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Biomedical subjects

H Landgraf

Publications and source records attributed to H Landgraf.

At least 19 recordsLinked to original sources
PubMed1999

[Economy class syndrome: fiction or fact?].

Several reports about the occurrence of deep vein thrombosis and pulmonary embolism following long-distance flights have led to the term "economy class syndrome". The underlying hypothesis was that a long term immobilisation in narrow economy class chairs of modern jet aircraft plays an important role for the development of deep vein thrombosis. Studies in healthy volunteers during several simulated long distance flights and during an actual long-distance flight confirmed the swelling of the lower legs complained by many long distance passengers, however, failed to reveal relevant changes of hemorheological or hemostaseological parameters. From these investigations no increased risk for thromboembolic diseases during long distance flights for healthy volunteers could be derived. Since this may be completely different for patients with risk factors for thromboembolic diseases prophylactic measures (compression stockings, anticoagulation) might be necessary.

Aircraft↗
PubMed1994

Muscle tissue PO2 during moderate altitude exposure in patients with peripheral arterial occlusive disease.

OBJECTIVES AND METHODS: In 10 patients with peripheral arterial occlusive disease (intermittent claudication) and in 10 healthy volunteers serving as controls, muscle tissue pO2, transcutaneous pO2, arterial pO2 and rheological parameters were measured before and during breathing (for 20 min) of an oxygen reduced gas mixture simulating an altitude of about 8500 feet (2600 m, approximately 116 mm Hg pO2). Oxygen pressure values were determined by means of a polarographic method according to Ehrly and Schroeder using atraumatic micro-pt-needle electrodes. RESULTS: Tissue oxygen tension in the tibialis anterior muscle of patients with peripheral arterial occlusive disease decreased significantly from 6.5 mm Hg to 2.4 mm Hg (medians). The pooled histograms were markedly shifted to hypoxic values. The controls showed a decrease from 20.8 to 12.2 mm Hg and a strong shift to the left. Transcutaneous pO2 measured in the diseased leg decreased from 53.4 +/- 11.6 to 36.1 +/- 9.3 mm Hg (controls 57.1 +/- 9.9 to 39.7 +/- 8.9 mm Hg), arterial pO2 decreased from 80.2 +/- 15.1 to 60.0 +/- 10.4 mm Hg (controls: 86.5 +/- 16.0 to 64.7 +/- 13.6 mm Hg) and pulsoximetrically determined O2-saturation from 95.0 +/- 2.5 to 90.0 +/- 5.5% (controls: 96.1 +/- 2 to 92.0 +/- 4.2%). CONCLUSIONS: Exposure of patients with intermittent claudication to moderate altitude led to a marked decrease of tissue pO2 values in the diseased legs without any evidence of clinical worsening, especially no rest pain. It may be discussed if rest pain in ischaemic legs is due to low pO2-values or to disturbed microcirculatory perfusion.

Aged↗
PubMed1994

Noninvasive methods in the early detection of restenosis after percutaneous transluminal angioplasty in peripheral arteries.

In a prospective study, several noninvasive methods were evaluated in the early detection of restenosis after percutaneous transluminal angioplasty in peripheral arteries. Sensitivity and specificity of various noninvasive resting and exercise methods for the detection of restenosis were determined. It is concluded that noninvasive follow-up after percutaneous transluminal angioplasty in peripheral arteries requires exercise testing with determination of ankle-arm index or segmental arterial pulse oscillography for the early detection of restenosis.

Aged↗
PubMed1994

Economy class syndrome: rheology, fluid balance, and lower leg edema during a simulated 12-hour long distance flight.

