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Biomedical subjects

Christian Seiler

Publications and source records attributed to Christian Seiler.

At least 37 records · Page 2Linked to original sources
PubMed2004

Comparison of medical treatment with percutaneous closure of patent foramen ovale in patients with cryptogenic stroke.

OBJECTIVES: The purpose of this study was to compare the efficacy of medical treatment with percutaneous closure of patent foramen ovale (PFO). BACKGROUND: Patients with cryptogenic stroke and PFO are at risk for recurrent cerebrovascular events. METHODS: We compared the risk of recurrence in 308 patients with cryptogenic stroke and PFO, who were treated either medically (158 patients) or underwent percutaneous PFO closure (150 patients) between 1994 and 2000. RESULTS: Patients undergoing percutaneous PFO closure had a larger right-to-left shunt (p < 0.001; 95% confidence interval [CI] 1.38 to 3.07) and were more likely to have suffered more than one cerebrovascular event (p = 0.03; 95% CI 1.04 to 2.71). At four years of follow-up, percutaneous PFO closure resulted in a non-significant trend toward risk reduction of death, stroke, or transient ischemic attack (TIA) combined (8.5% vs. 24.3%; p = 0.05; 95% CI 0.23 to 1.01), and of recurrent stroke or TIA (7.8% vs. 22.2%; p = 0.08; 95% CI 0.23 to 1.11) compared with medical treatment. Patients with more than one cerebrovascular event at baseline and those with complete occlusion of PFO were at lower risk for recurrent stroke or TIA after percutaneous PFO closure compared with medically treated patients (7.3% vs. 33.2%; p = 0.01; 95% CI 0.08 to 0.81, and 6.5% vs. 22.2%; p = 0.04; 95% CI 0.14 to 0.99, respectively). CONCLUSIONS: Percutaneous PFO closure appears at least as effective as medical treatment for prevention of recurrent cerebrovascular events in cryptogenic stroke patients with PFO. It might be more effective than medical treatment in patients with complete closure and more than one cerebrovascular event.

Adolescent↗
PubMed2004

Implantation of a second closure device in patients with residual shunt after percutaneous closure of patent foramen ovale.

Percutaneous closure of patent foramen ovale (PFO) in patients with presumed paradoxical embolism yields complete occlusion in > 90% of patients using contemporary closure devices. Patients with a residual shunt after percutaneous PFO closure have been found at increased risk for recurrent paradoxical events. Treatment options for such patients include medical treatment using antiplatelet drugs or oral anticoagulation, surgical device removal and patch closure, and percutaneous implantation of a second closure device. We report our experience with implantation of a second closure device in 10 patients with more than a minimal residual shunt < or = 6 months after percutaneous PFO closure. Procedure and fluoroscopy times were similar for the initial and repeat intervention (32 vs. 30 min and 5 vs. 6 min, respectively; P = NS). There were no procedural complications during implantation of the second closure device. Follow-up transesophageal echocardiography 6 months after the second percutaneous intervention revealed complete PFO closure in nine (90%) patients. Therefore, implantation of a second closure device in patients with persistence of more than a residual shunt after percutaneous PFO closure appears safe and effective.

Adult↗
PubMed2004

Coronary collateral perfusion in patients with coronary artery disease: effect of metoprolol.

BACKGROUND: The use of ultrathin Doppler angioplasty guidewires has made it possible to measure collateral flow quantitatively. Pharmacologic interventions have been shown to influence collateral flow and, thus, to affect myocardial ischaemia. METHODS: Twenty-five patients with coronary artery disease undergoing PTCA were included in the present analysis. Coronary flow velocities were measured in the ipsilateral (n = 25) and contralateral (n = 6; two Doppler wires) vessels during PTCA with and without i.v. adenosine (140 microg/kg.min) before and 3 min after 5 mg metoprolol i.v., respectively. The ipsilateral Doppler wire was positioned distal to the stenosis, whereas the distal end of the contralateral wire was in an angiographically normal vessel. The flow signals of the ipsilateral wire were used to calculate the collateral flow index (CFI). CFI was defined as the ratio of flow velocity during balloon inflation divided by resting flow. RESULTS: Heart rate and mean aortic pressure decreased slightly (ns) after i.v. metoprolol. The collateral flow index was 0.25+/-0.12 (one fourth of the resting coronary flow) during the first PTCA and 0.27+/-0.14 (ns versus first PTCA) during the second PTCA, but decreased with metoprolol to 0.16+/-0.08 (p<0.0001 vs. baseline) during the third PTCA. CONCLUSIONS: Coronary collateral flow increased slightly but not significantly during maximal vasodilatation with adenosine but decreased in 23 of 25 patients after i.v. metoprolol. Thus, there is a reduction in coronary collateral flow with metoprolol, probably due to an increase in coronary collateral resistance or a reduction in oxygen demand.

