Spinal cord stimulation. New regulation of national health insurance.

Since January 1, 2008, the Belgian national health insurance (INAMI/RIZIV) edited a new agreement for the prolongation of the pilot-study on spinal cord stimulation for chronic critical unreconstructable lower limb ischemia. After a short introduction and a summary of the results of the initial Belgian pilot study (2000-2005) on spinal cord stimulation, the official new text is now published in both languages.

Thrombolysis with human extrinsic (tissue-type) plasminogen activator in dogs with femoral vein thrombosis.

Extrinsic (tissue-type) plasminogen activator (plasminogen activator) was isolated either as a single-chain or as a two-chain molecule from the culture medium of a human melanoma cell line. The thrombolytic activity of both molecular forms of activator was investigated in beagle dogs with an experimental femoral vein thrombosis and compared with that of urokinase. The 125I-fibrinogen-labeled thrombus was formed in an isolated 4-cm segment of the vein, aged for 30 min, and the thrombolytic substances were infused over a 4-h period. The degree of thrombolysis was measured 2 h later as the difference between the injected and recovered 125I. In six control animals with a saline infusion the extent of thrombolysis was 16.3 +/- 3.8% (mean +/- SEM), in five dogs receiving 100,000 IU urokinase, 17.4 +/- 3.7% (P less than 0.4) and in four dogs with 1,000,000 IU urokinase 40.6 +/- 4.8% (P less than 0.001). Infusion of 100.000 IU single-chain plasminogen activator in five dogs resulted in 3.5 +/- 7.8% lysis (P less than 0.05) and of 100,000 IU two-chain plasminogen activator in five dogs in 60.1 +/- 10.8% (P less than 0.001). Infusion of 300,000 IU one-chain plasminogen activator yielded 57.5% lysis and of the same amount of two-chain plasminogen activator 72.9%. Significant activation of plasminogen, consumption of alpha 2-antiplasmin, and fibrinogen breakdown in plasma was only observed in animals receiving the high doses of urokinase but not in the saline, plasminogen activator, or the low-dose urokinase groups. It is thus concluded that in this thrombosis model human extrinsic plasminogen activator has a higher specific thrombolytic effect that urokinase. Plasminogen activator also appears to induce thrombolysis without systemic fibrinolytic activation and fibrinogen breakdown.

Platelet survival in patients with angiographically diseased and normal coronary arteries.

Platelets may contribute to the pathogenesis of atherosclerosis and to the complications of coronary artery disease. Therefore, platelet kinetics were studied in 69 patients with angiographically documented coronary artery disease and in 16 patients with a normal coronary angiogram. Platelet survival time was calculated from the decay of radioactivity after injection of 51Cr-labeled autologous platelets. None of the mathematical models used was able to discriminate between the two patients groups. No correlation existed between survival time and extent of the arterial disease. Patients with a high serum cholesterol did not exhibit an enhanced platelet consumption. Thus, these studies do not support the idea that turnover is enhanced in patients with coronary artery disease as compared to those with normal coronary arteries.

Emergency coronary bypass grafting for evolving myocardial infarction. Effects on infarct size and left ventricular function.

Emergency aorta-coronary bypass grafting was performed early in the course of evolving myocardial infarction in 48 patients. The time interval between the onset of symptoms and reperfusion was 169 +/- 80 minutes. Quantitative assessment of postoperative thallium 201 myocardial scans in 19 patients revealed a significant salvage of myocardium after surgical reperfusion: The size of the residual infarction was less than 50% of that in a matched, medically treated, prospective control group (n = 39) (p less than 0.05). Postoperative equilibrium-gated radionuclide blood pool studies (technetium 99m) showed an enhanced recovery of regional and global ejection fraction after operation as compared to after medical treatment (p less than 0.05). Ultrastructural evaluation of biopsy specimens obtained during the operation delineated subendocardial necrosis in the majority of cases (72%), but subepicardial necrosis was found in only 6% of instances. Q-wave abnormalities were observed on the postoperative electrocardiogram in 50% of cases. Operative mortality was 0% in low-risk patients (i.e., hemodynamically stable condition, n = 26) and 18% in high-risk patients (i.e., cardiogenic shock including total electromechanical dysfunction, n = 22). Survival rate at 18 months was 92% +/- 4%, and 95% +/- 4% of the survivors were event free. It is concluded that early surgical reperfusion of evolving myocardial infarction limits infarct size significantly, enhances functional recovery, and may be a lifesaving operation in patients having cardiogenic shock associated with unsuccessful resuscitation.