In order to study pathological changes that might lead to deep vein thrombosis and pulmonary embolism in long-distance air travel passengers, 12 healthy volunteers were investigated during 4 simulated 12-h flights (day and night). The influence of repeated leg exercise was compared with constant sitting. Plasma viscosity, hematocrit, albumin, fluid balance, and lower leg swelling were measured. Rheological studies showed only circadian rhythm alterations. An average of 1150 ml fluid was retained, which correlated with an increase in body weight. The lower leg volume increase was significant, but not pathological. Periodic leg exercising showed no measurable preventive effects. These changes in healthy human volunteers are within physiological variations and are not sufficient to provide a definitive cause of venous thrombosis in healthy passengers. They do, however, suggest alterations produced by long-distance air travel that could intensify the risk of developing deep venous thrombosis in passengers with predisposing risk factors.

Adult↗
PubMed1993

Recanalization of chronic arterial occlusions: low-speed rotational angioplasty. 5 years experience in peripheral and coronary vessels.

Chronic complete occlusions still represent the major technical limitation of percutaneous transluminal angioplasty, both in peripheral and coronary vessels. The clinical use of low-speed rotational angioplasty started in 1986 for the peripheral and in 1987 for the coronary arteries, and has already become part of the clinical routine in several centres. Up to now more than 350 patients with peripheral and 250 patients with coronary occlusions have been treated in Frankfurt; a multicentre questionnaire already contains information about 1,252 patients with peripheral vessel obstructions. In peripheral occlusions the acute success rate was more than 80% if low speed rotational angioplasty was used as the first attempt; after failure of conventional techniques still more than 60% of the vessels could be recanalized successfully. In addition to occlusions of the arteries of the lower limb, indications now may include the iliac artery and the subclavian artery. In each of the patients with chronic coronary occlusions an attempt with conventional techniques had failed before. Following a learning curve, which was also influenced by a better understanding of morphological preconditions, the acute success has now reached 70%. Both in patients with peripheral and those with coronary occlusions the technique turned out to be a safe procedure. Early angiographically documented long-term results in both indications are comparable with conventional balloon techniques. It is concluded that the use of low-speed rotational angioplasty (ROTACS) can improve the results of non-operative invasive treatment, both in peripheral and in coronary arteries.

Angioplasty↗
PubMed1993

[An unusual cause of arterial vascular occlusion with peripheral embolism].

A 34-year-old man presented with a three week history of a bluish discolouration, tingling paraesthesia and severe intermittent pain of the right foot. Angiography showed occlusion of the right superficial femoral artery above the knee, as well as embolic occlusion of the distal lower limb. A fluoroscopic study demonstrated a tirefond perforating the femoral bone just on the level of the occlusion. Two osteosynthetic operations had been performed after a comminuted fracture seventeen and five months earlier, respectively. After the initial fibrinolytic therapy was without improvement over a period of 32 hours, the osteosynthetic screw was removed surgically. It was covered by callous tissue und protruded through the cortical layer more than 15 mm. After extraction of the screw and removal of thrombotic material the femoral artery was patent on control angiography.

Adult↗
PubMed1992

[Reopening chronic arterial occlusions].

Chronic complete occlusions still represent the major technical limitation of percutaneous transluminal balloon angioplasty, both in peripheral and coronary vessels. The clinical use of low speed rotational angioplasty (ROTACS) started in 1986 for the peripheral and in 1987 for the coronary vessels, and has already become part of the clinical routine in several centers. Up to now, more than 300 patients with peripheral and more than 200 patients with coronary occlusions were treated in Frankfurt. In peripheral occlusions the acute success rate was more than 80% if used as the first attempt; after failure of conventional techniques still more than 60% of the vessels could be recanalized successfully. In addition to occlusions of the arteries of the lower limbs, the indication now includes the iliac artery and several other indications are under investigation. In each of the patients with chronic coronary occlusions an attempt with conventional techniques had failed before. Following a learning curve, which was also influenced by a better understanding of morphological preconditions, the acute success rate has now reached 70%. Both in patients with peripheral and those with coronary occlusions no deaths occurred. First angiographically documented long-term results in both indications are comparable to conventional balloon angioplasty. It is concluded that the use of low speed rotational angioplasty (ROTACS) can improve the results of nonoperative invasive treatment, both in peripheral and in coronary arteries.

