PPS-PEG surface coating to reduce thrombogenicity of small diameter ePTFE vascular grafts.

AIMS: Patency failure of small vascular synthetic grafts is still a major problem for coronary and peripheral revascularization. Thus, three new surface coatings of small synthetic grafts were tested in an acute pig model to evaluate their thrombogenicity (extracorporeal arterio-venous shunt) and in a chronic rat model to evaluate the tissue reaction they induced (subcutaneous implantation). METHODS: In five domestic pigs (25-30 kg) an extracorporeal femoro-femoral arterio-venous shunt model was used. The study protocol included first a non-heparinized perfusion sequence followed by graft perfusion after 10,000 UI iv heparin. Grafts were perfused for 3 and 9 minutes. The following coatings were tested on ePTFE grafts: poly-propylene sulphide (PPS)--poly-ethylene glycol (PEG) (wet and dry applications) as well as carbon. Two sets of control were used, one dry and one wet (vehicle only). After perfusion grafts were examined by scanning electron microscopy for semi-quantitative assessment (score 0-3) of cellular and microthrombi deposition. To assess tissue compatibility, pieces of each material were implanted subcutaneously in 16 Wistar rats. At 2, 4, 8, 12 weeks four animals each were sacrificed for semi-quantitative (score 0-3) histologic evaluation of tissue reaction. RESULTS: In the pig model, cellular deposition and microthrombi formation increased over time. In non- heparinized animals, the coatings did not improve the surface characteristics, since they did not prevent microthrombi formation and cellular deposition. In heparinized animals, thrombogenicity was lowest in coated grafts,especially in PPS -PEG dry (p<0.05), and highest in controls. Cell deposition was lowest in PPS-PEG dry, but this difference was not statistically significant vs.controls. In the rat model,no significant differences of the tissue reaction could be shown between materials. CONCLUSION: While all coatings failed to add any benefit for lowering tissue reaction, surface coating with PPS -PEG (dry application) reduced thrombogenicity significantly (in heparinized animals) and thus appears to be promising for improving graft patency of small synthetic vascular prostheses.

Homocysteine and B vitamins.

Homocysteine (tHcy) is an intermediate sulfur-containing amino acid which acts as a methyl group donor for methionine metabolism. Increased serum concentrations (=hyperhomocysteinemia, >10 micromol/l) have been associated with an increased cardiovascular risk. Homocystinuria, an infrequent genetic disease usually due to lack of cystathione beta-synthase, has been found with severely elevated serum homocysteine values (>150 micromol/l). Functional gene polymorphisms of key enzymes (e.g., N5,N10-methylene-tetrahydrofolate reductase) and dietary B-vitamin deficiencies in the elderly are, however, frequent in the 'Western' population. Hyperhomocysteinemia has been associated with other vascular effects such as atherothrombosis and endothelial dysfunction due to its auto-oxidative potential, thereby increasing the production of reactive oxygen species. Other effects may involve neurodegenerative diseases such as Alzheimer or dementia praecox of the elderly. Therapeutic interventions lowering tHcy may therefore offer novel tools for the prevention and treatment of atherosclerosis. B-vitamin supplementation (folic acid=vitamin B9, vitamin B6 and vitamin B12) is an efficient and safe tHcy-lowering therapy, decreases tHcy by 30%-50% and has been shown to lower cardiovascular morbidity and mortality. Furthermore, folic acid supplementation has been shown to reduce or even almost eliminate neurotubular birth defects (spina bifida) and to markedly decrease the rate of megaloblastic anemia. Thus, fortification of flour with folic acid in the USA was advocated several years ago in order to prevent these entities.

Do beta-adrenergic blocking agents increase coronary flow reserve?