Nifedipine as an adjunct to St. Thomas' Hospital cardioplegia. A double-blind, placebo-controlled, randomized clinical trial.

The cardioprotective effect of the addition of the slow calcium-channel blocker nifedipine to cardioplegic solution was tested in two double-blind placebo controlled randomized studies. The first study included 24 patients undergoing aortic-coronary bypass grafting, and the second included 24 patients undergoing aortic valve replacement. Nifedipine at a dose of 200 micrograms/L or placebo was added to St. Thomas' Hospital cardioplegic solution. The following markers of ischemia were used: adenosine triphosphate and its catabolites, creatine phosphate and inorganic phosphate, determined in transmural left ventricular biopsy specimens taken before, at the end of, and after aortic cross-clamping; hemodynamic recovery 15 minutes after cessation of cardiopulmonary bypass; clinical outcome in terms of the incidence of arrhythmias, low cardiac output, positive inotropic support immediately after operation, and follow-up at 15 months. The main difference between the two studies was that myocardial temperature during cross-clamping remained constant at 14 degrees C in coronary bypass grafting but increased to 25 degrees C in valve operations despite the application of the same amounts of cardioplegic solutions. This lower temperature resulted in better preservation of high-energy phosphates in coronary bypass operations as compared to the placebo group having valve replacement operations. According to analysis of variance, a drug effect could be demonstrated only in the aortic valve replacement study: Accumulation of breakdown products of the adenine nucleotide pool was less in the nifedipine group than in the placebo group (p less than 0.05). Adenosine triphosphate decreased only to 84% in the nifedipine group and to 72% in the placebo group. Despite this adenosine triphosphate-sparing effect, weaning from cardiopulmonary bypass was more difficult in the nifedipine group. Left ventricular stroke work index 15 minutes after bypass was decreased to 72% of the prebypass value in the nifedipine group (t test, p less than 0.01) and only to 86% in the placebo group (p = NS). In contrast, after the patients were admitted to the intensive care unit, the incidence of low cardiac output tended to be lower in the nifedipine group than in the placebo group: 33% versus 58% (p = NS). In conclusion, ischemia-induced degradation of nucleotides as it occurs when myocardial cooling is inadequate can be prevented by the addition of nifedipine to the St. Thomas' Hospital cardioplegic solution. This effect, however, is not associated with an improved clinical outcome.

Cardioprotective effects of lidoflazine in extensive aorta-coronary bypass grafting.

The cardioprotective effects of lidoflazine, a calcium entry blocker, were tested in patients undergoing multiple aorta-coronary bypass grafting (at least four grafts). Intermittent aortic cross-clamping at 25 degrees to 28 degrees C was used. Mean cross-clamp time was 11 minutes for one distal anastomosis. Patients were randomized into three groups: a control group (I), a group (II) pretreated with 0.5 mg . kg-1 lidoflazine intravenously before cardiopulmonary bypass (CPB), and a group (III) pretreated with 1 mg . kg-1 lidoflazine intravenously. The following markers of ischemia are used: (1) adenosine triphosphate (ATP), creatine phosphate (CP) and glycogen determined in transmural left ventricular biopsy specimens taken at the beginning and end of CPB; (2) ultrastructure in a similar pair of specimens; and (3) hemodynamic recovery 15 minutes after cessation of CPB. At the end of the intervention, ATP decreased to 73% in Group I but remained unchanged in Groups II (98%) and III (88%). CP decreased to 82% in Group I and remained unaltered in Groups II (100%) and III (110%). Glycogen decreased in Group I (to 44%) and in Group II (78%) but remained unchanged in Group II (138%). Ultrastructural study showed better preservation of the glycocalyx and sarcolemma in Group III than in Group I. Left ventricular stroke work index remained unaltered after CPB in Group III but decreased in Groups I and II to about 60% of its initial value. Thus lidoflazine pretreatment protects the myocardium in a dose-dependent manner against deterioration of myocardial function and structure.

