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Biomedical subjects

S Spitzer

Publications and source records attributed to S Spitzer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Factors affecting the restenosis rate after percutaneous transluminal coronary angioplasty.

In an open study follow-up angiographies were performed independently from the clinical course on altogether 131 consecutive patients (99 men, 32 women) six months after percutaneous transluminal coronary angioplasty (PTCA). During this period patients received at least 320 mg of aspirin daily. Possible factors affecting the restenosis rate included age, sex, diabetes mellitus, arterial hypertension, abnormal lipid metabolism, smoking, dosage of aspirin administered, degree of stenosis shown by affected vessels before dilatation, number of vascular segments dilated and platelet reactivity. Restenosis was defined as a renewed narrowing of the dilated segment by 50% or more, with an increase in stenosis by at least 20%. In the present study the following restenosis rates were found six month after a primarily successful PTCA: 30% for the entire sample (39 out of 131 patients); 25% in patients with normal platelet function, 50% in those with mildly abnormal platelet function, and 60% in those with frankly abnormal platelet function; 24% in non-diabetic patients and 45% in diabetics. Analysis of the findings showed that abnormal platelet function and the presence of diabetes mellitus were the most important factors in the subsequent development of restenosis after angioplasty. The same also applied in a more restricted manner to the degree of stenosis present before angioplasty.

Aged↗
PubMed1994

Hypervolemic hemodilution with or without venesection in peripheral arterial occlusive disease stage II.

Patients with peripheral arterial occlusive disease (PAOD) and marked atherosclerosis often present concomitant diseases like coronary heart disease, cerebral circulatory disorders or arterial hypertension. Thus, the extent of hypervolemia is limited in case of an infusion treatment without venesection. Therefore, it was tested whether a hypervolemic hemodilution without venesection is superior to a dilution with venesection in multimorbid patients suffering from PAOD stage II. The colloidal iso-molar solution used was Haes 200/0.5 6%. Both forms of hemodilution were significantly superior compared to a control group well hydrated with cristalloid saline solution; all groups practised walking exercise twice a week over a period of one hour. However, hypervolemic hemodilution without venesection was only slightly better than the dilution with venesection. The walking distance in the group without venesection increased by 68.6 m (36.7%) in the group without venesection, by 59.0 (30.4%) in the group with venesection and by 33.6 m (20.1%) in the control group. The results show that the decision to perform a hyperor isovolemic hemodilution should depend on the volume tolerance of each patient.

Adult↗
PubMed1994

Inhibitor-resistant tissue-type plasminogen activator: an improved thrombolytic agent in vitro.

Platelet-rich clots are inefficiently lysed by current fibrinolytic agents. Platelets contain a great deal of plasminogen activator inhibitor 1 (PAI-1), the principal endogenous inhibitor of tissue-type plasminogen activator (t-PA). We have tested whether PAI-1 resistant t-PAs would be more effective thrombolytic agents in an in vitro model of platelet-rich clots. Clots were formed with recalcified human plasma without or with the addition of platelets. The lysis of these clots was followed by the release of incorporated 125I-fibrinogen. Mutant and wild-type t-PA were almost equally effective against clots lacking platelets but the mutant was twice as effective at lysing platelet-rich clots. A mechanism for this effect is suggested by the demonstration that a complex between wild-type t-PA and extruded platelet contents resembles that between purified t-PA and PAI-1 and that the PAI-1 resistant t-PA does not interefer with formation of this adduct. Because of its enhanced ability to lyse platelet-rich clots in vitro, further in vivo work may find that PAI-1 resistant t-PA is a more efficacious therapeutic agent than wild-type t-PA in situations where platelets contribute to the failure of thrombolysis.

Animals↗
PubMed1993

Primary and secondary microcirculatory disorders in essential hypertension.