BACKGROUND: Beta-adrenergic blocking agents are the cornerstone in the treatment of coronary artery disease (CAD). The exact pathophysiologic mechanism is not clear but depends largely on the oxygen-sparing effect of the drug. Thus, the effect of metoprolol on coronary flow reserve and coronary flow velocity reserve (CFVR) was determined in patients with CAD. METHODS: Coronary blood flow velocity was measured with the Doppler flow wire in 23 patients (age: 56 +/- 10) undergoing percutaneous transluminal coronary angioplasty for therapeutic reasons. Measurements were carried out at rest, after 1-min vessel occlusion (postischemic CFVR) as well as after intracoronary adenosine (pharmacologic CFVR) before and after 5 mg intravenous metoprolol. In a subgroup (n = 15), absolute flow was measured from coronary flow velocity multiplied by coronary cross-sectional area. RESULTS: Rate-pressure product decreased after metoprolol from 9.1 to 8.0 x 10(3) mm Hg/min (p < 0.001). Pharmacologic CFVR was 2.1 at rest and increased after metoprolol to 2.7 (p = 0.002). Likewise, postischemic CFVR increased from 2.6 to 3.3 (p < 0.001). Postischemic CFVR was significantly higher than pharmacologic CFVR before as well as after metoprolol. Coronary vascular resistance decreased after metoprolol from 3.4 +/- 2.0 to 2.3 +/- 0.7 mm Hg x s/cm (p < 0.02). CONCLUSIONS: The following conclusions were drawn from this study. Metoprolol is associated with a significant increase in postischemic and pharmacologic CFVR. However, postischemic CFVR is significantly higher than pharmacologic CFVR. The increase in CFVR by metoprolol can be explained by a reduction in vascular resistance. The increase in CFVR (= increased supply) and the reduction in oxygen consumption (= decreased demand) after metoprolol explain the beneficial effect of this beta-blocker in patients with CAD.

Pathological apoptosis by xanthurenic acid, a tryptophan metabolite: activation of cell caspases but not cytoskeleton breakdown.

BACKGROUND: A family of aspartate-specific cysteinyl proteases, named caspases, mediates programmed cell death, apoptosis. In this function, caspases are important for physiological processes such as development and maintenance of organ homeostasis. Caspases are, however, also engaged in aging and disease development. The factors inducing age-related caspase activation are not known. Xanthurenic acid, a product of tryptophan degradation, is present in blood and urine, and accumulates in organs with aging. RESULTS: Here, we report triggering of apoptotic key events by xanthurenic acid in vascular smooth muscle and retinal pigment epithelium cells. Upon exposure of these cells to xanthurenic acid a degradation of ICAD/DFF45, poly(ADP-ribose) polymerase, and gelsolin was observed, giving a pattern of protein cleavage characteristic for caspase-3 activity. Active caspase-3, -8 and caspase-9 were detected by Western blot analysis and immunofluorescence. In the presence of xanthurenic acid the amino-terminal fragment of gelsolin bound to the cytoskeleton, but did not lead to the usually observed cytoskeleton breakdown. Xanthurenic acid also caused mitochondrial migration, cytochrome C release, and destruction of mitochondria and nuclei. CONCLUSIONS: These results indicate that xanthurenic acid is a previously not recognized endogenous cell death factor. Its accumulation in cells may lead to accelerated caspase activation related to aging and disease development.

Prevention of neointimal proliferation by immunosuppression in synthetic vascular grafts.

OBJECTIVE: Immunosuppressive agents have been proposed to reduce neointimal hyperplasia in synthetic vascular grafts. Thus, the purpose of the present study was to evaluate the safety and efficacy of rapamycins (systemic vs. local vs. oral administration) and mycophenolate mofetil (MMF) to reduce intimal hyperplasia in infrarenal synthetic vascular grafts of the rat. METHODS: Fifty-four Wistar rats (250 g) completed the study after a synthetic vascular graft (ePTFE, Gore-tex, 2 mm diameter, 10 mm length) was implanted end-to-end in the infrarenal aorta. The animals were divided into three groups: group 1 consisted of 12 control animals, group 2 consisted of 37 rats receiving rapamycins, either per os (RAD, 1.5 or 3 mg/kg), intraperitoneally (RPM, 1.5 or 3 mg/kg) or locally (RPM soaking of the graft); and in group 3 (n=5), MMF (40 mg/kg) was administered orally. The animals were followed weekly with weight controls and signs of toxicity for 30 (n=37) and 60 (n=17) days, respectively. All animals were sacrificed and underwent histological examination at completion of the study. RESULTS: All animals survived in groups 1 and 3, but five died in group 2. The weight gain was normal in all groups, except for the subgroup 2a receiving high dose rapamycins orally. All rats in group 3 suffered from diarrhea, whereas animals receiving high dose rapamycins showed toxic signs (hair loss, wound healing problems). Histological examination showed a significant increase in intimal hyperplasia in group 1 (0.03+/-0.01 and 0.14+/-0.05 microm after 30 and 60 days, respectively; P<0.01). Rapamycins in either application or dosage had no significant effect on intimal hyperplasia. CONCLUSIONS: Local or systemic administration of rapamycins has no effect on intimal hyperplasia in synthetic vascular grafts. In contrast, toxic signs with weight loss were observed in animals treated with high dose rapamycins, but not in those treated with MMF. Thus, in the rat model, immunosuppression with rapamycins or MMF cannot be recommended for the prevention of intimal hyperplasia in the synthetic vascular graft model.

