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Biomedical subjects

M Schlepper

Publications and source records attributed to M Schlepper.

At least 127 records · Page 7Linked to original sources
PubMed1982

Coronary hemodynamics in simulated paroxysms of ventricular tachycardia: role of myocardial impairment and of extravascular resistance.

In 6 patients with healthy hearts (controls), 17 with coronary artery disease (CAD) and 6 with left ventricular hypertrophy due to aortic valvular disease, aortic pressure, coronary sinus blood flow (CSF) and lactate extraction were determined before and after the sudden onset of a paced ventricular tachycardia of 170 bpm (VT 170 = simulated paroxysmal ventricular tachycardia). Comparison to parameter changes during dipyridamol vasodilation revealed reduced coronary vascular reserve for CAD and hypertrophy. While VT induced a reduction of aortic pressure (stabilized by an average of 22%, and most excessively for CAD; p less than 0.05) and CSF remained at/or slightly above control levels (by an average of 31%; p greater than 0.05) equally for all groups (p greater than 0.05), lactate production in the groups with CAD and hypertrophy indicated myocardial impairment by ischemia. Excessively greater increases of CSF during dipyridamol vasodilation (vs. VT) for all groups suggested VTs extravascular resistance increase to have limited the extent of the potential of coronary vascular decrease. With one variable being kept constant (i.e. 'clamping' the vascular component of coronary resistance at its limit by dipyridamol), tachycardia during dipyridamol (D) vasodilation (VT 170+D and VT 140+D) in the controls and in the CAD group resulted in a linear decrease of CSF, allowing quantification of impaired coronary reserve for CAD. We concluded from the observations that: (1) paroxysmal VT demands fast therapeutic action foremost in the impaired myocardium, and (2) tachycardia per se acts as limiting factor for coronary blood flow via increase in extravascular resistance (aside from a shortened diastole).

Aorta↗
PubMed1982

[Efficacy of nicorandil (SG-75), a substance with nitro-properties and long-term effects in coronary patients: improvement of LV-function and wall motility without pacing-induced myocardial ischemia].

Following trials in Japan, Nicorandil (SG-75) has been introduced as a new antianginal drug with coronary dilatory properties. The effects of 20 mg SG-75 administered sublingually were studied in 9 patients with coronary artery disease and reproducible pacing-induced myocardial ischemia (MIS) (rise in left ventricular enddiastolic pressure, changes in ST-segment, and angina). Changes in heart rate, arterial pressure and angiographic left ventricular ejection parameters, contractility, parameters derived from left ventricular function (ejection fraction, cardiac index, stroke work index) and cardiac work (left ventricular stroke work index, left ventricular work), myocardial oxygen consumption, cardiac efficiency (LVeff), and regional wall motion (RWM) were investigated for the following hemodynamic phases: 7th and 14th minute after SG-75, the immediate postpacing phase without medication (PPP), and the postpacing phase under the influence of SG-75 (PPP + SG). In the 7th and 14th minute after SG-75 and in the absence of stress, there was no variation from control values (p less than 0.05). In the 15th and 16th minute after SG-75 (serum-level control), under pacing stress equivalent to that measured in the PPP, the MIS observed in the absence of medication did not now occur. Moreover, in the PPP + SG-75 phase the following mean parameter changes were noted: ejection fraction +21%, cardiac index +37%, left ventricular stroke work index +48%, left ventricular work +52%, and LVeff +60%; RWM also improved. Prophylaxis of ischemia and improved hemodynamics under the influence of SG-75 were probably due to a decrease in preload (left ventricular enddiastolic pressure -41%) and afterload (stroke volume ratio -29%). Similar changes might have been expected after nitroglycerin, if given under equivalent conditions. Since no harmful effects, either subjective or objective, were apparent during or after application of SG-75, this seems to be a promising drug for the antianginal therapy of the future.

Aged↗
PubMed1982

[Heart rate reduction in atrial fibrillation with a rapid ventricular response by Gallopamil, a Ca-antagonist (author's transl)].

20 patients with atrial fibrillation and rapid ventricular response were treated with the new calcium-antagonist Gallopamil. The effects on heart rate were evaluated by Holter-monitoring. A significant decrease of heart rate with a duration of 10 hours was found in 10 patients after acute oral administration of 100 mg Gallopamil. In 5 patients a regularization of the ventricular response was observed, suggesting an AV junctional escape rhythm during AV nodal block. However, no relevant bradycardia was seen. The maximal decrease of heart rate was seen 2 to 4 hours after application. Oral administration of 3 times 50 mg Gallopamil daily decreased heart rate after a treatment period of 1 week to about 79% of its control values. This effect started 1 hour after application of the first dose in the morning and it lasted for 7 hours after the evening dose.