In this prospective cross-sectional study blood fluidity and peripheral microcirculation were measured in patients suffering from essential hypertension with and without macroangiopathy. The cutaneous microcirculation was evaluated by intravital microscopy and the intramuscular by pO2 needle electrode. Disorders in the microcirculation without macroangiopathy in the system of the feeding arteries are defined as primary microangiopathy. Disturbed microcirculation with macroangiopathy in the feeding arteries in one area but no detectable microcirculatory disorder in another region is defined as a secondary microcirculatory disorder. Of the 57 patients in this study 27 had a primary microcirculatory disorder. It was remarkable that all 27 hypertension patients had a microcirculatory disorder in the area of the skin. Intramuscular microcirculatory disorder on its own without affection of the skin was not detected in any case. An exclusively secondary microcirculatory disorder occurred in 16 patients. This study shows that 93% of the patients with long-term essential arterial hypertension have microcirculatory disorders. It is most interesting that about one-half of these hypertension patients had a primary microcirculatory disorder, i.e., no indication of a hemodynamically active stenosis was found in the large vessels.

Adult↗
PubMed1993

The stability of cardiovascular parameters under different behavioral challenges: one-year follow-up.

The stability of myocardial, peripheral vascular and systolic time-interval measures was assessed over a one-year period in a sample of ten healthy normotensive men. Subjects participated in three laboratory sessions, the first two of which were two weeks apart, and the third approximately one year later. Measures were sampled during the preparation and delivery of a speech, a mirror star tracing task, and the forehead cold pressor test. The results of intraclass correlations computed between the mean of the first two sessions and the third showed that baseline and task levels were highly reproducible across all tasks and most parameters over the one year interval. Results also showed that the long term stability of delta is largely task-dependent.

Adult↗
PubMed1993

Patterns and stability of cardiovascular responses to variations of the cold pressor test.

Test-retest reliabilities and patterns of heart rate and blood pressure responses were examined using variations in the cold pressor test in 113 normotensive white college men. Comparisons were made of stimulus site (forehead vs. foot) and bodily posture (seated vs. supine) across four separate groups of men. The stability of cardiovascular responses was examined over a 2-week-test-retest interval. Different cardiovascular response patterns emerged as a function of stimulation site and posture. Systolic and diastolic blood pressure increases were accompanied by bradycardia in the forehead cold pressor task but by tachycardia in the foot cold pressor task. Systolic blood pressure increases were larger for foot than for forehead stimulation. Heart rate increases were larger for supine than for seated men. Effects on response were independent of postural differences at baseline, and there were no stimulation site by posture interactions. The cardiovascular responses to stimulation did not attenuate across sessions in any experimental condition but were more reliable for foot than for forehead stimulation and for supine than for seated posture. Short-term stability for changes to the task approached that for baseline and task and was higher than has been reported elsewhere.

Adolescent↗
PubMed1993

Unusual A alpha 16Arg-->Cys dysfibrinogenaemic family: absence of normal A alpha-chains in fibrinogen from two of four heterozygous siblings.

We describe studies of fibrinogen from an asymptomatic family, Fibrinogen Frankfurt XIII, with the substitution A alpha 16Arg-->Cys. The mother's fibrinogen was normal as assessed by plasma fibrinogen assays but the father and four children were affected. Two affected siblings and their father had thrombin times approximately 20 s longer than controls, fibrinogen of 35-52 mg/dl by clotting assay and normal levels by immunoassay. Measured by HPLC their fibrinogen had decreased amounts of releasable fibrinopeptide A (FpA) relative to normal controls. In addition, their fibrinogen was partly coagulable with batroxobin and fully coagulable with thrombin; consistent with its incomplete FpA release. In contrast, plasma from the other two siblings had thrombin times > 2 min longer than controls, and their fibrinogen was < 10 mg/dl by clotting assay and normal by immunoassay. Their isolated fibrinogen did not release FpA (n = 5) and formed thrombin clots only at cold temperatures indicating formation of desBB fibrin. Assessed by SDS-PAGE, only monomeric fibrinogen was seen in isolated fibrinogen, washed and unreduced plasma immunoprecipitates, non-crosslinked plasma clots or 56 degrees C precipitates. DNA sequencing of PCR products using oligonucleotide primers which flanked sequences coding for A alpha 7Asp to 35Phe, disclosed mutant (C-->T, coding for A alpha 16Cys) and wild type alleles present in both severely affected siblings. It is concluded that circulating fibrinogen contained only mutant FpA. A possible second mutation, not apparent from plasma assays on the mother, is believed to account for the absence of releasable normal FpA in circulating fibrinogen.

