to hypertrophic obstructive cardiomyopathy, were responsible for the death of 21 patients (5.8%). In consideration of these data, the yearly total death rate was 2.2%; in close relation to hypertrophic obstructive cardiomyopathy it was about 0.6%. The cumulative survivals were 88% after 10 years and 72% after 20 years. In our long-term clinical experience it is increasingly evident, despite the restrictions of a retrospective study, that patients with symptomatic hypertrophic obstructive cardiomyopathy and failing medical therapy benefit from transthoracic subvalvular myectomy.

The surgical treatment of ventricular tachycardias. Simple aneurysmectomy versus electrophysiologically guided procedures.

Between 1971 and 1982, 41 patients were operated upon for recurrent sustained ventricular tachycardia. All but three had severe coronary artery disease with a history of myocardial infarction. In 10 patients (Group I) simple aneurysmectomy with or without aorta-coronary bypass grafting was done. Thirty-one patients (Group II) had an electrophysiologically guided procedure, mainly partial or complete encircling endocardial ventriculotomy (EEV) at the earliest source of electrical activity during ventricular tachycardia. The results in the two groups indicate a clear superiority of electrophysiologically guided procedures over a simple aneurysmectomy regarding early and late disappearance of tachycardiac rhythm problems (p = 0.01); the differences between the two groups in hospital mortality (p = 0.43) and long-term survival are not significant. We compared our data with results in 160 cases of simple aneurysmectomy and 224 cases of electrophysiologically guided operations recently published in the literature. This comparison confirms the higher efficiency of mapping-guided procedures in eradicating ventricular tachycardias. The improvements in hospital and long-term survival, again, are not significant.

Tracheal and alveolar gas composition during low-frequency positive pressure ventilation with extracorporeal CO2-removal (LFPPV-ECCO2R).

Tracheal and alveolar gas composition was studied by mass spectrometry in a patient with severe ARDS treated by low frequency positive pressure ventilation/extracorporeal CO2-removal (LFPPV-ECCO2R). Measured alveolar gas concentrations were compared with values derived from standard respiratory equations. As a result we found that during LFPPV-ECCO2R with a constant endotracheal O2-flow, alveolar gas composition cannot be predicted reliably from standard equations. The reasons for this finding are discussed. We conclude that monitoring of alveolar gas composition by mass spectrometry is of great value during LFPPV-ECCO2R if PAO2, P(A-a)O2 and Qva/Qt are to be determined correctly.

Extracorporeal CO2-removal with a heparin coated artificial lung.

Treatment of severe acute respiratory failure with extracorporeal gas exchange necessitating near complete systemic anticoagulation requires a delicate balance to be maintained between disseminated intravascular coagulation and hemorrhagic complications. The present study describes our first experience using a heparin coated extracorporeal artificial lung and circuitry during clinical extracorporeal CO2 removal. In spite of a partial thromboplastin time and activated clotting time within or close to the normal range, neither laboratory evidence for disseminated intravascular coagulation induced by the extracorporeal circuit nor thrombi in the pulmonary vasculature were found. Scanning electron microscopy of the heparin coated hollow fiber gas exchanger demonstrated only minor deposits on the surface. Use of a heparin coated artificial lung may enhance the margin of safety of extracorporeal gas exchange and ultimately broaden its indications.

Hypertrophic cardiomyopathy: a desensitized cardiac beta-adrenergic system in the presence of normal plasma catecholamine concentrations.