Adolescent↗
PubMed2004

Risk of decompression illness among 230 divers in relation to the presence and size of patent foramen ovale.

BACKGROUND: The risk of developing decompression illness (DCI) in divers with a patent foramen ovale (PFO) has not been directly determined so far; neither has it been assessed in relation to the PFO's size. METHODS: In 230 scuba divers (age 39+/-8 years), contrast trans-oesophageal echocardiography (TEE) was performed for the detection and size grading (0-3) of PFO. Prior to TEE, the study individuals answered a detailed questionnaire about their health status and about their diving habits and accidents. For inclusion into the study, > or =200 dives and strict adherence to decompression tables were required. RESULTS: Sixty-three divers (27%) had a PFO. Overall, the absolute risk of suffering a DCI event was 2.5 per 10(4) dives. There were 18 divers (29%) with, and 10 divers (6%) without, PFO who had experienced > or =1 major DCI events P=0.016. In the group with PFO, the incidence per 10(4) dives of a major DCI, a DCI lasting longer than 24 h and of being treated in a decompression chamber amounted to 5.1 (median 0, interquartile range [IQR] 0-10.0), 1.9 (median 0, IQR 0-4.0) and 3.6 (median 0, IQR 0-9.8), respectively and was 4.8-12.9-fold higher than in the group without PFO (P<0.001). The risk of suffering a major DCI, of a DCI lasting longer than 24 h and of being treated by recompression increased with rising PFO size. CONCLUSION: The presence of a PFO is related to a low absolute risk of suffering five major DCI events per 10(4) dives, the odds of which is five times as high as in divers without PFO. The risk of suffering a major DCI parallels PFO size.

Decompression Sickness↗
PubMed2004

Giant anastomotic pseudoaneurysm complicating aortic xenograft replacement.

A 74-year-old woman was referred for investigation of a 2-week history of progressive dyspnea. Her medical history included an aortic valve replacement with a stentless bioprosthesis followed 13 months later by the replacement of the aortic root with a porcine xenograft. Transesophageal echocardiography revealed a giant circular pseudoaneurysm of the aortic xenograft with compression of the prosthetic aortic valve and concomitant severe aortic regurgitation. Dehiscence of the proximal graft anastomosis was also diagnosed, and a possible distal anastomotic dehiscence was suspected. The latter turned out intraoperatively to be an almost complete dehiscence of the right coronary artery. The patient died intraoperatively.

Aged↗
PubMed2004

Collateral vessel physiology and functional impact- experimental evidence of collateral behaviour.

The clinical variable predicting the development of collateral arteries in humans is the hemodynamic severity of coronary stenoses. Hyperemia induces an overall increase in coronary collateral flow in patients with coronary artery disease (CAD). There is a reduction in hyperemia-induced myocardial perfusion in the collateral-dependent vascular area in about 10% of patients with CAD and superior collateral vessels (collateral steal). Collateral recruitment has a major impact in the equation: ischemic tolerance=preconditioning+collateral recruitment.

Animals↗
PubMed2004

Early clinical experience with a new tubular equine pericardial stentless aortic valve.

BACKGROUND: This study details a single-center experience with the 3F Therapeutics stentless aortic bioprosthesis(investigational device) and is part of a prospective,nonrandomized worldwide multicenter study. We assessed the implantation procedure and the valve's efficacy in terms of early mortality and morbidity and early echocardiographic valve performance. METHODS: Between June 2001 and March 2004, 24 patients (14 men/10 women) underwent aortic valve replacement(AVR) with a 3F valve. Mean age was 72 +/- 13 years(range, 31-88 years). Combined revascularization was performed in 12 patients; 1 patient received biatrial ablation therapy, 1 patient a myectomy, and 3 patients combined carotid endarterectomy. Echocardiographic systolic gradient and valve performance were investigated intra- and postoperatively by Doppler echocardiography. RESULTS: There were 2 perioperative deaths, 1 non-valve related, due to aortic rupture in an 83-year-old woman, and 1 fatal cerebral embolism in a 77-year-old woman 5 days postoperatively. Cardiopulmonary bypass time was 102 +/- 32 minutes,aortic cross-clamp time was 79 +/- 24 minutes. Sizes for implanted 3F valves were 5 x 23 mm, 6 x 25 mm, 7 x 27 mm,and 6 x 29 mm. Follow-up systolic gradient results were 11.5 +/- 4.7 mm Hg at 30 days (n = 21), 11.4 +/- 4.5 mm Hg at 6 months (n = 18), and 13.3 +/- 4.4 mm Hg at 12 months (n =13). During the follow-up period trivial central aortic valve regurgitation was found in 6 patients. CONCLUSION: The 3F aortic valve shows favorable preliminary hemodynamic results. Owing to the new valve design,implantation technique is simplified compared with other stentless valves. Anticoagulation treatment is mandatory for the first 3 months postoperatively. Long-term observation is necessary to assess life span and durability.

