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T Meinertz

Publications and source records attributed to T Meinertz.

At least 145 records · Page 8Linked to original sources
PubMed1997

[Estrogens for prevention of coronary heart disease?].

In recent years, reports of favourable effects of estrogen therapy on cardiovascular morbidity and mortality have led to enthusiasm for widespread use of estrogens by postmenopausal women. Guidelines for estrogen therapy issued by the American College of Physicians include the statement "Women who have coronary heart disease are likely to benefit from hormone therapy". What evidence support this recommendation? More than 30 observation studies have examined the effect of estrogen replacement therapy on cardiovascular event and all cause mortality. In addition there have been 13 case controlled studies. The majority showed lower morbidity and mortality from coronary heart disease among users of postmenopausal estrogens than among non-users. Recently, 2 meta-analyses estimated the reduction in coronary heart disease associated with estrogen use to be in the range of 35 to 44%, respectively. All of these observational studies share a fatal flaw: Women who take estrogens are different from women who do not. Some differences have been measured, others have not. Women who take estrogens are on average better educated, healthier, have higher incomes and have better access to health care. These difference rather than the estrogens may account for much of the lower risk of heart disease. At this time we cannot tell from these observational studies what the real benefit of estrogens on coronary heart disease might be. Estrogen replacement therapy is not without risk. Estrogens increase the risk of endometrial carcinoma approximately 6-fold, an effect that is eliminated by the addition of progestins. Controversy continues over whether estrogen replacement increases the risk of breast cancer. A number of prospective randomized studies are now under way that will establish whether estrogen replacement therapy definitely reduces the risk of cardiovascular disease in women with and without coronary lesions and whether it increases the risk of breast cancer. Until the results of these trials are available claims on the definite usefulness of hormone supplementation to prevent coronary heart disease in postmenopausal women remain premature. In the light of the probable usefulness estrogen replacement therapy for the prevention of cardiovascular events should be recommended for women with increased risk for or definitively proven coronary heart disease.

Bias↗
PubMed1997

The acute effects of intravenously administered mibefradil, a new calcium antagonist, on the electrophysiologic characteristics of the human heart.

OBJECTIVE: This multicenter, double-blind, placebo-controlled, parallel-group study was designed to assess the acute effects of intravenous mibefradil on the electrophysiologic characteristics of the human heart. METHODS: Seventy-one patients referred for routine electrophysiologic testing were randomized to receive one of three intravenous treatments: placebo n = 23, 15 mg mibefradil in 15 min followed by 25 mg in 60 min (group 1, n = 24), or 35 mg mibefradil in 15 min followed by 45 mg in 60 min (group 2, n = 24). Electrophysiologic evaluations were performed prior to study drug administration and 30 min after the start of the infusion. Plasma samples were obtained at the start of the infusion and after 15, 75, and 105 min. RESULTS: Sinus node recovery time decreased significantly in Group 1 patients (-103 ms). Corrected sinus node recovery time in group 2 patients was 68.7 ms (P = 0.053). Compared to placebo, mibefradil produced mild but significant slowing of conduction in group 2 patients as manifested by an increase in the AH interval of 6.7 ms. Atrioventricular (AV) nodal refractoriness was increased, as indicated by a prolongation of the Wenckebach point in patients in both group 1 (32.1 ms) and group 2 (32.5 ms), compared to placebo. All adverse events were classified as mild to moderate and only one event (vasovagal attack) was considered to be treatment related. CONCLUSIONS: At plasma levels close to those found after chronic oral administration of 50 and 100 mg mibefradil, the higher dose produced an increase in corrected sinus node recovery time. Mibefradil also produced small but significant effects on AV nodal conduction and increased AV nodal refractoriness. Mibefradil had no effect on any other electrophysiologic parameter and was well tolerated.

Benzimidazoles↗
PubMed1997

[Frequency of atrial pacing in patients with intermittent atrial fibrillation and 2nd or 3rd degree atrioventricular block. Thera DR Pacemaker Study Group].

