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Biomedical subjects

H R Arntz

Publications and source records attributed to H R Arntz.

At least 19 recordsLinked to original sources
PubMed2001

Prehospital thrombolysis in acute myocardial infarction.

Efficacy of reperfusion therapy in acute myocardial infarction (AMI) is strictly time-dependent. Most benefit is achieved with initiation of therapy within the first 60-90 min after onset of symptoms. The majority of patients with AMIs are seen within this time window by emergency medical services. Moreover, average time gain of about 60 min is possible by prehospital thrombolysis. Randomized studies yielded a better outcome when a time gain of 90 min and more was achieved. Prehospital diagnosis of AMI is reliable. Moreover, out-of-hospital thrombolysis has no additional specific risks nor is it an obstacle for later percutaneous intervention. Consequently, patients seen within the first 60-90 min after onset of symptoms or for whom a time gain of 90 min or more can be expected should receive immediate prehospital thrombolysis.

Emergency Medical Services↗
PubMed2001

Phased chest and abdominal compression-decompression versus conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest.

BACKGROUND: Several methods have been developed to improve the efficacy of mechanical resuscitation, because organ perfusion achieved with conventional manual resuscitation is often insufficient. In animal studies, phased chest and abdominal compression-decompression resuscitation by use of the Lifestick device has resulted in a better outcome compared with that of conventional resuscitation. In end-of-life patients, an increased coronary perfusion pressure was achieved. The aim of the present study was to determine the feasibility, safety, and efficacy of the Lifestick compared with conventional resuscitation in patients with sudden nontraumatic out-of-hospital cardiac arrest. METHODS AND RESULTS: The crews of 4 mobile intensive care units, staffed by an emergency physician and a paramedic, were trained to use the device. Fifty patients were randomized by sealed envelopes to either Lifestick (n=24) or conventional (n=26) resuscitation. No differences were found regarding demographic and logistical conditions between the groups. Nineteen of the patients (73%) with conventional resuscitation had ventricular fibrillation, 13 of whom survived to hospital admission (no survivals with other arrhythmias) and 7 were discharged. In contrast, in the Lifestick-CPR group, only 9 patients had ventricular fibrillation (38%; P=<0.02; OR, 2.5; 95% CI, 0.6 to 10.6). Four of these 9 patients and 5 of 15 patients with other arrhythmias survived to hospital admission, but none survived to hospital discharge. Autopsy in a subgroup of patients who died at the scene revealed less injuries with Lifestick than with conventional resuscitation. CONCLUSION: Lifestick resuscitation is feasible and safe and may be advantageous in patients with asystole or pulseless electric activity.

Abdomen↗
PubMed2001

Cold Monday mornings prove dangerous: epidemiology of sudden cardiac death.

Sudden cardiac death is the leading cause of death in industrialized countries, accounting for 10 to 20% of total mortality. Several studies have demonstrated a circadian variation of sudden death with a primary peak in the morning hours after awakening and a secondary peak in the late afternoon. Weekly and seasonal variations have been observed, with more frequent occurrence of sudden death on Mondays and in the winter compared with other days of the week and seasons, respectively. These patterns of disease occurrence indicate the presence of identifiable triggering factors. Interestingly, the circadian pattern of sudden death appears to be more pronounced in older patients and to be attenuated by beta-blocker therapy. Rupture of an atherosclerotic plaque with subsequent coronary thrombosis is the most common underlying pathophysiologic mechanism of sudden death. The variation in disease occurrence may reflect endogenous physiologic rhythms and the importance of external events (e.g., exertional physical activity) that trigger changes (e.g., surges in blood pressure) that lead to coronary plaque rupture. To reduce the long-term risk of sudden death, strategies of primary and secondary prevention must be further developed. To reduce short-term risk of sudden death, patients at risk for sudden death may require additional behavior modification and pharmacological intervention.

Age Factors↗
PubMed2000

Beneficial effects of pravastatin (+/-colestyramine/niacin) initiated immediately after a coronary event (the randomized Lipid-Coronary Artery Disease [L-CAD] Study).

