DNA Damage Repair in Huntington's Disease and Other Neurodegenerative Diseases

Recent genome-wide association studies of Huntington's disease (HD) primarily highlighted genes involved in DNA damage repair mechanisms as modifiers of age at onset and disease severity, consistent with evidence that more DNA repair genes are being implicated in late age-onset neurodegenerative diseases. This provides an exciting opportunity to advance therapeutic development in HD, as these pathways have already been under intense investigation in cancer research. Also emerging are the roles of other polyglutamine disease proteins in DNA damage repair mechanisms. A potential universal trigger of oxidative DNA damage shared in these late age-onset diseases is the increase of reactive oxygen species (ROS) in human aging, defining an age-related mechanism that has defied other hypotheses of neurodegeneration. We discuss the potential commonality of DNA damage repair pathways in HD and other neurodegenerative diseases. Potential targets for therapy that may prove beneficial across many of these diseases are also identified, defining nodes in the ataxia telangiectasia-mutated (ATM) complex, mismatch repair, and poly ADP-ribose polymerases (PARPs).

Reproductive biology of the greeneye spurdog Squalus chloroculus (Squaliformes, Squalidae)

The reproduction of the greeneye spurdog Squalus chloroculus was studied based on animals caught in the multispecies and multi-gear southern and eastern scalefish and shark fishery on the upper continental slope off southern Australia. One hundred and ninety-nine females (502-990 mm, total length, L_T ) and 189 males (515-810 mm L_T ) were examined. The female reproductive cycle, based on 41 breeding animals, is continuous and triennial, with the pregnancy period estimated to be 31-34 months, seasonal and synchronous with the ovarian cycle; a third of the breeding female population is estimated to give birth between September and December each year. The estimated L_T at which 50% of females are mature is 799 mm (95% c.i.: 794, 804), whereas the L_T at which 50% are maternal is 825 mm (95% c.i.: 817-833), but these estimates are probably biased by the phenomenon of apparent change of L_T at maternity and L_T at maturity following severe length-selective fishing mortality. Litters ranged from four to 15 embryos with a 1:1 sex ratio, and litter size increased with maternal length. The breeding cycle of males is neither seasonal nor synchronous with the female cycle. The estimated L_T of males where 50% are mature was 629 mm (95% c.i.: 603, 645).

Aggregation pheromone characterization and comparison inDrosophila ananassae andDrosophila bipectinata

(Z)-11-Octadecenyl acetate (Z11-18∶Ac) and (Z)-11-eicosenyl acetate (Z11-20∶Ac) were identified as the aggregation pheromones ofDrosophila ananassae, andZ11-20∶Ac was identified as the aggregation pheromone ofDrosophila bipectinata. Z11-18∶Ac andZ11-20∶Ac were not attractive alone; however, in combination with fermenting food odors, the acetates attracted flies of both sexes in a wind-tunnel olfactometer. The pheromones were present in the ejaculatory bulb of sexually mature male flies and transferred to the female during mating. MaleD. bipectinata released little if anyZ11-20∶Ac to the food; however, recently mated females releasedZ11-20∶Ac to the surrounding surfaces in just a few hours after mating.D. ananassae males, on the other hand, appeared to release moreZ11-18∶Ac andZ11-20∶Ac to the surroundings than mated females. AlthoughD. bipectinata males had noZ11-18∶Ac, flies were as attracted toZ11-18∶Ac as to an equal quantity ofZ11-20∶Ac.D. ananassae were attracted toZ11-18∶Ac but not toZ11-16∶Ac orZ11-20∶Ac. However,Z11-20∶Ac in combination withZ11-18∶Ac was significantly more attractive thanZ11-18∶Ac alone.

Underuse of cardiovascular preventive pharmacotherapy in patients presenting with ST-elevation myocardial infarction

BACKGROUND

Multiple medications have proven efficacy for the primary prevention of coronary heart disease (CHD), but the appropriate patient population remains controversial. Even in the presence of multiple cardiovascular risk factors, many patients are not considered high risk and are not offered preventive medications despite proven efficacy.

METHODS

We analyzed a prospective cohort of 1,710 consecutive ST-elevation myocardial infarction (STEMI) patients treated in a regional STEMI system from May 2007 to July 2010 and enrolled in a comprehensive database that includes preadmission medications.