Fatal cardiac arrhythmia after infusion of dimethyl sulfoxide-cryopreserved hematopoietic stem cells in a patient with severe primary cardiac amyloidosis and end-stage renal failure.

Amyloidosis (AL) is a rapidly fatal plasma cell dyscrasia causing progressive multiorgan failure. Recently, substantial improvement of survival was reported following high-dose chemotherapy with peripheral blood stem cell (PBSC) rescue. We describe a patient with AL with severe cardiac and renal involvement who received high-dose melphalan followed by fractioned autologous PBSC transplantation (455 ml on day 1 and 350 ml on day 2). Immediately after the second infusion of the PBSCs, life-threatening cardiac arrhythmias occurred and, despite intensive treatment, the patient died less than 24 h later. The infusion of cryopreserved PBSCs may be associated with complications, including cardiac toxicity. Dimethyl sulfoxide (DMSO) is the most frequently used cryopreservation agent. In the present case, we suggest that DMSO could have played an important role in causing the fatal cardiac arrhythmias. The mechanisms of the cardiovascular effects of DMSO and the possible preventive measures are discussed. Given the poor prognosis of AL and the promising results of dose-intensive chemotherapy with autologous PBSC transplantation, careful patient selection and intensive monitoring are mandatory in order to further pursue this therapeutic approach.

Transit time flow measurement: experimental validation and comparison of three different systems.

BACKGROUND: Bloodflow measurements are of major clinical importance for quality control in vascular surgery. They allow detection of low-flow situations which may influence outcome adversely. The purpose of the present study was to validate three different flow systems for measuring absolute blood flow. METHODS: Measurements were performed in an experimental flow model using arteries and veins and blood or saline at two different temperatures. As a reference method true flow was measured by volume sampling. RESULTS: Correlation coefficients between transit time flow and true flow measurements ranged between 0.71 and 0.92. Systematic overestimation and underestimation of transit time flow were observed, but after second-order correction all correlations were excellent, ranging from 0.93 to 0.95 irrespective of flow medium and temperature. CONCLUSIONS: Transit time flow measurements are exact and reproducible. Second-order correction yields good accuracy and high precision, with minimal differences among the three systems evaluated.

Tetrahydrobiopterin improves endothelial function in patients with coronary artery disease.

Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide synthase (NOS) and a scavenger of oxygen-derived free radicals. Decreased availability of BH4 leads, under in vitro conditions, to reduced nitric oxide (NO) production and increased superoxide formation. We studied the effect of exogenous BH4 on endothelial function of angiographically normal vessel segments in patients with coronary artery disease. Nineteen patients with coronary artery disease underwent quantitative coronary angiography with simultaneous coronary flow velocity measurements (Cardiometrics FloWire). Data were obtained in angiographically normal segments of the left coronary artery at baseline, after intracoronary (i.c.) administration of acetylcholine (Ach; 10(-4) M), after infusion of BH4 (10(-2) M), and after co-infusion of ACh and BH4. At the end of the study, 300 microg nitroglycerin (NTG) i.c. was administered to obtain maximal vasodilation. At each step, flow velocity was determined before and after 18 microg adenosine i.c. to assess coronary flow velocity reserve. In 15 patients, ACh induced coronary vasoconstriction of -18 +/- 3% (endothelial dysfunction; p < 0.0001 vs. baseline), and in four patients, vasodilation of +39 +/- 20%. In the 15 patients with endothelial dysfunction, BH4 alone did not influence vessel area but prevented vasoconstriction to ACh (+2 +/- 3%, NS, vs. baseline). Correspondingly, calculated volume flow showed the highest value after co-infusion of ACh and BH4. Coronary flow velocity reserve was comparable during the various infusion steps. BH4 prevents ACh-induced vasoconstriction of angiographically normal vessels in patients with coronary artery disease. Thus substitution of this cofactor of NOS may represent a new approach for the treatment of endothelial dysfunction.