Only few data are available concerning the biochemical and functional state of the beta-adrenergic system in hypertrophied human myocardium. The present study was to investigate the myocardial beta-adrenergic signal transduction system in hypertrophic obstructive cardiomyopathy (HOCM). Thin myocardial strips were prepared from surgically excised, septal myocardium from 7 patients with HOCM and their force of contraction was measured in vitro. The positive inotropic effects of calcium and dihydro-ouabain, both acting independently of beta-adrenoceptors and cAMP, were similar in these preparations to those, previously published, seen with nonfailing myocardium. In contrast, the beta-adrenoceptor agonist isoprenaline and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) had reduced positive inotropic effects. Their EC50-values were about 10 fold higher than the respective EC50-values published for nonfailing myocardium. The positive inotropic potencies of isoprenaline and IBMX were reduced in HOCM by as much as they were in the additionally investigated myocardium from 6 patients with severe mitral regurgitation (MR, NYHA III). In order to clarify whether the functional alterations are related to changes in the beta-adrenoceptors, beta-adrenoceptor density and beta 1: beta 2-adrenoceptor subtype distribution were determined in the same myocardium using 125I-Iodocyanopindolol saturation binding. Myocardial beta-adrenoceptor density was reduced to 68% in HOCM and to 56% in MR compared to nonfailing myocardium controls (NF: 64.8 +/- 6.5 fmol/mg protein). In HOCM, this reduction was due to a selective down regulation of beta 1-adrenoceptors (24.9 +/- 3.7 fmol/mg protein vs NF: 46.4 +/- 6.8 fmol/mg protein, P < 0.05), whereas beta 2-adrenoceptor density was unchanged (19.0 +/- 1.9 fmol/mg protein vs NF: 18.4 +/- 3.3 fmol/mg protein, n.s.). In MR both beta-adrenoceptor subtypes were reduced (beta 1: 26.9 +/- 1.4 fmol/mg protein, beta 2: 9.6 +/- 1.7 fmol/mg protein; both P < 0.05 vs NF). Electrochemically determined plasma catecholamine levels were elevated in MR. However, plasma catecholamine levels were normal or slightly below normal in HOCM. In summary, myocardial beta-adrenoceptors are downregulated and their function is impaired in HOCM. This desensitization is not caused by a negative feedback regulation due to increased plasma catecholamines. The present results show that the desensitizations of the beta-adrenergic system associated with HOCM has characteristics that indicate a major deviation in its development from that of the beta-adrenergic desensitization previously described to occur in congestive heart failure.

The effect of chordal preservation on late outcome after mitral valve replacement: a randomized study.

Postoperative survival, hemodynamic status and exercise tolerance with or without posterior chordal preservation were compared in a case-limited prospective randomized manner in 100 patients who underwent isolated mitral valve replacement with size 29mm or 31mm St. Jude Medical prostheses. The preoperative clinical and hemodynamic parameters were comparable in the two groups. The mean follow up was 293.3 months for those with and 263.1 months for patients without chordal preservation. Right heart cardiac catheterization was performed in every patients at the end of the follow up period and it demonstrated significantly better results with than without chordal preservation (cardiac index 2.81 +/- 0.47 vs. 2.63 +/- 0.52, p < 0.05; pulmonary arterial pressure 30 +/- 11 mmHg vs. 37 +/- 13 mmHg at 30 Watts bicycle exercise, p < 0.01; end-diastolic volume index 75 +/- 22 vs. 86 +/- 38 ml/m2, p < 0.02; and maximum exercise tolerance 1.8 +/- 0.3 vs. 1.2 +/- 0.5 Watt/kg, p < 0.01). Actuarial freedom from complications was 78.1 +/- 4.2% with and 70.7 +/- 6.2% without chordal preservation (p < 0.02). In particular, patients with severe mitral regurgitation benefited from the preservation of the posterior mitral leaflet with its chordal and papillary structure (p < 0.001).

Stroke is not a contraindication for urgent valve replacement in acute infective endocarditis.

