Evidence for Impaired Hepatic Vitamin K1 Metabolism in Patients Treated with N-Methyl-Thiotetrazole Cephalosporins

In 8 patients on no oral intake and with parenteral alimentation, administration of cephalosporins with N-methyl-thiotetrazole side chain (moxalactam, cefamandole), was associated with prolongation of prothrombin time, appearance in the circulation of descarboxy-prothrombin (counter immunoelectrophoresis and echis carinatus assay) and diminution of protein C. Acute administration of 10 mg vitamin Ki was followed by the transient appearance of vitamin K1 2,3-epoxide, indicating an impaired hepatocellular regeneration of vitamin K1 from the epoxide. Impaired hepatic vitamin K1 metabolism, tentatively ascribed to the N-methyl-thiotetrazole group, is one (but possibly not the only) cause of bleeding complications and depression of vitamin K1dependent procoagulants in patients treated with the new class of cephalosporins.

Vitamin K und medikamenteninduzierte Hypoprothrombinämie

Aus den vorliegenden Untersuchungen und aus den Mitteilungen der Literatur läßt sich auf die Bedeutung folgender zwei Faktoren für die Genese der Cephalosporin-induzierten HP schlieβen:

1. Latenter Vitamin-K-Mangelzustand des Organismus durch fehlende oder reduzierte exogene Vitamin-K-Zufuhr (z.B. bei ausschlieβlich parenteraler Ernährung) und möglicherweise durch Unterdrückung der Vitamin-K2-produzie-renden (Dünn-)Darmflora.

2. Kumarinartige Hemmung des Vit-amin-K1Stoffwechsels in der Leber durch bestimmte Cephalosporine (z.B. NMTT-Cephalosporine).

Das Zusammenwirken dieser Faktoren führt funktionell zu einem manifesten Vitamin-K-Mangelzustand, erkenntlich an einem Abfall der Vitamin-K-abhängigen Gerinnungsfaktoren. Aufgrund dieses Mechanismus ist es verständlich, daß die Cephalosporin-induzierte HP durch prophylaktische Vitamin-K1Gaben verhindert (ca. 10 mg Vitamin K1 pro Woche) bzw. eine manifeste HP korrigiert werden kann.

Der Vollständigkeit halber sei auf die hier nicht näher erläuterten Anta-bus®-ähnlichen Reaktionen nach Alkoholzufuhr hingewiesen, die - in Analogie zu der kumarinartigen Hemmung des Vitamin-K1Stoffwechsels -ebenfalls die Gruppe der NMTT- und MTD-Cephalosporine betreffen und durch entsprechende Alkoholkarenz vermeidbar sind (60).

Anticoagulation with low-molecular-weight heparin in patients with heart diseases

Low-molecular-weight heparins (LMWH) were investigated in different cardiac diseases requiring anticoagulation. In case of short term usage advantages over intravenous unfractionated heparin (UFH) are of relevance, such as simple subcutaneous application, possibility for outpatient treatment and predictable effect on anticoagulation enabling abstention of laboratory monitoring in most cases. Thromboprophylaxis in acute medically ill patients and therapy of non-ST-elevation acute coronary syndromes (NSTE-ACS) are important indications, in which significant advantages for special LMWH as compared to Placebo or UFH were shown. A significant effect versus Placebo was demonstrated for the LMWH Dalteparin in prolonged anticoagulation until revascularisation procedure in NSTE-ACS. Promising results from trials were also published concerning use of LMWH Dalteparin and Enoxaparin in TEE-guided cardioversion. Findings from cohort trials are available for temporary or long term switch from oral anticoagulation to LMWH. Due to limited data, determination of individual benefit-to-risk ratio is of special importance to select suitable anticoagulation regimen in this case. Further investigations as a basis of general recommendations on standard dosing regimen are outstanding for use of each LMWH in percutaneous coronary interventions, as combination with Glycoprotein IIb/IIIa-inhibitors, in acute myocardial infarction and in artificial heart valves. In cardiology, most studies were performed with Dalteparin and Enoxaparin, suggesting these to be used in established cardiac indications as well as in further investigations.