Administration, Oral↗
PubMed1982

[Mechanism and effects of the cardiotonic AR-L 115 BS in coronary heart disease: improved ventricular function and regional wall motility without angina pectoris].

UNLABELLED: The use of new cardiotonic drugs, such as AR-L 115 BS (ARL), in patients with coronary artery disease (CAD) might be limited by their aggravating myocardial ischemia (MIS). Accordingly, we investigated ARL's (2 mg/kg BW i.v.) hemodynamics, myocardial oxygen consumption (MVO2) and regional wall motion (RWM) in 30 patients with CAD presenting with pacing-induced MIS (angina, rise of LVEDP, lactate production). ARL improved LV-pump function in 13 group-1 patients (average increases: cardiac index by +25%; LV-work by +17%; dp/dtmax by +30%; coronary sinus flow by +39%), while there was a decrease in preload (LVEDP by -44%) and afterload (AOMP by -9%) and cardiac efficiency by -25%. Such ARL-effects required a rise of MVO2 by +41% but did not induce MIS. These beneficial results were corroborated by significant hemodynamic improvements also in 17 group-2 patients when comparing the non-medicated immediate post-pacing period (PPP) with MIS versus the ARL-medicated PPP (= PPP + ARL) without MIS, where RWM improved by an overall average of 26 +/- 11% in the phase PPP + ARL. CONCLUSION: In CAD ARL improves hemodynamics and RWM. The mechanism is pre- and afterload reduction, increase in contractility, MVO2 and CSF without MIS being induced.

Cardiotonic Agents↗
PubMed1982

[Hemodynamic consequences of suddenly abolished atrial contraction].

The effects of several modes of stimulation (right ventricular pacing during sinus rhythm, right ventricular pacing during induced atrial fibrillation, and atrioventricular (AV) sequential pacing with an AV delay of 130 msec) on blood pressure and cardiac output were investigated in 10 patients with normal left ventricular function. The stimulation rates were 110, 140, and 170/min for each stimulation mode. There were no significant differences between ventricular pacing in sinus rhythm and ventricular pacing in atrial fibrillation as regards blood pressure and cardiac output. Ventricular stimulation during atrial fibrillation resulted in a significant fall in systolic blood pressure (84%, p less than 0.05) even at a rate of 140/min, whereas in AV-sequential pacing systolic blood pressure only fell to 87% of the baseline value at a rate of 170/min. A significant decrease in cardiac output occurred at rates of 140/min ventricular pacing during atrial fibrillation and at rates of 170/min with AV-sequential pacing. The results underline the importance of active ventricular filling in tachycardia. There were no significant differences in the measured parameters when ventricular pacing with AV-dissociation was compared with ventricular pacing at identical rates during atrial fibrillation.

Atrial Fibrillation↗
PubMed1982

[Complications in the venous system in patients with transvenous implanted pacemakers].

There is a little account in the literature regarding early and late thrombotic complications in connection with permanent pacer application (PPA), although, clinically this is of relevance. Therefore, upper thoracic phlebography (UTP) was carried out 44 +/- 10 months after PPA in 100 consecutive pts with a mean age of 62 years. Sixty-one UPTs were normal, 15 UTPs showed occlusions of the axillary and/or subclavian vein and 24 presented with minor thrombotic changes. Reliable clinical diagnoses had been made in 10 pts only prior to UTP. In addition, 12 pts had UTPs 19 +/- 12 months after malfunctioning electrodes had been severed and each proximal stump left within the venous cavity on occasion of the repeated PPA. Clinical complications in these pts consisted of total occlusion of the superior caval vein in 2 and multiple pulmonic embolism (clinically and scintigraphically) in 3 pts. With the mobile part of the retained electrode above the left brachiocephalic vein inflow in 8 pts, occlusion had taken place in this very region. In addition, the free floating stump of the electrode was found in the pulmonary artery, in the right atrium and the right ventricle, in one pt each.

Adult↗
PubMed1981

[Clinidine-induced bradycardia: studies of the effect on the human sinus node (author's transl)].

