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Biomedical subjects

C Vallbracht

Publications and source records attributed to C Vallbracht.

At least 19 recordsLinked to original sources
PubMed2002

A polyhydroxybutyrate biodegradable stent: preliminary experience in the rabbit.

PURPOSE: The lifelong persistence of foreign bodies within the arteries may contribute to restenosis. Thus, biodegradable devices might decrease recurrence rates. METHODS: Eleven polyhydroxybutyrate biodegradable stents and 13 tantalum stents were implanted into the iliac arteries of New Zealand white rabbits for up to 30 weeks. After killing the animals, the specimens were harvested, fixed in formalin, processed in paraffin, and stained. RESULTS: Polyhydroxybutyrate instigated intense inflammatory and proliferative reactions with an increase in collagen (2.4- to 8-fold vs native segments), thrombosis and in-stent lumen narrowing (375.5-606.6 mm vs 655.6 +/- 268.8 mm in native segments). The elastic membranes were destroyed in all specimens. The tantalum stents increased the in-stent lumen progressively (769.7 +/- 366.6 mm vs 1309.9 +/- 695.3 mm), penetrated the external elastic membrane, and increased mural collagen content (6- to 8.6-fold vs native segments). Neither restenoses nor thromboses occurred. CONCLUSIONS: In the rabbit iliac artery, polyhydroxybutyrate stents caused intensive inflammatory vascular reactions which ban them from clinical use.

Animals↗
PubMed2001

[First results in an animal model on stents sheathed with a polytetrafluoroethylene membrane].

OBJECTIVES: Mechanisms of restenosis after coronary stent implantation include marked intimal proliferation as well as vascular tissue protrusion through the meshes. Thus, stent sheathed with membranes may be an alternative to improve the long-term outcome. METHODS: Seventeen cylindric serpentine shaped 316L stainless steel stents (nominal diameter 3.0 mm, length 15 mm) lined and covered by a polytetrafluoroethylene (PTFE) membrane and 10 unsheathed devices were implanted into the iliac arteries of 14 New Zealand White Rabbits for an observation period of 1 - 10, 11 - 20, and 21 - 30 weeks. After sacrificing the animals, specimens were harvested, fixed in formalin, processed in paraffin, serially sliced into 5 microm thick preparations, and stained (hematoxylin & eosin, elastica von Gieson). RESULTS: The polytetrafluoroethylene membrane stents increased the vascular lumen significantly (p < 0.04) to 1185.3 - 1620.4 microm compared with the native segments (655.6 +/- 268.8 microm). In the stainless steel stents the lumen decreased from 1873.1 microm to 719.1 microm. None of the devices penetrated the internal elastic membrane. There was no inflammatory vascular reaction. Compared to the native segments, the amount of elastic fibres was slightly less (native: 8.9 %, PTFE: 2.3 - 3.5 %, without PTFE: 1.9 - 5.5 %) whereas the collagen fibres increased marginally (native: 5.1 %, PTFE: 6 - 6.9 %, without PTFE: 6.4 - 8.4 %). CONCLUSIONS: In the rabbit iliac artery, stents sheathed with a microporous polytetrafluoroethylene membrane showed good tissue compatibility with no restenosis. These results warrant clinical trials.

Angioplasty, Balloon, Coronary↗
PubMed2001

Controlled balloon inflation reduces long-term restenosis after percutaneous transluminal coronary angioplasty.