Anticoagulation with the low-molecular-weight heparin dalteparin (Fragmin) in atrial fibrillation and TEE-guided cardioversion

BACKGROUND

Cardioversion (CV) in atrial fibrillation can cause arterial embolism. Effective anticoagulation clearly reduces the risk. In practice, in every third case anticoagulation is not in line with the recommendations. Simplification can be achieved, and time gained, by transesophageal echocardiography (TEE) due to the shorter anticoagulation period prior to CV, and by use of low-molecular-weight heparin (LMWH) for anticoagulation. As yet little data is available on LMWH in cardioversion. The aim of this cohort study was to investigate the administration of a LMWH in this indication under everyday clinical conditions.

METHODS

125 patients treated as inpatients for atrial fibrillation or -flutter received the LMWH Fragmin (dalteparin 2 x 100 anti-Xa units/kg, maximum dosage 2 x 10,000 anti-Xa units subcutaneously). In the presence of a relevant indication, TEE-guided CV was performed. The application of dalteparin was terminated as soon as effective anticoagulation had been achieved from phenprocoumon or once anticoagulation was no longer indicated.

RESULTS

125 patients with atrial fibrillation or -flutter received dalteparin for a median of 11 days (range of 3-41 days). TEE was performed in 39 patients. Five patients revealed a thrombus in the left atrial appendage in the TEE, and one patient died from suspected cerebral embolism over the further course. In the remaining 124 patients, no thromboembolic event was established. Successfully cardioverted were 26 of 34 patients (76%) who had no thrombus in the TEE. Serious adverse effects did not ensue.

CONCLUSION

Simple, well tolerated and effective anticoagulation is possible with dalteparin in TEE-guided CV. Due to the methodic limitations of a cohort study and the low incidence of emboli, the efficacy of dalteparin in this indication needs to be further confirmed by prospective and randomized studies.

[Diagnosis and treatment of streptococcal myositis]

HISTORY AND CLINICAL FINDINGS

Case 1: Following an influenza a 40-year-old patient was treated by intramuscular injections for backache. 24 hours later he was admitted to a hospital with massive pain in both lower extremities and a markedly reduced general condition. Case 2: Two days after a knee joint arthroscopy a 57-year-old man developed strong pain in the extremity treated by application of diclofenac. On the following day the patient was admitted to a university hospital in a septic state with a swollen, cold and blurry changed extremity.

INVESTIGATIONS

The myoglobin concentration was dramatically increased in both cases (> 15 000 mg/l). CRP values were elevated. The progressive septic state with acute renal failure was verified by elevation of creatinine concentration and decrease of leukocyte values in the second case (from 10/nl to 2,5/nl) shortly after admission.

DIAGNOSIS, TREATMENT AND COURSE

Both the patients died for septic shock. Case 1 died shortly after admission before surgical intervention. The second patient developed rapid progression of the myositis including the trunk despite radical surgical treatment (hip joint exarticulation).

CONCLUSION

In cases of sudden and painful swelling of an extremity of unknown origin or following intramuscular injection streptococcal myositis has to be taken into account. Only an immediate surgical intervention up to amputation of the affected extremity can stop the fatal course.

The effects of intravenous mexiletine on spectra of the signal-averaged ECG

This study examined the effects of intravenous mexiletine on the time-domain and spectrotemporal signal-averaged ECG (SAECG). SAECGs were recorded in 60 postmyocardial infarction (MI) patients with more than 100 premature ventricular beats per hour, before and after a constant infusion of mexiletine, 7 mg/kg, given over 1 hour. Spectrotemporal analysis was done on a fixed analyzed signal duration of QRS complex and ST segment of X, Y, and Z leads using a temporal window of rectangular type, measuring the signal content between 10-120 Hz. Intravenous mexiletine produced no significant change in the mean values of any of the time-domain variables. However, mexiletine either increased or decreased the power density spectrum (PDS) and PDS ratio (40-120 Hz/25-120 Hz) of the SAECG, and in rare cases only did it not alter the spectra of the SAECG. When PDS ratio in lead Z decreased after mexiletine, it was usually higher at baseline in comparison with that when the PDS ratio increased, or vice versa. When the treatment with mexiletine was effective, PDS increased in comparison with that when the drug was ineffective, or vice versa. Not all ranges (10-120 Hz) of spectra of the SAECG, but only certain frequency bands (25-40 Hz in lead Z, P = 0.0253; 40-55 Hz in lead Y, P = 0.0096; 55-70 Hz in X lead, P = 0.0018; and in lead Z, P = 0.0002; 70-85 Hz in lead X, P = 0.0025; and in lead Z, P = 0.0075, 85-100 Hz in lead X, P = 0.0033) were associated with mexiletine efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)