Heart rate, atrioventricular conduction, sinus-node recovery time and effectiveness of carotid-sinus massage on heart rate were measured before and every five minutes after intravenous injection of 0.15 mg clonidine (Catapresan) in 11 patients (averaged age 60 years) with symptomatic bradycardia (dizzy spells, syncope, palpitations). Th results indicated the following significant (P less than 0.05) mean maximal effects: heart rate fell by 12% (from 59 to 52/min), capacity of atrioventricular conduction by 9% (from 132 to 121/min), while maximal sinus-node recovery time ("over-drive suppression") doubled (from 1704 to 3562 ms), heart rates of 120, 150 and 200/min being used for diagnostic atrial overdrive stimulation at each five-minute period after clonidine. During clonidine administration three patients developed a so-called hypersensitive carotid sinus reflex, in two patients the effectiveness of carotid sinus massage decreased, in three if increased, while in three it remained normal. It is concluded that (1) during bradycardia, initiated or increased by sympatholytic drugs, tests should be undertaken to exclude latent sinus-node syndrome and (or) hypertensive carotid-sinus reflex; (2) clonidine should not be used in patients with signs of sinus-node dysfunction.

Aged↗
PubMed1981

Hemodynamic properties of St. Jude medical and Björk-Shiley valvular prostheses in mitral position in the pulse duplicator.

A general lack of standardization of the pre-clinical testing of artificial valves leads to an actual comparison of different prosthetic models at the time of a first clinical trial, frequently with contradictory results. Therefore, a pulse duplicator was developed in order to compare different valves of comparable size under identical standardized conditions in aortic and mitral positions. Comparison of Björk-Shiley and St. Jude medical prostheses in the duplicator revealed a linear relationship between pump setting and stroke volume delivered (r less than or equal to 0.9) for both valves. Pressure loss across the mitral valves showed a linear relationship to stroke volume (less than or equal to 0.9) and frequency (less than or equal to 0.9). The gradient, expressed per milliliter stroke volume, for identical frequencies appeared as the simplest and most suitable parameter for comparison of the hydraulic function of different valves. Using this parameter, the valves showed individual differences over a wide physiological range of testing. The differences, however, are of a magnitude that can hardly be detected under clinical testing conditions.

Aortic Valve↗
PubMed1981

Hemodynamics alterations induced by isoproterenol and pacing after aortic valve replacement with the Björk-Shiley or St. Jude medical prosthesis.

Stress evaluation was carried out in 26 patients approximately 7 months after aortic valve replacement with Björk-Shiley valves (13 patients) and St. Jude medical valves (13 patients). During isoproterenol infusion (0.3 micrograms/kg/min), cardiac output increased by a factor of 1.5 and aortic valve area decreased by 50% for both valve groups, while transvalvular gradients (rest: 7 +/- 2 vs 10 +/- 5 mm Hg, p greater than 0.05) increased by 42 +/- 18 vs 51 +/- 18 mm Hg (p greater than 0.05), i.e., to levels of moderate aortic stenosis. However, during pacing stress these values progressively decreased with rising heart rates. In other postoperative evaluations that included ergometric stress with isoproterenol and pacing, induced hemodynamic changes after aortic valve replacement were predictable and consistent with regard to both direction and magnitude, and they differed characteristically according to the type of stress used. We conclude that no functional differences between Björk-Shiley and St. Jude medical valves can be claimed. Standardized evaluation with isoproterenol is a sensitive stress test of prosthetic valvular hemodynamics. Because of the apparent magnification of residual obstruction after aortic valve replacement, it has advantages over pacing.

Aortic Valve↗
PubMed1981

Effects of clonidine on sinus node function in man.

Drugs interfering with sympathetic tone may result in depression of the function of the sinus node, especially in patients with disease of the sinus node. In 11 patients presenting with palpitations, vertigo, or syncope, the heart rate, the recovery time of the sinus node, the carotid sinus pressure slowing, and the atrioventricular conduction capacity were assessed before and every five minutes up to 30 minutes after intravenous administration of 0.15 mg of clonidine. The following significant maximal mean effects were noted at about 15 minutes after the administration of clonidine: the heart rate decreased 12 percent (59 vs 52 beats per minute); and the atrioventricular conduction capacity (ie, paced heart rate at second-degree atrioventricular block) decreased by 9 percent (132 vs 121 beats per minute), while the maximal recovery time of the sinus node increased by a factor of two (1,704 vs 3,562 msec) when atrial overdrives of 120, 150, and 200 beats per minute were used for each five minute period. In analyzing maximal carotid sinus pressure slowing after administration of clonidine, three of 11 patients developed hypersensitive carotid sinus reflex de novo, and two patients showed a decrease and three patients an increase of carotid sinus pressure slowing, while three patients had no carotid sinus pressure slowing both before and after administration of clonidine. We conclude that caution should be taken in administering clonidine to patients with signs indicative of dysfunction of the sinus node.

