Background: Myocardial infarction (MI), also known as heart attack, is the leading cause of morbidity and mortality among the heart diseases spectrum. It results from an insufficient supply of blood to the heart muscles. According to the United States (U.S.) Centers for Disease Control and Prevention (CDC), about 610 000 people die of heart disease in the U.S. every year. Myocardial infarction contributes 370 000 of these deaths annually. Every 40 seconds, someone in the U.S. experience heart attack. This burden is disproportionately distributed within the U.S. population. The rate of heart disease in Central Appalachia is 249 per 100 000, 42% higher than the national rate. Exploring further within the region, rural areas experience higher heart disease mortality rates; 27% higher than the region’s metro counties. According to 2018 America Health Ranking, the prevalence of heart attack in Tennessee is 5.9%, compared to the 4.9% nationwide, with the majority of the burden seen among adults aged ≥65 years and with a 1:1.8 female to male ratio. Patients with heart disease often have other comorbid conditions such as peripheral arterial disease (PAD), hypertension, diabetes, dyslipidemias, which contribute immensely to this chronic condition. Therefore, the aim of this study is to explore the association between cardiovascular comorbidities such as diabetes mellitus, hypertension and dyslipidemia, and the prevalence of heart attack among patients with PAD in rural Central Appalachia. Methods: We used a cross-sectional data of patients diagnosed with PAD in the Central Appalachian region. A total of 13455 patients with PAD were recruited using ICD 9 and 10 search terms for PAD from the electronic medical records (EMR) system between January 1, 2008, and April 30, 2018. Descriptive statistics of the variables were extracted. The association between the comorbidities, including hypertension, diabetes, dyslipidemia, body mass index(BMI) and the prevalence of MI was determined using a binomial logistic regression model. All analysis was done using IBM SPSS statistics 25. Results: Of the total 13455 patients with PAD, 3045 had MI (37.7% female and 62.3% male) with a mean age of 69±10.5years. While 93% had hypertension, 56% had diabetes. For the lipids, the mean of HDL, Cholesterol, and LDL among participants with a history of MI is 40.99mg/dl±13, 156.32mg/dl±45, 82.08mg/dl±36.35 respectively. The results of binomial logistic regression with stratification based on gender shows that female patients with diabetes had 86% increased odds of MI [OR: 1.858, C.I: 1.308-2.638, p-value=0.001), and for female hypertensives, 4.51 times increased odds of MI was found (C.I: 1.576-12.895, p-value=0.005). The male diabetics and hypertensives showed a similarly increased odds of MI with (OR 1.138, C.I: 0.870-1.489 p-value=0.345) and (OR 3.697C.I: 1.559-8.736, p-value=0.003) respectively. No significant association was found among the various lipid profiles examined. Conclusion: The results showed that female PAD patients with hypertension and diabetes have a significantly increased likelihood of having MI. In contrast, male with PAD also showed increased likelihood (although to a lesser degree) of MI in those with hypertension, but not those with diabetes. These findings underscore the importance of a proactive approach to preventive care and adequate control among PAD patients with diabetes and hypertension in a bid to curbing the morbidity and mortality associated with myocardial infarction among residents in Central Appalachia.