Signal-averaged ECG in prediction of the short-term suppression of ventricular premature beats by Mexiletine

We analyzed whether baseline parameters of time-domain and spectrotemporal analysis of a signal-averaged ECG or their changes during Mexiletine therapy can predict the antiarrhythmic efficacy of the drug. On 60 post-MI patients with > 100 ventricular premature beats per hour, signal-averaged ECGs were recorded before and after a constant infusion of Mexiletine (7 mg/kg) for 1 h and again after 4 days of oral Mexiletine therapy (Mexiletine SR, 360 mg twice daily). Spectrotemporal analysis was performed on a fixed analyzed signal duration of QRS-complex and ST-segment of X-, Y-, Z-leads using the temporal window of the rectangular type, measuring signals between 10-20 Hz. Intravenous and oral Mexiletine did not produce significant changes in mean values of any time-domain parameters. However, using informative variables of spectra of the signal-averaged ECG, we managed retrospectively to predict antiarrhythmic efficacy in 92% of the patients. Only certain frequency bands (from the range of the spectra at baseline, 10-120 Hz) were predictive for intravenous Mexiletine efficacy: 40-55 Hz in lead Y (P = 0.0116); 55-70 Hz in leads X and Z (P = 0.0063 and P = 0.0269, respectively); 70-85 Hz in lead Z, (P = 0.0227). When the treatment with intravenous Mexiletine was effective, the baseline power spectrum density was lower than when the drug was ineffective, and vice versa. Moreover, the efficacy of oral Mexiletine can be predicted by power density spectrum at baseline (10-25 Hz in lead Z, P = 0.0210; 70-85 Hz in lead Y, P = 0.0254) and by one of the possible (increased, decreased, unchanged) effects of intravenous Mexiletine on the spectra at frequency bands (70-85 Hz in lead X, P = 0.0432 and 40-120 Hz in lead Z, P = 0.0156). These results show the value of spectrotemporal signal-averaged ECG in selecting a subgroup of post-myocardial infarction patients that may benefit from Mexiletine therapy.

[Effect of low-dosage intravenous nitrate therapy on the anticoagulant effect of heparin]

BACKGROUND AND AIM

Controversial studies concerning the fact that simultaneous i.v. administration of heparin and glyceroltrinitrate (GTN) might reduce the anticoagulatory effect of heparin have been published. In a controlled and comparative study we therefore investigated the influence of the nitrates GTN or isosorbide dinitrate (ISDN) in comparison to placebo on the anticoagulatory effect of a constant heparin infusion in patients with CAD.

PATIENTS AND METHODS

22 stable and mobile inpatients (two female, 20 male; aged 47 to 80; documented CAD in 20 patients, one patient with atrial fibrillation, one patient with suspected CAD), kept on a therapeutic heparin infusion for several days (prolongation of the partial thromboplastin time [PTT] by 1.5 to two-fold), were included. Study course: Day 1: Discontinuation of nitrate medication, optimization of heparin therapy and fixation of the heparin dose (mean dose 33,800 E/24 h in the GTN group and 32,700 E/24 h in the ISDN group). Day 2: Intravenous simultaneous administration of 0.9% NaCl solution as placebo (3 ml/h) with heparin over 24 hours. Day 3: Substitution of NaCl solution by randomised single-blind intravenous administration of GTN (n = 10; 0.1%, solved in NaCl; dose 2.8 +/- 0.5 mg/h) or ISDN (n = 12; 0.1%, solved in NaCl, dose: 4.8 +/- 0.8 mg/h) for 24 hours. Day 4: Discontinuation of nitrates.