RESULTS

Of the 1,707 patients analyzed, 1,180 (69.1%) did not have known CHD before their event; and 482 (41.7%) of those patients had premature events (men <55 years old, women <65 years old). In patients without known CHD, cardiovascular risk factors were abundant (52.1% had hypertension, 43.6% had dyslipidemia, 41.4% had a family history of CHD, 58.5% were current or former smokers, and 14.9% were diabetic). Despite the high prevalence of risk factors, only 24.1% were on aspirin, 16.1% were on a statin, and only 7.8% were taking an aspirin and statin. Use of preventive medications was even less common in patients with premature events, including aspirin (15.2% vs 30.2%, P value < .001), statins (11.1% vs 19.5%, P value < .001), and the combination (5.6% vs 9.4%, P value < .001).

CONCLUSIONS

Approximately 70% of a contemporary STEMI population did not have known CHD before their event, and >40% of those events would be considered premature. Despite the significant burden of cardiovascular risk factors, use of preventive therapy was alarmingly low in patients presenting with STEMI.

Resolution of life-threatening dysphagia caused by caudal occipital malformation syndrome following foramen magnum decompressive surgery

A Cavalier King Charles Spaniel was presented with acute onset, life-threatening dysphagia suspected to be secondary to medulla oblongata compression caused by caudal occipital malformation syndrome. The patient required urgent tracheostomy tube placement to remain stable and was subsequently cured of the presenting neurological deficits by foramen magnum decompressive surgery. Neurogenic dysphagia is a relatively common presenting sign in human Chiari malformation syndromes, but has not been described as a major clinical sign in veterinary patients. Caudal occipital malformation syndrome should be included in the differential diagnosis list for susceptible breeds presenting with dysphagia. Early recognition favours expeditious surgical intervention and a positive outcome in human patients, and this may also be the case in veterinary patients.

Intraoperative parathyroid hormone concentration to confirm removal of hypersecretory parathyroid tissue and time to postoperative normocalcaemia in nine dogs with primary hyperparathyroidism

OBJECTIVE

To determine (1) whether the intraoperative parathyroid hormone concentration ([PTH]) during parathyroidectomy (PTX) can be used to indicate cure in dogs with primary hyperparathyroidism and (2) the time taken for postoperative serum calcium concentration to normalise.

DESIGN

Retrospective study (2005-10) from a private referral hospital in Sydney, New South Wales, Australia.

PROCEDURE

Nine client-owned dogs underwent surgical PTX for naturally occurring primary hyperparathyroidism. [PTH] was measured from serum samples taken immediately post-induction (pre-PTX]) and at least 20 min after adenoma removal (post-PTX) for all dogs, and during parathyroid gland manipulation (intra-PTX) for six dogs. The concentration of ionised calcium (iCa) was measured at various time points postoperatively until it normalised, then stabilised or decreased below reference ranges. Statistical analysis compared the mean pre-, intra- and post-PTX [PTH] and the average rate of decline of iCa concentration postoperatively.

RESULTS

All dogs demonstrated a significant decrease from mean pre-PTX [PTH] (168.51 pg/mL) to mean post-PTX [PTH] (29.20 pg/mL). There was a significant increase in mean intra-PTX [PTH] (279.78 pg/mL). The average rate of decline of iCa concentration postoperatively to within the reference range (1.12-1.40 mmol/L) occurred after 24 h.

CONCLUSION

Intraoperative measurements of [PTH] can be used clinically to determine cure of primary hyperparathyroidism. Parathyroid hormone increases significantly during parathyroid gland manipulation. Plasma iCa concentration returns to within the reference range on average 24 h after successful PTX. Not all dogs require vitamin D or calcium supplementation pre- or postoperatively.