BACKGROUND AND AIM OF THE STUDY: A treatment dilemma arises when endocarditis is complicated by cerebral embolism. Secondary cerebral hemorrhagic complications may arise following suppression of coagulation during extracorporeal circulation. Extensive valvular vegetation is regarded as an indicator for urgent surgery. The study aim was to determine the relative risk of thromboembolic complications, and to analyze the prognostic influence of different treatment strategies following onset of these complications, in particular, secondary cerebral hemorrhagic events after urgent surgery. METHODS: Between 1978 and 1993, endocarditis was diagnosed in 288 consecutive patients. Patients treated before 1982 (6.9%) were analyzed retrospectively. The remaining patients (93.1%) were followed prospectively (mean 4.3+/-1.7 years). RESULTS: In 50 patients (17.4%), the clinical course was complicated by one embolism, and in 58 patients (20.2%) by recurrent embolisms. In total, 71% of all embolisms were cerebral events. The operated patients were categorized with regard to the time between recurrent thromboembolic events and cardiac surgery (<72 h, 3-8 days, and >8 days). The prognosis for patients operated within 72 h was significantly more favorable (p <0.0001) than for those treated medically. Patients undergoing cardiac surgery more than eight days after stroke, and those treated conservatively, had poor prognoses. CONCLUSION: When endocarditis is complicated by stroke, it is recommended that cardiac surgery be performed within 72 h of the cerebral embolism, when the risk of secondary cerebral hemorrhage appears to be low. Cranial computed tomography is obligatory immediately before surgery in order to identify patients with early reperfusion hemorrhages due to spontaneous fragmentation of the thrombus. In these patients, cardiac surgery must be postponed because of the high risk of severe cerebral bleeding during extensive perioperative anticoagulation, and is only justified in the case of an otherwise unfavorable prognosis.

Diagnostic and therapeutic considerations in acute, severe mitral regurgitation: experience in 42 consecutive patients entering the intensive care unit with pulmonary edema.

Forty-two consecutive patients received emergency treatment for acute mitral insufficiency causing pulmonary edema between 1984 and 1992. The underlying diagnoses were acute myocardial infarction (n = 21), acute bacterial endocarditis on the native mitral valve (n = 9), prosthetic endocarditis in the mitral position (n = 4), acute failure of a replacement valve (n = 5), blunt chest trauma (n = 1) and chordal rupture in Marfan's syndrome (n = 2). Dysfunction of the subvalvular apparatus was present in 24 patients, verified by transthoracic echocardiography in 18 (75%) and by transoesophageal echocardiography in all patients in whom this technique was used. There were four cases of outflow strut fracture of a Björk-Shiley mitral prosthesis; a reliable diagnosis was made by fluoroscopy in all patients. Bedside hemodynamic monitoring was found to be unreliable both for differential diagnosis and for the quantitative assessment of the degree of mitral insufficiency. The right ventricular filling pressure was normal in 32/39 patients (82%), and the pulmonary artery and pulmonary capillary pressures elevated in 37/39 (95%). Diagnostically important, high pulmonary capillary v-waves were documented in 13 patients (33%). The left ventricular impedance could be influenced with sodium nitroprussid combined in some cases with dobutamin, and the resultant decrease of the peripheral vascular resistance from 1480 +/- 222 to 702 +/- 86 dyn x sec x cm-5 was followed by a proportionate reduction in the transmitral regurgitant fraction. Three patients died prior to the intended emergency surgical intervention. Emergency surgery was completed in 21 patients with an early mortality of 23.8% (n = 5). Ten patients underwent elective surgery within, and another three later than one year from the onset of the acute symptoms with an early mortality of 7.7% (n = 1). Four patients are alive and clinically well with medical treatment alone.

Thrombosis of two St. Jude Medical prostheses in one patient after triple valve replacement. Case report and review of the literature.

Reports of experience with the St. Jude Medical (SJM) valve state that thrombosis of the prosthesis is a rare complication. In a 57-year-old woman, reoperation was necessary 12 months after triple valve replacement using SJM prostheses because of thrombosis of the valves in the tricuspid and aortic positions. Dysfunction of both mechanical valves was detected clinically by changing heart sounds and the appearance of murmurs. Echocardiography and cinefluoroscopy confirmed at least one fixed leaflet of the tricuspid prosthesis, but abnormalities of the aortic prosthesis could not be detected. At reoperation, the SJM prosthesis in the tricuspid position was almost completely thrombosed and was replaced by an Ionescu-Shiley bioprosthesis. A thrombotic formation at the hinge point of the SJM aortic prosthesis was removed. To our knowledge, this is the first report of a thrombotic complication of two SJM prostheses after triple valve replacement in one patient.