Bakgrund: I sjuksköterskans profession ingår att främja hälsa, förebygga sjukdom, återställa hälsa och lindra lidande. En hjärtinfarkt är en omtumlande händelse och flera tusen drabbas varje år, för en sådan kris saknar ofta människor beredskap. En hjärtinfarkt kan ge plötslig, svår smärta samt ångest och orsakas av stopp i ett kranskärl, vilket leder till syrebrist i hjärtat. Anhöriga kände ett stort ansvar och saknade information från sjukvården. De kände även en oro att deras närstående skulle drabbas av ännu en hjärtinfarkt. Syfte: Att beskriva kvinnor och mäns erfarenheter efter en hjärtinfarkt.  Metod: Resultatet av denna litteraturstudie utgjordes av tio kvalitativa artiklar identifierade i databasen PubMed.     Huvudresultat: Det framkom att flera konsekvenser upplevdes efter hjärtinfarkten, såsom utmattning, ångest, oro och rädsla för att drabbas igen, vilket gav begränsningar i livet. Efter hjärtinfarkten kunde livet präglas av en rädsla att anstränga det sjuka hjärtat och minskad tro på hjärtats förmåga. Vidare framkom behovet av mer information från sjukvården. Närstående visade sig ha stor betydelse för tillfrisknandet samt möjligheten att få träffa andra i samma situation. Hjärtinfarkten var för många en väckarklocka som gav insikt om det viktiga i livet och kunde motivera till livsstilsförändringar. Slutsats: Hjärtinfarkten medförde många konsekvenser. Trots en rädsla att anstränga det sjuka hjärtat kunde händelsen motivera till livsstilsförändring. Anhöriga var ett stort stöd i tillfrisknandet, dock fanns en önskan om mer stöd och information från sjukvården. Denna litteraturstudie kan ge vårdpersonalen ökad förståelse för erfarenheter efter en hjärtinfarkt samt bidra med kunskap om hur eftervården kan utformas. / Background: The nursing profession includes promoting health, preventing disease, restoring health and relieving suffering. A heart attack is a dizzying event and several thousand are affected every year, because such a crisis often leaves people unprepared. A heart attack can cause sudden, severe pain and anxiety and is caused by a blockage in a coronary artery, which leads to a lack of oxygen in the heart. Relatives felt a great responsibility and lacked information from the health service. They also felt a concern that their loved ones would suffer another heart attack.Aim: To describe women's and men's experiences after a heart attack.Method: The results of this literature review consisted of ten qualitative articles identified in the PubMed database.Main results: It turned out that several consequences were experienced after the heart attack, such as fatigue, anxiety, worry and fear of being hit again, which gave limitations in life. After the heart attack, life could be marked by a fear of straining the diseased heart and diminished belief in the heart's ability. Furthermore, the need for more information from the health service emerged. Relatives proved to be of great importance for recovery and the opportunity to meet others in the same situation. For many, the heart attack was an alarm clock that provided insight into the important things in life and could motivate them to make lifestyle changes.Conclusion: The heart attack had many consequences. Despite a fear of straining the sick heart, the event could motivate a lifestyle change. Relatives were a great support in the recovery, however, there was a desire for more support and information from the health care. This literature study can give the care staff an increased understanding of experiences after a heart attack and contribute with knowledge of how aftercare can be designed.

Wnt/β-catenin signaling is activated in the heart after myocardial infarction (MI). This study aims to investigate if β-catenin deletion affects post-MI ion channel gene alterations and ventricular tachycardias (VT). MI was induced by permanent ligation of left anterior descending artery in wild-type (WT) and cardiomyocyte-specific β-catenin knockout (KO) mice. KO mice showed reduced susceptibility to VT (18% vs. 77% in WT) at 8 weeks after MI, associated with reduced scar size and attenuated chamber dilation. qPCR analyses of both myocardial tissues and purified cardiomyocytes demonstrated upregulation of Wnt pathway genes in border and infarct regions after MI, including Wnt ligands (such as Wnt4) and receptors (such as Fzd1 and Fzd2). At 1 week after MI, cardiac sodium channel gene (Scn5a) transcript was reduced in WT but not in KO hearts, consistent with previous studies showing Scn5a inhibition by Wnt/β-catenin signaling. At 8 weeks after MI when Wnt genes have declined, Scn5a returned to near sham levels and K⁺ channel gene downregulations were not different between WT and KO mice. This study demonstrated that VT susceptibility in the chronic phase after MI is reduced in mice with cardiomyocyte-specific β-catenin deletion primarily through attenuated structural remodeling, but not ion channel gene alterations.

Unplanned readmissions to the hospital are a problem faced by most health care organizations in the United States; hospitals are penalized for such readmissions. The project site identified high readmission rates for patients who were discharged after acute myocardial infarction (AMI), making careful transition home a necessity for post-AMI patients. The focus of this quality improvement (QI) project was implementation of an early follow-up appointment of AMI patients following discharge. The purpose of this project was to evaluate the effectiveness of changing follow-up appointments for patients with an AMI from 14-30 days to 7-14 days post discharge to reduce unplanned readmission rates. Bandura’s self- efficacy theory provided the theoretical framework for this project. An evaluation of the QI project was completed by comparing patient readmission rates 6 months before and 6 months after implementation of the early follow-up appointments. Data analysis demonstrated that the readmission rate was not improved in the first 6 months post QI project implementation. Using the plan-do-check-act process, a multifactorial approach was recommended to refine the QI project and address the system-wide readmission rates. The implications of this project for positive social change include providing early analysis of the readmission QI project, which allowed the hospital to restructure the QI approach and improve the plan for preventing readmission.

