Enantiopure N-acyldihydropyridones as synthetic intermediates: asymmetric synthesis of benzomorphans

[formula: see text] Concise asymmetric syntheses of several benzomorphan derivatives have been accomplished using enantiopure 2,3-dihydro-4-pyridones as chiral building blocks.

Troponin T measurement after myocardial infarction can identify left ventricular ejection of less than 40%

AIM

To determine whether measurement of serum troponin T concentration after first acute myocardial infarction can be used to identify patients with a left ventricular ejection fraction of < 40%, who have an adverse prognosis.

METHODS

Troponin T concentration was measured, and coronary and left ventriculography performed in 50 consecutive patients with acute myocardial infarction. Angiographic left ventricular ejection fraction was compared with serum troponin T concentration. Patients with previous myocardial infarction were excluded.

RESULTS

There was a strong negative correlation between left ventricular ejection fraction and troponin T concentration. Spearman's rank correlation coefficient (corrected for ties) was -0.72 (95% confidence intervals (CI) -0.55 to -0.83; p < 0.0001). Analysis by receiver operator characteristic curve produced an area under the curve of 0.9773 (95% CI 0.9409 to 1.0136). A troponin T concentration of > 2.8 micrograms/l predicted a left ventricular ejection fraction of < 40% with a sensitivity of 100% (CI 84.6 to 100.0) and specificity of 92.9% (CI 76.5 to 99.1). Exclusion of patients who did not receive thrombolytic treatment did not significantly affect the results.

CONCLUSION

Serum troponin T concentration measured 12-48 hours after admission for first myocardial infarction is a reliable, simple, quick, inexpensive, non-invasive method for identifying patients with a left ventricular ejection fraction of < 40% for whom there is a poor prognosis.

Direct current cardioversion does not cause cardiac damage: evidence from cardiac troponin T estimation

AIM

To determine whether elective direct current (dc) cardioversion of atrial fibrillation/flutter causes myocardial damage.

METHODS AND RESULTS

Cardiac troponin T and creatine kinase were estimated 20-28 hours after dc cardioversion in 51 patients who received dc shocks for elective cardioversion of chronic atrial fibrillation/flutter. Although creatine kinase was raised in 44 patients, cardiac troponin T was undetectable in all patients.

CONCLUSION

Cardiac damage does not occur as a result of cardioversion.

Multicenter comparative study of the efficacy and safety of sotalol in the prophylactic treatment of patients with paroxysmal supraventricular tachyarrhythmias

We performed a randomized, double-blind, placebo-controled, parallel-group comparison study of the efficacy and safety of sotalol in the prophylaxis of paroxysmal supraventricular tachyarrhythmias (PSVTs) (including paroxysmal atrial fibrillation and paroxysmal reentrant SVTs). The frequency of PSVT episodes while not receiving drug therapy was monitored during a baseline phase, the length of which depended on the frequency of PSVT events. In the double-blind phase, the duration of which depended on the baseline frequency of episodes of PSVT, patients received placebo, sotalol 80 mg twice daily, or sotalol 160 mg twice daily. PSVT events were documented by electrocardiogram and diary. The time to recurrence of PSVT was significantly less compared with placebo when receiving sotalol 80 mg (p = 0.018) and sotalol 160 mg (p = 0.0009). On subanalysis, sotalol was shown to be effective in the prophylaxis of both paroxysmal atrial fibrillation and paroxysmal reentrant arrhythmias. Sotalol was well tolerated, with no deaths, proarrhythmia, or cardiac failure. Because of adverse effects, drug therapy was discontinued in six patients.

Clinical experience with a new lead combining active fixation with steroid elution