Aged↗
PubMed1981

A new non-glycoside, non-adrenergic cardiotonic agent AR-L 115 BS. Hemodynamic proof of its efficacy after both i.v. and oral administration.

In 11 patients with New York Heart Association (NYHA) functional class III-IV symptoms we monitored the effect of 2-[(2-methoxy-4-methylsulfinyl)phenyl]-1H-imidazo[4.5-b]pyridine (AR-L 115 BS). Heart rate (HR), pulmonary arterial mean pressure (PAM), aortic systolic pressure (AoSP) and thermodilution cardiac output (CO) were measured before and up to 25 min after a bolus of AR-L 115 BS, 3 mg/kg body weight, i.v. The oral effect of AR-L 115, 200 mg, 3 times daily, was monitored in 18 patients with congestive cardiomyopathy (CC) over a period of 4 days. AR-L 115 BS is also orally active and thus is a very promising inotropic agent for the treatment of chronic heart failure in man.

Administration, Oral↗
PubMed1981

[Hemodynamics and metabolic-energetic expenses of the influence of AR-L115 in patients with coronary artery disease (author's transl)].

AR-L115 has been shown to substantially improve myocardial pump function in patients (pts) with advanced congestive cardiomyopathy by i.v. and by p.o.-route. Since AR-L115 effects on myocardial oxygen consumption (MVO2) and coronary blood flow (CSF) are unknown, the hemodynamic myocardial metabolic and ECG-responses to AR-L115 (2 mg/kg BW bolus) were monitored at the 9, 14 and 19-min interval in 7 patients coronary 3-vessel disease, exhibiting ischemia during pacing stress only. Maximal responses occurred at the 14th min after AR-L115. THere were (average) increases in cardiac index by 30%, in heart rate by 19%, in CSF by 39%, in MVO2 by 34%, and in dp/dt max by 27%. There were (average) decreases in peak systolic pressure by 13%, in PCW by 30%, in LVEDP by 42%, in systemic vascular resistance by 34%, and in coronary vascular resistance by 37%. All changes were significant (p less than 0.05). Unchanged (p greater than 0.05) remained myocardial lactate extraction, stroke work index, and stroke-index. The only moderate increase in MVO2 is possibly explained in that the increase in contractility was a least partially offset by the reductions in pre- and after load. The AR-L115-induced improved pump function was accompanied by moderate increases in MVO2 and CSF, but without evidence of myocardial ischemia.

Cardiac Pacing, Artificial↗
PubMed1981

Echocardiographic identification and analysis of function of the St. Jude medical heart valve prosthesis.

The St. Jude medical (SJM) heart valve prosthesis presents a new bi-leaflet design which in preclinical evaluation exhibited favourable haemodynamic characteristics. Therefore clinical trials started in February 1978. The entire valve is made of pyrolytic carbon which has a poor X-ray visibility and therefore an alternative for the noninvasive routine control of valvular function and postoperative follow-up had to be found. Experimental studies in a left heart simulator provided adequate echovisualisation of both leaflets, however, depending on the direction of their motion in relation to the echobeam. Identification of both leaflets and an analysis of their motion was possible with a transducer at right angles to the leaflet axis. The experimental data were confirmed by clinical observations after implantation of the SJM prosthesis in patients. Based on the information obtained, we are providing recommendations for the implantation of the SJM prosthesis in order to achieve optimal echocardiographic visualisation of the valve and its moving parts in the postoperative follow-up.

Echocardiography↗
PubMed1980

[Lowering the heart rate in tachycardiac atrial fibrillation by beta receptor blockade].

The effects of the long-acting beta-receptor blocking agent Nadolol on ventricular rate was evaluated by Holter monitoring in 14 patients with chronic atrial fibrillation, in whom no effective control of heart rate could be obtained by digitalis only. There was a significant drop of heart rate after the treatment with 2 times 60 mg Nadolol daily to 70% of control values (ten patients treated for one week). Treatment with 120 mg Nadolol once daily proved to be equally effective in four patients. Reduction of heart rate was most marked in periods of physical activity, while there was only a small effect during periods of rest.

Adrenergic beta-Antagonists↗