Intra- and postoperative quality control in minimally invasive direct coronary artery bypass (MIDCAB) surgery.

The introduction of new techniques allowing direct coronary artery revascularisation without sternotomy and extracorporeal circulation--called Minimally (or less) Invasive Direct Coronary Artery Bypass grafting (MIDCAB)--has opened up interesting perspectives for the treatment of patients with limited coronary artery disease. However, like any newer surgical technique, this approach to myocardial revascularisation requires a critical appreciation of the results which may be obtained; when introducing the MIDCAB technique in our institution we developed a quality control protocol based on intraoperative as well as early and late postoperative parameters. This protocol is designed to detect every significant adverse event, exercise capacity and quality of life of our patients. Moreover, several invasive parameters have to be recorded in the protocol, such as intraoperative flow in the internal mammary artery conduit, the angiographic verification of anastomotic patency at one-year follow-up and determination of coronary flow reserve. The results of the first 5 patients observed up to one year postoperatively are presented: all anastomoses were patent and the flow within the internal mammary artery was 69 +/- 40 ml/min at one-year follow-up angiography; this compares very favourably with the flow measured at the end of the operation, which was 31 +/- 8 ml/min. This demonstrates very clearly that internal mammary artery flow is recruitable and usually significantly increases within the first months postoperatively. Coronary flow reserve was 3.4 +/- 1.1 (normal value > 2.5). The results obtained in this pilot study, which was designed to establish a quality control protocol, are very satisfactory and confirm previous experience that this technique may be offered to selected patients with appropriate coronary anatomy.

Diastolic dysfunction and collagen structure in canine pacing-induced heart failure.

Heart failure is characterized not only by systolic, but also by diastolic dysfunction. The present study tested whether or not diastolic dysfunction is associated with changes in tissue properties and collagen network structure. Heart failure was induced in seven chronically instrumented, conscious dogs by rapid left ventricular pacing (2 50 min(-1)). After 2-5 [mean: 4+/-1 (S.D.)] weeks pacing, heart failure was apparent from clinical symptoms (ascites, cachexia, edema, exercise intolerance) and hemodynamic parameters (significant increases of heart rate and left ventricular end-diastolic pressure and decreases of left ventricular maximal pressure, dP/dtmax and systolic wall thickening). The left ventricle was dilated, as indicated by a decrease of end-diastolic wall thickness (6.3+/-2.0 v 7.2+/-2.1 mm; P<0.05; sonomicrometry). The left ventricular end-diastolic pressure-strain relation (strain: relative change of end-diastolic wall thickness) was obtained during alterations of loading conditions by inferior caval vein and descending thoracic aortic occlusion. The slope of this relation increased from 85+/-20 to 428+/-188 in heart failure, indicating an increase of left ventricular stiffness. Collagen was stained with picrosirius red and analyzed using polarized light microscopy. In heart failure, the collagen volume fraction remained unchanged (1.9+/-1.2 v 2.3+/-1.3%; N.S.), while the nonuniformity of collagen orientation, as reflected by its standard deviation, was increased (11.1+/-1.8 v 6.1+/-0.4 o; P<0.05). The nonuniformity of collagen fiber orientation correlated with left ventricular stiffness [r=0.75].

Transit-time flow measurement for detection of early graft failure during myocardial revascularization.