Alleles↗
PubMed1992

Effects of anger on left ventricular ejection fraction in coronary artery disease.

This study examined the comparative potency of several psychological stressors and exercise in eliciting myocardial ischemia as measured by left ventricular (LV) ejection fraction (EF) changes using radionuclide ventriculography. Twenty-seven subjects underwent both exercise (bicycle) and psychological stressors (mental arithmetic, recall of an incident that elicited anger, giving a short speech defending oneself against a charge of shoplifting) during which EF, blood pressure, heart rate and ST segment were measured. Eighteen subjects had 1-vessel coronary artery disease (CAD), defined by greater than 50% diameter stenosis in 1 artery as assessed by arteriography. Nine subjects served as healthy control subjects. Anger recall reduced EF more than exercise and the other psychological stressors (overall F [3.51] = 2.87, p = .05). Respective changes in EF for the CAD patients were -5% during anger recall, +2% during exercise, 0% during mental arithmetic and 0% during the speech stressor. More patients with CAD had significant reduction in EF (greater than or equal to 7%) during anger (7 of 18) than during exercise (4 of 18). The difference in EF change between patients with CAD and healthy control subjects was significant for both anger (t25 = 2.23, p = 0.04) and exercise (t25 = 2.63, p = 0.01) stressors. In this group of patients with CAD, anger appeared to be a particularly potent psychological stressor.

Anger↗
PubMed1991

Clinical pharmacology education in a division of cardiology.

A working model of how clinical pharmacology education can be interwoven into the matrix of an academic cardiology program that includes didactic teaching, clinical research, and patient care has been presented. Essential to the success of such a program is the commitment and dedication of both its full-time and voluntary faculty. Moreover, a comprehensive plan of organization and allocation of efforts is vital to the success of such a complex undertaking. As we look to the future, the discipline of clinical pharmacology will be increasingly relevant to the practicing cardiologist.

Cardiology↗
PubMed1991

Loss of atrial signal detection with increasing sensitivity settings: a software problem and its practical solution.

A logic error in the software of Cosmos II results in apparent malsensing of atrial signals at high rather than low sensitivity settings. The paradoxical function was found in 54 out of 87 units tested (= 62%) if the atrial sensitivity was increased and in 54 out of 87 units tested (= 62%) if the atrial sensitivity was increased and the ventricular refractory period was lengthened beyond critical limits that could be defined individually. The problem inherent in both unipolar (66%) and bipolar systems (54%) is attributed to a summation of a physiological signal and internal noise, which has to be detected at the atrial level within a specific timing window to disable atrial sensing for the next pacing cycle. The malfunction virtually disappears if the ventricular refractory period does not exceed 210 msec. It is recommended, therefore, that Cosmos II pacemakers be left at their nominal ventricular refractory value (200 msec).

Adult↗
PubMed1991

[Hyper- or isovolemic hemodilution in patients with stage II peripheral arterial occlusive disease].

The influence of hyper- and isovolaemic hemodilution using HES 200/0.5 6% (HES steril, Fresenius AG) on pain-free walking distance in patients with peripheral arterial occlusive disease stage II according to Fontaine was tested in a randomised investigation involving three groups. The increase in pain-free walking distance was significant both in the hypervolaemic and isovolaemic hemodilution group. The increase in both dilution groups did not differ but compared to a control group (infusion of Ringer lactate) it was significantly higher. Considerable changes concerning rheological parameters (decrease in haematocrit and plasma viscosity) were observed after isovolaemic hemodilution.

Adolescent↗
PubMed1991

[Hemorheologic and circulatory effects of hemodilution with medium molecular weight hydroxyethyl starch in two concentrations (HAES 200/0.62 10% and 6%)].