RESULT

As compared to placebo, the intravenous simultaneous administration of GTN or ISDN and heparin over 24 hours had no influence on the anticoagulatory effect of heparin when the areas under the curve of PTT values on days 2 and 3 were compared (PTT measurements at 8, 10 a.m., 1, 3, 6, 11 p.m.; Mann-Whitney test). After GTN or ISDN had been discontinued, no change in PTT values was seen during the following five hours.

CONCLUSION

There is no indication of a pharmacodynamic relevant interaction between heparin and low-dose intravenous nitrate therapy in patients with CAD.

[Ultrasonographic findings in varicose phlebitis of the great saphenous vein. Evidence of thrombus growth and detachment with asymptomatic lung embolism]

In five women (mean age 58 [31-74] years) with clinically diagnosed varicose phlebitis of the long saphenous vein appositional thrombus growth was demonstrated by serial ultrasonography (B-mode compression and colour-coded duplex sonography). In one patient the appositional thrombus was found to be free-floating as far as the common femoral vein, but this was not seen by phlebography. During therapeutic heparinization there was ultrasonographic evidence of softening and partial liquefaction of thrombus material in a cranial direction. There were no clinical signs of pulmonary embolism, but pulmonary perfusion scintigraphy demonstrated perfusion deficit characteristic of emboli. Four of the five patients had a surgical crossectomy and partial saphenous vein resection. The congruence between ultrasonographic and macro- as well as micropathological findings demonstrates the great value of B-mode and duplex ultrasound examination in the area of the epifascial veins. Ultrasonography should be performed in every case of varicose phlebitis of the large veins to exclude the presence of apposition thrombi.

Lack of effect of cefixime on the metabolism of vitamin K1

It seems that cephalosporins bearing a N-methyl-thio-tetrazole or a methyl-thiadiazole moiety in their molecule can cause hypoprothombinemia in patients via inhibition of the metabolism of vitamin K1 if they are in addition in a vitamin K1-deficient state. The authors therefore studied the effects of two different oral doses (200 and 400 mg) of the cephalosporin cefixime on the metabolism of vitamin K1 in healthy volunteers, because the accumulation of vitamin K1-2,3-epoxide in plasma is a sensitive marker of coumarin-like activity of drugs. The results indicate that the development of hypoprothrombinemia due to an impairment of the metabolism of vitamin K1 by cefixime seems unlikely because only trace amounts of vitamin K1-2,3-epoxide could be determined in the plasma of the subjects investigated.

Mechanism of cephalosporin-induced hypoprothrombinemia: relation to cephalosporin side chain, vitamin K metabolism, and vitamin K status

The mechanism of cephalosporin-induced hypoprothrombinemia has been investigated in hospitalized patients, with respect to cephalosporin structure, vitamin K metabolism, and vitamin K status. Cephalosporins containing side chains of N-methylthiotetrazole (latamoxef, cefmenoxime, cefoperazone, cefotetan, cefamandole) or methyl-thiadiazole (cefazolin) all caused the transient plasma appearance of vitamin K1 2,3-epoxide in response to a 10-mg intravenous dose of vitamin K1, whereas two cephalosporins without a heterocyclic side chain (cefotaxime and cefoxitin) did not. The plasma accumulation of vitamin K1 2,3-epoxide was qualitatively similar to, but quantitatively less than, that produced by the oral anticoagulant phenprocoumon. Patients eating normally had plasma vitamin K1 concentrations (176 to 1184 pg/mL) that were within the normal range (150 to 1550 pg/mL) and their clotting tests remained consistently normal for all antibiotics tested. Patients on total parenteral nutrition had lower plasma vitamin K1 concentrations (50 to 790 pg/mL) but normal clotting before starting antibiotic therapy. Of 19 parenterally fed patients, all seven treated with latamoxef developed hypoprothrombinemia, PIVKA-II and a decrease of protein C within four days whereas 12 patients treated with cefotaxime or cefoxitin showed no clotting changes. Latamoxef-associated hypoprothrombinemia was readily reversible by 1 mg of vitamin K1 given intravenously, but hypoprothrombinemia and sub-normal plasma vitamin K1 could recur within two to three days. The data suggest that NMTT-cephalosporins are inhibitors of hepatic vitamin K epoxide reductase and that a lower nutritional-vitamin K status predisposes to hypoprothrombinemia.