Secondary prevention of coronary heart disease by antilipidemic therapy beginning at > or =3 months after an acute coronary syndrome is well documented. The impact, however, of immediate initiation of antilipidemic therapy on coronary stenoses and clinical outcome in patients with acute coronary syndrome is unknown. In our study, patients were randomized, on average, 6 days after an acute myocardial infarction and/or percutaneous transluminal coronary angioplasty secondary to unstable angina, to pravastatin (combined, when necessary, with cholestyramine and/or nicotinic acid) to achieve low-density lipoprotein cholesterol levels of < or =130 mg/dl (group A, n = 70). In controls (group B, n = 56), antilipidemic therapy was determined by family physicians. Quantitative coronary angiography was performed at inclusion, and at 6- and 24-month follow-up. The combined clinical end points were total mortality, cardiovascular death, nonfatal myocardial infarction, need for coronary intervention, stroke, and new onset of peripheral vascular disease. Minimal lumen diameter in group A increased by 0.05 +/- 0.20 mm after 6 months and 0.13 +/- 0.29 mm after 24 months, whereas it decreased by 0.08 +/- 0.20 mm and 0.18 +/- 0.27 mm, respectively, in group B (p = 0.004 at 6 months and p <0.001 at 24 months). After 2 years, 29 patients of 56 patients in group B, but only 16 of 70 patients in group A, experienced a clinical end point (p = 0.005; odds ratio 0.28, confidence intervals 0.13 to 0.6). We conclude that pravastatin-based therapy initiated immediately after an acute coronary syndrome is well tolerated and safe, lessens coronary atherosclerosis, and has a pronounced clinical benefit.

Adult↗
PubMed2000

Diurnal, weekly and seasonal variation of sudden death. Population-based analysis of 24,061 consecutive cases.

AIMS: Several studies have reported circadian and seasonal variations in acute cardiovascular disease. In addition, a weekly variation has been observed in acute myocardial infarction. The aim of our study was to determine the circadian weekly, and seasonal variations of sudden death utilizing population-based data. METHODS AND RESULTS: We analysed the emergency medical system data of Berlin (West) from 1987-1991 with respect to all consecutive sudden deaths in subjects >18 years (n=24 061). There was a marked circadian variation of sudden death, with a minimum between 0 and 6 h and a maximum between 6 and 12 h (P<0.0001) for every day of the week. A minimum of events occurred on Sundays (n=3143), and a maximum on Mondays (n=3721), corresponding to a relative increase of 18.3% (P<0.0001). The increase was more pronounced (23.6%) in patients < or =65 than in patients >65 (15.7%). In addition, we found a significant seasonal variation (P<0.0001) in events, with a maximum during winter (December to February, n=6493), and a minimum during summer (June to August, n=5472), corresponding to a relative difference of 18.7%. The seasonal variation was more pronounced in patients >65 years. CONCLUSION: The present analyses demonstrate marked variations in the occurrence of sudden death with peaks during morning hours, on Mondays, and during winter months. The findings suggest that the onset of sudden death may be associated with endogenous rhythms and external factors including climatic conditions.

Adult↗
PubMed2000

Long-term prognosis of cardiovascular patients following mobile emergency care.

Mobile emergency care units provide immediate benefit for patients with acute cardiovascular disease, but the subsequent prognosis of this patient population is unclear. We, therefore, aimed to determine whether the long-term survival of patients with acute cardiovascular syndromes requiring emergency medical care differs from controls of the general population. The long-term survival was analysed in all consecutive patients who were treated for acute cardiovascular events (coronary syndromes/cardiac arrest, pulmonary oedema, stroke, vascular disorientation/unconsciousness) by a mobile emergency care unit or rescue helicopter in Berlin from 1987 to 1988 and were admitted to hospital. Subsequent mortality follow-up information was obtained throughout 1994 from medical records and official vital statistics. The survival of the patient population was compared with standardized mortality data of controls matched for gender, age, and residential location. A total of 1206 patients (48% men, 67 +/- 14 years, 52% women, 72 +/- 17 years) were included in the analysis. The 1-year survival of the patient population was significantly lower compared with controls (76% vs. 88%, p < 0.001), but during subsequent years this difference was continuously reduced. Seven years after the initial event, survival rates of patients and controls were similar (43% vs. 41%). The results were similar in both gender groups. Patients > 65 years of age had a markedly higher mortality compared with patients < or = 65 years, as would be expected. Older patients had a similar long-term survival compared with controls (27% vs. 28%), whereas younger patients sustained a relatively lower long-term survival compared with controls (75% vs. 86%, p < 0.05). It is concluded that a novel population-based approach demonstrates similar long-term prognosis of cardiovascular patients following mobile emergency care compared with matched controls. The present results may contribute to the assessment of long-term effectiveness and the appropriate design of emergency care systems.