PURPOSE: The trauma induced by balloon angioplasty has an impact on the outcome of coronary interventions, such as stent procedures. However, balloon inflation for PTCA is not yet standardized even though procedural and long-term outcomes might be affected. METHODS: During routine PTCA, a total of 454 patients [mean age, 60.9 +/- 9.0 years; 162 (35.7%) with 1-vessel disease; 159 (35%) with 2-vessel disease; 133 (29.3%) with 3-vessel disease] were allotted to computer-assisted dilatation (CAPS) with a pressure slope of 0.2 bar/s (CAPS 0.2; n = 149 patients), 1.0 bar/s (CAPS 1.0; n = 154 patients) or to standard inflation with a hand-driven pump (n = 151 patients). Angiographic follow-up rates after 4.1 +/- 3.2 months were 88.1% for the hand-driven pump, 94% for CAPS 0.2 and 87.7% for CAPS 1.0. RESULTS: Flow reducing (1.3-2.0%) and non-flow reducing (12.6-14.9%) dissections were equally distributed among all groups as were major adverse cardiac events (2.6-4.0%). The stent rate was 1.3% with the hand-driven pump, 0.7% with CAPS 0.2 and 1.3% with CAPS 1.0. Angiographic restenosis rate was 48.9% with the hand-driven pump, 44.3% with CAPS 0.2 and 32.6% with CAPS 1.0. (hand-driven pump versus CAPS 1.0, p < 0.007; CAPS 0.2 versus CAPS 1.0, p < 0.049). CONCLUSIONS: The pressure slope during balloon inflation in PTCA has a significant impact on restenosis. The impact on stent procedures has yet to be determined.

Adult↗
PubMed2000

Cardiovascular load of competitive golf in cardiac patients and healthy controls.

PURPOSE: Sports in cardiovascular patients (CVP) should serve for risk factor management, increase of exercise capacity, and reintegration into daily life. Competition of cardiac patients with healthy sportsmen is often discouraged and thus reintegration hampered. Golf, with its endurance component and exceptional rules (e.g., the handicap) should be an alternative. METHODS: In 20 male golfers (65.2 +/- 6.1 yr, 1.4 +/- 0.3 W x kg(-1) body weight (approximately 4.8 METs)) with cardiovascular diseases and eight controls (C) (62 +/- 5 yr, 2 +/- 0.4 W x kg(-1) body weight (approximately 6.9 METs)), the performance assessed in the laboratory (ergospirometry, serum lactate) allowed for comparison of the cardiovascular load on the golf course (lactate, Holter monitoring, blood pressure, urine catecholamines). RESULTS: In comparison with in the hospital, resting heart rates were significantly (P < 0.001) elevated in both groups immediately before the tournament (CVP: 76.1 +/- 10.8 vs 90.1 +/- 8.6 bpm; C: 74.8 +/- 6.3 vs 92.3 +/- 9.7 bpm). On the course, the mean heart rates of the patients were closer (P < 0.01) to the anaerobic threshold (105.4 +/- 11.0 vs 115.3 +/- 10.8 bpm) in comparison with controls (100.5 +/- 7.3 vs 125.6 +/- 16.6 bpm) corresponding to 0.9 +/- 0.3 W x kg(-1) (approximately 3.1 METs) or 76.0 +/- 13.1%VO2max (CVP) and to 0.9 +/- 0.2 W x kg(-1) (approximately 3.1 METs) or 55.3 +/- 9.1%VO2max (C). Serum lactate levels were 1.36 +/- 0.7 mmol x L(-1) (approximately 12.4 +/- 6.4 mg x dL(-1)) (CVP) and 1.1 +/- 0.4 mmol x L(-1) (approximately 9.1 +/- 3.6 mg x dL(-1)) (C). In patients, arrhythmias were lower in quantity and quality (LOWN) in comparison with other activities as registered by means of the 24-Holter-ECG. CONCLUSION: In cardiovascular patients, competitive golf reaches an intensity that may positively influence cardiovascular risk factors, depending on the type of the course and may provide patients the desired integration with healthy sportsmen.

Aged↗
PubMed1999

A surgical gauze appearing as a retrocardiac mass in a patient after coronary artery bypass surgery.

Five years after open chest surgery because of three vessel coronary artery disease a patient was referred for progressing dyspnea and recent onset of atrial fibrillation. A retrocardiac mass was detected on chest X-ray and echocardiography. On CT-scan, the inhomogenous tumor made the diagnosis of a retained surgical gauze likely. Through a left incision the sponge was removed uneventfully and the dyspnea resolved.