Intermittent aortic cross-clamping versus St. Thomas' Hospital cardioplegia in extensive aorta-coronary bypass grafting. A randomized clinical study.

Myocardial preservation was assessed in 72 patients undergoing extensive myocardial revascularization. The patients were allocated at random to three surgical techniques: Group 1, intermittent aortic cross-clamping at 32 degrees C; Group 2, intermittent aortic cross-clamping at 25 degrees C; and Group 3, St. Thomas' Hospital cardioplegia. As intraoperative markers of ischemic damage, adenosine triphosphate, creatine phosphate, and glycogen contents were determined in transmural left ventricular biopsy specimens taken at the beginning and at the end of cardiopulmonary bypass. Ultrastructure was studied in a similar pair of biopsy specimens. Release of myocardium-specific creatine kinase isoenzyme was determined intraoperatively and postoperatively. Functional recovery was assessed before and after weaning from cardiopulmonary bypass. The incidence of low cardiac output, myocardial infarction, and rhythm disturbances was compared between groups. Finally, actuarial survival and event-free curves were studied after 18 months' follow-up. The results show a better preservation of high-energy phosphates, glycogen, and ultrastructure in the cardioplegia group as compared to the two cross-clamp groups. However, severe myocardial damage was never observed. Release of MB creatine kinase isoenzyme was the same in all three groups. Functional recovery of the hearts immediately after cessation of cardiopulmonary bypass was better in the cardioplegia group, but the incidence of rhythm disturbances (atrioventricular conduction problems) was higher in the cardioplegia group than in the other two groups (p less than 0.05). Clinical outcome in terms of incidence of perioperative infarction, survival, and event-free follow-up was not different between groups. It is concluded that both techniques (aortic cross-clamping at 32 degrees C or 25 degrees C and St. Thomas' Hospital cardioplegia) offer good myocardial protection in extensive aorta-coronary bypass operations. St. Thomas' cardioplegia, however, in contrast to intermittent aortic cross-clamping, prevents the onset of ischemia-induced deterioration of cardiac metabolism, i.e., destruction of the adenine nucleotide pool.

Blood pressure during long-term converting-enzyme inhibition predicts the curability of renovascular hypertension by angioplasty.

Percutaneous transluminal renal angioplasty (PTRA) was performed in 28 hypertensive patients with 50% or more unilateral renal artery stenosis. Prospectively, the study compared the extent to which systolic (SBP) and diastolic (DBP) pressure during long-term converting-enzyme inhibition (CEI) and the ipsi- to contralateral renal vein renin ratio (RVR) predicted success of PTRA, defined as SBP less than 160 mmHg and DBP less than 95 mmHg. Both SBP and DBP after PTRA were positively correlated with pressure during CEI (P less than 0.001) and negatively with RVR (P less than 0.03). In multiple regression these associations were independent and remained statistically significant. In discriminant analysis, a SBP during CEI less than 160 mmHg, a DBP during CEI less than 95 mmHg, and a RVR greater than or equal to 1.5 identified with equal accuracy the success of PTRA. Furthermore, in patients with a SBP during CEI less than 160 mmHg, the demonstration of a RVR greater than or equal to 1.5 increased (P less than 0.05) the prediction of a positive outcome from 50 to 67%. In contrast, in 92% of the patients with a SBP during CEI greater than 160 mmHg, PTRA was not successful. Thus, blood pressure measurements during long-term CEI predict the curability by PTRA of renovascular hypertension and can be employed either alone or in association with the RVR.

Aortofemoral grafting: factors influencing late results.

During a 15-year period, the aortofemoral Dacron graft was used for revascularization of 615 limbs in 352 patients, with an overall operative mortality rate of 5.1% and a cumulative 10-year patency rate of 62%. The late complication rate was 27%, with late thrombosis being by far the most frequent complication (24%). Among several factors responsible for late occlusion, the presence of trifurcation disease and the site of the femoral anastomosis are by far the most important. Our procedure of choice for a thrombosed graft limb is thrombectomy and profundaplasty, which give a long-term patency rate of 68%.