Aged↗
PubMed2000

[3-D localization of cardiac structures in real time].

Radiographic 3-D localisation enables measurements to be made that facilitate the placement of the interventional device during cardiac intervention. To enable the reader to implement the method himself, we describe the computation of 3-D coordinates, acquisition of the imaging and projection data on-line, and the accuracy that can be expected with the method. The 3-D coordinates of a cardiac structure are calculated from the image point coordinates, the projection data and the system constants of a biplane isocentric X-ray unit. Technical imaging errors are corrected a priori. The biplane projection data of a run are acquired on-line and stored in a data base. The image pair of interest is identified automatically from the inscribed run number, and assigned to the projection data from the data base. The target image point is marked on the monitor for 3-D localisation. The accuracy of the method was determined by comparing the calculated and actual cross-sectional points of a centimetre grid imaged in biplane X-ray projections. 3-D localisation took an average of 9.8 +/- 1.2 seconds. Angles and distances were assessed with a standard error of 1.1 degrees and 0.8 mm. The run number is identified correctly in 98.5% of the cases. The mean absolute location error for all points and image pairs was 0.61 +/- 0.32 mm. The accuracy and precision was 0.03 +/- 0.40 mm. Radiographic 3-D localisation can be performed readily and accurately on-line. The results obtained with the method enable interventional decisions to be optimized.

Computer Graphics↗
PubMed1999

Evidence for the benefit of early intervention with pravastatin for secondary prevention of cardiovascular events.

Treatment with HMG-CoA reductase inhibitors (or statins) lowers total and LDL cholesterol and decreases the risk of cardiovascular events. The absolute benefits are greater in patients with a higher baseline cardiovascular risk, so statins are particularly suited to secondary prevention. Although three large studies have shown convincingly that, in patients with a history of cardiovascular disease, simvastatin or pravastatin treatment reduces the risk of further events and lowers overall mortality, those studies have not included patients in the period immediately after an acute coronary event. They are, therefore, of limited value in answering the question of when to start statin treatment. However, there are practical reasons for starting statin treatment as early as possible, and results of clinical studies have now shown this to be a safe option for pravastatin. Early treatment with pravastatin can stabilize coronary atherosclerosis and improve endothelial function. More importantly, there is also evidence that early treatment with pravastatin can produce a clinical benefit a few months after the initial coronary event.

Angina Pectoris↗
PubMed1999

[Short- and long-term effects of intensified versus conventional antilipidemic therapy in patients with coronary heart disease. Results from the Lipid-Coronary Artery Disease (L-CAD) Study].