Alteration of hemostasis associated with cefoperazone treatment

21 Patients with normal and impaired renal function were given cefoperazone in a recommended dose of 4 g/day, irrespective of renal function. Platelet function and plasmatic coagulation were analyzed before and on day 7 of therapy. In patients with normal renal function on their usual diets, there was neither impairment of platelet function nor plasmatic coagulation. High serum antibiotic trough levels, prolongation of bleeding time and decreased vitamin K-dependent coagulation factors, as verified by the prolongation of prothrombin time and the appearance of descarboxyprothrombin, could be observed in those patients with impaired renal function whose insufficiency was far advanced and accompanied by a complex clinical picture. In this situation vitamin K deficiency may be due to poor oral intake, along with interference of hepatic vitamin K metabolism, showing an effect similar to that seen after coumarin therapy. Dosage reduction of the antibiotic in advanced renal failure and repeated control of prothrombin time is advised.

Possible coumarin-like mechanism of action for cephalosporins

In three patients treated with cephalosporins (one patient with latamoxef, two patients with cefazedone) vitamin K1 was injected to investigate whether this was followed by an increase in vitamin K1 2,3-epoxide plasma concentrations as compared to controls. Such a rise in K1-epoxide concentrations in the plasma can be demonstrated following treatment with coumarins. This reflects an inhibition of the vitamin K1-epoxide reductase in the liver. Coumarins are thought to induce hypoprothrombinaemia by such a mechanism. In all three patients we found a considerable increase in the vitamin K1-epoxide plasma concentrations following injection of 10 mg vitamin K1, whereas in normal subjects only traces of K1-epoxide could be detected (less than 0.030 micrograms/ml). The K1-epoxide concentrations found in our three patients treated with cephalosporins were 0.12, 0.16 and 0.19 micrograms/ml, respectively. This indicates that latamoxef or cefazedone might reduce clotting factor synthesis by a coumarin-like mechanism of action in these patients. Although the effect of cephalosporins in enhancing vitamin K1-epoxide plasma concentrations is less than that of coumarins, it might cause severe hypoprothrombinaemia in the presence of latent vitamin K deficiency.

Evidence for impaired hepatic vitamin K1 metabolism in patients treated with N-methyl-thiotetrazole cephalosporins

In 8 patients on no oral intake and with parenteral alimentation, administration of cephalosporins with N-methyl-thiotetrazole side chain (moxalactam, cefamandole), was associated with prolongation of prothrombin time, appearance in the circulation of descarboxy-prothrombin (counter immunoelectrophoresis and echis carinatus assay) and diminution of protein C. Acute administration of 10 mg vitamin K1 was followed by the transient appearance of vitamin K1 2,3-epoxide, indicating an impaired hepatocellular regeneration of vitamin K1 from the epoxide. Impaired hepatic vitamin K1 metabolism, tentatively ascribed to the N-methyl-thiotetrazole group, is one (but possibly not the only) cause of bleeding complications and depression of vitamin K1-dependent procoagulants in patients treated with the new class of cephalosporins.