Internal mammary artery: methods of use and their effect on survival after coronary bypass surgery.

Hazard analysis of total and cardiac mortality after isolated primary coronary artery surgery was performed using univariate and multivariate methods with special emphasis on the importance of the use and method of use of the internal mammary artery (IMA) as a bypass graft. The clinical data of 5880 consecutive patients were studied. The sum of the real follow-up periods studied was 27,948 years. The hazard of total and cardiac mortality could be defined in three-phase parametric models with an early, a constant and a late phase. The total survival was 82% +/- 1% at 10 years and 59% +/- 3.6% at 15 years. The construction of a single IMA distal graft (using left or right IMA) had a positive influence on the hazard (P = 0.0004) in the late phase after surgery with a high estimate (-1.6). The cardiac survival was 89% +/- 0.8% at 10 years and 74% +/- 3.5% at 15 years. The use of the left IMA had a positive influence (P = 0.001) in the late phase after surgery with a very high estimate (-2.3). The generated simulation of the total survival of a median patient with an IMA graft is 97% at 5 years and 94% at 10 years; for a median patient without an IMA graft, it is 97% at 5 years and 88% at 10 years. If a patient has other risk factors reducing his life expectancy, the influence can be dissipated because of lower survival rates at 5 years after surgery, when the effect of the IMA becomes most apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

The return of clinically evident ischemia after coronary artery bypass grafting.

Although survival after coronary artery bypass grafting (CABG) is the most serious outcome information, the quality of life in living patients is largely determined by the freedom from ischemic events. The return of angina, acute myocardial infarct and sudden death were studied in a large (n = 5880) population of patients undergoing CABG between 1971 and 1987. The freedom from angina pectoris was 95%, 83% and 63% at 1, 5 and 10 years, respectively, after surgery. Early return of angina was related to both procedure incremental risk factors (incomplete revascularization and non-use of the internal mammary (thoracic) artery (IMA) as a conduit) and patient incremental risk factors (aggressiveness of the atherosclerotic process and severity of preCABG symptoms). Late angina return was related to patient risk factors including coexisting factors (hyperlipidemia and hypertension), preCABG symptom severity and gender (female). The freedom from an acute fatal or non-fatal postCABG myocardial infarct was 99%, 96% and 85% at 1, 5 and 10 years after surgery. The incremental risk factors for early infarction were related to incomplete revascularization, but late infarction was related to lipid levels, coexisting diseases (diabetes, positive family history) and non-use of IMA to LAD. The freedom from sudden death was 99.8%, 99% and 97% at 1, 5 and 10 years, respectively, after surgery. The incremental risk factors were dominated by the severity of the left ventricular dysfunction. The freedom from any ischemic event (any of the previous three) was 93%, 79% and 54% at 1, 5 and 10 years, respectively, after surgery. The incremental risk factors included all those cited above for the specific components. Patient-specific predictions validate the influences of these risk factors. They demonstrate that unlike the profound influence of the use of the IMA on survival, there is little benefit of the use of the IMA on return of ischemic events over and above the effect of revascularization per se. The study demonstrates that most patients will experience return of ischemic symptoms within a period of 15-20 years after surgery, but that this is most likely to be return of angina and rarely sudden death.

Autogenous venous reconstruction in the treatment of aortobifemoral prosthetic infection.

The Authors describe a patient, in whom an infected aortobifemoral Dacron prosthesis was successfully replaced by an autogenous venous graft. A review of the literature is presented and it is concluded that autogenous reconstruction of the infected field represents a feasible alternative to extra-anatomical revascularisation in the treatment of selected patients with vascular prosthetic infection.

The sequential internal mammary artery graft. Long term results of a consecutive series of 364 patients.