In a prospective, randomized study of patients with acute manifestation of coronary heart disease and hypercholesterolemia (LDL cholesterol >/= 130 </= 250 mg/dl), we compared the effect of an early-initiated, intensified therapy to usual care antilipidemic therapy with respect to coronary lesions and clinical events. Patients were included immediately following acute myocardial infarction and/or PTCA because of severe/instable angina pectoris. The intensified therapy consisted of pravastatin 20-40 mg with addition of colestyramine and/or nicotinic acid, if necessary, to achieve an LDL cholesterol </= 130 mg/dl. In the control group, antilipidemic therapy was left up to the private physician. The group with intensified therapy consisted of 70 patients (LDL cholesterol 179 +/- 27 mg/dl, age 55 +/- 10 years, 81% males), the control group of 56 patients (LDL cholesterol 177 +/- 28 mg/dl, age 58 +/- 11 years, 79% males). Cholesterol was reduced longterm by 28% under intensified therapy, but it remained constant in the control group. Quantitative coronary angiography revealed a mean of increase minimal lumen diameter of 0.05 mm after 6 months with intensified therapy and of 0.13 mm after 24 months. Under conventional therapy, however, it decreased by 0.08 mm after 6 months, and by 0.18 mm after 24 months (p < 0.01). In addition, within 12 months of therapy, significantly (p < 0.01) less cardiovascular clinical events were observed in patients under intensified therapy. After 2 years 43% (n = 22) of the controls, but only 17% (n = 14) of the patients with intensified therapy experienced a major clinical event (p < 0.03), i. e. death, myocardial infarction, necessary coronary intervention, cerebral infarction or new peripheral vascular disease. This study is the first to show that aggressive early - initiated cholesterol-lowering therapy can induce regression and reduce progression of coronary lesions already after 6 months. These changes are accompanied by a significant reduction in clinical events. The results of our study underline the necessity of immediate cholesterol screening and early intensive antilipemic therapy at the latest when of coronary heart disease becomes manifest.

Adult↗
PubMed1999

[Development and validation of a graphic method for spatial interpretation and evaluation of biplanar coronary angiograms].

Visual evaluation and measurement of the lesion geometry is impaired by the foreshortening of the radiographically displayed target coronary segment. For this reason, we developed and validated a simple graphic procedure that facilitates the spatial interpretation and allows an objectifiable assessment of the view of the target coronary segment. The method computes a spatial axis of the coronary segment imaged in two planes and determines its inclination in the radiation path of each projection view. A triangle made up of the axis of the imaged segment, the unforeshortened axis of the imaged segment and the foreshortening height is displayed in each projection plane. The shape of the triangle indicates the degree of foreshortening while its position in the angiogram indicates the orientation of the spatial axis relative to the observer. The method was validated by comparing calculated and true foreshortening in the radiographic views of a centimetre grid obtained in the usual angiographic projections. The method has an accuracy and precision of 0.05 +/- 0.62%. It is applied clinically to evaluate biplane segmental visualization during coronary interventions and to select valid segmental views for measurements during quantitative biplane coronary angiography. This application may considerably facilitate the interpretation and assessment of biplane angiograms.

Computer Graphics↗
PubMed1998

The impact of vessel and catheter position on the measurement accuracy in catheter-based quantitative coronary angiography.

BACKGROUND: The calculation of absolute artery dimensions in quantitative coronary angiography is usually carried out by catheter calibration. It is based on the proportional comparison of the dimension of the imaged artery segment to the dimension of the imaged angiographic catheter of known size. This calibration method presumes an identical radiographic magnification between angiographic catheter and artery segment of interest. However, due to the different intrathoracic location of both objects the radiographic magnification or calibration factor is often not identical for a given angiographic projection. The aim of this study was to quantify the magnification error (out-of-plane magnification error) for the major coronary artery segments imaged in frequently used angiographic projections. METHODS: The intrathoracic spatial location of 468 coronary segments (RCA 196, LAD 156, LCX 116) and their respective coronary catheters were established with biplane angiography and known imaging geometry data. The error in the radiographic magnification or calibration factor was then calculated for all 936 monoplane projections using the spatial coordinates and imaging geometry data. RESULTS: The mean magnitude of magnification error was 4% within all 936 measurements. The magnitude and direction of error varied with the lesion localization and the angiographic projection angle (range -12.6% to +10.6%). The error characteristics could be described with six typical error groups by stratifying the data according to the three main coronaries and two angiographic planes. In 24% of measurements, the magnification error exceeded the 5.2% error limit acceptable for reference vessel sizing. Measurements of left coronary arteries were mainly affected by it. CONCLUSION: The magnification error contributes to the calibration error in measuring arterial dimensions by quantitative angiography. This error may affect the reliability of clinical studies and the proper sizing of interventional devices. These findings could be used to improve current error correction algorithms in order to reduce the effect of the magnification error in measuring arterial dimensions.

