Asger Ken Pedersen

Optimal diagnosis in acute myocardial infarction. A cost-effectiveness study.

The predictive value of a diagnostic test estimates the likelihood for presence or absence of disease in a patient with a positive or negative test result (PV, O, or PVYR.,). We evaluated the predictive values of serum activities of the heart-specific creatine kinase isoenzyme MB (CK-MB), aspartate aminotransferase, lactate dehydrogenase, CK, and ECG in 401 consecutively admitted patients suspected of acute myocardial infarction (AMI). The study showed that CK-MB (PVPOI = 0.98, PV.g, = 1.00) was better than the other enzymes (single as well as serial) and ECG, evaluated both separately and in combinations. In all cases of AMI CK-MB was positive within 17 hours from admission. Replacement of the standard enzymes with CK-MB provides a faster and safer diagnosis of AMI and reduces hospitalization time considerably for patients without AMI.

The Tertiary picrites of West Greenland: contributions from ‘Icelandic’ and other sources

New isotope and trace element data are presented for suites of tholeiitic picrites from Disko, Ubekendt Ejland and Svartenhuk Halvo of the West Greenland Tertiary Volcanic Province. Geographic and stratigraphic subgroups are identified by major element, trace element and Sr and Nd isotope systematics. Early picrites on Disko haveeNd = +8to+10 andeSr = −22to−15, similar to subaerial Icelandic lavas, and overlap compositionally with North Atlantic MORB. Most other picrites of the province are enriched relative to MORB but still haveeNd > +6 andeSr < −10. Crustal sources cannot explain the observed geochemical variation. Modelling of the major oxides Al2O3, CaO and TiO2 and FeO′ suggests that the main part of the West Greenland picrites was derived from a source similar to the most enriched Icelandic picrites by rather high degrees of partial melting (highCa/OAl2O3) at relatively high pressures (high FeO′). These features and the high MgO (19 wt% in liquids) are in accordance with their derivation from very hot plume mantle below the continental lithosphere. In the same group of picrites, both major elements, incompatible elements and Sr and Nd isotopes are coupled and are thought to identify the Icelandic plume end member at ca. 63 Ma and today:eSr = −15to−18,eNd = +7.5 to +8.5,Al/2O3TiO2= 7–10 andZr/Nb= 14–26, and a trace element pattern as in the picrites of the Ordlingassoq Member at Disko and Group 1 of the equivalent lower formation at Svartenhuk Halvo. Lithospheric influence in the picrites is only detected in the northern part of the province. The influence from MORB mantle seen in the older Naujanguit Member of Disko decreases with time. The results lead to discussion and revision of recent models for continental flood basalt volcanism and mantle plumes [1,2] with regard to the site of picrite production relative to the plume axis and the timing of continental flood basalt volcanism in West and East Greenland during the early Tertiary.

Paleomagnetism of large igneous provinces: case-study from West Greenland, North Atlantic igneous province

Abstract We present new paleomagnetic and multi-model stereo photogrammetry data from lava sequences in the West Greenland part of the North Atlantic igneous province (NAIP). The joint analyses of paleomagnetic and photogrammetric data yield a well-defined paleomagnetic pole located at Lat=73.6°N, Long=160.5°E ( N =44, α 95 =6.2°, K =13.1; age ∼61–55 Ma), which is statistically indistinguishable from a pole recently obtained for the Eurasian part of the NAIP on Faroe Islands [Riisager et al., Earth Planet. Sci. Lett. 201 (2002) 261–276]. Combining the two datasets we obtain a joint NAIP paleomagnetic pole in Greenland coordinates: Lat=71.1°N, Long=161.1°E ( N =87, α 95 =4.3°, K =13.6; age ∼61–54 Ma). The results presented here represent the first study in which photogrammetry profiles were photographed at the exact same locations where paleomagnetic fieldwork was carried out, and a direct flow-to-flow comparison of the two datasets is possible. Photogrammetry is shown to be particularly useful because of (i) highly precise dip/strike measurements and (ii) detailed ‘field observations’ that can be made in the laboratory. Highly precise determination of the structural attitude of well-exposed Kanisut Mb lava sequences demonstrates that their apparently reliable in-field dip/strike measurements typically are up to ∼6° wrong. Erroneous dip/strike readings are particularly problematic as they offset paleomagnetic poles without affecting their confidence limits. Perhaps more important for large igneous provinces is the recognition of a variable temporal relationship between consecutive lava flows. We demonstrate how correct interpretation of paleosecular variation, facilitated by the detailed photogrammetry analysis, is crucial for the rapidly emplaced Vaigat Formation lavas. Inaccurate tectonic correction, non-averaged paleosecular variation and unrecognized excursional directions may, perhaps, explain why coeval paleomagnetic poles from large igneous provinces are often discordant. The difference between the joint NAIP paleomagnetitc pole and apparent polar wander path poles suggests that they may be less reliable than suggested by their confidence limits.