Significance of ventricular arrhythmias in idiopathic dilated cardiomyopathy

The incidence and prognostic significance of ventricular arrhythmias identified by 24-hour ambulatory electrocardiography (Holter) was prospectively assessed in 74 patients with idiopathic dilated cardiomyopathy (IDC). The criteria for diagnosis of IDC were based on clinical and cardiac catheterization findings. Holter monitoring was performed at the time of entry into the study. Patients were followed for 2 to 21 months (mean 11 +/- 3). Frequent ventricular premature complexes (VPCs) (greater than 1,000/24 hours) were seen in 35%, and complex VPCs (Lown grade III and IV) in 87% of the patients. Forty-nine percent of the patients had nonsustained ventricular tachycardia (VT) consisting of 3 to 32 beats with rates from 110 to 230 beats/min, and 20% had ventricular pairs. No correlation was found between clinical symptoms or the degree of left ventricular (LV) impairment and the number of ventricular pairs or episodes of VT. During follow-up, 19 patients died, 7 from congestive heart failure (CHF) and 12 suddenly. Patients who died suddenly had significantly more episodes of VT, ventricular pairs or total VPCs (p less than 0.01 each) compared with survivors and those who died from CHF. No significant differences were found between patients who died from CHF or suddenly with respect to LV end-diastolic pressure, LV end-diastolic volume index, LV ejection fraction (EF) and cardiac index. A linear stepwise discriminant function analysis using hemodynamic (LVEF and cardiac index) and arrhythmic (number of VT episodes and ventricular pairs) variables resulted in a meaningful separation between survivors and patients who died from CHF or suddenly.(ABSTRACT TRUNCATED AT 250 WORDS)

Alinidine in angina

Alinidine--N-allyl-clonidine--reduces heart rate without blocking beta adrenoreceptors. It may be used in patients with angina without inducing the adverse effects of beta-adrenergic blockers. We therefore evaluated alinidine efficacy in patients with angiographically proven coronary artery disease and stable angina during a 10-wk placebo-controlled randomized double-blind trial. Alinidine (40 mg three times a day) reduced the number of anginal attacks and the average number of nitroglycerine capsules consumed. The double product was slightly lowered during rest but more pronounced during exercise. This effect was mainly due to decreased heart rate. The ischemic S-T segment depression was diminished. Exercise tolerance was clearly improved in six, slightly improved in two, and unchanged in four subjects.

Cyclic interconversion of vitamin K1 and vitamin K1 2,3-epoxide in man

The disposition of a single intravenous bolus dose of 10 mg vitamin K1 and vitamin K1-2,3-epoxide were studied in two healthy subjects without and with 12 h pretreatment dose of phenprocoumon (0.4 mg/kg). For each compound administered alone the plasma concentration-time profile was adequately fitted by a biexponential equation, with an average terminal half-life of 2.0 and 1.15 h for the administered vitamin K and its 2,3-epoxide respectively. While vitamin K1 was measurable in plasma following administration of vitamin K1-2,3-epoxide, the epoxide was not detectable following administration of vitamin K1. Following pretreatment with phenprocoumon and after intravenous administration of vitamin K1, both the average half-life and area under the plasma concentration-time profile of vitamin K1 were marginally reduced to 1.5 h and 1.76 mg l-1 h respectively, while the plasma concentration of vitamin K1-2,3-epoxide was readily measurable and its half-life markedly prolonged to 14.7 h. Following pretreatment with phenprocoumon and after oral administration of vitamin K1-2,3-epoxide, no vitamin K1 was detectable in plasma and the half-life of the epoxide was 13.8 h. Based on area considerations the data suggest that either phenprocoumon does more than just inhibit the reduction of vitamin K1-2,3-epoxide to vitamin K1, or that the simple model describing the interconversion between vitamin K1 and its epoxide is inadequate. The same conclusion is drawn from the analysis of comparable data in dogs, obtained by Carlisle & Blaschke (1981).

[Diagnosis of thoracic aortic aneurysms with 2-dimensional echography]

Eight patients with thoracic aortic aneurysms were investigated by angiography, computed tomography and two-dimensional echography. According to results of computed tomography or angiography six patients had a dissecting aortic aneurysm (five patients type 1 and one patient type 3 according to DeBakey) and two patients had a thoracic aortic aneurysm without dissection. In addition, thrombi in the descending aorta were shown in three patients by computed tomography or by angiography. Type and extent of the aneurysms could be evaluated by two-dimensional echography in all patients. Only in one patient could the origin of dissection in the ascending aorta not be localised precisely by echography. In three patients thrombi in the descending aorta could be demonstrated. For assessment of type and extent of the aneurysm the suprasternal approach was superior to precordial, subcostal and apical imaging. Parasternal investigation resulted in echographic demonstration of dissection in only two cases. Two-dimensional echography is a technically less demanding and useful method in the diagnosis of thoracic aortic aneurysms.