UNLABELLED: Patients with 2nd or 3rd degree AV-block and paroxysmal atrial fibrillation could be suitable for VDDR pacemakers, if they are not or rarely paced in the atrium. We studied in 23 of these patients 1 month after DDDR pacemaker implantation, how often they were paced in the atrium with usual pacemaker programmings; patients with < 10% atrial pacing were compared with patients with > or = 10% atrial pacing. In case automatic mode switch was programmed, the number of mode switch episodes was assessed as a marker for the frequency of atrial tachyarrhythmias. Atrial pacing < 10% of the time occurred in seven, pacing from 10 to 19% in six, from 20 to 29% in two, and > or = 30% of the time in eight patients. Five of the seven patients with < 10% atrial pacing were paced in the DDD mode, but only four of 16 patients with > or = 10%. Usual clinical findings were unable to predict patients with rare atrial pacing. Patients with < 10% as well as with > or = 10% atrial pacing had < 10 mode switch episodes in 67% each. CONCLUSIONS: During short-term follow-up after DDDR pacemaker implantation 30% of the patients with paroxysmal atrial fibrillation and second or third degree AV-block, with present usual pacemaker programmings, rarely had atrial pacing, that means < 10% of the time. These patients would be probably suitable for VDDR pacemakers. Rare atrial pacing had no influence on the occurrence of automatic mode switch episodes.

Adult↗
PubMed1997

[Endothelins in cardiovascular diseases].

Endothelins are peptides with powerful vasoconstrictor and mitogenic properties. It has become evident that endothelins are involved in many regulatory mechanisms of the circulation in which they have a modulating role both in short and in long term. However, in many cases it remains unclear whether the alteration of the endothelin metabolism is a primary pathology or a secondary phenomenon. The synthesis of endothelin receptor antagonists and animal models with altered endothelin metabolism have opened a new era of endothelin research that will allow insight into the mechanisms of endothelin-action and eventually might lead to new therapeutic concepts. This review discusses the evidence both in favor and against pathogenic effects of endothelins in cardiovascular disease.

Animals↗
PubMed1997

[Increased serum concentration of myosin heavy chain in aortic dissection: discussion of 2 cases].

Despite the availability of diagnostic modalities such as transesophageal echocardiography, computed tomography or magnetic resonance imaging up to 30% of patients with acute aortic dissection remain undiagnosed before death. A novel immunoassay of serum smooth muscle myosin heavy chain was recently developed as a potential diagnostic tool for the detection of aortic dissection. The immunoassay was applied in two patients with an acute chest pain syndrome but no initial clinical suspicion of aortic disease. In both patients myocardial ischemia was ruled out by laboratory, electrocardiographic and echocardiographic examinations. In the first patient both dilation of the aorta and long-standing arterial hypertension were known; however, it was not before 48 h until dissection was suspected and a spiral-CT was performed demonstrating a localized ascending aortic dissection. At this time (48 h after onset of symptoms) the smooth muscle myosin heavy chain concentration in the serum was close to normal. In the other patient there was neither a suggestive history nor any clinical sign of aortic dissection. Widening of the abdominal aortic wall on an ultrasound examination was the key to the incidental diagnosis of a clinically unsuspected type B dissection. The serum test 12 h after onset of pain revealed elevated (diagnostic) serum levels of smooth muscle myosin heavy chains. Both cases exemplify important gaps in the diagnostic strategy for the detection of acute aortic dissection. A novel immunoassay for smooth muscle myosin heavy chains provides rapid and reliable diagnostic information especially in patients without clinically suspected aortic dissection and may avoid limitations in the diagnostic work-up of patients with acute aortic disease, if used early in the evaluation of patients with chest pain syndromes.

Aged↗
PubMed1997

Subthreshold stimulation in the region of the slow pathway during atrioventricular node reentrant tachycardia: correlation with effect of radiofrequency catheter ablation.

OBJECTIVES: The present study sought to investigate the role of subthreshold stimulation in patients with atrioventricular node reentrant tachycardia (AVNRT) undergoing catheter ablation of the slow pathway. BACKGROUND: Subthreshold stimulation applied to right atrial sites has been demonstrated to terminate AVNRT but has not been correlated with the effects of radiofrequency current delivery to the area of the slow pathway. METHODS: Eighteen patients with common AVNRT were prospectively included in the study. Sustained AVNRT was reproducibly inducible in all patients (cycle length 334 +/- 58 ms). Anatomic and electrogram guided mapping of the slow pathway was started posteroseptally and continued to more midseptal sites if required. Subthreshold stimulation (3 s, up to 5 mA) during induced AVNRT was performed at each site eligible for slow pathway ablation until termination of AVNRT or capture was observed. Irrespective of the effect of subthreshold stimulation, radiofrequency current was delivered at each site after exclusion of catheter dislocation. RESULTS: Termination of AVNRT due to block of the anterograde slow pathway induced by subthreshold stimulation occurred without apparent capture in 15 of 18 patients. This phenomenon was exclusively observed at successful posteroseptal to midseptal ablation sites. Subthreshold stimulation was not successful at any of 30 target sites with ineffective radiofrequency current delivery. Thus, subthreshold stimulation identified successful target sites with 83% sensitivity and 100% specificity. Atrioventricular node reentrant tachycardia was abolished in all patients after a median of two (range one to nine) radiofrequency current applications. CONCLUSIONS: Subthreshold stimulation delivered to the region of the slow pathway terminates AVNRT with high safety and efficacy. High sensitivity and specificity for prediction of the effect of radiofrequency current application suggest that subthreshold stimulation may become a new tool for identifying target sites for slow pathway ablation.