BACKGROUND: A low-flow situation in arterial and venous grafts has been associated with high rates of perioperative infarction and mortality. This study was designed to look at intraoperative graft flow and resistance in patients with coronary artery disease. METHODS: Coronary artery bypass graft flow was measured in 46 patients. Transit-time flow was used for coronary flow measurements at rest as well as after maximal vasodilation with adenosine infusion. RESULTS: Forty-three of the 46 patients showed normal internal mammary artery graft flow (>20 mL/min); 3 patients had no or minimal graft flow. Redoing the graft anastomosis in these 3 patients resulted in normalization of graft flow. The mean flow increased significantly after correction from 0.5 +/- 0.7 mL/min to 15.7 +/- 9.6 mL/min (p < 0.02). Conversely, vascular resistance decreased significantly from 138 +/- 10 to 4.8 +/- 1.8 Ohmv (p < 0.0001), as did the pulsatility index (from 146.9 +/- 95.7 to 3.4 +/- 1.8; p < 0.001). After correction, coronary flow reserve was 2.5 +/- 1.1. CONCLUSIONS: Measurements of intraoperative flow and resistance as well as derived variables allow assessment of early graft function and thus help prevent graft failure and reduce perioperative infarction. Transit-time volume flow might be a simple tool for quality control in coronary bypass procedures.

Determinants of left ventricular diastolic function during myocardial ischemia: influence of myocardial structure and pericardial constraint.

OBJECTIVE: To assess the influence of myocardial structure and pericardial constraint during exercise ischemia on regional left ventricular passive elastic properties. METHODS: Left ventricular regional function was assessed at rest and during exercise using biplane angiography and high-fidelity pressure measurements. Twenty patients with either normal (n = 7) or stenotic coronary arteries (n = 13) were studied before and after successful bypass surgery. At the time of surgery, left ventricular transmural biopsies were taken from a normally perfused and a hypoperfused left ventricular region. RESULTS: Regional stiffness increased in the ischemic zone during exercise, but remained unchanged after revascularization. Regional fibrosis was significantly enhanced in the ischemic region compared with that in the normally perfused zone. No correlation was found between structural data and regional passive elastic properties, but there was a significant correlation between right atrial pressure and the asymptote of the diastolic pressure--volume relationship. CONCLUSIONS: Acute regional diastolic dysfunction can be observed during exercise in patients with coronary artery disease. Structural changes seem to have a minor role in the occurrence of diastolic dysfunction in the absence of myocardial infarction. The observed upward shift of the pressure-volume relationship during ischemia can be attributed to pericardial constraint that is manifested by an increase in right arterial pressure.

Long-term follow up of patients with endomyocardial fibrosis: effects of surgery.

AIMS: To determine the long-term outcome of patients with endomyocardial fibrosis and to compare echocardiographic and haemodynamic data before and after ventricular endocardial resection. PATIENTS: Seventeen patients (11 women and six men; mean age 35.5 years) diagnosed with endomyocardial fibrosis at the University Hospital in Zurich, Switzerland from 1971 to 1995. Twelve patients (70%) had partial obliteration of both ventricles and in five patients (30%) the fibrotic lesions were limited to the left ventricle. METHODS: Fourteen of the 17 patients had surgical resection: fibrosis was resected from both ventricles in five patients and from the left ventricle only in nine patients. Ten patients had mitral valve replacement and two had tricuspid valve replacement. Left ventricle endocardial resection was done without reconstruction or replacement of the atrioventricular valve in three patients. Preoperative and postoperative echocardiographic data were available for 11 patients and haemodynamic data for six patients. Patients were followed up for 0.4-19 years (mean 8.6). RESULTS: Preoperatively four patients were NYHA functional class IV and 10 were class III; postoperatively one patient was class III, seven class II, and six class I. Preoperatively, echocardiography showed obliteration of the left ventricular apex and inflow tract in all patients, which decreased or disappeared after surgery. Left ventricular end diastolic pressure decreased from 25 mm Hg before surgery to 14 mm Hg after successful resection of the fibrosis. Left ventricular and diastolic volume (normal 93 (17) ml/m2) increased from 65 ml/m2 to 97 ml/m2 (p < 0.05) after surgery. Ejection fraction was normal preoperatively (57%) and decreased slightly (52%) after surgery. One patient died five months after surgery from heart failure. Four surgically treated patients died during the follow up period: one each from systolic dysfunction, recurrence of endomyocardial fibrosis, pneumonia, and food poisoning. Overall survival was 65% at five years and 59% at 10 years; the survival rates of the operated patients was 72% and 68%, respectively. Only one of the medically treated patients survived longer than three years from diagnosis. CONCLUSIONS: Endomyocardial fibrosis is a rare disease in European countries and is found mainly in women. The clinical picture is characterised by severe congestive heart failure but heart size is only moderately increased. Systolic performance is normal or only slightly depressed despite severe restriction to filling, atrioventricular valve regurgitation or both. Partial obliteration of the right and/or left ventricle may be detected by echocardiography. Endocardial resection with atrioventricular valve replacement is the treatment of choice with appreciable postoperative improvement and 10 year survival of approximately 70%.