Biological vulnerability of two exploited sharks of the genus Deania (Centrophoridae)

Life-history parameters of Deania calcea and Deania quadrispinosa suggested that their productivity was very low. Maturity (L(T50) ) occurs at c. 80% of maximum observed total lengths (L(T) ) for both species and sexes. A large proportion of mature females were neither pre-ovulatory nor pregnant, and the reproductive cycle included a distinct resting phase after pregnancy. For D. calcea, mean ovarian fecundity was 12 and maximum observed litter size was 10 (average of six); D. quadrispinosa averaged 17 pups per litter. Birth L(T) was 28-33 cm for D. calcea and 23-25 cm for D. quadrispinosa. The male and female reproductive cycles were aseasonal, and consequently, the length of the reproductive cycle could not be determined. Preliminary ageing data from dorsal-spine growth bands suggested that female D. calcea lived to 31-36 years and males to 24-32 years. The L(T) -at-age data using external bands on the spines showed maturity occurring at 15·5 years (males) and 21·5 years (females), whereas banding on the internal dentine indicated maturity at 10·5 and 17·5 years for males and females. Thus, a female lifetime of 31-36 years allowed for a maximum of 7 litters if a 2 year cycle is assumed or only five litters with a 3 year cycle, resulting in a lifetime fecundity of only 42 pups (2 year cycle) or even lower (3 year cycle).

Therapeutic hypothermia after out-of-hospital cardiac arrest: evaluation of a regional system to increase access to cooling

BACKGROUND

Therapeutic hypothermia (TH) improves survival and confers neuroprotection in out-of-hospital cardiac arrest (OHCA), but TH is underutilized, and regional systems of care for OHCA that include TH are needed.

METHODS AND RESULTS

The Cool It protocol has established TH as the standard of care for OHCA across a regional network of hospitals transferring patients to a central TH-capable hospital. Between February 2006 and August 2009, 140 OHCA patients who remained unresponsive after return of spontaneous circulation were cooled and rewarmed with the use of an automated, noninvasive cooling device. Three quarters of the patients (n=107) were transferred to the TH-capable hospital from referring network hospitals. Positive neurological outcome was defined as Cerebral Performance Category 1 or 2 at discharge. Patients with non-ventricular fibrillation arrest or cardiogenic shock were included, and patients with concurrent ST-segment elevation myocardial infarction (n=68) received cardiac intervention and cooling simultaneously. Overall survival to hospital discharge was 56%, and 92% of survivors were discharged with a positive neurological outcome. Survival was similar in transferred and nontransferred patients. Non-ventricular fibrillation arrest and presence of cardiogenic shock were associated strongly with mortality, but survivors with these event characteristics had high rates of positive neurological recovery (100% and 89%, respectively). A 20% increase in the risk of death (95% confidence interval, 4% to 39%) was observed for every hour of delay to initiation of cooling.

CONCLUSIONS

A comprehensive TH protocol can be integrated into a regional ST-segment elevation myocardial infarction network and achieves broad dispersion of this essential therapy for OHCA.

A Regional System to Provide Timely Access to Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction

Background— Percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) is superior to fibrinolysis when performed in a timely manner in high-volume centers. Recent European trials suggest that transfer for PCI also may be superior to fibrinolysis and increase access to PCI. In the United States, transfer times are consistently long; therefore, many believe a transfer for PCI strategy for STEMI is not practical.

Methods and Results— We developed a standardized PCI-based treatment system for STEMI patients from 30 hospitals up to 210 miles from a PCI center. From March 2003 to November 2006, 1345 consecutive STEMI patients were treated, including 1048 patients transferred from non-PCI hospitals. The median first door-to-balloon time for patients <60 miles (zone 1) and 60 to 210 miles (zone 2) from the PCI center was 95 minutes (25th and 75th percentiles, 82 and 116 minutes) and 120 minutes (25th and 75th percentiles, 100 and 145 minutes), respectively. Despite the high-risk unselected patient population (cardiogenic shock, 12.3%; cardiac arrest, 10.8%; and elderly [≥80 years of age], 14.6%), in-hospital mortality was 4.2%, and median length of stay was 3 days.

Conclusions— Rapid transfer of STEMI patients from community hospitals up to 210 miles from a PCI center is safe and feasible using a standardized protocol with an integrated transfer system.

Feasibility of transcatheter intervention for severe aortic stenosis in patients ≥90 years of age: Aortic valvuloplasty revisited

OBJECTIVES

The goals of this study were to determine the feasibility, safety, and early outcomes of balloon aortic valvuloplasty (BAV) for severe aortic stenosis in a nonagenarian population.

BACKGROUND

This very elderly population is expanding rapidly, has a high incidence of aortic stenosis, and uncommonly undergoes surgical aortic valve replacement. These patients may best be treated with a transcatheter approach due to comorbidities, surgical risk, and personal preference.