Adult↗
PubMed1997

Antiarrhythmic effects of increasing the daily intake of magnesium and potassium in patients with frequent ventricular arrhythmias. Magnesium in Cardiac Arrhythmias (MAGICA) Investigators.

OBJECTIVES: This study sought to assess potential antiarrhythmic effects of an increase in the daily oral intake of magnesium and potassium in patients with frequent ventricular arrhythmias. BACKGROUND: Magnesium and potassium contribute essentially to the electrical stability of the heart. Despite experimental and clinical evidence for the antiarrhythmic properties of the two minerals, controlled data in patients with stable ventricular arrhythmias are lacking. METHODS: In a randomized, double-blind study, 232 patients with frequent ventricular arrhythmias (> 720 ventricular premature beats [VPBs]/24 h) confirmed at baseline and after 1 week of placebo therapy were subsequently treated over 3 weeks with either 6 mmol of magnesium/12 mmol of potassium-DL-hydrogenaspartate daily or placebo. RESULTS: Compared with placebo pretreatment, active therapy resulted in a median reduction of VPBs by -17.4% (p = 0.001); the suppression rate was 2.4 times greater than that in patients randomized to 3 weeks of placebo therapy (-7.4%, p = 0.038). The likelihood of a > or = 60% (predefined criterion) or > or = 70% suppression rate (calculated from the placebo-controlled run-in period) was 1.7 (25% vs. 15%, p = 0.044) and 1.5 times greater in the active than in the placebo group (20% vs. 13%, p = 0.085), respectively. No effect of magnesium and potassium administration was observed on the incidence of repetitive and supraventricular arrhythmias and clinical symptoms of the patients. CONCLUSIONS: To our knowledge, this study is the first to provide controlled data on the antiarrhythmic effect of oral administration of magnesium and potassium salts when directed to patients with frequent and stable ventricular tachyarrhythmias. A 50% increase in the recommended minimum daily dietary intake of the two minerals for 3 weeks results in a moderate but significant antiarrhythmic effect. However, with the given therapeutic regimen, repetitive tachyarrhythmias and patient symptoms remain unchanged.

Adult↗
PubMed1997

Tachyarrhythmias following coronary artery bypass graft surgery: epidemiology, mechanisms, and current therapeutic strategies.

The distribution pattern of perioperative complications of coronary artery bypass graft surgery (CABG) is currently changing, due to the fact that it has become a routine operation with an increasing proportion of patients older than 70 years. Supraventricular and ventricular tachyarrhythmias are among the most commonly observed postoperative adverse events following CABG. The aim of this review is to give an update on epidemiology and mechanisms of postoperative arrhythmias and to present current diagnostic tools and therapeutic strategies.

Anti-Arrhythmia Agents↗
PubMed1997

Comparison of electrical characteristics between a steroid-eluting single-pass VDD lead and a standard steroid-eluting ventricular lead. Thera Pacemaker Study Group.

