Coronary wedge pressure: a predictor of restenosis after coronary balloon angioplasty

Coronary wedge pressure is the pressure recorded distal to a stenosis while the inflated balloon occludes the coronary artery during angioplasty. This pressure has been shown to reflect actual (visible) and potential (recruitable) collateral flow to the stenosed artery, distal to the angioplasty site. In 100 consecutive vessels (91 patients) for which coronary wedge pressure had been measured at the time of angioplasty, the long-term (7 +/- 3 months) angiographic results was evaluated. The overall angiographic restenosis rate was 37%. It was 52% (25 of 48) in arteries with a coronary wedge pressure greater than or equal to 30 mm Hg and 23% (12 of 52) in arteries with a coronary wedge pressure less than 30 mm Hg (p less than 0.01). The mean coronary wedge pressure was 30 +/- 10 mm Hg for vessels with restenosis and 26 +/- 9 mm Hg for those without restenosis (p less than 0.01). The prevalence of angiographically visible collateral flow was 42% and 29%, respectively (p = NS). Neither age, sex, presence of unstable angina, left ventricular function, number of diseased vessels nor initial and final transstenotic pressure gradient and degree of stenosis were significantly associated with the long-term outcome after angioplasty. Restenosis rate is significantly increased when coronary wedge pressure measured at the time of angioplasty is high (greater than or equal to 30 mm Hg). This suggests a negative influence of competitive collateral flow on long-term results of angioplasty.

[Change in indications for coronary angiography in a decade]

To characterize the changes in indications for coronary angiography we compared indications and therapeutic conclusions of cardiac catheterization, including coronary angiography, in 100 consecutive patients in 1975 and 100 consecutive patients in 1985. The baseline characteristics of the patients in the two groups were similar, except for age (50 +/- 10 vs 56 +/- 9 years, p less than 0.0001) and prior angioplasty (0 vs 12, p less than 0.0001). The main indications for coronary angiography in the two groups were (1975 vs 1985) chest pain in 67 vs 62 (n.s.), myocardial infarction in 10 vs 17 (n.s.), prior coronary surgery in 3 vs 0 (n.s.), major arrhythmias in 1 vs 1 (n.s.), and incidental (coronary pathology not the primary issue) in 19 vs 8 (p less than 0.05). We further analyzed each of the main indications in the two groups. Chest pain: angina ruled out in 21% vs 26% (n.s.), stable angina 64% vs 61% (n.s.), unstable angina 15% vs 13% (n.s.), positive non-invasive tests 39% vs 44% (n.s.). Myocardial infarction: acute intervention 0 vs 12% (n.s.), angina after infarction 20% vs 47% (n.s.), positive non-invasive tests after myocardial infarction 20% vs 41% (n.s.). Incidental: valvular heart disease 57% vs 63% (n.s.), cardiomyopathy 26% vs 13% (n.s.), congenital heart disease 11% vs 0 (n.s.), aortic dissection 5% vs 25% (n.s.), other 5% vs 0 (n.s.). Overall, clinical suspicion of coronary artery disease was confirmed and documented in 80% (65/81) vs 77% (61/79) of patients (n.s.), and normal coronary arteries were found in 20% (16/81) vs 23% (18/79) of patients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermodilution determination of right ventricular volume and ejection fraction: a comparison with biplane angiography

In 13 patients without tricuspid incompetence, we compared the values of right ventricular ejection fraction (RVEF) and right ventricular end-diastolic volume (RVEDV) obtained with biplane angiography and thermodilution at end-inspiration. A modification of Simpson's rule was used to measure angiographic volumes, and a new pulmonary artery catheter equipped with a rapid response thermistor was used to measure the ejection fraction by the Holt plateau method. The correlation between the two methods was acceptable (r = 0.83 for RVEF, r = 0.71 for RVEDV) despite the limitations of both angiography and thermodilution. Thermodilution underestimated RVEF and overestimated RVEDV when compared to angiography. The variation coefficient with thermodilution for five measurements of the RVEF per patient was 12 +/- 5%. In addition to pressure and cardiac output measurements, monitoring of RVEF and RVEDV in the ICU should be possible with such a catheter. Further work is needed to assess the clinical relevance of these added data and their use for optimizing the therapy of right ventricular failure in acutely ill patients.

