Acute myocardial infarction and sudden death in Sioux Indians.

While some Indian tribes have low rates of acute myocardial infarction, Northern Plains Indians, including the Sioux, have rates of morbidity and mortality from acute myocardial infarction higher than those reported for the United States population in general. In a review of diagnosed cases of acute myocardial infarction over a 3-year period in 2 hospitals serving predominantly Sioux Indians, 8% of cases were found misclassified, and 22% failed to meet rigorous diagnostic criteria, although the patients did indeed have ischemic heart disease. Patients had high frequencies of complications and risk factors and a fatality rate of 16% within a month of admission. Sudden deaths likely due to ischemic heart disease but in persons not diagnosed as having acute myocardial infarction by chart review occurred 3 times more frequently than deaths occurring within a month of clinical diagnosis.     

F2-isoprostanes as an indicator and risk factor for coronary heart disease

Coronary heart disease (CHD) is the leading single cause of death in the United States and most Western countries, killing more than 400,000 Americans per year. Although CHD often manifests suddenly as a fatal myocardial infarction, the atherosclerosis that gives rise to the infarction develops gradually and can be markedly slowed or even reversed through pharmacological and lifestyle interventions. These same atherosclerotic processes also drive related vascular diseases such as stroke and peripheral artery disease, and individuals surviving occlusive events often develop additional complications including ischemic cardiomyopathy and heart failure. Therefore, better detection of subclinical atherosclerosis, along with more effective treatments, could significantly reduce the rate of death from CHD and related vascular diseases in the United States. In recent years, oxidation of polyunsaturated fatty acids (PUFAs) in plasma lipoproteins has been postulated to be a critical step in the development of atherosclerosis. If so, then monitoring lipid peroxidation should be a useful indicator of disease risk and progression. This review focuses on the evidence that specific PUFA peroxidation products, the F(2)-isoprostanes, are useful biomarkers that could potentially be utilized as indicators of CHD.     

Temporal Trends in Incidence of Myocardial Infarction and Ischemic Stroke by Socioeconomic Position in Sweden 1987–2010

Background

We analyzed temporal trends in the incidence of myocardial infarction and ischemic stroke in Sweden by socioeconomic position and investigated whether social inequalities in incidence of these diseases changed over time.

Materials and Methods

We studied a cohort of almost three million Swedish residents born between 1932 and 1960 followed from 1987 until 2010. Incident cases of myocardial infarction and ischemic stroke were identified in the Swedish National Inpatient Register and Cause of Death Register. Socioeconomic position was retrieved from the Population and Housing Censuses. Incidence rates of myocardial infarction and ischemic stroke and incidence rate ratios comparing levels of socioeconomic position were estimated using flexible parametric survival models adjusted for calendar year, attained age, sex, and birth country.

Results

The overall incidences of myocardial infarction and ischemic stroke decreased over time among men, but were stable over time among women. With regard to ischemic stroke incidence, socioeconomic inequality increased over time in the age group 55 to 59: the incidence rate ratios for low manual compared to high non-manual increased from 1.3 (95% CI: 1.2–1.4) in 1997 to 1.5 (1.4–1.7) in 2010 among men, and from 1.4 (1.3–1.6) in 1997 to 2.1 (1.8–2.5) in 2010 among women. The socioeconomic inequality in incidence of myocardial infarction was stable over time for both men and women.

Conclusion

There was a decrease in myocardial infarction and ischemic stroke incidence over time among men but no significant change for women. Our study highlights existing, and in some cases increasing, social inequalities in the incidence of cardiovascular diseases.     

Soluble ICAM-1: a marker of vascular inflammation and lifestyle

The circulating form of a membrane-bound intercellular adhesion molecule-1 (ICAM-1), has been the source of recent debate as a candidate marker of vascular inflammation in atherosclerosis and myocardial infarction, although its increased levels were also observed in other diseases affecting the cardiovascular system, such as myocarditis, inflammatory cardiomyopathy and heart failure per se. Faulty dietary habits, a sedentary mode of life, smoking, and alcohol abuse, are factors which at least in part contribute to atherosclerosis. This paper describes the responses of sICAM-1 levels to nutrients, physical activity, smoke exposure and alcohol consumption.     