Long-term follow-up in hypertrophic obstructive cardiomyopathy after septal myectomy.

BACKGROUND: Controversy exists about the choice of treatment for patients with hypertrophic obstructive cardiomyopathy. The purpose of this study was to evaluate clinical and echocardiographic long-term results in patients with hypertrophic obstructive cardiomyopathy after septal myectomy and to determine predictors of event-free survival in these patients. METHODS: Between 1965 and 1995, 110 consecutive patients 2 to 66 years old (mean age, 37 +/- 15 years) with an invasively measured left ventricular outflow tract gradient of 86 +/- 39 mm Hg (81 +/- 42 mm Hg by Doppler echocardiography) underwent either septal myectomy only (n = 87) or myectomy combined with additional procedures (n = 23). Mean follow-up was 11.7 +/- 7.5 years. Predictors of late events were calculated using multivariate Cox regression analysis. RESULTS: The perioperative mortality rate was 3.6% (n = 4). The cumulative survival rate at 5, 10, and 15 years was 93%, 80%, and 72%, respectively, and symptom-free survival, 77%, 50%, and 33%, respectively. Predictors of late death were New York Heart Association class III or IV (p < 0.05), congestive heart failure (p < 0.05) and additional procedures (p < 0.05). The left ventricular outflow tract gradient was nearly eliminated in all patients, the left atrial dimension decreased significantly during the early years, and left ventricular dilatation occurred late in 17 patients. CONCLUSIONS: Septal myectomy is associated with a low perioperative mortality and a high late survival rate (72% at 15 years' follow-up). Septal myectomy is still an excellent modality in the treatment strategy for symptomatic patients with hypertrophic obstructive cardiomyopathy.

Cardiac risk after mediastinal irradiation for Hodgkin's disease.

PURPOSE: To evaluate the risk of cardiac lesions after conventionally fractionated irradiation (Rt) of the mediastine with or without chemotherapy (Ct) in patients with Hodgkin's disease (HD) and to relate them to known cardiovascular risk factors. PATIENTS AND METHODS: Between 1964 and 1992, 352 (total group) patients with HD were treated with curative intention using Rt with or without Ct including the mediastine and had a follow-up of at least 1 year. More than 96% of the patients had a complete follow-up. One hundred forty-four patients (64% of the living patients, heart study group) have regular follow-up in our department and had a special heart examination including rest and exercise ECG, echocardiography and myocardial perfusion scintigraphy (112 patients). Doses per fraction in the anterior heart region were between 1.3 and 2.1 Gy. Total doses were between 30.0 and 42.0 Gy in 93% of cases. The mean length of follow-up was 11.2 years (range 1.0-31.5 years). Other cardiovascular risk factors evaluated were body mass index, blood pressure, smoking history, diabetes mellitus, hypercholesterolemia and history of coronary artery disease before Rt. RESULTS: In the total group, the risk of fatal cardiac ischemic events and/or of sudden unexpected death was significantly higher than expected with a relative risk of 4.2 for myocardial infarction and 6.7 for myocardial infarction or sudden death. In female patients and in patients without other cardiovascular risk factors, the risk of fatal or non-fatal ischemic cardiac events was not significantly different from the expected value. In the subgroup with no cardiovascular risk factors and treatment without Ct, there was no ischemic or other major cardiac event. Echocardiography showed valvular thickenings in a large amount of the patients (the cumulative risk after 30-year follow-up was above 60%) but mostly without hemodynamic disturbance. In patients without hypertension and without coronary artery disease, findings of perfusion scintigraphy and echocardiographic evaluation of systolic and diastolic function were normal. Treatment with Ct was not a significant risk factor for cardiac events but the number of patients whose treatment included adriamycin and with a follow-up exceeding 10 years is to low for a definitive evaluation. CONCLUSIONS: In patients without the usual cardiovascular risk factors (smoking, hypertension, obesity, hypercholesterolemia, diabetes mellitus) the risk of serious cardiac lesions after conventionally fractionated irradiation of the mediastinum with an intermediate total dose between 30 and 40 Gy is low. Also the cardiac risk of the combination of this irradiation with Ct including adriamycin with a total dose between 200 and 300 mg/m2 seems low but further long-term observation is necessary.