Diagnostic and prognostic implications of transient isolated negative T waves in suspected acute myocardial infarction

The diagnostic and prognostic implications of transient isolated negative T waves were studied in 127 patients in whom acute myocardial infarction (AMI) was suspected. Eight-four patients with no AMI and no electrocardiographic changes served as the control group. The 2 groups were well matched. Twenty-nine patients (23%) with isolated negative T wave had a significant increase in serum creatine kinase (CK)-MB levels and fulfilled the diagnostic criteria for AMI. The increase in serum CK-MB levels did not predict a higher risk of hospital mortality, but during follow-up (median 31 months), a serum CK-MB level above 30 U/liter identified patients with a significantly increased risk of dying (p less than 0.05). Both the number of affected electrocardiographic leads and the sum of negative T-wave amplitudes were significantly related to the follow-up mortality rate (p less than 0.01). The comparison between control subjects and patients with negative T waves during follow-up showed more events among the patients: AMI (17% vs 8%, p less than 0.02); death (24% vs 12%, p less than 0.01); and AMI or death (31% vs 19%, p less than 0.01). Thus, only 25% of patients with aggravated chest pain and isolated negative T waves have AMI. However, the long-term prognosis for the entire group of patients with isolated negative T waves is poor, and any therapeutic intervention should be initiated immediately.

Petrology of mugearite-hawaiite: Early extrusives in the 1973 Heimaey eruption, Iceland

Abstract Rocks which erupted during the first few weeks are described and chemical analyses of rocks and microprobe analyses of minerals are presented. An outline of the eruption history and of the geology of the area is given. A gradational change in chemistry from mugearitic to hawaiitic composition is recorded. Xenoliths of hypersthene gabbro not cognate with magma were discovered in the mugearite. One xenolith has reacted with the mugearite magma at depth to form pargasitic hornblende and kaersutite. It is argued that the magma reacted with the xenoliths at a total pressure well below 8–9 kbar and at a gas pressure higher 1 kbar.

Cor triatriatum: a rare malformation of the heart, probably amenable to surgery: report of a case, with review of literature.

Abstract A case report of a 29-year-old woman with increasing cardiac distress is reported. No murmur could be heard. The heart was not enlarged, but a prominent second left arch and pulmonary congestion were found on the roentgenogram. Moreover, the lower lobe of the left lung was markedly emphysematous. An electrocardiogram showed right ventricular hypertrophy. On heart catheterization, an excessive pulmonary hypertension was found, and the pulmonary “capillary pressure”, too, was very high. A mitral disease, therefore, was suggested, and the patient submitted to surgery. Thoracotomy revealed a normal mitral valve, and a normal pressure in the left atrium was measured directly. At post mortem the findings were fully explained, as a transverse septum with only one small perforation was separating the opening of the pulmonary veins from the rest of the atrium (so-called cor triatriatum). A review is made of the literature concerning anomalous, congenital structures within the left atrium. Thin cords or even broad bands across the lumen have been of no significance. The real cor triatriatum, however, was a serious disorder. Many of the patients died shortly after birth, and only a few reached the adult age. The clinical symptoms and signs were by no means characteristic, and no help was obtained from the usually employed investigations. An in-vivo diagnosis, therefore, must certainly be left for an explorative thoracotomy. The possibility of an effective surgical treatment is briefly discussed.