Diabetes mellitus and cardiac function

Cardiovascular complications are the most common causes of morbidity and mortality in diabetic patients. Coronary atherosclerosis is enhanced in diabetics, whereas myocardial infarction represents 20% of deaths of diabetic subjects. Furthermore, re-infarction and heart failure are more common in the diabetics. Diabetic cardiomyopathy is characterized by an early diastolic dysfunction and a later systolic one, with intracellular retention of calcium and sodium and loss of potassium. In addition, diabetes mellitus accelerates the development of left ventricular hypertrophy in hypertensive patients and increases cardiovascular mortality and morbidity. Treating the cardiovascular problems in diabetics must be undertaken with caution. Special consideration must be given with respect to the ionic and metabolic changes associated with diabetes. For example, although ACE inhibitors and calcium channel blockers are suitable agents, potassium channel openers cause myocardial preconditioning and decrease the infarct size in animal models, but they inhibit the insulin release after glucose administration in healthy subjects. Furthermore, potassium channel blockers abolish myocardial preconditioning and increase infarct size in animal models, but they protect the heart from the fatal arrhytmias induced by ischemia and reperfusion which may be important in diabetes. For example, diabetic peripheral neuropathy usually presents with silent ischemia and infarction. Mechanistically, parasympathetic cardiac nerve dysfunction, expressed as increased resting heart rate and decreased respiratory variation in heart rate, is more frequent than the sympathetic cardiac nerve dysfunction expressed as a decrease in the heart rate rise during standing.     

Controlled trial of oxygen in uncomplicated myocardial infarction.

Two-hundred consecutive patients thought to have suffered a myocardial infarction were admitted to a randomised, double-blind controlled trial of oxygen or air administered by MC mask throughout the first 24 hours in hospital. Forty-three patients in whom myocardial infarction was not subsequently confirmed were excluded from the analysis. The remaining air and oxygen groups were comparable except for a significantly higher PaO2 and serum aspartate aminotransferase level in the oxygen group. There was no significant difference in mortality, incidence of arrhythmias, use of analgesics, or systolic time intervals between the two groups, although a higher incidence of sinus tachycardia was found in those given oxygen. There appears to be no evidence of benefit from the routine administration of oxygen in uncomplicated myocardial infarction.     

心血管危重症继发交感风暴37例临床分析

目的:探讨心血管危重症继发交感风暴的病因分布特点和治疗方法。方法:回顾性分析我院2001年-2011年37例心血管危重症继发交感风暴临床资料。结果:37例心血管危重症继发交感风暴患者,其中男性22例,女性15例,年龄55-82岁,平均68.25岁。病因分布为:心肌梗死29例,心衰3例,扩张性心肌病2例,电解质紊乱2例,Brugada综合征1例。治疗方法包括β受体阻滞剂、胺碘酮、利多卡因、电除颤等。其中,17例因反复发作室颤,经抗心律失常药物和电除颤治疗无效死亡,余20例病情得到控制。结论:心血管危重症继发交感风暴临床病因多样,病情凶险,应用β受体阻滞剂及抗心律失常药物,同时积极针对病因及诱因治疗,可以改善临床症状和预后。     

Unexpected sudden death due to recreational swimming and diving in men in Croatia in a 14-year period

