Clinical Value of the Postpacing Interval for Mapping of Ventricular Tachycardia in Patients with Prior Myocardial Infarction

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72569/1/j.1540-8167.1999.tb00640.x.pd

Radiofrequency Ablation of Idiopathic Left Anterior Fascicular Tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71580/1/j.1540-8167.1995.tb00389.x.pd

Driving Restrictions Advised by Midwestern Cardiologists Implanting Cardioverter Defibrillators: Present Practices, Criteria Utilized, and Compatibility with Existing State Laws

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73175/1/j.1540-8159.1992.tb03115.x.pd

Incidence, presentation, diagnosis, and management of malfunctioning implantable cardioverter-defibrillator rate-sensing leads

Recognition of tachyarrhythmia by an implantable cardioverter-defibrillator (ICD) requires an intact rate-sensing lead. We retrospectively examined 266 consecutive patients requiring an ICD to characterize the incidence, clinical presentation, diagnosis, and management of a defective rate-sensing lead. To identify clinical parameters that may contribute to lead complications, we also assessed the effects of age, gender, type of rate-sensing lead, manufacturer of the lead, and surgeon. Over a follow-up period of 30 +/- 22 months (mean +/- standard deviation), a defective lead was found in 9 (3.4%) patients, in 9 (1.7%) of 514 leads over a period of 2 to 39 (mean 17 +/- 15) months after implantation. Except for 1 patient, in whom a lead fracture was incidently found during ICD generator replacement, these patients had multiple inappropriate shocks of recent onset. Clinical parameters were not helpful in identifying patients at risk for lead complication. An abnormal beeping signal obtained while the patients performed various maneuvers was helpful in confirming a defect. All of the defective leads were epicardial. These cases were managed by placement of a transvenous endocardial lead.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31233/1/0000136.pd

Effectiveness of prophylactic implantation of cardioverter-defibrillators without cardiac resynchronization therapy in patients with ischaemic or non-ischaemic heart disease: a systematic review and meta-analysis

Aims: Much controversy exists concerning the efficacy of primary prophylactic implantable cardioverter-defibrillators (ICDs) in patients with low ejection fraction due to coronary artery disease (CAD) or dilated cardiomyopathy (DCM). This is also related to the bias created by function improving interventions added to ICD therapy, e.g. resynchronization therapy. The aim was to investigate the efficacy of ICD-only therapy in primary prevention in patients with CAD or DCM.Methods and results: Public domain databases, MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials, were searched from 1980 to 2009 for randomized clinical trials of ICD vs. conventional therapy. Two investigators independently abstracted the data. Pooled estimates were calculated using both fixed-effects and random-effects models. Eight trials were included in the final analysis (5343 patients). Implantable cardioverter-defibrillators significantly reduced the arrhythmic mortality [relative risk (RR): 0.40; 95 confidence interval (CI): 0.27-0.67] and all-cause mortality (RR: 0.73; 95 CI: 0.64-0.82). Regardless of aetiology of heart disease, ICD benefit was similar for CAD (RR: 0.67; 95 CI: 0.51-0.88) vs. DCM (RR: 0.74; 95 CI: 0.59-0.93).Conclusions: The results of this meta-analysis provide strong evidence for the beneficial effect of ICD-only therapy on the survival of patients with ischaemic or non-ischaemic heart disease, with a left ventricular ejection fraction ≤35, if they are 40 days from myocardial infarction and ≥3 months from a coronary revascularization procedure

Matrix gla protein in xenopus laevis: molecular cloning, tissue distribution, and evolutionary considerations

Matrix Gla protein (MGP) belongs to the family of vitamin K-dependent, Gla-containing proteins and in higher vertebrates, is found in the extracellular matrix of mineralized tissues and soft tissues. MGP synthesis is highly regulated at the transcription and posttranscription levels and is now known to be involved in the regulation of extracellular matrix calcification and maintenance of cartilage and soft tissue integrity during growth and development. However, its mode of action at the molecular level remains unknown. Because there is a large degree of conservation between amino,acid sequences of shark and human MGP, the function of MGP probably has been conserved throughout evolution. Given the complexity of the mammalian system, the study of MGP in a lower vertebrate might be advantageous to relate the onset of MGP expression with specific events during development. Toward this goal, MGP was purified from Xenopus long bones and its N-terminal amino acid sequence was determined and used to clone the Xenopus MGP complementary DNA (cDNA) by a mixture of reverse-transcription (RT)- and 5'- rapid amplification of cDNA ends (RACE)-polymerase chain reaction (PCR). MGP messenger RNA (mRNA) was present in all tissues analyzed although predominantly expressed in Xenopus bone and heart and its presence was detected early in development at the onset of chondrocranium development and long before the appearance of the first calcified structures and metamorphosis. These results show that in this system, as in mammals, MGP may be required to delay or prevent mineralization of cartilage and soft tissues during the early stages of development and indicate that Xenopus is an adequate model organism to further study MGP function during growth and development.NATO/CRG940751/SA5.2.05, Praxis XXI/BIA 469/94, (NIH; grant AR 25921) (Praxis XXI/BPD/18816) (Praxis XXI/BICJ-2985

Analysis During Sinus Rhythm of Critical Sites in Reentry Circuits of Postinfarction Ventricular Tachycardia

Background: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46421/1/10840_2004_Article_5100325.pd

Meiotic Transmission of Drosophila pseudoobscura Chromosomal Arrangements

Drosophila pseudoobscura harbors a rich gene arrangement polymorphism on the third chromosome generated by a series of overlapping paracentric inversions. The arrangements suppress recombination in heterokaryotypic individuals, which allows for the selective maintenance of coadapted gene complexes. Previous mapping experiments used to determine the degree to which recombination is suppressed in gene arrangement heterozygotes produced non-recombinant progeny in non-Mendelian ratios. The deviations from Mendelian expectations could be the result of viability differences between wild and mutant chromosomes, meiotic drive because of achiasmate pairing of homologues in heterokaryotypic females during meiosis, or a combination of both mechanisms. The possibility that the frequencies of the chromosomal arrangements in natural populations are affected by mechanisms other than adaptive selection led us to consider these hypotheses. We performed reciprocal crosses involving both heterozygous males and females to determine if the frequency of the non-recombinant progeny deviates significantly from Mendelian expectations and if the frequencies deviate between reciprocal crosses. We failed to observe non-Mendelian ratios in multiple crosses, and the frequency of the non-recombinant classes differed in only one of five pairs of reciprocal crosses despite sufficient power to detect these differences in all crosses. Our results indicate that deviations from Mendelian expectations in recombination experiments involving the D. pseudoobscura inversion system are most likely due to fitness differences of gene arrangement karyotypes in different environments

Mechanism of Ventricular Tachycardia Termination by Pacing at Left Ventricular Sites in Patients with Coronary Artery Disease

Objective: The mechanism by which pacing terminates ventricular tachycardia (VT) may depend on the location of the pacing site relative to the reentry circuit. The purpose of this study was to compare the mechanisms by which pacing terminates VT at left ventricular (LV) sites with and without concealed entrainment (CE) in patients with prior myocardial infarction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46394/1/10840_2004_Article_391630.pd