Percutaneous transluminal coronary angioplasty by high-volume and low-volume operators

We retrospectively compared the results of percutaneous transluminal coronary angioplasty (PTCA) of three low-volume operators (1.3 PTCAs/month) to those of a relatively high-volume operator (14.9 PTCAs/month) in 396 consecutive procedures (358 patients). PTCA for multiple vessels, total occlusions, or evolving acute myocardial infarction had been excluded. For low-volume operators experienced assistance was considered present when the high-volume operator participated as second operator. The three low-volume operators performed 42, 38, and 24 PTCAs, respectively. Success rates per procedure for these operators were 88%, 84%, and 83%, and the complications rates 5%, 3%, and 13%, respectively. The success rates for assisted vs. nonassisted procedures were 89% vs. 88%, 100% vs. 78%, and 90% vs. 71%, and the complications rates were 6% vs. 4%, and 0% vs. 21%, respectively. The high-volume operator performed 292 PTCAs, with a success rate of 93%, and a complication rate of 5%. The cumulated success rate of the three low-volume operators of 85% was significantly (p less than 0.05) lower than the 93% success rate of the high-volume operator, while the complication rates of 6% and 5%, respectively, were not significantly different. Low-volume operators in an experienced center can perform PTCA safely even without assistance by a high-volume operator. However, their success rate is lower.

Coronary angioplasty: results with expanded indications

We reviewed 600 consecutive percutaneous transluminal coronary angioplasty procedures in 530 patients. There were 475 men (89%) and 55 women (11%) with a mean age of 55 +/- 9 years. Primary success per patient was 87%. Major acute complications occurred in 58 patients (10%): 2 deaths, vessel or side branch occlusion in 44 patients and ventricular fibrillation in 12 patients. Clinical follow-up was available in 344 of the first 348 patients (99%) at 12 +/- 6 months. Of these, 242 patients (70%) underwent control angiography at 12 +/- 6 months. Including repeat angioplasty, 82% of patients (281/344) with primary success were improved by at least one New York Heart Association functional class. Coronary events among the patients with no improvement were one sudden death, one myocardial infarction, and 16 bypass operations. Four subgroups of special interest were analysed: multivessel angioplasty (100 patients), angioplasty for chronic total occlusion (100 patients), angioplasty for evolving myocardial infarction (50 patients), and repeat coronary angioplasty (70 patients). Primary success rates were 87, 56, 84 and 90%, complication rates 9, 0, 9, and 3%, and recurrence rates 41, 48, 23, and 48%, respectively. At follow-up, improvement by at least one New York Heart Association class was observed in 77, 85, 88, and 80% of patients, respectively. Successful coronary angioplasty including repeat procedures achieved a long-term clinical success in about 80% of patients.

Improvement of left ventricular contraction and relaxation synchronism after recanalization of chronic total coronary occlusion by angioplasty

Twenty patients with a chronic total coronary artery occlusion were studied before and 1 to 48 months (mean 9) after successful recanalization by angioplasty and compared with a group of 20 normal subjects. Before angioplasty, 19 of these 20 patients had angina. Collateral vessels to the distal part of the occluded vessel were visible in all 20 patients. A previous myocardial infarction was documented in 14 patients (9 with a Q wave and 5 with a non-Q wave infarction). At the time of follow-up, three patients were symptomatic: one had unstable angina and two had a positive stress test. The follow-up angiogram showed a significant restenosis in six patients and reocclusion in two. The mean ejection fraction had improved slightly from 59 +/- 11% to 63 +/- 9% (p less than 0.05). Left ventricular wall motion synchronism was studied using two variables for 128 shortening segments: the "time of peak contraction" and the "time of peak relaxation," as obtained from biharmonic Fourier transformation for each segment. Their respective standard deviations reflect the synchronism of contraction and relaxation. The mean standard deviations of the two variables expressed in degrees of one cardiac cycle (360 degrees) were respectively: 5.5 +/- 0.4 degrees for the time of peak contraction and 6.0 +/- 0.5 degrees for the time of peak relaxation in the 20 normal subjects, 11.7 +/- 1.7 degrees and 23.0 +/- 3.0 degrees before recanalization and 9.6 +/- 1.8 degrees and 12.5 +/- 2.2 degrees at follow-up in the group of 20 patients. These values were significantly higher (p less than 0.05) in the patients than in the normal group.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous transluminal coronary angioplasty for chronic total coronary arterial occlusion