Compared to regular ventricular leads, single-pass VDD leads have two additional floating electrodes proximal to the ventricular tip, which enables them to detect atrial signals. Because of the latter, VDD leads are thicker than ventricular leads, which could affect ventricular pacing. The purpose of the present study was to compare ventricular pacing of a steroid-eluting single-pass VDD lead (CapSure VDD, Medtronic; n = 107) with the same steroid-eluting regular lead (CapSure SP, Medtronic; n = 39) implanted in the ventricle; both leads were connected to the same types of pacemakers. At implantation, pacing thresholds were measured at 0.5-ms pulse duration and impedance by means with the PSA. At discharge, as well as after 1 and 3 months, pulse duration thresholds were determined at 2.5 V pulse amplitude and impedance by telemetry. At implantation, pacing thresholds and impedance were not different in the VDD (0.38 +/- 0.16 V; 691 +/- 122 omega) and ventricular lead group (0.44 +/- 0.17 V; 648 +/- 150 omega). During follow-ups, no differences in pulse duration threshold were detected between the two groups neither at discharge (VDD = 0.05 +/- 0.03 ms; ventricular 0.05 +/- 0.02 ms), nor after 1 (VDD = 0.05 +/- 0.02 ms; ventricular 0.08 +/- 0.07 ms) and 3 months (VDD = 0.06 +/- 0.03 ms; ventricular 0.09 +/- 0.10 ms). There were also no significant differences for impedance at discharge (VDD = 675 +/- 113 omega; ventricular = 594 +/- 113 omega), after 1 (VDD = 678 +/- 131 omega; ventricular = 627 +/- 112 omega) and 3 months (VDD = 652 +/- 99 omega; ventricular = 628 +/- 105 omega). Pacing thresholds and impedance were neither significantly different at implantation nor during follow-ups between patients with steroid-eluting VDD leads and patients with an equivalent ventricular lead indicating that the thicker VDD lead does not affect ventricular pacing.

Aged↗
PubMed1997

Mapping of the coronary sinus and great cardiac vein using a 2-French electrode catheter and a right femoral approach.

INTRODUCTION: Local electrograms recorded from the coronary sinus and great cardiac vein provide important information for the diagnosis of various arrhythmias and identification of target sites for ablation of left-sided accessory pathways. One limitation of present techniques is the inability, in many cases, to probe the great cardiac vein at the anterior mitral annulus. We tested the feasibility of a new technique for catheterization of the coronary sinus and great cardiac vein by means of a small-diameter electrode catheter advanced via a right femoral approach through an angiography catheter. METHODS AND RESULTS: Of 22 patients (12 men and 10 women; ages 44.5 +/- 13.4 years) undergoing radiofrequency ablation of a supraventricular tachycardia, cannulation of the coronary sinus orifice using a 6-French 1L or 2L Amplatz catheter was achieved in 20 patients (91%) within 0.9 +/- 0.6 minutes; after cannulation, a 2-French octapolar electrode catheter with a soft radiopaque tip and a 3-mm interelectrode distance could be advanced in all 20 patients through the guiding catheter to the great cardiac vein in the anterior region of the AV sulcus within 0.8 +/- 0.7 minutes. Atrial and ventricular local potentials were recorded all along the mitral annulus during sinus rhythm, atrial and ventricular pacing, or supraventricular tachycardia. Variation of local potential amplitude never exceeded 20% of the mean and presented similar stability at all annular regions. The arrhythmogenic substrate was identified in all patients. Of 18 patients with 21 left-sided accessory pathways, an accessory pathway potential could be recorded at the ablation site by one or more adjacent epicardial electrode pairs in 10 pathways. No procedure-related complications were observed. CONCLUSIONS: The technique introduced in this study proved feasible in 91% of patients. Its main advantages are the simplicity and rapidity of coronary sinus cannulation and the ability to advance the electrode catheter to the anterior cardiac vein. In addition, closely spaced bipolar electrograms resulted in enhanced atrial, ventricular, and accessory pathway potential resolution.

Adult↗
PubMed1997

[Personal experiences with emergency coronary artery revascularization after failed PTCA--early and late results].

In recent years the equipment and techniques for percutaneous transluminal coronary angioplasty (PTCA) have been improved and today complex and distal stenoses are also treated in this way. Subsequent to failed PTCA some patients undergo emergency CABG. Between January 1991 and March 1995 3,520 patients have been treated by PTCA in our hospital. 61 patients (1.7%), mean age 61.1 years, underwent subsequent emergency CABG after PTCA. 46% had single-, 33% double and 21% had triple-vessel-disease, the mean left ventricular function (LVEF) was 65%. The mean number of bypass grafts was 1.9. The internal mammary arteries were never used under these emergency conditions. 9 patients (15%) developed perioperative myocardial infarction and in two of them the LVEF decreased under 30%. The hospital mortality was 6.6% (= 4 perioperative deaths). 6 of 61 patients were lost for follow-up; 90% of the hospitals survivors were followed for 244 months (mean 17). During this period there were 4 late deaths (3 cardiac and 1 non-cardiac). Actuarial survival at one year was 90%. 80% of the long-term survivors were in the NYHA functional classes I and II. In patients with double- or triple-vessel-disease PTCA almost always effects an incomplete revascularisation. Emergency CABG following failed PTCA is associated with an increased mortality and morbidity. The long-term prognosis is similar to that of an age-sex matched general population.