Landslide and Tsunami 21 November 2000 in Paatuut, West Greenland

A large landslide occurred November 21, 2000 at Paatuut, facing the Vaigat Strait onthe west coast of Greenland. 90 million m3 (260 million tons) of mainly basalticmaterial slid very rapidly (average velocity 140 km/h) down from 1,000–1,400 maltitude. Approximately 30 million m3 (87 million tons) entered the sea, creatinga tsunami with an run-up height of 50 m close to the landslide and 28 m at Qullissat,an abandoned mining town opposite Paatuut across the 20 km wide Vaigat strait. Theevent was recorded seismically, allowing the duration of the slide to be estimated tocirca 80 s and also allowing an estimate of the surface-wave magnitude of the slideof 2.3. Terrain models based on stereographic photographs before and after the slidemade it possible to determine the amount of material removed, and the manner ofre-deposition. Simple calculations of the tsunami travel times are in good correspondencewith the reports from the closest populated village, Saqqaq, 40 km from Paatuut, whererefracted energy from the tsunami destroyed a number of boats. Landslides are notuncommon in the area, due to the geology with dense basaltic rocks overlying poorlyconsolidated sedimentary rocks, but the size of the Paatuut slide is unusual. Based onthe observations it is likely at least 500 years since an event with a tsunami of similarproportions occurred. The triggering of the Paatuut slide is interpreted to be caused byweather conditions in the days prior to the slide, where re-freezing melt water inpre-existing cracks could have caused failure of the steep mountain side.

Anomalous Breakdown in Uniform Field Gaps in SF6

Experiments showing anomalously low breakdown voltages in uniform field gaps in SF6 are discussed. A generalized quantitative criterion suitable for computer calculations of breakdown voltages in known fields in SF6 and other strongly electronegative gases is described, and it is shown that the anomaly in the uniform field gap breakdown voltages can be satisfactorily accounted for. Similar anomalies can occur in other field geometries and in other gases; it is shown how to avoid such breakdowns.

Prognosis of late versus early ventricular fibrillation in acute myocardial infarction

To determine the prognosis of late ventricular fibrillation (VF) after acute myocardial infarction (AMI), the length of the monitoring period after AMI was extended. All patients in this series were continuously monitored in a coronary care unit to ensure observation of all VF within 18 days of AMI. From 1977 to 1985, 4,269 patients were admitted with AMI and 413 (9.6%) had in-hospital VF. Of these 281 (6.8%) had early VF (less than 48 hours after AMI) and 132 (3.2%) had late VF (greater than or equal to 48 hours after AMI). In-hospital mortality was 50 and 54% for early and late VF, respectively (p = 0.31). Kaplan-Meier survival analysis showed better survival after discharge for patients with early versus late VF (p = 0.009) but this difference was fully explained by the presence of heart failure. Survival analysis showed the same prognosis after 1, 3 and 5 years for early and late VF, when VF was not associated with heart failure. When VF was associated with heart failure (secondary VF) early VF had a greater mortality than late VF after 2 and 5 years. Logistic regression analysis showed that heart failure (relative risk 1.9 [1.1 to 3.1]) and cardiogenic shock (relative risk 3.9 [1.8 to 8.5]) were significant risk factors for in-hospital death. Late VF compared to early VF had no prognostic implication (relative risk 1.0 [0.6 to 1.6]). For patients discharged from the hospital, risk factors were heart failure (1.8 [1.1 to 2.8]) and previous AMI (1.6 [1.3 to 2.1]).(ABSTRACT TRUNCATED AT 250 WORDS)

Sudden cardiac arrest outside the hospital--value of defibrillators in ambulances.

In a region with a population of 250,000 people, all emergency calls for cardiac arrest were prospectively registered during a period of 6 years. Timing of events were carefully registered as were treatment and the participation of 3 ambulances equipped with defibrillators. When time until initial treatment of cardiac arrest was below 5 min, 12% could be resuscitated and discharged alive. This figure decreased to 2% in the period between 5 and 10 min and was zero to above 10 min. Similarly, a reasonable 12% of patients experiencing ventricular fibrillation at a public place could be resuscitated and discharged alive whereas only 5% of ventricular fibrillation occurring at the patients home could be successfully resuscitated. Asystolia was rarely treated successfully. Faster treatment improved results much and 63% of patients having ventricular fibrillation in the emergency room left hospital alive. Results of cardioversion in ambulances did not depend on time from initiation of cardiac arrest, but all patients receiving cardioversion later than 10 min died without regaining consciousness. The results were compared with other more effective programs. The study region apparently had much fewer cardiac arrest than a similar region in Seattle, U.S.A. In those cases where treatment could be initiated within 5 min, results were comparable.