The article deals with 17 sudden deaths which occurred during recreational swimming and diving in men in Croatia in a 14-year period: from January 1, 1998 to December 31, 2011. The sample is taken out from the total number of 61 sudden deaths in men during or immediately after sport or recreational exercise. Included are also sudden deaths of 8 foreigners spending holidays at the Croatian Adriatic Coast. In all of them forensic medicine autopsy was done. Thirteen males from Croatia died during recreational swimming. Three of them were aged 15-29 yrs: one had signs of hypertrophic cardiomyopathy, the second suffered from chronic myopericarditis with left ventricular aneurysm, and the third had cardiomegaly and blood alcohol level of 1.7 per thousand. Five were aged 30-64 yrs: four of them have suffered from coronary atherosclerosis and left ventricular hypertrophy of 15-18-18-22 mm, and one with left ventricular hypertrophy drowned suddenly, probably because of malignant ventricular arrhythmia. The fifth suffered stroke and drowned. Five elderly men, aged 65-85 yrs, have suffered from coronary atherosclerosis, myocardial fibrosis or myocardial scars, and three of them had left ventricular hypertrophy of 19 mm. Four males died during recreational diving. One aged 26yrs drowned, at autopsy he had left ventricular hypertrophy of 17 mm. Three males were middle-aged: two had coronary atherosclerosis, two of them had a severe degree of coronary atherosclerosis and one had coronary atherosclerosis of medium degree but with myocardial fibrosis and left ventricular hypertrophy of 18 mm. Seven male foreigners died, five of them during swimming: two aged 30-64 and two aged 65-85. They all have had coronary atherosclerosis: one of them had an acute myocardial infarction of the posterior wall, and one hypertrophic cardiomyopathy as well. One middle-aged and one elderly man died during diving, and both had an acute myocardial infarction of the posterior wall. One elderly foreign woman died during swimming, she had coronary atherosclerosis and a myocardial scar. In Croatia, death rate during both swimming and diving in men aged 15-29 years amounted to 0.63/1,000.000 (p=1.0000); in those aged 30-64 it reached 0.56/1,000.000 (p=0.3698), and in those aged 65-85 it was 1.41/1,000.000 (p=0.1849). The death rate during swimming in men aged 15-29 amounted to 1.47/1,000.000 (p=0.9864), in men aged 30-64 it reached 0.35/1,000.000 (p=0.2245), and in those aged 65-85 it was 1.41/1,000.000 (the difference is significant, p=0.0472). The death rate during diving in men aged 15-29 was 0.16/1,000.000, and in men aged 30-64 the observed rate was 0.21/1,000.000 (p=1.0000).     

高龄（80-89 岁）非ST 段抬高心肌梗死早期 介入治疗的疗效观察

目的:研究调查高龄(80-89岁)非ST段抬高心肌梗死(non-ST-segment elevation myocardial infarction,NSTEMI)患者行早期经皮冠状动脉介入治疗(percutaneous coronary intervention,PCI)的有效性。方法:回顾分析2008年8月-2009年10月期间我院住院的66例80-89岁NSTEMI患者,冠状动脉造影检查后45例行PCI术,5例因为左主干病变或者严重的三支病变行冠脉搭桥(CABG)术,其余16例做保守治疗。发病到行介入治疗时间<72h。结果:45例行PCI术中42例成功,再血管化的成功率为63.6%,失败的3例PCI术病人中2例因导丝或球囊未能通过病变,1例为顽固性室速。共植入支架80枚,术后梗死相关动脉血流均达到TIMI2-3级。术后死亡2例(心源性休克、颅内出血各1例),死亡率为4.8%。住院期间出血并发症较高,有4(9.5%)例(穿刺部位血肿2例,消化道、颅内出血各1例)。住院期间无再发心肌梗死,偶发心绞痛2例。结论:穿刺尽管高龄(80-89岁)非ST段抬高心肌梗死冠脉早期介入主要出血事件较多,但可改善住院期间的预后。     

Establishment of a Novel Murine Model of Ischemic Cardiomyopathy with Multiple Diffuse Coronary Lesions

Objectives

Atherosclerotic lesions of the coronary arteries are the pathological basis for myocardial infarction and ischemic cardiomyopathy. Progression of heart failure after myocardial infarction is associated with cardiac remodeling, which has been studied by means of coronary ligation in mice. However, this ligation model requires excellent techniques. Recently, a new murine model, HypoE mouse was reported to exhibit atherogenic Paigen diet-induced coronary atherosclerosis and myocardial infarction; however, the HypoE mice died too early to make possible investigation of cardiac remodeling. Therefore, we aimed to modify the HypoE mouse model to establish a novel model for ischemic cardiomyopathy caused by atherosclerotic lesions, which the ligation model does not exhibit.