Adult↗
PubMed1996

[Low stimulation impedance in pacemaker patients with cardiac diseases. The Thera Pacemaker Study Group].

BACKGROUND AND AIM OF THE STUDY: As increasing impedance of the pacing impulse decreases pacing current, high pacing impedance lowers pacing current and subsequently prolongs pacemaker longevity. The present assumption of a standard 500 ohms impedance disregards interindividual differences. In the present study, the interindividual range of pacing impedance was assessed at implantation. Additionally clinical parameters of patients with low pacing impedance were compared to those of patients with high values. PATIENTS AND METHODS: The same lead and the same pacemaker (CapSure VDD; Thera VDD; Medtronic) were implanted in 126 patients (79 men, 47 women, mean age 65 +/- 16 years). Patients with an impedance below or similar to the median were compared to patients with an impedance above the median in respect to clinical (age, gender, arterial hypertension, cardiac diseases such as coronary heart disease, valvular heart disease, cardiomyopathy) and electrical parameters (pacing threshold at 0.5 ms pulse duration, R-wave amplitude). RESULTS: Mean impedance was 687 +/- 121 ohms with a range from 333 to 1040 ohms and a median of 670 ohms. 64 patients had an impedance < or = 670 ohms and 62 patients > 670 ohms. Mean age, gender and the occurrence of arterial hypertension were similar in the two groups. Cardiac diseases occurred significantly (P < 0.01) more often in patients with lower (n = 23) than with higher impedance (n = 9). Intraoperative pacing thresholds and R-wave amplitudes were not different between the two groups. CONCLUSIONS: The range of pacing impedance was 707 ohms for the studied lead. Under consideration of permanent pacing with 2.5 V pulse amplitude and 0.5 ms pulse duration this would vary expected longevity of the implanted pacemaker from 7.8 to 9.3 years. Patients with lower impedance more often had cardiac diseases than patients with higher impedance.

Adult↗
PubMed1996

Diagnosis of patent foramen ovale by transesophageal echocardiography and correlation with autopsy findings.

Transesophageal echocardiography (TEE) is accepted as the method of choice for the diagnosis of the patent foramen ovale (PFO). However, direct anatomic confirmation regarding the presence or absence of a PFO on transesophageal imaging has been obtained in only a limited number of patients. Consequently, this study was performed to assess the diagnostic accuracy of contrast and color Doppler TEE for detection of a PFO by comparing the results of TEE with autopsy. The study population comprised 35 consecutive patients (mean age 64 +/- 14 years) who underwent autopsy and prior TEE with examination of the atrial septum. For diagnosis of a PFO, the following criteria were used: (1) no defect in the continuity of the atrial septum on 2-dimensional imaging; (2) > or = 1 bright microbubble appearing in left the atrium within 3 heart cycles after opacification of the right atrium during contrast TEE; and (3) turbulent color jet within the atrial septum by color Doppler TEE. For estimating the PFO size, positive contrast studies were graded semiquantitatively (from 1 to 3), and the maximal color Doppler jet width was measured within the atrium septum at the area of maximal turbulence. At autopsy, a PFO was present in 9 of 35 patients (26%). All were correctly diagnosed by color Doppler TEE. The color Doppler jet width correlated well with the PFO diameter determined at autopsy (r=0.99, SEE=0.51 mm, p<0.0001). By contrast TEE, 8 of the 9 patients with autopsy-proven PFO were correctly identified. In 1 case with left heart disease and a long interatrial channel, a PFO was missed by contrast TEE but clearly demonstrated by color Doppler TEE. All patients with a PFO diameter >10 mm showed intense left atrial opacification of grade 3. With both methods, there were no false-positive results. Sensitivity and specificity for diagnosis of a PFO were 89% and 100% respectively, for contrast TEE, and both 100% for color Doppler TEE. Thus, contrast and color Doppler TEE are complementary and represent a highly sensitive and specific method for diagnosis of a PFO and for estimation of the PFO size.

Adult↗