Aortic Valve↗
PubMed2003

Impact of acute hypoxic pulmonary hypertension on LV diastolic function in healthy mountaineers at high altitude.

In pulmonary hypertension right ventricular pressure overload leads to abnormal left ventricular (LV) diastolic function. Acute high-altitude exposure is associated with hypoxia-induced elevation of pulmonary artery pressure particularly in the setting of high-altitude pulmonary edema. Tissue Doppler imaging (TDI) allows assessment of LV diastolic function by direct measurements of myocardial velocities independently of cardiac preload. We hypothesized that in healthy mountaineers, hypoxia-induced pulmonary artery hypertension at high altitude is quantitatively related to LV diastolic function as assessed by conventional and TDI Doppler methods. Forty-one healthy subjects (30 men and 11 women; mean age 41 +/- 12 yr) underwent transthoracic echocardiography at low altitude (550 m) and after a rapid ascent to high altitude (4,559 m). Measurements included the right ventricular to right atrial pressure gradient (DeltaP(RV-RA)), transmitral early (E) and late (A) diastolic flow velocities and mitral annular early (E(m)) and late (A(m)) diastolic velocities obtained by TDI at four locations: septal, inferior, lateral, and anterior. At a high altitude, DeltaP(RV-RA) increased from 16 +/- 7 to 44 +/- 15 mmHg (P < 0.0001), whereas the transmitral E-to-A ratio (E/A ratio) was significantly lower (1.11 +/- 0.27 vs. 1.41 +/- 0.35; P < 0.0001) due to a significant increase of A from 52 +/- 15 to 65 +/- 16 cm/s (P = 0.0001). DeltaP(RV-RA) and transmitral E/A ratio were inversely correlated (r(2) = 0.16; P = 0.0002) for the whole spectrum of measured values (low and high altitude). Diastolic mitral annular motion interrogation showed similar findings for spatially averaged (four locations) as well as for the inferior and septal locations: A(m) increased from low to high altitude (all P < 0.01); consequently, E(m)/A(m) ratio was lower at high versus low altitude (all P < 0.01). These intraindividual changes were reflected interindividually by an inverse correlation between DeltaP(RV-RA) and E(m)/A(m) (all P < 0.006) and a positive association between DeltaP(RV-RA) and A(m) (all P < 0.0009). In conclusion, high-altitude exposure led to a two- to threefold increase in pulmonary artery pressure in healthy mountaineers. This acute increase in pulmonary artery pressure led to a change in LV diastolic function that was directly correlated with the severity of pulmonary hypertension. However, in contrast to patients suffering from some form of cardiopulmonary disease and pulmonary hypertension, in these healthy subjects, overt LV diastolic dysfunction was not observed because it was prevented by augmented atrial contraction. We propose the new concept of compensated diastolic (dys)function.

Acute Disease↗
PubMed2003

Early exercise after coronary stenting is safe.

OBJECTIVES: In this study, we sought to assess safety of symptom-limited exercise stress tests the day after coronary stenting. BACKGROUND: Isolated cases of coronary stent thrombosis have been linked to early exercise stress testing, thereby questioning the safety of unrestricted physical activity after the coronary procedure. METHODS: At a single center, 1,000 patients were randomized to a symptom-limited stress test the day after coronary stenting or no stress test. The antiplatelet regimen consisted of acetylsalicylic acid and postprocedural ticlopidine or clopidogrel. The primary end point of the study was the incidence of clinical stent thrombosis at 14 days. The secondary end point was the occurrence of access site complications. RESULTS: Clinical stent thrombosis occurred in five patients (1%) undergoing stress test and in five patients (1%) randomized to no stress test (p = 1.0). Access site complications were detected in 4% and 5.2% of cases, respectively (p = 0.37). CONCLUSIONS: Symptom-limited exercise stress testing the day after coronary stenting does not increase the risk of clinical stent thrombosis or access site complications. Further investigations on safety of early vigorous exercise after coronary stenting in a non-supervised setting are warranted.