METHODS

We reviewed 31 consecutive patients >or=90 years of age who underwent BAV at our institution from July 2003 to August 2006 for data pertinent to patient characteristics, procedural techniques, and 30-day outcomes.

RESULTS

Our patients had a mean age of 93 +/- 3.0 years (90-101). The society of thoracic surgery risk score was 18.5 (+/-10.2) and logistic Euroscore was 35.8 (+/-19.3). Twenty-five patients (81%) underwent retrograde BAV and 6 (19%) antegrade BAV. Five patients (16%) underwent combined BAV and coronary stenting. Overall mean aortic valve area increased from 0.52 cm2 (+/-0.17) to 0.92 cm2 (+/-0.22) and mean New York Heart Association (NYHA) functional class improved from 3.4 to 1.8. Intraprocedural mortality occurred in one patient (3.2%) and 30-day mortality in three patients (9.7%).

CONCLUSIONS

BAV can be carried out in high risk nonagenarian patients with an acceptable complication rate, low perioperative mortality, and early improvement in NYHA functional class.

Radiation following percutaneous balloon aortic valvuloplasty to prevent restenosis (RADAR pilot trial)

OBJECTIVES

We wished to determine the feasibility and early safety of external beam radiation therapy (EBRT) used following balloon aortic valvuloplasty (BAV) to prevent restenosis.

BACKGROUND

BAV for calcific aortic stenosis (AS) has been largely abandoned because of high restenosis rates, i.e., > 80% at 1 year. Radiation therapy is useful in preventing restenosis following vascular interventions and treating other benign noncardiovascular disorders.

METHODS

We conducted a 20-patient, pilot study evaluating EBRT to prevent restenosis following BAV in elderly patients with calcific AS. Total doses ranging from 12-18 Gy were delivered in fractions over a 3-5 day post-op period to the aortic valve. Echocardiography was performed pre and 2 days post-op, 1, 6, and 12 months following BAV.

RESULTS

One-year follow-up is completed (age 89 +/- 4). There were no complications related to EBRT. Eight patients died prior to 1 year; 5 of 10 (50%) in the low-dose (12 Gy) group and 3 of 10 (30%) in the high-dose (15-18 Gy) group. None of these 8 patients had restenosis, i.e., > 50% loss of the initial AVA gain, and only three deaths were cardiac in origin. One patient underwent aortic valve replacement and none repeated BAV. By 1 year, 3 of the initial 10 (30%) in the low-dose group and 1 of 9 (11%) in the high-dose group demonstrated restenosis (21% overall).

CONCLUSIONS

EBRT following BAV in elderly patients with AS is feasible, free of early complications, and holds promise in reducing the 1 year restenosis rate in a dose-dependent fashion.

Soil water content and organic carbon availability are major determinants of soil microbial community composition

Exploration of environmental factors governing soil microbial community composition is long overdue and now possible with improved methods for characterizing microbial communities. Previously, we observed that rice soil microbial communities were distinctly different from tomato soil microbial communities, despite management and seasonal variations within soil type. Potential contributing factors included types and amounts of organic inputs, organic carbon content, and timing and amounts of water inputs. Of these, both soil water content and organic carbon availability were highly correlated with observed differences in composition. We examined how organic carbon amendment (compost, vetch, or no amendment) and water additions (from air dry to flooded) affect microbial community composition. Using canonical correspondence analysis of phospholipid fatty acid data, we determined flooded, carbon-amended (+C) microcosm samples were distinctly different from other +C samples and unamended (-C) samples. Although flooding without organic carbon addition influenced composition some, organic carbon addition was necessary to substantially alter community composition. Organic carbon availability had the same general effects on microbial communities regardless of whether it was compost or vetch in origin. In addition, flooded samples, regardless of organic carbon inputs, had significantly lower ratios of fungal to bacterial biomarkers, whereas under drier conditions and increased organic carbon availability the microbial communities had higher proportions of fungal biomass. When comparing field and microcosm soil, flooded +C microcosm samples were most similar to field-collected rice soil, whereas all other treatments were more similar to field-collected tomato soil. Overall, manipulating water and carbon content selected for microbial communities similar to those observed when the same factors were manipulated at the field scale.