[Diuretics in the treatment of heart failure: current pathophysiological aspects]. / Diuretika in der Behandlung der Herzinsuffizienz: neue pathophysiologische Aspekte.

From a pathophysiologic point of view heart failure can be divided into systolic and diastolic dysfunction. Systolic dysfunction is characterized by a decreased ejection fraction and increased chamber volume which can be typically found in young people with congestive cardiomyopathy. Diastolic dysfunction is associated with an enhanced filling pressure but with a normal systolic pump function. This disorder can be typically found in elderly patients with myocardial hypertrophy. Treatment of congestive heart failure includes. 1.) reduction of central blood volume (preload reduction) 2.) decrease of peripheral resistance afterload reduction) 3.) regression of myocardial hypertrophy (improving myocardial stiffness) 4.) maintenance of atrial contraction (atrial kick) 5.) decrease of heart rate (prolongation of diastolic filling time and increase in contractility) 6.) improvement of LV relaxation (positive lusitropic effect) and 7.) prevention of myocardial ischemia (improvement in contractility and relaxation). The primary goal of medical therapy is symptomatic improvement. Reduction in morbidity and mortality is only a secondary consideration. To achieve this goal ACE-inhibitors and in certain cases betablockers (cave: neg. inotropic action) are suited best. Additionally, digitalis-especially in the presence of atrial fibrillation- and vasodilators can be used to further improve quality of life. In the case of severe heart failure with or without atrial fibrillation oral anticoagulation is indicated to prevent systemic embolication. Diuretics are often used for symptomatic improvement but have no effect on long-term survival. Aldosterone antagonists (e.g, spironolactone) have a beneficial effect on LV remodeling and probably also on mortality. The role of endothelin antagonists and atriopeptidase inhibitors in the treatment of heart failure are not yet clear.

Age dependency of left ventricular diastolic function in pressure overload hypertrophy.

OBJECTIVES: We sought to evaluate whether age is a determinant of left ventricular (LV) pressure overload hypertrophy and whether diastolic function influenced the aging process. BACKGROUND: The adaptation of the left ventricle to chronic pressure overload is a complex process of hormonal, structural and hemodynamic factors. Different responses in the elderly patients have been described. METHODS: LV biplane cineangiography, micromanometry and endomyocardial biopsies were carried out in 57 patients with pure or predominant aortic stenosis. Patients were classified into a senior (< 60 years, mean age +/- SD 46 +/- 10 years, n = 35) and an elderly (< 65 years; mean age 70 +/- 4 years, n = 22) study group. LV systolic function was evaluated from biplane ejection fraction and midwall fractional shortening, whereas diastolic function was assessed from the time constant of LV pressure decay, peak filling rate and the constant of myocardial stiffness. Biopsy samples were examined morphometrically for interstitial fibrosis, fibrous content, muscle fiber diameter and volume fraction of myofibrils. RESULTS: Gender distribution and the severity of aortic stenosis were comparable in the two patient groups. LV peak systolic and end-diastolic pressures were significantly higher in the elderly than in the senior group. LV ejection fraction and midwall fractional shortening were comparable in the two groups. The time constant of relaxation and the myocardial stiffness constant were greater in the elderly than in the senior group whereas the early peak filling rate was significantly reduced in the elderly group. Interstitial fibrosis was increased, although not significantly (p < 0.06), and fibrous content was enhanced (p < 0.001) in elderly patients with respect to the senior group. There was a linear correlation between age and myocardial stiffness (r = 0.55), p < 0.0001) and an inverse relation between age and early peak filling rate (r = 0.52, p < 0.0001). CONCLUSIONS: In the presence of a comparable degree of aortic valve stenosis, elderly patients (> 65 years) present with more severe LV hypertrophy than do senior patients (< 60 years). Therefore elderly patients have a more pronounced impairment of LV diastolic function, whereas systolic function is preserved. Thus, there is an age dependency of LV pressure overload hypertrophy that can be explained by the longer duration of pressure overload or an exhaustion of the adaptation process in the elderly.

