M D Gammage

University of Birmingham, Birmingham, ENG, United Kingdom

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Publications (92)419.13 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The right ventricular apex (RVA) has been the elective site for placing endocardial pacing leads since 1959 when Furman described the use of the transvenous route for pacemaker implantation. This site was used because it is easily accessible, readily identified and associated with a stable position and reliable chronic pacing parameters. It was recognised, however, that pacing from the RVA did not reproduce normal ventricular conduction or contraction. With the advent of reliable active fixation leads, alternative right ventricular sites became accessible and began to be explored. In this review, the detrimental effects of RVA pacing are outlined, the right ventricular outflow tract is defined and the evidence for selective site pacing is discussed.
    Heart (British Cardiac Society) 10/2009; 95(24):2030-9. · 5.01 Impact Factor
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    Michael D Gammage
    Europace 10/2009; 11(10):1265-6. · 2.77 Impact Factor
  • Michael Gammage
    Europace 05/2009; 11(5):542-3. · 2.77 Impact Factor
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    Michael D Gammage
    Europace 06/2008; 10(5):572-3. · 2.77 Impact Factor
  • Michael D Gammage
    Clinical medicine (London, England) 05/2008; 8(2):176-7. · 1.32 Impact Factor
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    ABSTRACT: In clinically euthyroid subjects on long-term amiodarone therapy free thyroxine (T4) concentrations were increased and free triiodothyronine (T3) levels reduced. There was also a marked increase in reverse T3 in the treated group. These changes are consistent with inhibition of peripheral deiodination of T4 and reverse T3. Despite the rise in T4 serum thyrotrophin (TSH) levels were increased, suggesting an effect of amiodarone on the anterior pituitary. To investigate the interaction of amiodarone with the cellular actions of thyroid hormones we examined the influence of the drug in vitro on the binding of T3 to isolated nuclei prepared from rat anterior pituitary tissue. Amiodarone inhibited the nuclear binding of T3 in a dose dependent fashion. Addition of amiodarone in vitro also stimulated TSH release from cultured rat anterior pituitary cells, consistent with a T3 antagonistic effect. These studies provide evidence for a direct influence of amiodarone on the thyrotroph, mediated via nuclear T3 receptor binding.
    Clinical Endocrinology 03/2008; 22(3):257 - 264. · 3.40 Impact Factor
  • Jayne A Franklyn, Michael D Gammage
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    ABSTRACT: A 75-year-old man had a myocardial infarction complicated by poor left ventricular function and non-sustained ventricular tachycardia. He began treatment with amiodarone and 12 months later developed symptoms of thyrotoxicosis. Thyroid function tests after commencement of amiodarone revealed a high-normal level of free T4 and low-normal level of free T3 with a normal serum TSH. When symptoms of thyrotoxicosis developed, significant rises in T4 and T3 levels and suppression of TSH were observed. Thyroid autoantibodies were detected and thyroid ultrasonography revealed a small multinodular goiter. Amiodarone-induced thyrotoxicosis (AIT) with features consistent with both AIT type I (in which thyroid antibodies and nodular goiter are present) and AIT type II (which is not responsive to thionamide therapy and eventually leads to permanent hypothyroidism). The patient continued to be treated with amiodarone. He commenced thionamide (carbimazole) therapy but failed to improve, even after a dose increase. Glucocorticoid (prednisolone) therapy was therefore added. Combination therapy was associated with gradual clinical and biochemical improvement. The patient became persistently hypothyroid after stopping thionamide and glucocorticoid therapy and was stabilized on long-term thyroxine replacement.
    Nature Clinical Practice Endocrinology &#38 Metabolism 10/2007; 3(9):662-6. · 7.55 Impact Factor
  • Michael D Gammage
    European Heart Journal 08/2007; 28(14):1668-9. · 14.10 Impact Factor
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    ABSTRACT: Previous studies have suggested that minor changes in thyroid function are associated with risk of atrial fibrillation (AF). Our objective was to determine the relationship between thyroid function and presence of atrial fibrillation (AF) in older subjects. A population-based study of 5860 subjects 65 years and older, which excluded those being treated for thyroid dysfunction and those with previous hyperthyroidism. Main outcome measures included tests of thyroid function (serum free thyroxine [T(4)] and thyrotropin [TSH]) and the presence of AF on resting electrocardiogram. Fourteen subjects (0.2%) had previously undiagnosed overt hyperthyroidism and 126 (2.2%), subclinical hyperthyroidism; 5519 (94.4%) were euthyroid; and 167 (2.9%) had subclinical hypothyroidism and 23 (0.4%), overt hypothyroidism. The prevalence of AF in the whole cohort was 6.6% in men and 3.1% in women (odds ratio, 2.23; P<.001). After adjusting for sex, logistic regression showed a higher prevalence of AF in those with subclinical hyperthyroidism compared with euthyroid subjects (9.5% vs 4.7%; adjusted odds ratio, 2.27; P=.01). Median serum free T(4) concentration was higher in those with AF than in those without (1.14 ng/dL; interquartile range [IQR], 1.05-1.27 ng/dL [14.7 pmol/L; IQR, 13.5-16.4 pmol/L] vs 1.10 ng/dL; IQR, 1.00-1.22 ng/dL [14.2 pmol/L; IQR, 12.9-15.7 pmol/L]; P<.001), and higher in those with AF when analysis was limited to euthyroid subjects (1.13 ng/dL; IQR, 1.05-1.26 ng/dL [14.6 pmol/L; IQR, 13.5-16.2 pmol/L] vs 1.10 ng/dL; IQR, 1.01-1.21 ng/dL [14.2 pmol/L; IQR, 13.0-15.6 pmol/L]; P=.001). Logistic regression showed serum free T(4) concentration, increasing category of age, and male sex all to be independently associated with AF. Similar independent associations were observed when analysis was confined to euthyroid subjects with normal TSH values. The biochemical finding of subclinical hyperthyroidism is associated with AF on resting electrocardiogram. Even in euthyroid subjects with normal serum TSH levels, serum free T(4) concentration is independently associated with AF.
    Archives of Internal Medicine 05/2007; 167(9):928-34. · 11.46 Impact Factor
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    ABSTRACT: This study sought to prospectively evaluate the prevalence of cardiovascular abnormalities in patients with overt hyperthyroidism before and after antithyroid therapy. Overt hyperthyroidism is associated with recognized cardiovascular effects believed to be reversed by antithyroid therapy; however, increasing data suggest significant long-term cardiovascular mortality. A total of 393 (312 women, 81 men) consecutive unselected patients with overt hyperthyroidism were recruited and compared with 393 age- and gender-matched euthyroid control subjects. Hyperthyroid patients were re-evaluated after antithyroid therapy. Findings in patients and matched control subjects were compared at presentation, after treatment when patients had subclinical hyperthyroidism biochemically, and when patients were rendered biochemically euthyroid. All had a structured cardiovascular history and examination, including measurements of blood pressure (BP) and pulse rate. All had resting 12-lead electrocardiogram and 24-h digital Holter monitoring of cardiac rhythm. A higher prevalence of cardiovascular symptoms and signs, as well as abnormal hemodynamic parameters, was noted among hyperthyroid patients at recruitment compared with control subjects. Cardiac dysrhythmias, especially supraventricular, were more prevalent among patients than among control subjects. Palpitation and dyspnea, postural decrease in systolic pressure, and atrial fibrillation (AF) remained more prevalent in treated hyperthyroid subjects with subclinical hyperthyroidism compared with control subjects, and remained more prevalent after restoration of euthyroidism. Predictors for successful reversion to sinus rhythm in those with AF associated with hyperthyroidism were lower BP measurements at recruitment and an initial hypothyroid state induced by antithyroid therapy. Mortality was higher in hyperthyroid subjects than in control subjects after a mean period of follow-up of 66.6 months. Cardiovascular abnormalities are common in patients with overt hyperthyroidism at presentation, but some persist despite effective antithyroid therapy.
    Journal of the American College of Cardiology 02/2007; 49(1):71-81. · 14.09 Impact Factor
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    ABSTRACT: Population-based screening has been advocated for subclinical thyroid dysfunction in the elderly because the disorder is perceived to be common, and health benefits may be accrued by detection and treatment. The objective of the study was to determine the prevalence of subclinical thyroid dysfunction and unidentified overt thyroid dysfunction in an elderly population. A cross-sectional survey of a community sample of participants aged 65 yr and older registered with 20 family practices in the United Kingdom. Exclusions included current therapy for thyroid disease, thyroid surgery, or treatment within 12 months. Tests of thyroid function (TSH concentration and free T4 concentration in all, with measurement of free T3 in those with low TSH) were conducted. EXPLANATORY VARIABLES: These included all current medical diagnoses and drug therapies, age, gender, and socioeconomic deprivation (Index of Multiple Deprivation, 2004). Standardized prevalence rates were analyzed. Logistic regression modeling was used to determine factors associated with the presence of subclinical thyroid dysfunction. A total of 5960 attended for screening. Using biochemical definitions, 94.2% [95% confidence interval (CI) 93.8-94.6%] were euthyroid. Unidentified overt hyper- and hypothyroidism were uncommon (0.3, 0.4%, respectively). Subclinical hyperthyroidism and hypothyroidism were identified with similar frequency (2.1%, 95% CI 1.8-2.3%; 2.9%, 95% CI 2.6-3.1%, respectively). Subclinical thyroid dysfunction was more common in females (P < 0.001) and with increasing age (P < 0.001). After allowing for comorbidities, concurrent drug therapies, age, and gender, an association between subclinical hyperthyroidism and a composite measure of socioeconomic deprivation remained. Undiagnosed overt thyroid dysfunction is uncommon. The prevalence of subclinical thyroid dysfunction is 5%. We have, for the first time, identified an independent association between the prevalence of subclinical thyroid dysfunction and deprivation that cannot be explained solely by the greater burden of chronic disease and/or consequent drug therapies in the deprived population.
    Journal of Clinical Endocrinology &amp Metabolism 01/2007; 91(12):4809-16. · 6.43 Impact Factor
  • Khalid Abozguia, Sylvia Chudley, Michael Gammage
    International journal of cardiology 11/2006; 113(1):E9-10. · 7.08 Impact Factor
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    ABSTRACT: Routine statistics and epidemiologic studies often distinguish between types of cardiac death. Our aim was to assess agreement between doctors on cause of death given identical clinical information, and to assess agreement between a physician panel and the original cause of death as coded on national statistics. Clinical information and autopsy reports on 400 cardiac deaths were randomly selected from a defined population in the West Midlands, UK. A panel of eight clinicians was assembled, and batches of 24-25 cases were sent to pairs of these clinicians who, blinded to the certified cause of death, independently of each other assigned underlying cause of death. Physician panel decision was achieved by consensus. Levels of agreement were assessed using the kappa statistic. Reviewers agreed on cause of death in 54% of cases (kappa = 0.34). Consensus decision of reviewers agreed with death certificate diagnosis in 61.5% (kappa = 0.39). Agreement was higher if an autopsy had been performed (kappa = 0.49). The process of identifying underlying cause of death is of limited reliability, and therefore, limited accuracy. This has implications for design of epidemiologic studies and clinical trials of cardiovascular disease.
    Journal of Clinical Epidemiology 09/2006; 59(8):862-7. · 5.33 Impact Factor
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    ABSTRACT: Reduced lead diameter and reliability can be designed into transvenous permanent pacing leads through use of redundant insulation and removal of the stylet lumen. The model 3830 lead (Medtronic Inc., Minneapolis, MN, USA) is a bipolar, fixed-screw, steroid-eluting, lumenless, 4.1-Fr pacing lead. Implantation can be performed in a variety of right heart sites using a deflectable catheter (Model 10600, Medtronic). Lead performance and safety were studied. Two prospective trials of 338 implanted subjects from 56 global sites were conducted. Electrical and safety data were obtained at implant, pre-discharge, and up to 18 months post-implant. Leads were implanted at traditional and alternate right heart sites. The study enrolled 338 subjects (204 males, 70.6 +/- 11.6 years) followed-up for a mean of 10.2 months (range, 0-21.6). Mean P-wave amplitudes ranged from 3.2 mV at 3 months to 2.9 mV at 18 months, while mean atrial pulse width thresholds at 2.5 V ranged from 0.07 ms at 3 months to 0.09 ms at 18 months. Mean R-wave amplitudes ranged from 11.3 mV to 11.1 mV and mean ventricular pulse width thresholds at 2.5 V ranged from 0.10 ms to 0.14 ms. There were 22 ventricular and 12 atrial lead complications within 3 months post-implant. Survival from lead-related complications improved to a clinically acceptable rate in the cohort of patients when revised implant techniques were employed. With the use of recommended implant techniques, the study results support the electrical efficacy and safety of a catheter-delivered, lumenless lead in traditional or alternate right atrium or right ventricle sites through 18 months post-implant.
    Pacing and Clinical Electrophysiology 09/2006; 29(8):858-65. · 1.75 Impact Factor
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    ABSTRACT: This study examined the effectiveness of cardiac pacing using the Thera DR rate-drop response algorithm for prevention of recurrent symptoms in patients with carotid sinus syndrome (CSS) or vasovagal syncope. The algorithm comprises both diagnostic and treatment elements. The diagnostic element consists of a programmable “window” used to identify heart rate changes compatible with an evolving neurally mediated syncopal episode. The treatment arm consists of pacing at a selectable rate and for a programmable duration. Forty-three patients (mean age 53 ± 20.4 years) with CSS alone (n = 8), CSS in conjunction with vasovagal syncope (n = 4), or vasovagal syncope alone (n = 31) were included. Thirty-nine had recurrent syncope, while the remaining four reported multiple presyncopal events. Prior to pacing, 40 ± 152 syncopal episodes (range from 1 to approximately 1,000 syncopal events) over the preceding 56 ± 84.5 months. Postpacing follow-up duration was 204 ± 172 days. Three patients have been lost to follow-up and in one patient the algorithm was disabled. Among the remaining 39 individuals, 31 (80%) indicated absence or diminished frequency of symptoms, or less severe symptoms. Twenty-three patients (23/29, or 59%) were asymptomatic with respect to syncope or presyncope. Sixteen patients had symptom recurrences. Of these, seven experienced syncope (7/39, or 18%) and 9 (29%) had presyncope: the majority of patients with recurrences (6/7 syncope and 7/9 presyncope) were individuals with a history of vasovagal syncope. Consequently, although symptoms were observed during postpacing follow-up, they appeared to be of reduced frequency and severity. Thus, our findings suggest that a transient period of high rate pacing triggered by the Thera DR rate-drop response algorithm was beneficial in a large proportion of highly symptomatic patients with CSS or vasovagal syncope.
    Pacing and Clinical Electrophysiology 06/2006; 20(3):832 - 839. · 1.75 Impact Factor
  • Faizel Osman, Jayne A Franklyn, Michael D Gammage
    The American Journal of Medicine 11/2005; 118(10):1175. · 4.77 Impact Factor
  • M. Brignole, M. Gammage, E. Puggioni
    ACC Current Journal Review 08/2005; 14(8):55.
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    ABSTRACT: Left ventricular (LV) and biventricular (BiV) pacing are potentially superior to right ventricular (RV) apical pacing in patients undergoing atrioventricular (AV) junction ablation and pacing for permanent atrial fibrillation. Prospective randomized, single-blind, 3-month crossover comparison between RV and LV pacing (phase 1) and between RV and BiV pacing (phase 2) performed in 56 patients (70+/-8 years, 34 males) affected by severely symptomatic permanent atrial fibrillation, uncontrolled ventricular rate, or heart failure. Primary endpoints were quality of life and exercise capacity. Compared with RV pacing, the Minnesota Living with Heart Failure Questionnaire (LHFQ) score improved by 2 and 10% with LV and BiV pacing, respectively, the effort dyspnoea item of the Specific Symptom Scale (SSS) changed by 0 and 2%, the Karolinska score by 6 and 14% (P<0.05 for BiV), the New York Heart Association (NYHA) class by 5 and 11% (P<0.05 for BiV), the 6-min walked distance by 12 (+4%) and 4 m (+1%), and the ejection fraction by 5 and 5% (P<0.05 for both). BiV pacing but not LV pacing was slightly better than RV pacing in the subgroup of patients with preserved systolic function and absence of native left bundle branch block. Compared with pre-ablation measures, the Minnesota LHFQ score improved by 37, 39, and 49% during RV, LV, and BiV pacing, respectively, the effort dyspnoea item of the SSS by 25, 25, and 39%, the Karolinska score by 39, 42, and 54%, the NYHA class by 21, 25, and 30%, the 6-min walking distance by 35 (12%), 47 (16%), and 51 m (19%) and the ejection fraction by 5, 10, and 10% (all differences P<0.05). Rhythm regularization achieved with AV-junction ablation improved quality of life and exercise capacity with all modes of pacing. LV and BiV pacing provided modest or no additional favourable effect compared with RV pacing.
    European Heart Journal 04/2005; 26(7):712-22. · 14.10 Impact Factor
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    ABSTRACT: Patients with subclinical and treated overt hyperthyroidism have an excess vascular mortality rate. Several symptoms and signs in overt hyperthyroidism suggest abnormality of cardiac autonomic function that may account in part for this excess mortality rate, but few studies have examined cardiac autonomic function in untreated and treated hyperthyroidism. We assessed heart rate turbulence (HRT) and time-domain parameters of heart rate variability in a large, unselected cohort of patients with overt hyperthyroidism referred to our thyroid clinic (n = 259) and compared findings with a group of normal subjects with euthyroidism (n = 440). These measures were also evaluated during antithyroid therapy (when serum-free thyroxine and triiodothyronine concentrations returned to normal but thyrotropin remained suppressed (i.e., subclinical hyperthyroidism, n = 110) and when subjects were rendered clinically and biochemically euthyroid (normal serum thyrotropin, free thyroxine and triiodothyronine concentrations, n = 219). We found that overall measures of heart rate variability and those specific for cardiac vagal modulation were attenuated in patients with overt hyperthyroidism compared with normal subjects; measurements of overall heart rate variability remained low in those with low levels of serum thyrotropin but returned to normal in patients with biochemical euthyroidism. Measurements of HRT (onset and slope) were also decreased in patients with overt hyperthyroidism, but HRT slope returned to normal values with antithyroid treatment. This study is the first to evaluate HRT in overt and treated hyperthyroidism.
    The American Journal of Cardiology 09/2004; 94(4):465-9. · 3.21 Impact Factor
  • Harry G Mond, Michael D Gammage
    Pacing and Clinical Electrophysiology 07/2004; 27(6 Pt 2):835-6. · 1.75 Impact Factor

Publication Stats

1k Citations
419.13 Total Impact Points

Institutions

  • 1987–2009
    • University of Birmingham
      • • Department of Primary Care Clinical Sciences
      • • Group of Medical Science and Education
      • • Institute for Biomedical Research
      Birmingham, ENG, United Kingdom
  • 2007
    • Aston University
      Birmingham, England, United Kingdom
  • 1989–2006
    • Queen Elizabeth Hospital Birmingham
      Birmingham, England, United Kingdom
  • 2004
    • Harper University Hospital
      Detroit, Michigan, United States
  • 2001
    • Azienda Sanitaria Locale 4 Chiavarese
      Genova, Liguria, Italy
  • 1986–1999
    • University Hospitals Birmingham NHS Foundation Trust
      • Department of Cardiovascular Medicine
      Birmingham, ENG, United Kingdom
  • 1987–1998
    • The Queen Elizabeth Hospital
      Tarndarnya, South Australia, Australia