Coronary Artery Bypass↗
PubMed1999

[Pressure-volume recording of PTCA catheters with balloons of lower and higher compliance].

In this report, the results of complementary studies of pressure-volume (p-V) measurements on balloon catheters with balloons of low (LC) and high compliance (HC) used for percutaneous transluminal coronary angioplasty are discussed. The measurements were performed with balloons unconfined in air (free dilatation) and also confined in different shells. In the case of rigid shells, a surprisingly high self-expansion of the catheters was found. Although this self-expansion does not contribute to the radial dilatation, it cannot be neglected, but must be taken into account when the success of balloon dilatation is determined on the basis of measured p-V curves. The investigations performed using wrapped shells clearly show the different dilatation properties of LC and HC balloons. The results provide important information on the feasibility of controlled balloon dilatation on the basis of p-V measurements performed on-line during PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1999

Collagen application for sealing of arterial puncture sites in comparison to pressure dressing: a randomized trial.

UNLABELLED: One-hundred patients undergoing routine diagnostic or interventional catheterization were randomly assigned to receive either percutaneously applied collagen (group A; n = 50) or conventional pressure dressing (group B; n = 50) for sealing of the femoral artery. Clinical variables were comparable in both groups. The heparin dose was 100 IU/kg in 30 patients and 200 IU/kg in 20 patients of either group. The average compression time was 4.3 minutes in group A and 42.3 minutes in group B (p < 0.001). Bleeding was not observed in group A but was observed in 6/50 patients in group B. The time to ambulation was 6.4 hours (range: 4-12 hours) in group A and 21.6 hours (range: 10-48 hours) in group B (p < 0.001). Hematomas with a diameter of > 6 cm developed in 4/50 patients in group A and in 11/50 patients in group B (p < 0.05). Blood transfusion or surgical interventions were not required and there was no loss of ankle pulses in either group. CONCLUSION: Percutaneously applied collagen reduced compression time and duration of bedrest after diagnostic catheterization and PTCA. Despite earlier ambulation, the incidence of bleeding was lower with collagen than with conventional pressure dressing.

Aged↗
PubMed1997

Vasospasm in smooth coronary arteries as a cause of asystole and syncope.

In a patient with proven myocardial infarction, coronary artery disease was excluded angiographically. Four weeks later the patient experienced recurrent syncope of unknown cause. By means of Holter monitoring, ST-segment elevation with subsequent first-degree AV block progressing to asystole and resulting in loss of consciousness were documented. Treatment with gallopamil and a VVI-pacemaker led to complete relief of all symptoms. Hence, Prinzmetal's angina may be a rare cause of syncope even in smooth coronary arteries.

Angina Pectoris, Variant↗
PubMed1997

Preliminary results achieved by a computer-assisted system for controlled balloon dilatation of coronary and peripheral arteries.

In percutaneous balloon angioplasty the extent of trauma to the vessel as determined by slope of balloon inflation, peak pressure, and inflation time is crucial to the success of the intervention. These parameters are still not standardized and hence open to the operator. To elucidate this problem, a computer-assisted PTCA system (CAPS) was developed. CAPS is composed of a motor driven unit, a central processing and power unit, and a notebook. A syringe is clamped onto the motor unit and connected to a pressure gauge. CAPS may be linked to all types of balloon catheters. The notebook allows for preselection of peak pressure, slope of pressure increase, and inflation time. During balloon inflation, adjustments are made in a closed-loop system. On a screen, the inflation process is supervised in digital numbers and analogous curves. After the procedure, patient data and inflation curves may be recalled for analysis. In conclusion, CAPS by controlled inflation theoretically may reduce the mechanical trauma to the arteries. Further refinements should aim at gaining information on the lesions' characteristics and on the dilatation process itself.

Angioplasty, Balloon, Coronary↗
PubMed1997

Traumatology--the Achilles heel in the rehabilitation of cardiovascular outpatients?