Sequential, bilateral and free mammary grafts are employed in the current operative treatment of coronary pathology to maximize the benefit of the enhanced long-term patency of the internal mammary graft. This study reports the early and late results of a consecutive series of 364 patients in whom an internal mammary artery jumpgraft was performed. The total perioperative mortality was 1.6%, the cardiac perioperative mortality 1.0%. The perioperative infarct rate was 2.5%; the infarct rate in the mammary outflow field 1.4%. The total survival at 90 months (operative mortality included) was 92.2%, the cardiac survival at 90 months was 95.8% and the event-free group of the operative survivors was 85.2% at 90 months. The mammary artery jumpgraft can be performed without additional risk to the patient, it has a very good late result and it should be standard tool in the current coronary surgery technique. It is essential in coronary redo surgery and in patients after bilateral saphenectomy.

Long-term patency of the aortofemoral Dacron graft. A graft limb related study over a 25-years period.

Graft limb patency was studied retrospectively in a consecutive series of 912 patients (1605 limbs), who received an aorto(bi)femoral Dacron graft for occlusive disease over a 25 years period (1963-1987). The mean follow-up for the series was 5.35 years (range 1 month to 23 years) and 18.5% of the patients were followed for at least 10 years. Primary patency decreased progressively to 83% at 10 years and 77% at 15 years. It was significantly improved to 90% (at 10 years) and 84% (at 15 years) by means of operative thrombectomy (secondary patency). Factors influencing patency (univariate analysis) were (1) concomitant femoropopliteal occlusive disease, (2) the site of the femoral anastomosis and (3) the date of the operation. Multivariate analysis in relation to the femoral anastomosis stressed the importance of profunda femoris artery disease and the date of operation. It is concluded that the negative effects of concomitant superficial femoral artery disease may be completely relieved by an adequate profundaplasty. Furthermore the substantial progress, we documented over the years of the study, supports our view that aortofemoral reconstruction may also be offered as the solution of choice to patients with milder forms of claudication.

Time constraints in the emergency coronary bypass surgery for acute evolving myocardial infarction.

Fourty four patients underwent emergency coronary grafting for evolving myocardial infarction. All patients but one had undergone coronary angiography before the new infarction, 50% were in cardiogenic shock or under cardiopulmonary resuscitation. The mean time interval between the onset symptoms and opening of the bypass to the threatened area was 171 minutes. The operative mortality was 6.8%. At 30 months after surgery, the cardiac actuarial survival was 93.2%, the angina free group 94.2% of the operative survivors. Infarct size and regional ejection fraction of these patients at late follow-up were compared to those of controls treated conventionally for acute infarction. The thallium defects were smaller and the regional ejection fraction of the involved segment was higher after early surgery (less than 3 hours ischemia) than in controls. In the late surgery group the thallium defects and the regional ejection fractions were similar. Ultrastructural studies on biopsy samples taken from the center of the threatened area show reversible changes in the early surgery group but irreversible mitochondrial damage and cell membrane rupture in the late surgery group. Biochemical analysis of similar cardiac biopsies shows recovery after one hour empty beating reperfusion but only in the early surgery group. Our results suggest that coronary surgery can be beneficial to the patient with an evolving myocardial infarction, if the clinical situation does not permit intracoronary thrombolysis. However, one hour reperfusion of the empty beating heart before weaning off bypass is essential. The time constraints for both emergency surgery or thrombolysis are similar.

Is the outcome of coronary artery bypass graft surgery predictable in patients with severe ventricular function impairment?

Sixty consecutive patients, with a mean ejection fraction of 31.8% underwent coronary revascularization at the K. U. Leuven (Belgium). The operative mortality was 6%. At twelve months after surgery, the total actuarial survival was 90.0%, at twenty four months the total survival was down to 77.9%. All the preoperative data were entered into a mathematical model and using the stepwise logistic regression method, the predictability of death at 18 months postoperatively was analyzed. Using only the ejection fraction the accuracy of the prediction was 83.3%, the sensitivity 36.4% and the specificity 93.9%. Combining ejection fraction and NYHA functional classification before surgery the accuracy increased to 91.7%, the sensitivity to 72.7% and the specificity to 95.9%. Ejection fraction alone is a poor predictor of late death with only 36.4% sensitivity, but combining it with other parameters it is possible to construct a formula predicting death at 18 months with an accuracy of 91.7%.