The Medtronic lead engineering model number 10335A represents a new concept in lead design combining active fixation with steroid elution. It aims for immediate stability and low chronic thresholds. Twenty-one leads, 9 atrial and 12 ventricular, were implanted in 13 patients (10 males, mean age 68; range 22-91 years). The atrial leads showed no rise in pulse width threshold at a voltage of 1.6 volts (mean thresholds at implant, 1, and 26 weeks; 0.1 +/- 0.09 msec, 0.15 +/- 0.04 msec, and 0.1 +/- 0.03 msec, respectively). The ventricular leads had a small but significant rise between implant and 1 week at an output of 1.6 volts (0.07 +/- 0.03 msec increasing to 0.11 +/- 0.04 msec; P < 0.02) but no significant later rise (0.1 +/- 0.04 msec at 2 weeks and 0.1 +/- 0.05 msec at 6 months). These low chronic thresholds would allow early reprogramming of the unit to low voltages resulting in a battery saving with prolongation of the unit's life. There were no significant changes in the P and R wave amplitudes, but there was a fall in lead impedance in the ventricular leads between implantation and 1 week (P < 0.02) but none subsequently, and there was no significant change in atrial impedance. There were no sensing failures and no lead displacements. Despite impressive pacing characteristics, the study was suspended because of a high level of mechanical complications. Of the 96 patients implanted worldwide with 136 leads there were eight helix deformations, which will require redesign.(ABSTRACT TRUNCATED AT 250 WORDS)

An unusual C-4a hydroxylated decahydroquinolone

The crystal structure and the relative stereochemistry of the four asymmetric centers of an unusual C-4a hydroxylated decahydroquinolone, phenyl 1,2 alpha,3,4,-4a alpha,5 beta,6,7,8,8a alpha-decahydro-4a-hydroxy-4-oxo-2-propyl-5-vinylquinoline-1 -carboxylate, C21H27NO4, are reported. The H and OH groups at the ring juncture are cis to each other as are the two H atoms alpha to the N atom. The vinyl and OH groups are also cis to each other. The N atom is sp2 hybridized.

4-Methoxy-1-[(1R,4S,5R)-8-phenyl-menthoxycarbonyl]pyridinium hexachloroantimonate, C23H30NO3+.SbCl6-

The 4-methoxypyridinium and oxycarbonyl moieties are coplanar and approximately parallel to the phenyl ring. The latter is involved in a number of short intramolecular interactions with the pyridinium and the oxycarbonyl atoms. Crystal packing is characterized by the presence of hydrophobic and hydrophilic channels, the former consisting of phenylmenthyl groups and the latter of pyridinium and SbCl6- ions.

Choosing the pacemaker; a rational approach to the use of modern pacemaker technology

Sophisticated pacemakers now afford greater benefit than only relief of syncope for patients with symptomatic bradyarrhythmia. For clinical reasons it is inappropriate to implant ventricular demand (VVI) pacemakers in every patient, but for both clinical and economic reasons it is also undesirable to use dual-lead or rate-responsive systems indiscriminately. However, the published guidelines for pacemaker choice and investigation are inadequate. We have analysed the clinical assessment and the investigations required in a series of 150 patients with various electrophysiological disorders, considered consecutively for pacemaker implantation using an algorithm to assist decisions. Holter electrocardiography in 77.3%, exercise testing--formal (in 9.3%) or informal (during Holter electrocardiography), electrophysiology study (EPS)--full in 15.3% and partial in 29.3%, and trial of pacing (10.7%) were all used to characterize dysfunction and to define appropriate pacing mode. 142 patients were paced--57.0% with single lead modes (12.7%) AAI, 44.3% VVI) and 43.0% dual-lead (2.8% DVI, 23.9% VDD or VAT, 16.2% DDD). Three patients received rate-responsive systems (VVIR) which, if available, would have been used in nine; four would have been suitable for AAIR and four for dual-lead responsive pacing (DVIR, DDIR or DDDR). We offer a rational approach based on published data for investigation and pacemaker choice in the management of patients with bradyarrhythmia.

Herpes zoster pericarditis

A healthy 22-year-old man developed acute varicella pericarditis, characterised by an enanthem with diagnostic rising titres of varicella zoster antibodies but without the typical exanthem. This, the third reported case of varicella pericarditis, is the first to be documented without a typical varicella eruption.

Electrophysiological properties of mexiletine assessed with respect to plasma concentrations

Electrophysiological measurements were made before and after the intravenous administration of mexiletine in 14 patients with preexcitation syndromes. Following a single infusion of 3 mg/kg body weight plasma concentrations of mexiletine fell rapidly and after 15 min, significant changes in electrophysiological measurements were not found. Higher plasma mexiletine concentrations, bringing about a pharmacological effect, were attained when a second intravenous infusion was also given. The results suggest a minimum effective plasma concentration for mexiletine of about 0.5 mg/l. Side-effects were minimal and their production was largely dependent on the rate of drug infusion. Electrophysiological measurements in previous studies may have been made at a time when plasma mexiletine concentrations were below an effective level and this could explain a disparity in their findings.