Methods and Results

In our study, the sustained Paigen diet for the HypoE mice was shortened to 7 or 10 days, allowing the mice to survive longer. The 7-day Paigen diet intervention starting when the mice were 8 weeks old was adequate to permit the mice to survive myocardial infarction. Our murine model, called the “modified HypoE mouse”, was maintained until 8 weeks, with a median survival period of 36 days, after the dietary intervention (male, n = 222). Echocardiography demonstrated that the fractional shortening 2 weeks after the Paigen diet (n = 14) significantly decreased compared with that just before the Paigen diet (n = 6) (31.4±11.9% vs. 54.4±2.6%, respectively, P<0.01). Coronary angiography revealed multiple diffuse lesions. Cardiac remodeling and fibrosis were identified by serial analyses of cardiac morphological features and mRNA expression levels in tissue factors such as MMP-2, MMP-9, TIMP-1, collagen-1, and TGF-β.

Conclusion

Modified HypoE mice are a suitable model for ischemic cardiomyopathy with multiple diffuse lesions and may be considered as a novel and convenient model for investigations of cardiac remodeling on a highly atherogenic background.     

Pregnancy-related myocardial infarction

Introduction

The risk of acute myocardial infarction in young women is low, but increases during pregnancy due to the physiological changes in pregnancy, including hypercoagulability. Ischaemic heart disease during pregnancy is not only associated with increased maternal morbidity and mortality, but also with high neonatal complications. Advancing maternal age and other risk factors for cardiovascular diseases may further increase the risk of ischaemic heart disease in young women.

Methods

We searched the coronary angiography database of a Dutch teaching hospital to identify women with acute myocardial infarction who presented during pregnancy or postpartum between 2011 and 2013.

Results

We found two cases. Both women were in their early thirties and both suffered from myocardial infarction in the postpartum period. Acute myocardial infarction was due to coronary stenotic occlusion in one patient and due to coronary artery dissection in the other patient. Coronary artery dissection is a relatively frequent cause of myocardial infarction during pregnancy. Both women were treated by percutaneous coronary intervention and survived.

Conclusion

Physicians should be aware of the increased risk of myocardial infarction when encountering pregnant or postpartum women presenting with chest pain.

     

Serum levels of the MCP-1 chemokine in patients with ischemic stroke and myocardial infarction

Chemokine-driven migration of inflammatory cells has been implicated in pathogenesis of atherosclerosis-associated conditions such as ischemic stroke and myocardial infarction. In this study, a candidate chemokine, monocyte chemoattractant protein (MCP)-1, was investigated in patients with both aforementioned manifestations of atheroslerotic inflammation. MCP-1 levels in serum were determined by ELISA in 40 healthy, control subjects (C), 40 patients with ischemic stroke (IS), and in 64 patients with myocardial infarction (MI). Statistical analysis utilised Mann-Whitney test, Fisher's exact test, and Spearman's rank correlation (P < .05). In comparison to control subjects (C; median/interquartile range: 239/126 pg/mL), MCP-1 serum levels were increased in both investigated patient cohorts (IS: 384/370, P < .001; MI: 360/200, P < .002). There was a substantial variability of MCP-1 serum levels, especially in the IS group. No relationship was observed between chemokine levels and atherosclerosis risk factors (hypertension, diabetes, smoking, and alcohol consumption), and MCP-1 was also not related to age or gender. Elevation of MCP-1 in circulation of patients with atherosclerosis-associated complications implicates this CC chemokine ligand (CCL)2 in inflammatory processes, which contribute to pathogenesis of myocardial infarction and ischemic stroke. Further investigations, including patient stratification, are however necessary to evaluate if MCP-1 can be utilised for clinical management of patients with these diseases.     