Effect of intermittent warm blood cardioplegia on functional recovery after prolonged cardiac arrest.

BACKGROUND: There is some evidence that continuous warm blood cardioplegia offers good myocardial protection; however, the effects of interrupting cardioplegia remain controversial. To study this, we compared the effects of continuous and intermittent antegrade warm (37 degrees C) blood cardioplegia on functional recovery after prolonged cardiac arrest (180 minutes). METHODS: Twenty-four juvenile pigs were randomly assigned into four groups. Group 1 received continuous cardioplegia, group 2 underwent several periods of 15 minutes of cardioplegia interrupted by 5 minutes of normothermic ischemia, and group 3 underwent several periods of 10 minutes of cardioplegia interrupted by episodes of 10 minutes. The hearts of group 4 received no cardioplegia. Left ventricular systolic function was assessed from fractional left ventricular shortening and percentage left ventricular wall thickening, and left ventricular diastolic function was determined from the time constant of relaxation and the constant of myocardial stiffness. RESULTS: Systolic and diastolic functions were slightly depressed 1 and 2 hours after cross-clamp removal in all four groups, without significant differences among the groups. CONCLUSIONS: These data suggest that antegrade warm blood cardioplegia can be interrupted for up to 10 minutes without obvious negative effects on left ventricular function in the normal myocardium, provided that the intermittent doses of cardioplegia are sufficient to restore the metabolic demands of the arrested myocardium.

Normalization of left ventricular nonuniformity late after valve replacement for aortic stenosis.

The aim of the present study was to evaluate nonuniformity in pressure overload hypertrophy due to aortic stenosis. Twenty patients were included in the present analysis. Ten patients with severe aortic stenosis were studied preoperatively as well as early (21 +/- 8 months) and (89 +/- 21 months) after aortic valve replacement (AVR) using left ventricular biplane angiograms, high-fidelity pressure measurements and endomyocardial biopsies. Ten normal subjects served as controls. LV systolic function was assessed from biplane ejection fraction, and diastolic function from the time constant of relaxation, the peak filling rate and the constant of myocardial stiffness. Nonuniformity was evaluated from the coefficient of variation of the time to end-systole (systolic asynchrony) and peak filling rate (diastolic asynchrony) of 12 regions in right anterior oblique and left anterior oblique projection. Ejection fraction was comparable in patients with aortic stenosis and in controls, whereas preoperatively diastolic dysfunction with prolonged relaxation and increased stiffness was present in patients with aortic stenosis and was normalized late after AVR. LV systolic asynchrony was present (>25D of controls) in 7 and diastolic asynchrony in 10 of 10 patients with aortic stenosis. Early as well as late after AVR systolic asynchrony was normalized in 9 of 10 patients. Diastolic asynchrony was present early AVR in all but one patient, although there was a significant improvement with respect to the preoperative evaluation. Late after AVR there was a normalization of diastolic asynchrony in 9 of 10 patients with aortic stenosis. Thus, it is concluded that systolic asynchrony is normalized early after AVR probably due to its load-sensitivity, whereas diastolic asynchrony persists probably due to residual LV hypertrophy with increased interstitial fibrosis and myocardial stiffness. Late after AVR, diastolic asynchrony is normalized due to structural remodeling with regression of both myocardial hypertrophy and interstitial fibrosis.