Isosorbide dinitrate kinetics and dynamics after intravenous, sublingual, and percutaneous dosing in angina

Isosorbide dinitrate (ISDN) kinetics and dynamics were examined after various routes of administration for angina. Given intravenously, ISDN kinetics were apparently linear over the range of infusion rate (0.083 and 0.133 mg/min) and duration (15 min and 1 and 2 hr) studied. Mean +/- SD systemic clearance of ISDN was 3.4 +/- 1.4 l/min and volume of distribution (VdSS or Vdarea) about 100 l. These data are consistent with the presence of extensive extrahepatic metabolism. In six patients, sublingual ISDN (5 mg) was also given and mean bioavailability of 59% (19% to 93%) for this route was determined. For this group, sublingual absorption of intact ISDN was incomplete and variable. The presence of a longer disappearance t 1/2 after sublingual dosing suggested that the input process may be rate limiting. After percutaneous application of a topical formulation (100 mg over an area of 400 cm2), steady-state plasma concentrations at about 7 ng/ml were maintained from 6 to 24 hr. The bioavailability of the topical application was estimated at 30%. At the doses given, intravenous ISDN had no apparent effect on heart rate but induced significant reduction in standing systolic blood pressure. The effect vs the ISDN concentration profile was described by a hysteresis loop, indicating that changes in blood pressure response lag behind changes in plasma ISDN concentration. After intravenous dosing, peak plasma ISDN concentration and peak effect (maximum change in standing systolic blood pressure). At the doses used, both sublingual and percutaneous ISDN induced less distinct circulatory changes than the intravenous infusion.

[Incidence and clinical significance of ventricular arrhythmias in dilated cardiomyopathy]

The diagnosis of dilated (congestive) cardiomyopathy was made in 75 patients on the basis of clinical, ECG, echo and angiographic-haemodynamic findings. Ambulatory 24-hour monitoring was undertaken in all patients. Nearly all of them (93%) had ventricular extrasystoles (VES), 35% more often than 1000/24 h. In 15% VES occurred in pairs, in 44% as ventricular tachycardia. In general, frequent VES (greater than 30/h) also came in pairs and/or as ventricular tachycardia. On the other hand, not all patients with such complex arrhythmias also had frequent VES. In about 70% of all patients with ventricular tachycardia such episodes were registered repeatedly, in more than 40% more than five tachycardia episodes per 24 hours. In the majority of patients the tachycardia consisted of three (33%), four (12%) or five (18%) consecutive ventricular complexes. All episodes of ventricular tachycardia ended spontaneously and were clinically largely silent. Apparently there was no clinically relevant correlation between frequency and severity of the arrhythmia, on the one hand, and extent of abnormal ventricular function, on the other. These findings indicate that frequent and complex ventricular arrhythmias are a characteristic feature of dilated (congestive) cardiomyopathy. If they occur in heart disease of seemingly unknown aetiology, dilated cardiomyopathy should be suspected. Preliminary findings of long-term observation indicate that patients with frequent ventricular tachycardias have a higher risk of sudden death.

[Separation of the left atrium from the right pulmonary artery in the suprasternal echocardiogram: a parameter of left atrial pressure]

A separation of the left atrium from the right pulmonary artery during atrial contraction may be observed in the suprasternal echocardiogram. In 280 catheterized patients with sinus rhythm, we investigated whether left atrial separation is a parameter from which an estimate of the left atrial pressure can be obtained. In 239 of the 280 patients, the suprasternal echograms were of a quality such that it could be seen whether there was, a left atrial separation. In 182 patients, a normal left atrial pressure (greater than or equal to 12 mm Hg) was found; in 57 patients, the left atrial pressure was elevated. An atrial separation was observed in 183 patients, and in 56 patients it was lacking. Lack of left atrial separation indicates a left atrial pressure elevation with a sensitivity of 73.7% and a specificity of 92.3%. If a left atrial pressure above 18 mm Hg was considered elevated, the sensitivity of this echoparameter amounted to 90.3%, and the specificity was 86.5%. The study shows that the left atrial separation from the right pulmonary artery separation from the right pulmonary artery in the suprasternal echocardiogram is a parameter valuable in providing a rough estimate of the left atrial pressure.