Algorithms↗
PubMed1998

Circadian variation and triggers of acute coronary syndromes.

Myocardial infarction and sudden cardiac death demonstrate a marked circadian variation with an increased risk during the morning after awakening and arising. The recognition of the morning increase of acute coronary heart disease has convinced many that morning activities can 'trigger' its onset. It is of note, however, that coronary events may occur throughout the day--even if at lower frequency compared with the morning. There is a strong association between external triggers and onset of myocardial infarction and sudden cardiac death beyond that expected by chance alone. The magnitude of this association (relative risk two- to threefold) is comparable to that of other known long term risk factors of cardiac disease. Trigger factors occur relatively frequently and may play a causative role in up to 20% of cases of acute coronary syndromes. Physical exertion, burst of anger and sexual activity have been proven to have triggering potential. Other possible triggers include external and environmental events such as earthquakes, war threat and climatic factors. The pathophysiological links between external triggers and onset of coronary syndromes are important in addressing the question of a causal relationship between triggers and disease onset and, perhaps, in improving preventive strategies.

Acute Disease↗
PubMed1998

Prehospital thrombolysis in acute myocardial infarction.

Efficacy of reperfusion therapy in acute myocardial infarction is strictly time dependent. As is evidenced by several studies, most benefit in terms of myocardial salvage and short- and long-term mortality is achieved with initiation of therapy within the first 60-90 minutes after onset of symptoms. Nearly exclusively, prehospital initiation of thrombolysis makes it possible to take advantage of this early time window. Moreover a time gain of more than 30 minutes, up to 130 minutes, is possible by prehospital initiation of thrombolysis, depending on local circumstances. Randomized studies yielded a better outcome when a time gain of > or = 90 minutes was achieved. Since it has been shown that prehospital diagnosis of an acute myocardial infarction is reliable and out-of-hospital initiation of therapy has no additional specific risk, patients seen within the first 60-90 minutes after onset of symptoms or for whom a relevant time gain of > or = 90 minutes can be expected are ideal candidates for, and therefore should receive, prehospital thrombolysis.

Emergency Medical Services↗
PubMed1996

[Are emergency physicians' diagnoses accurate?].

METHODS AND AIM OF THE STUDY: The on-scene performance during all missions of the emergency physician-operated rescue helicopter and mobile intensive care unit based at a large-city hospital over a period of 1 year was retrospectively analysed; 2,254 hospital discharge reports were available (92% of the patients treated by the emergency physicians [n = 2,493]). The following parameters were investigated: reliability of the primary diagnosis established by the emergency physician (by comparison with the discharge diagnoses); initial on-scene therapeutic measures; means of transportation (with or without accompanying emergency physician); and level of care of the target hospital. RESULTS: The most common reasons for a mission were cardiopulmonary diseases (55%), neurological disorders (18%), and traumatic events (7%). The diagnoses, therapeutic measures, and mode of transportation were correct in 2,033 (90%) patients with a discharge report. Severe errors of assessment by the emergency physician were identified in 73 patients (3%): life-threatening conditions were not recognised and/or grossly incorrect therapeutic measures were taken and/or the chosen means of transportation was unsuitable. Relative errors in assessment occurred in 4% (n = 83): the most crucial diagnosis was not made, but the patient was escorted by the emergency physician (without therapeutic errors) to a suitable hospital. In 3% (n = 65) of the cases, the patient's condition was overestimated by the emergency physician as suggested by the obviously exaggerated on-scene therapy. Underestimations of the severity were most common in patients with cardiopulmonary diseases and increased in frequency and severity with increasing age and the presence of a concomitant neurologic deficit. Underestimations of a severe condition in younger patients were extremely rare; overestimations of the severity and consequent overtreatment were particularly common in traumatised patients independent of age. CONCLUSIONS: In the context of quality management measures, a careful evaluation of on-scene diagnoses, therapeutic measures, and decisions made by the emergency physician is a suitable procedure for identifying systematic errors. A high percentage of correct diagnoses and therapy at the emergency site can only be ensured by clinically experienced physicians who constantly deal with patients with acutely life-threatening conditions.

Adolescent↗