Hemodynamic findings in patients with left bundle branch block after myectomy in hypertrophic obstructive cardiomyopathy (HOCM)

To determine the hemodynamic effects of postoperative left bundle branch block (LBBB) in patients with hypertrophic obstructive cardiomyopathy (HOCM), we investigated 28 patients using Swan-Ganz pulmonary artery catheterization at rest and on exercise. Fourteen patients had postoperative LBBB (group A) and 14 had undisturbed intraventricular conduction (group B). All patients were examined by clinical investigation, electrocardiogram and bicycle ergometer exercise preoperatively and postoperatively (mean 6 months). Pulmonary artery pressure and pulmonary capillary wedge pressure were continuously measured, stroke volume index and cardiac index were obtained by the thermodilution method. All patients showed an improvement of their clinical symptoms (NYHA class: 2.8 +/- 0.45 before and 1.7 +/- 0.22 after operation) (P < 0.05). The postoperative exercise capacity (Watt) increased significantly (P < 0.05) in group A by 38% and in group B by 30%. The maximum mean pulmonary artery pressure on physical exercise decreased in group A from 40.7 +/- 9.1 to 32.5 +/- 8.7 mmHg and in group B from 42.8 +/- 12.4 to 32.4 +/- 9.2 mmHg (P < 0.05). The maximal stroke volume index and cardiac index improved significantly in 9 of 14 patients in each group. Thus, patients with HOCM and LBBB after myectomy have a marked improvement in postoperative hemodynamics, the results equaling those of patients with undisturbed intraventricular conduction.

Aprotinin counterbalances an increased risk of peri-operative hemorrhage in CABG patients pre-treated with Aspirin.

OBJECTIVE: As Aspirin (ASA) has proven efficacy in preventing patients with CAD from complications related to cardiovascular diseases, most patients scheduled for CABG are treated with ASA therapy. Consequently, impaired hemostasis is a problem in the management of CABG patients. Clinical studies have shown that Aprotinin can reduce bleeding and the use of blood products by 50% in patients both with and without pre-operative ASA therapy. Concerning the combined effect of peri-operative low-dose ASA therapy and intra-operative high-dose Aprotinin therapy, the gathering of additional and prospective data seemed to be necessary. METHODS: We conducted a double-blind two-centre randomised three-arm study in patients with elective primary CABG surgery. Three groups have been tested, comprising 119 patients in total (group A: ASA + Aprotinin, group B: placebo + Aprotinin, group C: placebo + placebo) to investigate a possible reduction of bleeding in Aprotinin treated patients. For all patients, thromboxane levels were used to identify ASA or placebo treatment. RESULTS: The post-operative blood loss is significantly reduced by 21% after Trasylol administration (B vs. C; P = 0.009). The unexpected result of this study has been that the pre-treatment with ASA led to a further reduction of 18% (A vs. C; P < 0.0001). The difference between the two Aprotinin groups (A and B) is significant (P = 0. 01) in favour of ASA pre-treatment. Myocardial infarction (MI) had been diagnosed at levels of 1.8% in total (2/113), 2.6% (1/38) in group B and 3.2% (1/31 ) in group C. An additional blinded evaluation of ECG, enzyme levels and clinical status revealed 'definite, probable and possible' MIs of 5% in group A, compared to 16% in group B and 13% in group C, thus providing no evidence for a higher risk of infarction by Aprotinin treatment. When comparing the ASA group to non-ASA pre-treatment, a strong trend towards a reduction in MI rate becomes obvious, from 15% to 5% in favour of the ASA pre-treatment (P = 0.08). Concerning other peri-operative complications, no statistical difference between the groups could be detected. CONCLUSIONS: A reduction in post-operative blood loss in primary elective CABG surgery with intra-operative Aprotinin treatment could be confirmed. A low-dose ASA treatment combined with a high-dose aprotinin administration during surgery not only neutralized a potentially higher risk of bleeding, but did in fact reduce the post-operative blood loss. The protective effect of ASA on peri-operative MI has been evident through a reduction of MI rate in ASA treated patients.