Aged↗
PubMed2003

Is there functional collateral flow during vascular occlusion in angiographically normal coronary arteries?

BACKGROUND: Thus far, it is unknown whether there is functional collateral flow through preexisting anastomoses in patients with angiographically normal coronary arteries. Such preformed coronary collateral vessels could form the basis for subsequently developing protective natural bypasses in the presence of coronary artery disease. METHODS AND RESULTS: Among 100 patients, the collateral flow index (CFI) was measured in coronary arteries without stenotic lesions. The CFI was determined by simultaneous measurement of mean aortic pressure, central venous pressure, and coronary wedge pressure via a sensor-tipped guidewire at the end of a 1-minute balloon occlusion. Patients were divided in 2 groups according to complete angiographic absence (51 patients) or partial presence (49 patients) of stenotic lesions in coronary arteries other than that undergoing collateral measurement. CFI in all patients (61+/-10 years; men/women, 69/31) amounted to 0.18+/-0.08 (range, 0.04 to 0.36). It showed a normal Gaussian frequency distribution; 22 individuals had a CFI > or =0.25, a value that was empirically found to represent well-developed collaterals protective against myocardial ischemia during coronary occlusion. Accordingly, 17 patients did not reveal signs of myocardial ischemia during coronary balloon occlusion, as assessed from an intracoronary ECG, and 26 patients did not experience angina pectoris during occlusion. CONCLUSIONS: In humans with angiographically normal coronary arteries, there are functional collateral vessels to the extent that one fifth to one quarter of them do not show signs of myocardial ischemia during brief vascular occlusions.

Angioplasty, Balloon, Coronary↗
PubMed2003

Four French catheters for diagnostic coronary angiography.

A randomized study was conducted to assess the feasibility of 4 Fr catheters for diagnostic coronary angiograms. A total of 1,114 consecutive patients were randomized to 4 or 5 Fr catheters. Ease of use of catheters was subjectively assessed by the primary operator and the picture quality was assessed by two independent observers with a good interobserver variability (r = 0.94; P < 0.001). Predischarge local complications were recorded by the attending physician. No statistically significant difference was observed in the picture quality for the left coronary artery, right coronary artery, aorta, left ventricle, venous grafts, or renal arteries between the two groups. Fluoroscopy time (7.1 +/- 5.6 for 4 Fr vs. 6.7 +/- 5.7 min for 5 Fr) and contrast quantity (140 +/- 58 vs. 144 +/- 57 ml) were comparable between the two groups. There was a statistically significant difference in favor of the 5 Fr group as regards maneuverability of catheters (93% vs. 79%; P < 0.001), and 5 Fr pigtail catheters crossed the aortic valve easier than the 4 Fr pigtail catheters (91% vs. 81%; P < 0.001). Crossover to the other catheter size or a larger sheath was more frequent with 4 Fr catheters (33/522 vs. 3/592; P < 0.001). Median time to hemostasis was 9 min for 4 Fr and 14 min for 5 Fr (P < 0.001). Of the 4 Fr patients, 84% could be mobilized at 1 hr and 86% of 5 Fr patients at 2 hr. Significant hematomas were observed in 2% with 4 Fr or 5 Fr and small hematomas in 10% and 16%, respectively (P = NS). Time to discharge was comparable in both groups (4.0 +/- 3.2 with 4 Fr vs. 4.3 +/- 3.7 hr with 5 Fr). The 4 Fr catheters are a good alternative for diagnostic coronary angiograms. The increased difficulty in maneuverability and a need for catheter changes in 70% are compensated for in part by easier hemostasis. With increasing use and finesse of these catheters, the difficulty in maneuverability are likely to be overcome.

Aged↗
PubMed2003

Reduced hepatic glycogen stores in patients with liver cirrhosis.