Pervenous retrieval of embolized catheters from the right heart and pulmonary arteries

Successful removal of embolized or retained catheter fragments from the right heart was achieved in two out of four patients using pervenous catheter techniques. For the first time a fragment, radiolucent on image intensification, was retrieved from the right pulmonary artery using a wire snare. In a second case a hook-loop was made in the right ventricle with a Judkins left femoral coronary angiographic catheter, which has advantages over previously described hooking devices, to withdraw a fragment to the iliac vein for subsequent snaring. Failure of retrieval occurred only in specially difficult circumstances; when a catheter embolized to the pulmonary artery of a Tetralogy of Fallot, and when in spite of successful ensnarement, a fractured electrode was firmly adherent to the right ventricular apex. Successful pervenous retrieval may require a combination of techniques which move or dislodge, such as a hook or balloon combined with those which ensnare, such as a wire loop or bioptome. Using such techniques, with minimal additions to standard equipment, retrieval procedures can be offered as a routine cardiac catheterization service with a high rate of success.

Long-term atrial pacing for sinus node disease with output-terminal programmagle pacemakers

Long-term transvenous atrial pacing for symptomatic sinus node disease, in the absence of atrioventricular conduction disease, confers the advantages of increased cardiac performance and probable freedom from systemic thromboembolism. Conventional ventricular pacing has been preferred, however, because of the complications of atrial pacing, mainly those of electrical and mechanical instability of currently available atrial electrodes. These complications have been circumvented with a new pacemaker, programmable for output terminal. This has allowed the institution of atrial pacing in seven patients, with its attendant advantages and the ability to reprogram noninvasively to ventricular pacing should atrial pacing fail. Such reprogramming has been accomplished without difficulty in one patient who developed second-degree atrioventricular block and one with electrode microdisplacement.

Value of positive myocardial infarction imaging in coronary care units

Positive myocardial imaging was undertaken on 120 unselected patients admitted to a coronary care unit with clinical suspicion of acute myocardial infarction. Multipurpose mobile gamma-cameras were used for serial imaging after administration of 99mtechnetium-labelled imidodiphosphonate, a low-cost radiopharmaceutical that is 97% specific for myocardial necrosis, with myocardial uptake and blood clearance most suitable for myocardial imaging. The sensitivty of detection was 94% for patients whose infarction was unequivocal on the ECG; when the presence of raised enzyme concentrations was also used as a criterion for myocardial necrosis, the overall sensitivity for all 120 patients remained 94%. In 73 patients (61%), whose ECGs were unhelpful or difficult to interpret, scintigraphy allowed infarction to be diagnosed in 11 (15%) and to be excluded in five (7%). In 32 (44%) of this group whose ECGs were totally uninterpretable due to previous myocardial damage or disorders of electrical activation, scintigraphy provided confirmation of a diagnosis that otherwise rested only on whether enzyme concentrations were raised. Myocardial imaging is thus a useful technique that permits more definite diagnosis in patients for whom ECG and enzyme data are uncertain.

99mTc-imidodiphosphonate: a superior radio-pharmaceutical for in vivo positive myocardial infarct imaging. II: Clinical data

99mTc-Imidodiphosphonate was investigated as a new myocardial infarct imaging agent. In the acute phase, 50 patients admitted to the coronary care unit were serially scanned over a period of 7 days. A mobile gamma camera linked on line to a remote data processor was used. Because of higher uptake in infarcted myocardium and faster blood clearance, superior images than those recorded with 99mTc-pyrophosphate were obtained. Its ease of preparation, low cost, and favourable dosimetry (because of its label with conventional 99mTc) transforms this agent into the present radiopharmaceutical of choice for acute infarct imaging in particular if sizing and follow-up is intended versus time and type of treatment. In this series, no false positive cases were seen. The sensitivity of the method in the detection of full thickness myocardial infarction was 95%. It dropped to 70% in the detection of subendocardial infarction. However, some of these apparent false negative cases may reflect severe ischaemia without infarction. It is postulated that this discrimination may not always be realistic.