Experience is reported with 100 consecutive patients in whom percutaneous transluminal coronary angioplasty (PTCA) was attempted on chronically occluded coronary arteries that had no visible anterograde flow. Ninety-eight patients had angina and all had collateral vessels to the occluded artery on angiography. A movable guidewire/dilatation system was used in all cases. Overall initial PTCA success rate was 56% and was related to duration of occlusion (69% success rate for occlusions of 1 month or less, 50% for 1 to 6 months and 11% after 6 months). Complications were minor; no patient died or required emergency bypass operation. Of the 44 patients in whom PTCA failed, 20 underwent elective bypass surgery for relief of angina and 24 were treated medically. Follow-up at a mean of 8 months (range 1 to 48) was available for 49 of the 56 patients in whom PTCA was successful: 40 had subjective improvement, 6 no change and 3 felt worse. Control angiography was carried out in 40 of the 56 patients with primary success and showed long-term success in 18 and reocclusion or significant stenosis in 22. Of these 22, 11 were successfully treated by a second PTCA, 2 underwent operation and 9 were treated medically. Recanalization of totally occluded coronary arteries with no forward flow has a lower initial success rate (56%) than PTCA for stenoses and the recurrence rate is higher (55%), but effective relief of angina is achieved in successful cases. The risk of serious complications appears to be low.

Lifelong reversal of the metabolic abnormalities of advanced diabetes in rats by whole-pancreas transplantation

Evidence suggests that metabolic abnormalities are responsible for the widespread microvascular complications of insulin-dependent diabetes mellitus (IDDM). Interest in endocrine pancreas replacement therapy, including pancreas transplantation, is based on the hope that such treatment will reverse the complications of IDDM by providing more precise metabolic control than conventional therapy. To determine if whole pancreas transplantation is capable of reversing well-established metabolic abnormalities of diabetes mellitus (DM) and maintaining strict metabolic control for life, we performed monthly metabolic studies for 2 years in 141 nondiabetic control rats, 273 diabetic control rats with alloxan-induced DM, and 267 diabetic rats that received syngeneic whole pancreaticoduodenal transplants 6, 9, 12, 15, 18, and 21 months after induction of DM with alloxan. Whole-pancreas transplantation in rats with long-standing DM permanently reversed the metabolic disorders. Elevated plasma glucose concentrations were permanently reduced to normal, depressed plasma insulin levels were permanently increased to normal, elevations of BUN and serum creatinine were permanently normalized, and there was a striking gain in body weight. Hyperglycemia during glucose tolerance tests was of lesser magnitude and shorter duration than normal, as a result of greater-than-normal plasma insulin levels. The only abnormality that persisted was hyperglucagonemia, but it did not interfere with control of hyperglycemia and is of unknown significance. These results indicate that whole-pancreas transplantation produces the most complete and sustained correction of the metabolic abnormalities of experimental DM of any available therapeutic modality.

The hemodynamic effects of heparin and their relation to ionized calcium levels

Heparin complexes calcium in vitro and possesses vasodilating properties when given as an intravenous bolus. To investigate the possibility that these hemodynamic effects could be related to the ability of heparin to induce hypocalcemia in vivo, we studied the response to a bolus of heparin, 300 IU/kg, in 20 patients undergoing cardiopulmonary bypass for cardiac operations. Ionized calcium decreased significantly after heparin administration, as did mean arterial pressure and systemic vascular resistance. In a further nine patients, 125 mg of calcium chloride was given immediately before the heparin bolus. It induced a small rise in calcium levels and maintained the mean arterial pressure at unchanged values. Our data confirm the vasodilating effect of an intravenous bolus of heparin and show that it is related to an acute lowering of ionized calcium levels. When calcium levels are not allowed to drop, the blood pressure is maintained at stable values. We advise slow injection of the heparin bolus and special attention to the ionized calcium levels before cardiopulmonary bypass.

Morphology of healing in vascular prostheses

Vascular grafts differ in shape and size, material, mode of construction, and porosity. The latter was found to be of great importance with respect to tissue response of the host to the graft. The first reaction of the host after implantation represents the phase of exsudation. An aggregate of platelets and fibrin will cover most of the luminal and external surface of the graft, which is also seen between the interstices. The following phase of resorption develops within 2 weeks. It is characterized by replacement of the fibrinous material on the outer surface and between the interstices by capillaries, histiocytes, and myofibroblasts. Organisation of the outer capsule will then occur, and is also seen inside the transprosthetic bridges within one month. However, organization of the luminal lining remains very slow and is almost never completed. Healing depends on blood flow and local hemodynamic factors, and a mismatch in mechanical properties between the graft and host vessel may be important. Sources of endothelium in graft healing are anastomotic sites, pluripotent cells growing through the graft wall or deposition of pluripotent cells from the blood. Early failure of a prosthetic vascular graft occurs mainly as a result of separation at its sites of attachment. Late complications may be the result of mechanical failure (anastomotic sites or within the graft), kinking, inadequate or incomplete healing, and infection. The incidence of infectious complications varies from 0.25% to 6.0%, usually associated with high mortality rates.