BACKGROUND: Patients with alcoholic liver cirrhosis have reduced hepatic glycogen stores but the mechanisms leading to this finding are not clear. METHODS: We therefore determined the hepatic glycogen content in patients with alcoholic (n = 9) or biliary cirrhosis (n = 8), and in control patients undergoing liver surgery (n = 14). All patients were in the postabsorptive state. In addition, we performed a morphometric analysis of the livers, and measured activities and mRNA expression of several enzymes involved in glycogen metabolism. Cirrhotic and control patients were similar regarding age and body weight. RESULTS: Cirrhotic patients had a reduced glycogen content per gram liver wet weight (17 +/- 11 versus 45 +/- 17 mg/g, P < 0.05), per milliliter hepatocytes (28 +/- 16 versus 52 +/- 21 mg/ml, P < 0.05) and per liver (28 +/- 17 versus 64 +/- 22 g, P < 0.05), the reduction being observed in both patients with alcoholic or biliary cirrhosis. Liver histology confirmed these findings and revealed that the decrease in liver glycogen in cirrhotic patients was not homogeneous across cirrhotic lobules. Activities of glycogen synthase and phosphorylase (total activity and active form) were not different between cirrhotic and control patients, whereas hepatic mRNA expression was decreased in cirrhotics by approximately 50%. The activity of glucokinase was decreased in cirrhotic as compared in control patients (0.06 +/- 0.30 versus 0.42 +/- 0.21 U/ml hepatocytes, P < 0.05), the reduction being observed in both patients with alcoholic or biliary cirrhosis. CONCLUSIONS: We conclude that patients with alcoholic or biliary cirrhosis have decreased hepatic glycogen stores per volume of hepatocytes and per liver. Decreased activity of glucokinase may represent an important mechanism leading to this finding.

3-Hydroxybutyric Acid↗
PubMed2003

Exercise-induced human coronary collateral function: quantitative assessment during acute coronary occlusions.

In 50 patients undergoing percutaneous transluminal coronary angioplasty because of chronic angina pectoris, a collateral flow index (CFI) was determined at the start and the end of two 1-min coronary occlusions, randomly accompanied by a resting state or a 3-min dynamic handgrip exercise (DHE). CFI expressing collateral flow relative to normal antegrade flow was determined by simultaneous coronary occlusive pressure, mean aortic pressure and central venous pressure measurements. When comparing CFI without and with DHE at the start as well as at the end of balloon occlusions, a significant increase was observed with DHE (overall p < 0.0001); start: 0.18 +/- 0.12 vs. 0.22 +/- 0.13, respectively (p = 0.01); end of occlusion: 0.21 +/- 0.14 vs. 0.25 +/- 0.14, respectively (p = 0.007).

Acute Disease↗
PubMed2003

Aortic root replacement with a new stentless aortic valve xenograft conduit: preliminary hemodynamic and clinical results.

BACKGROUND AND AIM OF THE STUDY: Beside aortic valve-sparing surgery, a composite graft, homograft or (more rarely) an autograft are the most common options to replace a diseased or destroyed aortic root in adults. Recently, a new stentless xenograft valved conduit (Shelhigh, No-React) was introduced in Europe. This totally biologic conduit is glutaraldehyde cross-linked, detoxified and heparin-treated with No-React; this process eliminates residual glutaraldehyde and ensures stable tissue cross-linking. The initial clinical and hemodynamic results with this porcine valved conduit in the aortic position are presented herein. METHODS: Among 308 patients who underwent thoracic aorta surgery during a 30-month period, 127 had aortic root repair or replacement. The Shelhigh stentless aortic valve conduit was implanted in 35 patients (30 males, 5 females; mean age 68 +/- 7.2 years; mean body mass index 27.5 +/- 4.1 kg/m2). Of these patients, 15 had aortic valve stenosis and ascending aortic aneurysm, 10 had a dilated aortic root with or without aortic regurgitation, four had acute aortic dissection type A, and six had a complex pathology (destructive endocarditis or re-do surgery). RESULTS: One patient with prosthetic valve endocarditis died on postoperative day 1 from uncontrolled septicemia (30-day mortality, 2.7%). There were no conduit-related adverse events in the surviving patients, but one re-exploration was required for bleeding in a re-do case. Transthoracic echocardiography was available in 30 patients after six months, and in 15 patients after 12 months. The mean gradient across the aortic valve was 8.5 +/- 5.1 mmHg (range: 6 to 14 mmHg for conduit sizes 21 to 29 mm). CONCLUSION: The Shelhigh valved conduit shows promising hemodynamic properties. As the conduit contains no fabric or mechanical components, it is ideal for treatment of the infected aortic root, and an excellent alternative to homografts. In older patients, this conduit has the additional advantage that no long-term anticoagulation is required.

Adult↗