Angiography↗
PubMed1991

[Pain in chronic arterial occlusive disease--the effect of improved macrocirculation on pseudo-radicular irritation].

In chronic obliterating arteriopathy the maximum walking distance does not correlate well with the ankle arm index of arterial pressure measured by Doppler ultrasound. Beside reduced macrocirculation and microcirculatory maldistribution in skeletal muscle, pseudoradicular irritation was established as a relevant factor for the onset of pain during walking. The present study investigates the influence of the macrocirculation on hyperalgesia at rest in intermittent claudication. In 35 patients with chronic obliterating arteriopathy of the lower limbs (stage II according to Fontaine) the ankle/arm index of arterial pressure and the walking tolerance, as well as the pain at rest on applying pressure to the calf muscles were determined before and 3 weeks after percutaneous transluminar angioplasty (PTA). All 3 parameters improved after dilatation. Improved macrocirculation leads not only to a decreased production and improved clearance of pain-inducing metabolites in muscle tissue, but also--through a decrease of sympathetic stimulation of the muscle--to an elevation of the pain threshold. Apart from the reduction in pain-inducing metabolites, an absence of booster effects on pseudoradicular irritation and the regeneration of sensitive cutaneous afferents with resultant inhibition of reflex pain development are considered as possible factors in the achievement of pain relief following PTA.

Angioplasty, Balloon↗
PubMed1991

[Hemodilution in acute cerebral ischemia].

Hemodilution therapy in acute cerebral infarction is still a controversial issue. This is mainly due to the different results achieved in clinical studies so far. Criticism, however, is justified in some points. The reason for the different results of the studies is very likely to be the selection of the patients, i.e. the poor differentiation of acute cerebral infarctions. In addition, the different therapy regimens applied must be taken into account. Thus, several questions arise in connection with the clinical application and the further investigation of this therapy which have so far been answered not at all or only in part. Since there is at present no appropriate alternative treatment for acute cerebral infarction, hemodilution is most likely to remain an important therapy in this indication.

Blood Flow Velocity↗
PubMed1989

[Rotational angioplasty--recanalization of chronic arterial occlusion using a slowly rotating catheter. Clinical results with 100 patients].

Between December 1986 and January 1989, 100 patients with chronic occlusions of peripheral arteries were treated with the new technique of low speed rotational angioplasty. This uses a relatively thick, flexible and blunt catheter, which is driven by an electric motor (100 to 200 r.p.m.). The success rate in the superficial femoral and popliteal arteries of the initial intervention for occlusions less than 10 cm was 90%, for occlusions of less than 10 cm, it was 80%. Occlusions on which conventional techniques had failed were successfully recanalized in 65%. Recanalisation was also successful in seven out of 12 patients with occluded iliac arteries. There were no perforations or other serious complications. It is concluded that the new method is particularly effective and safe for recanalisation of chronic vascular occlusions and should also be considered for cases which previously could only be treated surgically.

Adult↗
PubMed1989

Low-speed rotational angioplasty in chronic peripheral artery occlusions: experience in 83 patients. Work in progress.

Between December 1986 and October 1988, 83 patients with chronic peripheral artery occlusions were treated with a new technique. In 56 patients, the superficial femoral artery was completely occluded; in 21 patients, the popliteal artery; and in six patients, the iliac artery. The length of occlusion ranged from 5 to 35 cm (mean, 12.5 cm). The duration, estimated by history, was 5-48 months (mean, 16.5 months). In seven patients, durations of 6-36 months were documented angiographically. A flexible, blunt, motor-driven rotating catheter was introduced through an 8-F sheath, and rotational angioplasty was performed at low speed (up to 200 rpm). In 49 of 60 (82%) patients in whom this new technique was used as the primary intervention, the occlusions were successfully reopened. In 23 patients in whom conventional methods had failed more than 4 weeks earlier, the success rate for rotational angioplasty was 67% (12 of 18 patients); when the time interval was less than 4 weeks, only one of five patients was treated successfully. In none of the 83 patients did a perforation occur. This new technique can reopen chronic artery occlusions with a high degree of success and without the danger of vessel-wall perforation, even after failure of conventional techniques.