L’objectif de ce travail est de présenter et évaluer une nouvelle méthode, PGRx,systématique cas-référents en pharmaco-épidémiologie avec son application à l’étudede l’infarctus du myocarde (IDM). Elle se distingue par la collecte systématique etcontinue de cas d’événements dans des centres spécialisés et d’un pool de référenceen médecine générale dont sont tirés les témoins appariés aux cas. L’évaluation durisque d’IDM associé au diclofénac (OR 1.5) et celle du bénéfice associé aux statines(OR 0.75) montrent des résultats similaires à ceux publiés (respectivement OR 1.4 etOR 0.74). Nous montrons que les référents sont un échantillon représentatif de lapopulation française en termes de motif de consultation et valide en termesd’évaluation de facteurs de risque. La concordance entre la mesure de l’exposition parla déclaration du patient et par les prescriptions médicales est excellente pour lesmédicaments cardiovasculaires (95%). Notre travail sur une série d’études montre quela collecte systématique de cas et d’un pool de référence, selon la méthode PGRx, estfaisable, reproductible et valide en termes de résultats et d’indicateurs de qualité. / The objective of this work is to present and assess PGRx, a new systematic case-referentsmethod in pharmacoepidemiology and its application on the study of themyocardial infarction (MI). The originality of PGRx is the systematic and on-goingcollect of cases of events in a network of specialized centres and of a pool of referentsin general practice (GP), from which controls are selected by matching to the cases.The assessment of the risk of MI associated with diclofenac (OR 1.5) and of thebenefit on MI associated with statins (OR 0.75) displays similar results than theliterature (respectively OR 1.4 and OR 0.74).We show that the pool of referents is arepresentative sample of the French population in terms of reasons of consulting a GPand valid in terms of risk factors’assessment. Agreement between the measure ofexposure from patients’ self-report and from physician’s report of their prescriptionsis excellent on cardiovascular drugs (95%). Our work, through several studies, showsthat the systematic collect of cases and of a reference pool by the PGRx method isfeasible, reproducible and valid in terms of results and quality indicators.

Le pronostic à long-terme actuel après un accident ischémique transitoire (AIT) ou un infarctus cérébral reste mal connu. Ainsi, j’ai déterminé les risques absolus à long-terme de récidive d’infarctus cérébral et d’évènement coronarien aigu après un AIT ou un infarctus cérébral et identifié les individus qui restent à haut risque absolu de récidive ischémique malgré la prévention secondaire actuelle.Dans une cohorte populationnelle contemporaine de patients ayant eu un AIT ou un infarctus cérébral (OXVASC study, 2002-2014), les risques absolus de récidive d’infarctus cérébral et d’infarctus du myocarde après un AIT/infarctus cérébral ont significativement diminué au cours de la période d’étude, très probablement du fait de l’amélioration de la prévention secondaire avec le temps. Cependant, malgré la prévention secondaire actuelle les sous-groupes de patients avec un antécédent de pathologie coronarienne et ceux sans antécédent coronaire mais avec un score Essen 4 sont exposés à un risque absolu de récidive d’évènement ischémique suffisamment élevé pour justifier d’une intensification du traitement. Néanmoins, les thérapeutiques de prévention secondaire futures nécessitent de permettre d’obtenir une réduction absolue du risque de récidive d’évènement ischémique importante pour compenser un risque augmenté d’effets indésirables ou de surcoût par rapport aux thérapeutiques actuelles. En effet, chez ces sous-groupes de patients à haut risque de récidive ischémique, une réduction plus intensive du taux de cholestérol avec les inhibiteurs des PCSK-9 parait tout à fait justifiée, cependant nous avons montré que le coût de ces traitements excède la limite du rapport coût-efficacité généralement accepté tandis que le bénéfice d’une majoration du traitement antithrombotique semble contrebalancé par l’augmentation du risque hémorragique extracrânien. / The current long-term prognosis after transient ischaemic attack (TIA) or ischaemic stroke is not well known. I aimed to determine the long-term absolute residual risks of recurrent stroke and coronary events after TIA or ischaemic stroke and identify individuals who remain at high absolute risk of recurrent ischaemic events despite current secondary prevention management.In a population-based cohort of consecutive TIA or ischaemic stroke patients (OXVASC study, 2002-2014), the overall absolute risks of recurrent ischaemic stroke and coronary events after TIA/ischaemic stroke have decreased over the study period, and are likely to be explained by the improvement of secondary prevention over time. However, despite current secondary prevention, the subgroups of patients with prior coronary artery disease and those without prior coronary artery disease but with an Essen score of 4 remain at sufficiently high absolute risk of recurrent ischaemic events to justify more intensive treatment. Nevertheless, future secondary prevention therapies would need to achieve a substantial absolute risk reduction to outweigh increased side effects or cost compared to current therapies. Indeed, in these high-risk subgroups, more intensive lipid-lowering therapies might be justified, but we showed that the total cost of PCSK-9 inhibitors seems to exceed the generally accepted cost-effectiveness threshold while benefit from increased antithrombotic treatment might be offset by the higher risk of extracranial bleeding.

Zusammenfassung der Arbeit Dissertation zur Erlangung des akademischen Grades Dr. med. Zusammenhang zwischen dem sozioökonomischem Status und der Entwicklung akuter ST – Strecken – Elevations – Myokardinfarkte eingereicht von Susanne Seide, geb. Gärtner, 02.12.1979 in München angefertigt am Institut für Herz- und Kreislaufforschung des Klinikum Links der Weser Bremen Klinik für Kardiologie und Angiologie Senator Wessling Strasse 1 28277 Bremen Betreuer: Prof. Dr. med. Rainer Hambrecht eingereicht im Februar 2015 An der Entwicklung der koronaren Herzkrankheit und dem damit verbundenen Auftreten akuter ST – Strecken – Elevations – Myokardinfarkte sind neben klassischen Risikofaktoren wie Bluthochdruck, Rauchen, Diabetes mellitus, Übergewicht und Fettstoffwechselstörungen andere Faktoren, wie Alter, Geschlecht, Bewegungsmangel und der psychosoziale Status beteiligt. Frühere Untersuchungen haben darüber hinaus gezeigt, dass die Entwicklung kardiovaskulärer Erkrankungen in einem Zusammenhang mit dem sozioökonomischen Hintergrundes steht. Inwieweit die Zugehörigkeit zu einer bestimmten sozialen Schicht Einfluss auf die Infarktrate der Bremer Bevölkerung hat, und ob es Unterschiede im Risikoprofil, in der Behandlung und Prognose von Patienten aus unterschiedlichen sozialen Milieus gibt, sollte mit dieser Arbeit untersucht werden. Hierzu wurden Daten von 2062 Patienten aus dem STEMI Register des Herzzentrums Bremen ausgewertet. Die Patienten aus dem Stadtgebiet Bremen wurden anhand der Postleitzahl ihrer Heimatadresse einer von vier Gruppen zugeordnet. Hiernach wurde für sie ein hoher sozioökonomischer Status (G1), ein intermediär hoher sozioökonomischer Status (G2), ein intermediär niedrig sozioökonomischer Status (G3) oder ein niedriger sozioökonomischer Status (G4) ermittelt. Der sozioökonomische Status der jeweiligen Gruppe wurde mit Hilfe des so genannten „Bremer Benachteiligungsindexes“, einem Maß für die soziale Stellung eines Stadtteiles, und anhand von Einkommensstatistiken der Bremer Stadtteile bestimmt. Die vier Gruppen wurden hinsichtlich ihrer Infarktinzidenzen verglichen. Innerhalb der Patientengruppen wurden Baselinecharakteristika (Alter zum Infarktzeitpunkt, Geschlecht, Vorerkrankungen, kardiovaskuläre Risikofaktoren), Surrogat – Parameter der Krankheitsausprägung (Mehrgefäßerkrankung, hämodynamische Stabilität, linksventrikuläre Ejektionsfraktion nach Myokardinfarkt), und der Therapie (PTCA, ACVB – Operation, Door – to – balloon Zeiten und Medikamentengabe) sowie Prognosedaten (30 Tage – Mortalität, 5 Jahres – Überleben) erhoben und die Gruppen anhand dieser Ergebnisse miteinander verglichen. Die wesentlichen Ergebnisse lassen sich wie folgt zusammenfassen: ➢ Die alters- und geschlechtsadjustierte Inzidenz akuter transmuraler Myokardinfarkte war in den sozial benachteiligten Bremer Stadtteilen signifikant höher als in Stadtbezirken mit geringerer Benachteiligung (G1: 47 ± 5 STEMIs pro 100.000 Einwohner pro Jahr versus G4: 66 ± 5 STEMIs pro 100.000 Einwohner pro Jahr; p < 0,01). ➢ Insbesondere junge Menschen waren von diesem sozialen Abwärtsgradienten betroffen (18 – 49 Jahre RR G4 2,01 versus 65 – 79 Jahre RR G4: 1,39). ➢ Herzinfarktpatienten aus sozial benachteiligten Stadtteilen waren zum Infarktzeitpunkt signifikant jünger (G1: 67±13 Jahre versus G4: 63±13 Jahre; p = 0,026), häufiger Raucher (G1: 35,9% versus G4: 51,2%; p < 0,01) und übergewichtig (G1:.15,3% BMI > 30 kg/qm versus G4: 26,1% BMI > 30 kg/qm; p < 0,01). ➢ Bezüglich der Infarktschwere und der Therapie zeigten sich keine wesentlichen Unterschiede zwischen den Gruppen (Mehrgefäßerkrankung G1: 62,4% versus G4: 57,0%; p = 0,27; Killip – Stadium III/IV G1: 12,5% versus G4: 13,0%; p = 0,84; LVEF nach Myokardinfarkt < 30% G1: 6,0% versus G4: 7,6%; p = 0,4; primäre PTCA G1: 89,8% versus G4: 89,8%; p = 0,92; ACVB - Operation G1: 11,6% versus G4: 12,6%; p = 0,13; Door – to – balloon Zeit G1: 54±38 min. versus G4 52±41 min.; p = 0,74; ASS G1: 94,4% versus G4: 94,7%; p = 0,64; ADP – Antagonist G1: 90,0% versus G4: 93,8%;p = 0,23; Betablocker G1 82,8% versus G4 83,9%; p = 0,25; Statin G1: 85,8% versus G4: 86,4%; p = 0,97; ACE – Hemmer oder AT1 – Rezeptorantagonisten G1: 77,4% versus G4: 79,3%; p = 0,90). ➢ Die alters– und geschlechtsadjustierte inhospitale Mortalität war in allen Gruppen vergleichbar hoch (G1: 4,8% versus G4: 3,9%; p = 0,3), für Patienten aus den sozioökonomisch am stärksten benachteiligten Stadtgebieten zeigte sich aber ein starker Trend hin zu einem geringeren 5 Jahres – Überleben (G4 versus G1: HR 1,55, 95% KI 0,98-2,5, p = 0,067). Die Ergebnisse dieser Studie demonstrieren, dass das relative Risiko für einen ST – Strecken – Elevations – Myokardinfarkt mit abnehmendem sozioökonomischem Status der Bevölkerung steigt, und dass das kardiovaskuläre Risikoprofil von Patienten aus sozioökonomisch benachteiligten Stadtteilen ausgeprägter ist. Trotz gleicher Initialtherapie aller STEMI Patienten, unabhängig von der sozialen Herkunft, haben diejenigen aus sozioökonomisch benachteiligten Wohnbezirken eine deutlich schlechtere Prognose. Daher besteht unseres Erachtens vor allem in den sozioökonomisch benachteiligten Stadtteilen nicht nur in Bremen ein erhöhter Handlungsbedarf hinsichtlich konsequenter primär– und sekundärpräventiver Maßnahmen.

Bakgrund: En hjärtinfarkt är en irreversibel ischemisk skada i hjärtmuskeln orsakad av en ocklusion. I Sverige är hjärt- och kärlsjukdomar den största folksjukdomen och årligen drabbas cirka 26 400 människor, av de avlider ungefär 5 900. För att uppnå en god livskvalitet är aspekterna gemenskap, mening, trygg identitet och en känsla av glädje grundläggande. Syfte: Syftet var att beskriva hur patienter upplever sin livskvalitet efter en hjärtinfarkt. Metod: En allmän litteraturöversikt baserad på 13 studier med deskriptiv kvalitativ ansats. Studierna identifierades med hjälp av databasen PubMed och dess kvalitet granskades genom SBU:s (2014) granskningsmall. Resultat: Resultatet sammanställdes utifrån sju kategorier och fem subkategorier vilka beskrev att: Patienterna drabbades primärt av chock och en nära-döden-upplevelse som resulterade i tacksamhet över att leva. Oro, rädsla, osäkerhet, ångest, depression, bröstsmärta, andfåddhet och fatigue var vanliga psykologiska och fysiologiska följder som kom att påverka patienterna i det dagliga livet. Relationen till familjemedlemmar blev negativt påverkad och de kände sig socialt begränsade. För att klara av den förändrade livssituationen var stöd och bearbetning nödvändigt. I efterförloppet ledde händelsen till nya prioriteringar och en förändrad syn på livet. Slutsats: Efter en hjärtinfarkt påverkas livskvaliteten negativt ur ett socialt, psykologiskt, emotionellt, fysiologiskt och existentiellt perspektiv. Då människan dagligen begränsas samt ställs inför utmaningar och påfrestningar krävs det en stor ansträngning för att klara av och hantera det dagliga livet. Denna information kan tillsammans med vidare forskning kring området användas som grund för utökade riktlinjer. / Background: A myocardial infarction is an occlusion-caused, irreversible ischemic injury in the heart muscle. In Sweden cardiovascular disease is the largest public health disease and approximately 26 400 people suffer from a myocardial infarction annually, of which about 5 900 die. To achieve a good quality of life it’s fundamental to have community, meaning, a secure identity and a sense of joy. Aim: The aim was to describe how patients experience their quality of life after a myocardial infarction. Method: A general literature review of 13 studies with descriptive and qualitative approaches. The studies were identified using the PubMed database and their quality was assessed using the SBU (2014) review template. Results: The result was compiled on the basis of seven categories and five sub-categories which described that: Patients were primarily affected by shock and a near-death experience that resulted in a gratitude for being alive. Concerns, fears, insecurities, anxiety, depression, chest pain, shortness of breath and fatigue were common psychological and physiological consequences that affected the patients in their daily life. The relationship with family members was negatively affected and they felt socially restricted. In order to cope with the changed life situation, it was of the utmost importance to get support and to process the consequences of the disease. In the aftermath, the event led to new priorities and a changed view of life. Conclusion: A myocardial infarction affects the patient's quality of life in a negative way from a social, psychological, emotional, physiological and existential perspective. Mainly because they are limited and daily faced with challenges and stress, which means that a great deal of effort is required in order for them to be able to carry out and manage their daily life. This information can together with further research be used as a basis for extended guidelines.

Background: Histone deacetylases (HDACs) play a critical role in modulating myocardial protection and cardiomyocyte survivals. However, Specific HDAC isoforms in mediating myocardial ischemia/reperfusion injury remain currently unknown. We used cardiomyocyte-specific overexpression of active HDAC4 to determine the functional role of activated HDAC4 in regulating myocardial ischemia and reperfusion in isovolumetric perfused hearts. Methods: In this study, we created myocyte-specific active HDAC4 transgenic mice to examine the functional role of active HDAC4 in mediating myocardial I/R injury. Ventricular function was determined in the isovolumetric heart, and infarct size was determined using tetrazolium chloride staining. Results: Myocyte-specific overexpressing activated HDAC4 in mice promoted myocardial I/R injury, as indicated by the increases in infarct size and reduction of ventricular functional recovery following I/R injury. Notably, active HDAC4 overexpression led to an increase in LC-3 and active caspase 3 and decrease in SOD-1 in myocardium. Delivery of chemical HDAC inhibitor attenuated the detrimental effects of active HDAC4 on I/R injury, revealing the pivotal role of active HDAC4 in response to myocardial I/R injury. Conclusions: Taken together, these findings are the first to define that activated HDAC4 as a crucial regulator for myocardial ischemia and reperfusion injury.

Myocardium lacks the ability to regenerate following injury. This is in contrast to skeletal muscle (SKM), in which capacity for tissue repair is attributed to the presence of satellite cells. It was hypothesized that SKM satellite cells multiplied in vitro could be used to repair injured heart muscle. Fourteen dogs underwent explantation of the anterior tibialis muscle. Satellite cells were multiplied in vitro and their nuclei were labelled with tritiated thymidine 24 h prior to implantation. The same dogs were then subjected successfully to a myocardial injury by the application of a cryoprobe. The cells were suspended in serum-free growth medium and autotransplanted within the damaged muscle. Medium without cells was injected into an adjacent site to serve as a control. Endpoints comprised histology using standard stains as well as Masson trichrome (specific for connective tissue), and radioautography. In five dogs, satellite cell isolation, culture, and implantation were technically satisfactory. In three implanted dogs, specimens were taken within 6-8 wk. There were persistence of the implantation channels in the experimental sites when compared to the controls. Macroscopically, muscle tissue completely surrounded by scar tissue could be seen. Masson trichrome staining showed homogeneous scar in the control site, but not in the test site where a patch of muscle fibres containing intercalated discs (characteristic of myocardial tissue) was observed. In two other dogs, specimens were taken at 14 wk postimplantation. Muscle tissue could not be found. These preliminary results could be consistent with the hypothesis that SKM satellite cells can form neo-myocardium within an appropriate environment. Our specimens failed to demonstrate the presence of myocyte nuclei. It is therefore further hypothesized that in the late postoperative period, the muscle regenerate failed to survive.