In outpatient rehabilitation involving cardiac patients apprehension of the rare cardiovascular complications are crucial determinants of the sports activities whereas prophylactics of injuries is thought to be less important. Retrospectively, questionnaires to specify injuries were answered by 903 patients (61.7 +/- 8 years, 753 men, 150 women from 116 coronary care groups, approximately 270,000 patient exercise hours [PEH]). Independently of the patient's age and frequency of participation 123 traumas (1 per 2,200 PEH) occurred. Ball games accounted for the majority of the injuries (101/123 = 82.1%). Overstrains and distorsions were most frequent (53.7% approximately equal to 1 per 4,100 PEH) followed by bruises/ hematomas (15.4% approximately equal to 1 per 14,200 PEH), ruptured muscles, tendons and ligaments (12.2% approximately equal to 1 per 18,000 PEH), bone fractures (11.4% approximately 1 per 19,300 PEH), and abrasions or slashes (6.5% approximately 1 per 33,750 PEH). Two of the slashes and the loss of eyesight in one patient were caused by broken spectacles. Strains and distorsions were primarily located in the upper (25/27 = 43.8%) or lower limbs (22/57 = 38.6%). All ruptured muscles, tendons and ligaments were of the lower extremities. The 14 bone fractures were localized over the body. In sports with cardiac patients physicians must focus on the cardiovascular system and stress the prophylaxis of injuries by teaching motor and technical skills as well as tactics. Non-breakable spectacles are mandatory.

Adolescent↗
PubMed1997

Chronic coronary occlusions: age, morphology and chance of reopening.

In chronic coronary occlusions the chance of successful reopening by angioplasty can be judged from the age of the occlusion. Often, however, time since occlusion cannot be accurately assessed. Therefore we determined whether the chance of reopening can be predicted from angiographic morphology. In cineangiograms from 60 consecutive patients with chronic coronary occlusions morphological details in at least two projections were evaluated in relation to the rate of success and the estimated age of occlusion. Morphological features associated with a higher rate of success (type A) were a clearcut proximal stump, absence of side branches at the site of occlusion, absence of bridging collaterals, and only slight filling of the distal part of the vessel. Features associated with a low success rate (type B) were absence of proximal stump, side branches at the site of occlusion, bridging collaterals, and rapid high-contrast filling of the distal part of the vessel. 48/60 (80%) of occlusions could be classified as type A or type B. The success rate was 17/21 (81%) in type A versus 5/27 (18.5%) in type B (P < 0.0002). The estimated age of type B occlusions was higher than that of type A medians 8 and 4 months (P < 0.002). Thus in chronic coronary occlusions the likelihood of successful reopening can be judged in many patients from morphological features.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Traumatological risk in ambulatory cardiological rehabilitation].

BACKGROUND: In Israel in 1956 Gottheiner introduced outpatient rehabilitation programs in patients who had survived a myocardial infarction. In Germany one decade later these WHO phase III activities were established as well. At present any patient with cardiovascular disease is included unless suffering from acute illnesses or presenting with symptoms at rest. Gymnastics, stretching and the "historic" volleyball are completed by jogging, soccer, basketball and anaerobic exercise. Thus, a notable trauma rate would be expected especially in the elderly and those who are on anticoagulation. METHODS: A retrospective analysis evaluated questionnaires of 903 patients in 116 outpatient coronary care groups covering approximately equal to 270,000 patient exercise hours. RESULTS: 101 of 123 injuries (approximately equal to 1/2 200 patient exercise hours) occurred during games the majority of which having been distortions (53.7%), hematomas, or bruises (15.4%). Severe traumas included bone fractures (11.4%) and ruptured muscles, tendons, or ligaments (12.2%). One patient lost the sight of one eye due to a broken spectacle frame. Patients who had felt exercise as too exhausting (p < 0.001) or complained of cardiovascular symptoms (p < 0.01) showed a significantly elevated trauma rate. CONCLUSIONS: Thus, in outpatient cardiac rehabilitation the trauma rate is within the range of healthy sports men. To prevent injuries sports should be limited to the patient's level of activity. Improved skills in techniques and strategies as well as unbreakable glasses are recommended.

Aged↗
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↗