Adult↗
PubMed1989

[Rotation angioplasty--clinical experiences in 83 patients with chronic arterial vascular occlusion].

Chronic, total vascular occlusion represents the limit for use of balloon dilatation. Occlusions of the superficial femoral artery and popliteal artery of more than 10 cm in length have a low recanalization rate of 50 to 60% with conventional angioplasty. In iliac artery occlusions, in addition to a high rate of complications, the recanalization rate is only about 30 to 40%. Starting in 1984, we developed a slowly rotating (100 to 200 r.p.m.), electrically-driven, flexible catheter with a blunt tip, inside lumen and outer diameter of 2.2 mm for the purpose of recanalization (Figure 1). The theoretical basis was that such a catheter would seek the soft occluding thrombus as the path of least resistance. Since 1986, the procedure has been carried out in 56 patients with occlusion of the superficial femoral artery, 21 with occlusion of the popliteal artery and six with occlusion of the iliac artery. The duration of occlusion ranged between five and 48 months and the length of the occlusions between 5 and 35 cm (mean 12.5 cm); the patients were in Fontaine stage II and IV, the ankle arm-index ranged between 0 and 0.86 (mean 0,51). After antegrade or retrograde puncture of the common femoral artery and intra-arterial injection of 5,000 units of heparin, the rotation catheter was advanced through an 8F sheath through the occlusion by means of slow rotation (Figure 2). After contrast medium injection to document the intraluminal position of the catheter and the catheter exchange over a 0.35'' wire, the channel created was dilated.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Results of low speed rotational angioplasty for chronic peripheral occlusions.

After experimental investigation using postmortem human arteries, 19 patients with chronic peripheral artery occlusions were treated with a new angioplasty technique between December 1986 and October 1987. In 17 patients the superficial femoral artery and in 2 patients the popliteal artery were completely occluded. The length of the occlusions ranged between 5 and 25 cm (mean 11). The duration--estimated according to patients' history--was 5 to 48 months (mean 17). In 5 patients, durations of up to 30 months had been documented by angiography. A flexible, blunt, motor-driven rotating catheter was introduced through an 8 or 9Fr sheath and rotational angioplasty was performed at low speeds (up to 200 rpm). In 11 of 14 patients in whom this new technique was used as the primary intervention, the occlusions could be successfully reopened. In 2 patients after failure of conventional techniques the rotating catheter could not bypass the preexisting dissections in the same intervention. In 2 of 3 further patients after failure of conventional techniques the occlusions could be successfully reopened in a second intervention after several weeks. In none of the 19 patients did a perforation occur. It is concluded that with the new technique chronic peripheral artery occlusions can be reopened with a high success rate and without the danger of arterial wall perforation. The method can also be used in patients in whom conventional techniques have failed.

Adult↗
PubMed1988

Influence of videofilm-induced emotional stress on the flow properties of blood.

The hemorheologic effects of emotional stress induced by a videofilm were investigated in 10 healthy volunteers. Blood samples were obtained from the antecubital vein before, during, and after the end of the videofilm. Blood pressure and heart rate were simultaneously measured. There was a statistically significant increase in blood and plasma viscosity during and immediately after the end of the videofilm, which correlated with an increase in plasma catecholamine concentrations. This hemorheologic behavior can be explained as a result of an endogenous hemoconcentration that takes place if the Starling equilibrium of intravascular vs extravascular fluid is changed. These observations could lead to new aspects of the pathophysiology of acute myocardial infarction initiated by severe emotional stress.

Adult↗