This study was designed to investigate whether the positive effect occurring after infusion of a 10% hydroxyethyl starch solution 200.000/0.62 on cutaneous capillary blood flow could still be increased by using a 6% solution having a lower initial viscosity (HES 6% 200.000/0.62). A single blind study of 10 female volunteers was carried out to study the influence of a hypervolemic hemodilution using 500 ml of a 10% solution hydroxyethyl starch solution at first and that of 6% hydroxyethyl starch solution on macro- and microcirculation, transcutaneous oxygen partial pressure and blood fluidity. After hydroxyethyl starch infusion blood flow in the macro- and microvessels increased significantly. This increase occurred considerably earlier after administration of 6% solution than after infusion of 10% solution. Thus blood flow had already increased after 1 hour and continued to show a tendency of increase over about three hours. 6 hours after end of infusion blood flow had almost dropped to its initial value. The volume effect of the 6% solution immediately after infusion was less pronounced than that after infusion of the 10% solution, but it reached the value of the 10% solution at a later point in time. The course of the haematocrit reflected this process. Average decrease in haematocrit value compared to that following the 10% solution was not as pronounced at hour 3. After 6 hours the decreases were comparable. Similar observations were made of plasma viscosity and platelet aggregation. One hour after infusion plasma viscosity and erythrocyte aggregation had hardly changed but haematocrit had clearly dropped. Thus, blood viscosity at this point in time was essentially lowered.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Coincidence of hypertensive changes of the eye fundus and regulation disorders of peripheral microcirculation: I--Skin].

In cases of arterial hypertension, funduscopy is an established method of estimating systemic vascular lesions. In this study the relation between the extent of retinal vascular changes and dynamic processes in the microcirculation of the skin was investigated by nailfold capillaroscopy in 88 patients. With increasing vascular changes a progressive loss of vasodilator reserve and transcutaneous partial pressure was observed (no morphologic changes--fundus hypertonicus II--fundus hypertonicus III). It thus appears possible to evaluate the functional state of the macro- and microcirculation by funduscopy.

Adult↗
PubMed1990

[Coincidence of hypertensive fundus changes and regulatory disorders of peripheral microcirculation. II--Skeletal muscles].

In patients with hypertensive fundus changes considerable morphologic changes of the entire vascular system may be assumed. In the present study, the effects of these processes on the partial oxygen pressure of the skeletal musculature were investigated in 62 patients via a macro puncture electrode placed in the tibial muscle. The extent of fundus changes and the reduction in muscular partial oxygen pressure were found to be correlated. With advancing stages of fundus changes, blood flow measured in the common carotid artery decreased. Vascular changes which are clearly recognizable in the hypertensive fundus thus appear to be accompanied by a deterioration in partial oxygen pressure in muscular tissue and restriction of flow in the macrocirculation.

Aged↗
PubMed1990

Haemodilution with medium molecular weight hydroxyethyl starch in patients with peripheral arterial occlusive disease stage IIb.

The basic therapy of peripheral arterial occlusive disease stage IIb, according to Fontaine, is exercise. It should be determined whether a mild hypervolaemic haemodilution with hydroxyethyl starch or Ringer lactate can produce a further increase in walking distance. For this purpose, three groups of 25 patients each were formed. One group exercised three times weekly and the second group, in addition to exercise, underwent a mild hypervolaemic to isovolaemic dilution therapy with HES for a period of 6 weeks. In the final group the haematocrit was reduced to the same extent by venesections and volume substitution using Ringer lactate. The walking distance in the HES group increased from 216 m to 311 m (44%), in the Ringer lactate group from 214 m to 258 m (20%), and in the exercise group from 213 m to 242 m (14%). On comparison of the groups, the increase in pain-free walking distance in the HES group differs significantly (P less than 0.05) from that achieved in the other groups. It was demonstrated that haemodilution with HES in combination with exercise brings about a clinical effect three times that achieved by exercise alone. Venesection with subsequent administration of Ringer lactate and exercise is superior to exercise alone but markedly inferior to the combination therapy with HES.

Adult↗
PubMed1990

Posture, place, and mood effects on ambulatory blood pressure.

Ambulatory blood pressure was studied as a function of posture, place, and mood in 131 subjects classified according to race, gender, and hypertensive status. The effect of posture was significant and explained a substantial proportion of within-subject variability. After controlling for posture, significant place and mood effects were observed when subjects were sitting but not when they were standing. Home vs. work differences in both systolic and diastolic blood pressure were significantly greater in Whites than in Blacks. Similar differences in systolic blood pressure were greater in mild hypertensive than in normotensive subjects. The results of this study underscore the need to control for effects of posture when interpreting ambulatory blood pressure readings.

Adult↗