[Importance of echocardiography for the assessment of left-ventricular function and cardiac complications in dilative cardiomyopathy]

One- and two-dimensional echocardiographic findings in 17 patients with dilated cardiomyopathy were compared with haemodynamic and angiographic results of cardiac catheterization. In a further 52 unselected patients with dilated cardiomyopathy, who had been seen as out- or in-patients over a period of two years, the frequency of intracardiac thrombi was investigated echocardiographically. A significant correlation (r = 0.66 and r = 0.68) was found between echocardiographically determined left-ventricular end-diastolic and end-systolic volumes on the one hand and volumes determined angiographically on the other. However, ventricular volumes were clearly underestimated by echocardiography. In contrast, both methods showed good agreement for the magnitude of the ejection fraction (r = 0.79). The aortic valve opening surface estimated with one-dimensional echocardiography correlated with left-ventricular ejection volume (r = 0.93). Thrombi were demonstrated in 7 out of 52 patients: 5 were located in the left, one in the right and a further one in the central pulmonary vascular system. Considering the aforementioned limitations, echocardiography is a useful method for evaluation of left-ventricular function and for demonstration of intracardiac thrombi in dilated cardiomyopathy.

Comparison of the antiarrhythmic activity of mexiletine and lorcainide on ventricular arrhythmias

In a blind cross-over study, 12 patients with ventricular arrhythmias (VPC's; Lown Grades II-IVB) resistant to a daily dose of quinidine 1.2 g, disopyramide 0.8 g, N-propyl-ajmaline 0.1 g were randomly given, each dose for one week, placebo (PL), mexiletine (MEX; 400, 600, 800 mg daily) and lorcainide (LOR; 200, 300, 400 mg daily). On the last day of each treatment period, patients were evaluated by 24-h continuous ambulatory monitoring, 6-channel surface ECG, plasma concentrations and side-effects. During PL I (before) and PL II (after drug treatment), the mean number of VPCs per hour was 670 and 701. VPCs were reduced in 5 of the 12 patients with MEX by 43% (400 mg), 74% (600 mg) and 91% (800 mg). VPCs were reduced in 10 patients with LOR by 60% (200 mg), 78% (300 mg) and 93% (400 mg). Log. lin. plasma conc. effect relationships were constructed for MEX and LOR. Vomiting, nausea, and abdominal pain were seen in 2 patients with MEX; insomnia and feeling heat in 10 patients with LOR. At the end of the LOR-treatment, these side-effects were less in 5 and absent in 5 patients. In this study, LOR seems superior to MEX in refractory ventricular arrhythmias.

Haemodynamic effects of a single intravenous dose of lorcainide in patients with heart disease

The cardiovascular effects of a single i.v. dose (2 mg/kg over 5 min) of lorcainide were studied in 14 patients with heart disease. In the haemodynamic part of the study (6 patients), the aortic and pulmonary systolic, diastolic and mean pressures, left ventricular systolic and end-diastolic pressures, cardiac output and the rate of rise of left ventricular pressure were measured before and for 30 min after administration of the drug. Lorcainide produced a slight and short-lasting decrease in the aortic and pulmonary systolic pressures, and all other pressure values remained unchanged. The cardiac output and systemic vascular resistance were not altered by lorcainide. It consistently depressed the rate of rise of left ventricular pressure (maximum mean decrease 19%). In the angiographic part of the study (8 patients), the ejection fraction and the mean velocity of circumferential fiber shortening were measured before and 5 min after lorcainide. In all but one patient, lorcainide decreased the ejection fraction (mean decrease 11.6%), and the mean velocity of circumferential fiber shortening was uniformly diminished by lorcainide (mean decrease 29.7%). Thus, lorcainide moderately impaired myocardial performance in patients with normal and reduced left ventricular function without producing hypotensive side effects.