Thrombotic risk in patients with aortic bioprostheses

Thrombosis of Mosaic aortic valve bioprostheses occurring at more than one month after surgery occurs in 0.8% (95% CI 0.33-1.67%) of patients. In the two cases reported here, each patient had risk factors for thrombus formation, namely severe left ventricular impairment in one patient, while the other patient was heterozygous for prothrombin variant G20210A. The cases were treated successfully, by thrombolytic therapy with streptokinase in the first case, and by repeat aortic valve replacement in the second case. Thrombosis of bioprosthetic valves in the aortic position is rare, and a period of anticoagulation postoperatively does not invariably protect against this serious complication. In conclusion, patients with risk factors for thrombus formation should be considered for long-term anticoagulation.

Fatty acid composition and dynamics of selected fungal-feeding nematodes and fungi

Fatty acid profiles of fungal-feeding nematodes, Aphelenchus avenae and Aphelenchoides composticola, and selected fungi were determined in microcosm cultures of agar, broth, or sand amended with organic matter. Fatty acids of A. avenae and A. composticola included 16:0 18:0, 18:1omega7, 18:1omega9, 18:2, 20:0, 20:1, 20:2, 20:3 and 20:4 phospholipid fatty acids (PLFAs) and neutral lipid fatty acids (NLFAs). The nematodes differed in relative amounts of saturated and C(18) fatty acids. Similar C(16) and C(18) PLFAs and whole-cell fatty acids were found in Rhizoctonia solani, Fusarium oxysporum and Trichoderma sp. with 18:2omega6 as the major component. The C(20) fatty acids were not found in these fungi. Although only present in the nematodes, C(20) PLFAs were only detected when nematode population levels were > or =22 per gram of sand, suggesting that there is a detection threshold that might limit their use as biomarkers in the soil community. After removal of nematodes from a food source, the relative amount of C(20) PLFAs (structural components of nematode cell membranes) decreased more slowly than the C(16) and C(18) PLFAs, which may have reflected ingested fungal cytoplasm in the nematode intestine. In the early stage of organic matter decomposition, total and fungal PLFAs were lower in the presence of A. composticola then in its absence at C:N ratios > or =30:1.

Coronary Artery Bypass Graft Degenerative Disease

The choice of conduit is the most important factor influencing long-term patency of coronary artery bypass grafts (CABGs); arterial grafts are far superior to saphenous vein bypass grafts (SVGs) in this regard. Aspirin therapy should be started early in the perioperative period and continued indefinitely. Warfarin (Coumadin; Dupont, Wilmington, DE) and other platelet inhibitors offer no added value to aspirin, but may be used with benefit in aspirin-intolerant patients. Every effort should be made to reduce low-density lipoprotein cholesterol (LDL-C) to a value well below 100 mg/dL. In most instances, this will require the use of an 3-hydroxy-3-methyglutaryl coenzyme A (HMG CoA) reductase inhibitor. Avoidance of cigarette smoking is imperative. Achieving a normal blood pressure, ideal body weight, and a regular exercise program are helpful. Those patients who have important obstruction in a SVG or arterial graft and who are symptomatic, or who have important myocardial ischemia with orjwithout symptoms should be treated with a procedure to improve perfusion to the myocardium supplied by the occluded bypass graft. Successful percutaneous transluminal coronary angioplasty (PTCA) and stenting of the obstructed graft usually will lead to improved myocardial perfusion, although in other clinical circumstances repeat CABG surgery will be required. On occasion, reperfusion of the myocardium can be achieved by PTCA of the native coronary artery with or without stenting while the degenerated graft is abandoned. When planning therapy for myocardial ischemia, the higher rate of PTCA related restenosis and the increased risks from repeat CABG must be carefully considered.

Epidemiology of hypertrophic cardiomyopathy-related death: revisited in a large non-referral-based patient population

BACKGROUND

Death resulting from hypertrophic cardiomyopathy (HCM), particularly when sudden, has been reported to be largely confined to young persons. These data emanated from tertiary HCM centers with highly selected referral patterns skewed toward high-risk patients.