Changes of adrenomedullin and receptor activity modifying protein 2 (RAMP2) in myocardium and aorta in rats with isoproterenol-induced myocardial ischemia

Adrenomedullin is a potent vasodilator peptide originally isolated from a pheochromocytoma. Recently, a novel adrenomedullin receptor has been identified as a complex of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 2 (RAMP2). To explore the pathophysiological roles of adrenomedullin and its receptor component RAMP2 in ischemic cardiovascular diseases, we studied the changes of adrenomedullin and RAMP2 mRNA in myocardium and aorta in rats with isoproterenol (ISO)-induced myocardial impairment. In ISO-treated rats, heart became enlarged markedly, the ratio of heart to body weight was increased by 54% (P<0.01), and myocardial malondialdehyde content and plasma lactate dehydrogenase activity was elevated by 43% (P<0.01) and 138% (P<0.01), respectively. Immunoreactive adrenomedullin (ADM) in plasma, myocardium and aorta was augmented by 116.7% (P<0.01), 50.8% (P<0.01) and 12.5% (P>0.05), respectively. ADM mRNA in myocardium and aorta was increased by 96.8% (P<0.01) and 38.5% (P<0.01), respectively. RAMP2 mRNA in myocardium and aorta was increased by 19.6% (P<0.05) and 15.8% (P<0.01), respectively. These results suggest that the increase of ADM level and the up-regulation of ADM and RAMP2 gene in myocardium and aorta may be significant in the pathogenesis of ischemic myocardiopathy.     

Postmortem mRNA Expression Patterns in Left Ventricular Myocardial Tissues and Their Implications for Forensic Diagnosis of Sudden Cardiac Death

Sudden cardiac death (SCD), which is primarily caused by lethal heart disorders resulting in structural and arrhythmogenic abnormalities, is one of the prevalent modes of death in most developed countries. Myocardial ischemia, mainly due to coronary artery disease, is the most common type of heart disease leading to SCD. However, postmortem diagnosis of SCD is frequently complicated by obscure histological evidence. Here, we show that certain mRNA species, namely those encoding hemoglobin A1/2 and B (Hba1/2 and Hbb, respectively) as well as pyruvate dehydrogenase kinase 4 (Pdk4), exhibit distinct postmortem expression patterns in the left ventricular free wall of SCD subjects when compared with their expression patterns in the corresponding tissues from control subjects with non-cardiac causes of death. Hba1/2 and Hbb mRNA expression levels were higher in ischemic SCD cases with acute myocardial infarction or ischemic heart disease without recent infarction, and even in cardiac death subjects without apparent pathological signs of heart injuries, than control subjects. By contrast, Pdk4 mRNA was expressed at lower levels in SCD subjects. In conclusion, we found that altered myocardial Hba1/2, Hbb, and Pdk4 mRNA expression patterns can be employed as molecular signatures of fatal cardiac dysfunction to forensically implicate SCD as the primary cause of death.     

Catecholamine-Induced Cardiomyopathy

ObjectiveTo review the pathogenesis as well as the clinical and laboratory features of catecholamine-induced cardiomyopathy associated with pheochromocytoma and other disorders and discuss the various treatment options available.MethodsMaterials used for this article were identified through MEDLINE, PubMed, and Google Scholar searches of the relevant literature from 1955 to the present.ResultsCatecholamines and their oxidation products cause a direct toxic effect on the myocardium. Catecholamines also exert a receptor-mediated effect on the myocardium. Catecholamine-mediated myocardial stunning has been implicated in the pathogenesis of stressinduced cardiomyopathy. Biopsy of the myocardium in patients with pheochromocytoma or those with stressinduced cardiomyopathy shows similar pathologic findings. The clinical features in pheochromocytoma-related cardiomyopathy include hypertension, dilated or hypertrophic cardiomyopathy, pulmonary edema due to cardiogenic and noncardiogenic factors, cardiac arrhythmias, and even cardiac arrest. Stress-related cardiomyopathy such as takotsubo cardiomyopathy occurs primarily in postmenopausal women. These patients may present with clinical features suggestive of an acute myocardial infarction or a hemodynamically compromised state. The definitive management of cardiomyopathy associated with pheochromocytoma includes medical treatment with α-adrenergic blockade, possibly along with angiotensinconverting enzyme blockers and β₁-adrenergic receptor blockers, followed by excision of the tumor. Stressinduced cardiomyopathy is usually self-limiting; patients may require support with nonadrenergic inotropes.ConclusionRecognition of catecholamine-induced cardiomyopathy, especially in patients with pheochromocytoma, before surgical treatment is important to minimize morbidity and mortality. (Endocr Pract. 2008;14:1137- 1149)     