Intermolecular hydrogen transfer catalyzed by a flavodehydrogenase, bakers' yeast flavocytochrome b2

Bakers' yeast flavocytochrome b2 is a flavin-dependent L-2-hydroxy acid dehydrogenase which also exhibits transhydrogenase activity. When a reaction takes place between [2-3H]lactate and a halogenopyruvate, tritium is found in water and at the halogenolactate C2 position. When the halogenopyruvate undergoes halide ion elimination, tritium is also found at the C3 position of the resulting pyruvate. The amount tau of this intermolecular tritium transfer depends on the initial keto acid-acceptor concentration. At infinite acceptor concentration, extrapolation yields a maximal transfer of 97 +/- 11%. This indicates that the hydroxy acid-derived hydrogen resides transiently on enzyme monoprotic heteroatoms and that exchange with bulk solvent occurs only at the level of free reduced enzyme. Using a minimal kinetic scheme, the rate constant for hydrogen exchange between Ered and solvent is calculated to be on the order of 10(2) M-1 S-1, which leads to an estimated pK approximately equal to 15 for the ionization of the substrate-derived proton while on the enzyme. It is suggested that this hydrogen could be shared between the active site base and Flred N5 anion. It is furthermore shown that some tritium is incorporated into the products when the transhydrogenation is carried out in tritiated water. Finally, with [2-2H]lactate-reduced enzyme, a deuterium isotope effect is observed on the rate of bromopyruvate disappearance. Extrapolation to infinite bromopyruvate concentration yields DV = 4.4. An apparent inverse isotope effect is determined for bromide ion elimination. These results strengthen the idea that oxidoreduction and elimination pathways involve a common carbanionic intermediate.

[Sudden death outside the hospital: evaluation of the activities of an intensive care mobile unit in Geneva]

A prospective study on the treatment of out-of-hospital cardiac arrest by a mobile intensive care unit was conducted in Geneva for 1 year. 76 attempts at cardiopulmonary resuscitation (CPR) were made: 25 patients were admitted to the intensive care unit (33%) and 13 lived to be discharged from hospital (17%). Age, initial arrhythmia and duration of cardiopulmonary arrest (CPA) were important factors in determining the initial success of CPR. Long-term survival was associated with CPA of less than 4 minutes duration, with bystander-initiated CPR and with CPR lasting less than 30 minutes. Better education of the public and more direct access to the system should make it possible to treat more patients in more favourable conditions and improve overall results. A more determined effort to educate the public in CPR would also improve the prognosis in out-of-hospital cardiac arrest.

Facilitated determination of ionized calcium

Using a calcium-containing heparin preparation for anticoagulation, we determined [Ca2+], the mean concentration of ionized calcium, in whole blood of 120 healthy blood-donors to be 1.23 (SD 0.04) mmol/L. Similarly, for 50 intensive-care patients selected without conscious bias, the correlation between [Ca2+] in serum (mean 1.15, SD 0.10 mmol/L) and in whole-blood samples anticoagulated with the same heparin preparation (mean 1.15, SD 0.09 mmol/L) was very good (r = 0.95). Storing samples anaerobically on ice for as long as 2 h did not alter whole-blood [Ca2+]. On the other hand, various concentrations of calcium-free heparin preparations all induced a significant decrease in measured [Ca2+]. By using whole-blood samples, rather than plasma or serum, for [Ca2+] determination with a calcium-selective electrode, repetitive measurements can be made with simple handling procedures, facilitating rapid implementation of appropriate therapeutic measures for critically ill patients.

Facilitated determination of ionized calcium

Using a calcium-containing heparin preparation for anticoagulation, we determined [Ca2+], the mean concentration of ionized calcium, in whole blood of 120 healthy blood-donors to be 1.23 (SD 0.04) mmol/L. Similarly, for 50 intensive-care patients selected without conscious bias, the correlation between [Ca2+] in serum (mean 1.15, SD 0.10 mmol/L) and in whole-blood samples anticoagulated with the same heparin preparation (mean 1.15, SD 0.09 mmol/L) was very good (r = 0.95). Storing samples anaerobically on ice for as long as 2 h did not alter whole-blood [Ca2+]. On the other hand, various concentrations of calcium-free heparin preparations all induced a significant decrease in measured [Ca2+]. By using whole-blood samples, rather than plasma or serum, for [Ca2+] determination with a calcium-selective electrode, repetitive measurements can be made with simple handling procedures, facilitating rapid implementation of appropriate therapeutic measures for critically ill patients.

Baker's yeast flavocytochrome b2. A mechanistic study of the dehydrohalogenation reaction

It has been shown that reduced flavocytochrome b2 not only catalyzes reduction of bromopyruvate [P. Urban, P.M. Alliel and F. Lederer (1983) Eur. J. Biochem. 134, 275-281] but also transforms it into pyruvate in a reductive elimination process. The dehydrohalogenation reaction also takes place when oxidized enzyme acts on bromolactate, but the reaction is more difficult to observe under these conditions because of its low efficiency compared to the normal oxidative process. The maximal rates of pyruvate production from bromopyruvate and chloropyruvate differ by a factor of less than 10, whereas elimination from fluoropyruvate cannot be detected. These results support a mechanism in which the dehydrohalogenation reaction takes place from a carbanion intermediate of the normal reductive-oxidative pathway.

Thromboxane A2 in acute myocardial infarction

We evaluated the presence of thromboxane B2, the stable metabolite of thromboxane A2, early in the course of acute myocardial infarction (AMI) in both animal and patient studies. In an open-chest model, the left anterior descending artery (LAD) was isolated and the great cardiac vein was cannulated in nine dogs. Following occlusion of the LAD, there was an increase in thromboxane B2 concentration from 0.77 +/- 0.0093 to 1.79 +/- 0.46 pmol/ml (p less than 0.05) and 1.96 +/- 0.48 pmol/ml (p less than 0.05) at 1 and 5 minutes, respectively, following coronary occlusion. At 30 and 60 minutes after occlusion there was no significant increase compared to the baseline. In 17 patients with AMI the mean thromboxane B2 concentration was 0.96 +/- 0.13 pmol/ml at 4.88 +/- 0.40 hours after the onset of chest pain. In 12 patients with sequential samples before and after restoration of patency of the occluded vessel, the initial concentration was 0.71 +/- 0.058 pmol/ml. At 5 minutes after restoration of patency thromboxane B2 concentration was 1.1 +/- 0.17 pmol/ml (p = 0.05). One hour later a return to baseline was noted (0.82 +/- 0.75 pmol/ml). Two patients with the highest thromboxane B2 concentrations (2.0 and 2.6 pmol/ml) were unable to have successful recanalization. We conclude that generation of thromboxane A2 occurs during the early stages of AMI and may be an important pathophysiologic phenomenon in AMI.

Limitation of infarct size with thrombolytic agents--electrocardiographic indexes

Forty-four patients with acute transmural myocardial infarction underwent cardiac catheterization 4.7 +/- 1.3 hours (+/- SD) after the onset of persistent chest discomfort. Thirty-nine patients had total occlusion of infarct-related vessels; 27 of these 39 had successful intracoronary thrombolysis. Twenty of these 27 patients (74%) had reperfusion arrhythmia. Accelerated idioventricular rhythm was most often observed with reperfusion of all myocardial zones, while sinus bradycardia and hypotension accompanied reperfusion of the inferoposterior left ventricle. Three patients with spontaneous accelerated idioventricular rhythm had patient, stenosed, infarct-related vessels on the initial coronary angiogram. Patients with unsuccessful intracoronary thrombolysis did not demonstrate these specific arrhythmias. While there is rapid control of injury current with successful intracoronary thrombolysis, Q waves develop rapidly after reperfusion; however, in the days after intracoronary thrombolysis, there is a decline in Q wave with partial regrowth in R wave amplitude in some patients. Thus, specific arrhythmias, most notably accelerated idioventricular rhythm, are useful markers for the occurrence and timing of successful coronary arterial recanalization. In addition, rapid control of injury current and partial regrowth of R waves are electrocardiographic markers of myocardial salvage.

On the transhydrogenase activity of baker's yeast flavocytochrome b2

It is shown that, when baker's yeast flavocytochrome b2 is incubated with bromopyruvate in the presence of excess lactate, a transhydrogenation reaction takes place which produces bromolactate and pyruvate. The heme remains reduced during the reaction. It is further shown that reduced flavocytochrome b2 can catalyze the reduction of a number of other keto acids like pyruvate (the product of the physiological reaction) and other halogenopyruvates. Determinations of forward and reverse reaction rates, as well as of the redox potentials of the halogenolactate/halogenopyruvate couples lead to the conclusion that the transhydrogenation reaction is under thermodynamic control. Determinations of the steady-state deuterium isotope effect show that the rate-limiting step in the oxidation of halogenolactates is abstraction of the alpha-hydrogen (probably as a proton), as is the case for lactate itself. According to the principle of microscopic reversibility, the rate-limiting step in the reverse reaction must be protonation of the putative carbanion.