Effect of implantable cardioverter/defibrillator lead placement in the right ventricle on defibrillation energy requirements. A combined experimental and clinical study.

OBJECTIVES: The effect of implantable cardioverter/defibrillator (ICD) lead placement in the right ventricle (RV) on defibrillation efficacy has not been thoroughly investigated. Therefore, the goal of this combined experimental and clinical study was to evaluate the effect of a septal and a non-septal position of the right ventricular endocardial spring lead on defibrillation energy. METHODS: In 12 isoflurane-anaesthetized swine and subsequently in 8 patients who underwent ICD implantation, two different positions of the distal spring lead in the RV were investigated in randomized order: non-septal position (free wall of the RV) and septal position (interventricular septum). For each position, separate 50% probability determinations of energy (E50), peak voltage (V50) and peak current (A50) were calculated using the three reversal up/down defibrillation procedure. The E50, V50, A50 and impedance (I) were averaged and compared using the two-sided t-test for paired samples. RESULTS: Both the experimental study and the clinical study demonstrated that placing the distal defibrillation lead near to the septum rather than near to the ventricular free wall resulted both in the swine and in the patients in significantly lower E50-31.6%/ - 37.1%, V50-16.1%/-20.9% and A50 -10.0%/ - 24.2%, respectively. Defibrillation impedances were significantly reduced only in the experimental study. CONCLUSIONS: Defibrillation efficacy depends on the position of the distal spring electrode in the RV. A septal position significantly reduces the energy requirements compared to a non-septal position. The decrease in energy requirements might be explained by an increase in current flow through the septum and the posterolateral wall of the left ventricle. reserved

Energy demand of cardioplegically perfused human hearts.

Human adult hearts with aortic valve disease (n = 20) and hypertrophic obstructive cardiomyopathy (n = 1) were perfused intraoperatively with cold histidine buffered Bretschneider solution. During a seven minute cardioplegic perfusion the temperature level, the electrolyte level, the resistance of the left (LCA) and right coronary artery (RCA), and myocardial O2 consumption were analysed. Equilibration of K+ was terminated shortly after the start of the perfusion while Na+ equilibration lasted for about 5 minutes. Resistance of RCA did not change significantly, but that of the LCA was diminished significantly (p less than 0.025) within the perfusion period indicating a delayed washout of calcium from the extracellular space. Myocardial O2 consumption was reduced from 2.71 ml/min (1. minute) to 1.51 ml/min (4. minute) to 0.93 ml/min (7. minute) although the temperature had reached a low level after 3 minutes. The difference between 4. to 7. minutes is significant (p less than 0.001). By our results it is concluded that in adult hearts high-volume cardioplegic perfusion at a flow rate of 1 ml/min X gm at a perfusion pressure of 40 to 50 mmHg should be performed for at least 6 to 7 minutes to achieve a sufficient intra-ischemic myocardial protection.

Intermittent aortic cross-clamping for coronary artery bypass grafting: a review of a safe, fast, simple, and successful technique.

Since the very beginning of coronary artery bypass grafting, the search for optimal myocardial protection has fascinated both clinicians and basic researchers. This retrospective review of a large patient cohort aims to display the advantages of one of the protective procedures, namely simple, intermittent aortic cross-clamping (IAC). Thus, this review aims to significantly contribute to daily bypass surgery. This review reports on coronary patients who were all operated on in international centers using IAC such that this review presents the state of the art on IAC. In addition, this review reports on the usage of IAC for more than 2 decades in the clinic of Dr. Bircks, Duesseldorf (DE) and the clinics of his former students. A meta-analysis of published data of international centers summarizes 7 837 operated patients with a total mortality of 123 (=1.6%). This excellent outcome compares well to the results of the Bircks'-related centers, where between 1978 and 2001, a total of 41 573 patients were revascularized with the help of IAC according to the original protocol. The total mortality was 778 (1.9%), with the lowest mortality rate (1.2%) in the largest center (Bad Oeynhausen, DE). According to the presented experience, IAC for coronary revascularization proves to be a highly effective method for myocardial protection; it has convincingly proven to be simple, safe and cost-efficient.