Effect of repaglinide on endothelial dysfunction during a glucose tolerance test in subjects with impaired glucose tolerance

Background

Secondary treatment of arteriosclerosis may be applicable for the primary prevention of atherosclerosis in diabetic patients. This prospective, 2-year follow-up study was designed to determine the efficacy and safety of antiplatelet therapy in the prevention of atherosclerosis of diabetic subjects.

Methods

Patients with type 2 diabetes and arteriosclerosis obliterans from the Eastern Asian countries were registered online and randomly assigned either to the aspirin group (81–100 mg/day) or the cilostazol group (100–200 mg/day) in this international, 2-year, prospective follow-up interventional study.

Results

The primary study endpoint was changes in right and left maximum intima-media thickness of the common carotid artery. Secondary endpoints include changes in right and left maximum intima-media thickness of the internal carotid artery; semiquantitative evaluation of cerebral infarction by magnetic resonance imaging; cardiovascular events including sudden death, stroke, transient cerebral ischemic attacks, acute myocardial infarction, angina, and progression of arteriosclerosis obliterans; overall death; withdrawal; and change in ankle-brachial pressure index.

Conclusion

This is the first study to use an online system that was developed in Asian countries for pooling data from an international clinical trial. These findings are expected to help in the prevention of diabetic atherosclerosis and subsequent cardiovascular and cerebrovascular disease.     

Cholera toxin enhances ischemia-induced arrhythmias in the isolated rat heart--involvement of a guanine nucleotide binding protein (Gs)

Cholera toxin (CTX) at a dose, which disturbed the intestinal functions, was administered into the rat via the tail vein. At 3 hr after injection, the heart was removed and perfused or subject to global ischemia in the Langendorff isolated heart preparation. Electrocardiogram (ECG) was recorded throughout the experiment. The myocardial cAMP content was measured in the intact non-ischemic heart, and in the isolated ischemic heart at 2.5, 5 and 10 min after ischemia. It was found that the incidence and severity of malignant ventricular arrhythmias including ventricular tachycardia (VT) and ventricular fibrillation (VF) was significantly increased during ischemia in the CTX treated group. The cAMP content was also significantly increased in the CTX treated group in both intact non-ischemic and ischemic hearts, indicating an activation of the guanine nucleotide regulatory protein (Gs). The results of the present study provide evidence that activation of Gs during ischemia may also contribute to the genesis of arrhythmia.     

Perception of arterial hypertension and myocardial infarction in hypertensive and normotensive men and women

The research aims were to test perception of arterial hypertension and myocardial infarction in hypertensive and normotensive men and women as well as to test perception of arterial hypertension and myocardial infarction as predictors of blood pressure control in hypertensives. In the research 470 subjects of 4 general practices from Rijeka, Croatia participated, hypertensive group from the list of hypertensive patients without cardiovascular complications and other major chronic conditions, normotensive group from the list of patients without chronic conditions. Each group had 235 subjects, 128 men and 107 women. Perception of hypertension and myocardial infarction was measured as the result on semantic differential questionnaire. Factor analysis extracted evaluation, potency and activity factor. Blood pressure control was interpreteted on the five degrees scale. Statistical significance was defined under 5% (p < 0.05). