Biomedical subjects

E D de Muinck

Publications and source records attributed to E D de Muinck.

25 records · Page 2Linked to original sources

PubMed1993

In vitro evaluation of blood flow through autoperfusion balloon catheters.

The effective flow rates with human blood through an autoperfusion catheter cannot be monitored in vivo and have not been experimentally determined in vitro. The manufacturers (Advanced Cardiovascular Systems [ACS], Temecula, CA) have suggested that "the flow rate" through the Stack over the wire and the RX-60 monorail catheter is 60 ml/min with a pressure gradient of 80 mmHg. We measured human blood flow rates in vitro through these catheters under different continuous pressure regimens (between 40 and 120 mmHg), with varying hematocrit levels (between 25% and 62%). Measured blood flows at a gradient of 80 mmHg were found to vary from 32 to 65 cc/min, with hematocrit levels of 62-25%. Minor variations in the circuitry, besides the viscosity of the medium, cause significant changes in observed flow rates (such as kinking of the catheter and blood sedimentation). In vitro determinations of blood flows cannot automatically be transferred to the in vivo condition, primarily because in vitro determinations do not account for the systolic intramural pressure increase (which may overcome the aortic pressure). If such a phenomenon is also considered, then the in vitro flow rates reported here should be multiplied by a factor of 0.40-0.60 to determine effective in vivo flow rates. Such information is relevant for the clinical operator of angioplasty, especially in the treatment of patients at high risk for undergoing percutaneous transluminal coronary angioplasty.

Angioplasty, Balloon, Coronary↗

PubMed1993

Late onset atrioventricular nodal tachycardia.

AV nodal tachycardia may present at any age, but onset in late adulthood is considered uncommon. To evaluate whether onset of AV nodal tachycardias at older age is related to organic heart disease (possibly setting the stage for re-entry due to degenerative structural changes) 32 consecutive patients with symptomatic AV nodal tachycardia were studied. The age at onset of attacks showed a bimodal pattern, with 2 peaks: one between 15 and 35 years (22 patients) and one around 55 years (10 patients). Significantly more older patients had an underlying heart disease (60% versus 14%, P < 0.01), with coronary artery disease in 4 and hypertensive heart disease in 3. Frequent supraventricular ectopic activity was seen during baseline 24-h ambulatory monitoring in all the older patients, versus in only half of the younger patients (P = 0.005). These results indicate that late onset AV nodal tachycardia (i.e. > age 45 years) is not infrequent (33%). The frequent supraventricular arrhythmias on one hand and age-related structural AV nodal changes, potentially enhanced by underlying heart disease on the other, both may contribute to the development of late onset re-entrant AV nodal tachycardia.

Adult↗

PubMed1993

The PUCA pump: a left ventricular assist device.

Left ventricular assist devices (LVADs) that are being used clinically still have specific drawbacks. Therefore, a new concept for mechanical circulatory support was developed, the pulsatile catheter (PUCA) pump. It consists of an extracorporeally placed, pneumatically driven membrane pump that is connected to a valved catheter. The catheter is introduced into an easily accessible artery and positioned with its distal tip in the left ventricle. Blood is aspirated from the left ventricle and ejected into the ascending aorta. Potential advantages of the catheter pump are its simple design and its fast application with minimal surgery. Preliminary in vitro tests with a first prototype showed that it is possible to create a pulsatile flow of 3 L/min and proved that further developing the PUCA pump will be worthwhile.

Heart-Assist Devices↗

PubMed1992

Autoperfusion balloon catheter for complicated coronary angioplasty: a prospective study with retrospective controls.

Prolonged angioplasty balloon inflation with an autoperfusion balloon for failed conventional coronary angioplasty, was compared with emergency surgery for this condition. Restenosis was assessed 6 weeks after successful intervention with the autoperfusion balloon. Forty consecutive patients with persistent acute occlusion and/or severe intimal dissection during conventional angioplasty, were treated with the autoperfusion balloon. They were candidates for emergency surgery if it failed. Total inflation time was significantly longer (p < 0.001) with the autoperfusion balloon (27.5; 10-180 min) than with the standard balloon (10; 1-20 min) (median; range). The number of inflations was significantly lower (p < 0.001) with the autoperfusion balloon (2; 1-5 times) than with the standard balloon (5; 2-14 times) (median; range). Two patients died, one before surgery could be performed. The autoperfusion balloon was successful in 26 patients (65%). After 6 weeks, 16 (62%) were asymptomatic without anti-anginal medication, 24 underwent repeat angiography, 10 (42%) had restenosis, 7 (27%) underwent elective bypass surgery. Emergency surgery remained necessary in 13 patients (33%), 9 received arterial grafts. In 31 retrospective controls, who had undergone immediate surgery for the same indication, only venous grafts could be used. Thus, prolonged autoperfusion balloon inflation was successful in 65% of the cases of failed, conventional angioplasty. The angiographic restenosis rate after 6 weeks was 42%. If emergency surgery remained necessary, the autoperfusion balloon facilitated the use of arterial bypass grafts.

Angioplasty, Balloon, Coronary↗

PubMed1992

Comparison of the safety and efficacy of bisoprolol versus atenolol in stable exercise-induced angina pectoris: a Multicenter International Randomized Study of Angina Pectoris (MIRSA).

Bisoprolol 10 mg and atenolol 100 mg once daily were compared regarding efficacy and safety in stable effort angina in a 12-week, multicenter, double-blind, randomized, parallel-group study. Efficacy was evaluated with angina pectoris diaries and bicycle exercise tests. Spontaneously mentioned complaints and side effects were recorded at each visit. In 11 centers, 147 patients completed the study; 76 received bisoprolol 10 mg, and 71 received atenolol 100 mg. After 12 weeks, weekly anginal attack rate was reduced significantly (p less than 0.05) with bisoprolol (5 +/- 0.5 to 2 +/- 0.6) and with atenolol (4 +/- 0.4 to 1 +/- 0.2). Peak exercise capacity (in W x min) increased significantly (p less than 0.05) with bisoprolol (772 +/- 47 to 878 +/- 52) and with atenolol (891 +/- 46 to 986 +/- 53). Rate pressure product (RPP) at peak exercise (in beats/min x mm Hg) decreased significantly (p less than 0.05) with both bisoprolol (25,003 +/- 692 to 20,116 +/- 637) and atenolol (26,544 +/- 557 to 21,603 +/- 576) (all values are mean +/- SE). The differences between the groups were not statistically significant. There were no significant differences regarding nature and incidence of adverse events between the groups. Thus, bisoprolol 10 mg once daily and atenolol 100 mg once daily are equipotent in their effects on stable effort angina. Both regimens were comparable with respect to incidence and nature of side effects.

Adult↗

PubMed1990

Safety and efficacy of beta-blockers in the treatment of stable angina pectoris.

In stable exercise-induced angina pectoris, beta-blockers exert their beneficial effects mainly through a reduction in heart rate, blood pressure. and contractility. Additional beneficial effects are an improvement in myocardial oxygen supply through a redistribution of coronary flow, a lengthening of diastole, a facilitation of aerobic metabolism, and a rightward shift of the oxygen-hemoglobin dissociation curve. Cardioselective beta-blockers can be expected to have fewer side effects than the nonselective drugs. Apart from a reduction in anginal attack rate and an improvement in exercise capacity, a reduction in silent ischemia may be desirable when treating patients with stable effort angina, beta-blockers effectively reduce asymptomatic ischemia. Bisoprolol is a new beta1-selective beta-blocker with a clear 24-h duration of action regarding symptoms and improvement of exercise capacity in patients with stable exercise-induced angina pectoris. Bisoprolol 10 mg and atenolol 100 mg are equipotent in achieving these effects.

Adrenergic beta-Antagonists↗

PubMed1990

Bisoprolol pilot studies in myocardial infarction.

The efficacy of beta-blockade after myocardial infarction (MI) has been investigated in a series of studies. When beta-blockers are used during the first hours after the onset of MI, a reduction in infarct size, mortality, and nonfatal reinfarction may occur. Bisoprolol is a highly beta1-selective beta-blocker, without intrinsic sympathomimetic activity (ISA), and with a plasma elimination half-life of 10-12 h, permitting treatment with one daily dose. Because no experience with bisoprolol was available in MI, its safety and efficacy were studied in two open, uncontrolled pilot studies. The first study was a dose-finding study in 37 patients with a 3-day-old MI. Bisoprolol was given intravenously and carefully titrated in steps of 1 mg up to a cumulative maximum dose of 5 mg. Subsequently, the patients received 10 mg of oral bisoprolol once daily (o.d.) until the end of the study. Based on the results of this first pilot study, a second pilot study was performed in which bisoprolol was given within the first 6 h after the onset of MI. Intravenous (i.v.) bisoprolol was titrated in two steps of 2.5 mg each, directly followed by 10 mg of oral bisoprolol o.d. The aim of this study was to investigate the influence of i.v. and subsequent oral bisoprolol on central hemodynamics. The results of these studies demonstrate that i.v. and subsequent oral administration of bisoprolol is well tolerated and indicate that the selected dose regimen is hemodynamically safe.

Administration, Oral↗