METHODS AND RESULTS

The present analysis was undertaken in an international population of 744 consecutively enrolled and largely unselected patients more representative of the overall HCM spectrum. HCM-related death occurred in 86 patients (12%) over 8+/-7 years (mean+/-SD). Three distinctive modes of death were as follows: (1) sudden and unexpected (51%; age, 45+/-20 years); (2) progressive heart failure (36%; age, 56+/-19 years); and (3) HCM-related stroke associated with atrial fibrillation (13%; age, 73+/-14 years). Sudden death was most common in young patients, whereas heart failure- and stroke-related deaths occurred more frequently in midlife and beyond. However, neither sudden nor heart failure-related death showed a statistically significant, disproportionate age distribution (P=0.06 and 0.5, respectively). Stroke-related deaths did occur disproportionately in older patients (P=0.002). Of the 45 patients who died suddenly, most (71%) had no or mild symptoms, and 7 (16%) participated in moderate to severe physical activities at the time of death.

CONCLUSIONS

HCM-related cardiovascular death occurred suddenly, or as a result of heart failure or stroke, largely during different phases of life in a prospectively assembled, regionally based, and predominantly unselected patient cohort. Although most sudden deaths occurred in adolescents and young adults, such catastrophes were not confined to patients of these ages and extended to later phases of life. This revised clinical profile suggests that generally held epidemiological tenants for HCM have been influenced considerably by skewed reporting from highly selected populations. These data are likely to importantly affect risk stratification and treatment strategies importantly for the prevention of sudden death in HCM.

Polygenic influence on plasma homocysteine: association of two prevalent mutations, the 844ins68 of cystathionine beta-synthase and A(2756)G of methionine synthase, with lowered plasma homocysteine levels

A moderately elevated plasma total homocysteine (tHcy), whether measured during fasting or post-methionine load (PML), is increasingly being recognized as a risk factor for coronary artery diseases (CAD). However, etiologies for moderately elevated plasma tHcy, particularly with regard to the role of genetic influence on plasma tHcy levels, are still not well understood. In the current investigation, we studied 1025 individuals with respect to the effect of the 68-bp insertion (844ins68 variant) of the cystathionine beta-synthase (CBS) gene, the A(2756)G transition of the B(12)-dependent methionine synthase (MS) gene and the C(677)T transition of the methylenetetrahydrofolate reductase (MTHFR) gene on fasting and 4 h PML tHcy. Of these individuals, 153 (14.9%) were heterozygous for the 68-bp insertion, 329 (32.1%) were heterozygous for the G(2756) allele and 122 (11.9%) were homozygous for the C(677)T transition. Individuals heterozygous for the insertion had significantly lower PML increase in tHcy concentrations, while individuals homozygous for the A(2756)G transition had significantly lower fasting tHcy levels. A 2-way ANOVA showed that there was no interaction between the 844ins68 and the A(2756)G transition for either fasting tHcy or PML increase in tHcy, confirming the fact that the effect of these two genotypes on plasma tHcy levels are additive. The effects are opposite but additive with the C(677)50% of all individuals in this study carried polymorphic traits, which predisposed them to either higher or lower plasma tHcy concentrations, thus providing new evidence of the importance of genetic influences as determinants of tHcy levels.

Blunt chest trauma and the heart

The Green Lane Hospital experience of patients presenting with cardiac damage as a result of chest trauma has been reviewed following the recent referral of a patient with tricuspid regurgitation due to trauma. A retrospective search of surgical records was made over the preceding 28 years which yielded a further nine patients. Our group has experienced a number of unusual causes of non-fatal cardiac trauma that have followed accidents. In nine out of ten cases closed chest injury resulted in damage to the heart. In some, diagnosis had been delayed for years. Echocardiography is a very useful diagnostic tool. Surgery was undertaken in all cases.

Genetic causes of mild hyperhomocysteinemia in patients with premature occlusive coronary artery diseases

Elevated plasma homocysteine is increasingly being recognized as a risk factor for coronary artery disease (CAD). Although there is general agreement on the importance of micronutrients and genetic predisposition to elevated plasma homocysteine, the exact influence of the known prevalent mutations in genes which regulate homocysteine metabolism is not clear. We studied 376 cases of individuals with premature CAD with respect to their fasting and post-methionine load (PML) total homocysteine (tHcy) concentrations. We also determined the presence or absence of the T833C and G919A mutations of the cystathionine-beta-synthase (CBS) gene, the C677T mutation of the methylene tetrahydrofolate reductase (MTHFR) gene, and the A2756G transition of the B12 dependent methionine synthase (MS) gene. Our objectives were therefore both to confirm the relationship of plasma homocysteine with premature CAD and to examine the importance of genetic influence on both fasting and PML homocysteine. Approximately 32% of the CAD patients had fasting hyperhomocysteinemia and 16% had PML hyperhomocysteinemia. Of these, 8.5% had both forms of hyperhomocysteinemia (combined hyperhomocysteinemia). The T133C mutation in the CBS gene and the thermolabile C677T mutation in the MTHFR gene seem to play an important role in the subset of individuals with combined hyperhomocysteinemia. The A2756G transition in the MS gene is not associated with elevated plasma tHcy. Many cases (47%) of hyperhomocysteinemia are not associated with micronutrient deficiencies, impaired renal function, and/or currently known genetic mutations. Further work is needed to study whether unknown mutations, particularly those residing in the intronic sequences of the genes involved in homocysteine metabolism, other environmental factors, or interaction of gene, nutrient, and environmental factors may be the cause of currently unexplained cases of mild hyperhomocysteinemia.

Multicenter experience with a bipolar tined polyurethane ventricular lead

A multicenter study was undertaken to determine the failure rate of a specific bipolar tined polyurethane ventricular pacing lead, the Medtronic 4004/4004M pacing lead. Seven centers in the United States and Canada implanted 586 Medtronic 4004/4004M pacing leads. The study was designed to determine the probability and clinical manifestations of lead failure. Only failures compatible with an insulation problem were included. The Kaplan-Meier estimate of the percentage of 4004/4004M lead failures within 4 years after implantation was 14.1% (95% confidence interval: 8.5%-19.3%). Failures were manifested as sensing abnormalities, failure to capture, early battery depletion, and significant decrease in measured impedance compared with previous impedance measurements. The observed rate of failure is unacceptable, and strong consideration should be given to replacing the 4004/4004M pacing lead in pacemaker dependent patients and closely monitoring nondependent patients.

Coronary artery surgery in the elderly: long-term follow-up

BACKGROUND

There has been controversy concerning the indications for coronary artery surgery in the elderly, particularly in countries where health resources are restricted.

AIMS

To assess the results of coronary artery bypass grafting (CABG) in a large group of elderly subjects with regard to initial risks and long term follow-up.

METHODS

Ninety-six consecutive patients aged 70 years or older underwent isolated CABG between January 1981 and December 1985. Long term follow-up was obtained in 94 (98%).

RESULTS

The mean age was 71.6 years (70-78) and mean duration of follow-up 73 months. Seventy (73%) were male. In 80 cases the myocardial score was > 10. In 22 of 90 who had left ventricular angiography the ejection fraction was < 50%. Hospital survival was 96% and the five year survival 77%. It was not influenced by gender, myocardial score, ejection fraction or age at the time of operation. The status of survivors was reviewed in 1991. Of the 55 long term survivors 35 (64%) were free of angina. Eight (15%) and ten (18%) were in the Canadian Cardiovascular Society Angina classes 1 and 2 respectively. Seventeen patients (31%) had symptoms of heart failure with 14 (25%) in NYHA class 2 and 3 (5%) in class 3. Eight patients (15%) had survived a cerebrovascular event during follow-up. There were 35 late deaths (37%). Sixteen of these were cardiac, 18 due to other causes and one unknown.

A multicenter experience with a bipolar tined polyurethane ventricular lead

A multicenter study was undertaken to determine the failure rate of a specific polyurethane bipolar tined pacing lead, the Medtronic 4012 pacing lead. Six centers in the United States and Canada implanted 1,190 Medtronic 4012 pacing leads. The study was designed to determine the probability and clinical manifestations of lead failure. Only failures compatible with an insulation problem were included. The probability of a 4012 lead failure by Kaplan-Meier analysis was 20.9% at 6 years after implantation. Failures were manifested as sensing abnormalities, failure to capture, early battery depletion, and significant decrease in measured impedance compared with the previous impedance measurements. Of the 95 definite lead failures, 16 (16.8%) were associated with symptoms similar to those experienced before pacemaker placement. The observed failure rate is unacceptable, and strong consideration should be given to replacing the 4012 pacing lead in pacemaker-dependent patients and closely monitoring nondependent patients.

Cardiac transplantation in New Zealand: an initial report

During the first 18 months of its establishment, the cardiac transplant unit at Green Lane Hospital has undertaken 10 transplant operations. Fifty potential recipients have been referred and 15 were accepted for transplantation. Of the ten who have had surgery, 2 are making good progress at school, 1 is active at home and 5 have returned to work. Two patients have died.

Arrhythmia prophylaxis after aorta-coronary bypass. The effect of minidose propranolol

After aorta-coronary bypass grafting, 164 consecutive patients were randomized to receive propranolol 5 mg every 6 hours orally (n = 82) or to serve as control subjects (n = 82). All patients were receiving beta blockers preoperatively. There were no significant differences between the two groups. The incidence of sustained supraventricular (nonsinus) tachyarrhythmias was 23% in the control group and 9.8% in the treated group (p = 0.02). The incidence of ventricular arrhythmias was 15% in the control group and 2.4% in the treated group (p = 0.005). The overall difference in clinically important arrhythmias was 38% in the control group and 12.2% in the treated group (p = 0.0002). We conclude that low-dose oral propranolol in patients who were receiving beta blockers preoperatively is effective in reducing the incidence of clinically important arrhythmias occurring after aorta-coronary bypass grafting.

Aortocaval fistulae: an occasional cause of congestive cardiac failure

Two atypical patients with spontaneous aortocaval fistulae with a successful outcome, are presented. Lack of physician awareness is considered an important contributor to diagnostic delay. A finding at cardiac catheterization is described. Review of the English literature shows that satisfactory results in the management of this condition can now be expected.

Coronary surgery after recurrent myocardial infarction: progress of a trial comparing surgical with nonsurgical management for asymptomatic patients with advanced coronary disease

A randomized trial of surgical vs nonsurgical management was carried out in men 60 years of age or younger who had recovered from a recurrent myocardial infarction. Of 205 patients considered, 100 had few or no symptoms and had coronary vessels favorable for bypass grafting; these patients fulfilled the trial conditions and were randomized (50 surgical and 50 nonsurgical). In 41 patients (elective nonsurgical group), randomization was not considered justifiable because of relatively unfavorable coronary anatomy or severe left ventricular dysfunction. Nineteen patients had elective surgery because of disabling angina despite full medical treatment or because of significant left main coronary stenosis. In 45 patients, coronary angiography was not undertaken because of medical contraindications or reluctance of the patient to enter the study. Actuarial survival curves (mean follow-up 4.5 years) show an annual mortality rate of 3-4% per year for all investigated patients, and no advantage for the randomized surgical over the randomized nonsurgical group. The results suggest that in the absence of disabling angina or left main coronary artery stenosis, coronary artery surgery need not be advised for survivors of recurrent infarctions who have severe coronary artery disease. Moreover, the prognosis for the group of patients not treated surgically appears to be better than has been previously described.

Isolated mitral replacement with stent-mounted antibiotic-treated aortic allograft valves

The results of valve replacement with a stent-mounted antibiotic-treated aortic allograft valve are reported in 129 patients with isolated mitral valve disease. Of these patients, 70 per cent were in N.Y.H.A. Class IV. The hospital mortality rate was 3.9 percent. The cumulative complication-free rate at 5 years was only 37 percent as 21 percent died late, a further 15 percent were alive following reoperation, 4 percent had an embolic episode, 4 percent were alive with important incompetence, and 20 percent had unimportant incompetence. Proved valve failure was due mainly to detachment of the aortic wall remnant of the valve from the pillar of the rigid metal stent (16 percent incidence at 5 years) and methods for preventing this complication are discussed. Because of these complications the use of this device in the mitral position has been discontinued.

Cardiac rupture with false aneurysm after myocardial infarction

A case of cardiac rupture is reported after myocardial infarction. Leaking blood was contained within the pericardium and a false aneurysm developed. Ten months later this was successfully repaired. The neck of the aneurysm was transected, the defect in the left ventricle closed and saphenous vein bypass grafts were applied to the anterior descending and right coronary arteries. The literature on this subject is briefly reviewed.

Catheter emboli to the heart and pulmonary artery

Experiences with intracardiac catheter embolus in 6 patients over a 6-year period is reported, and a brief review of the literature made.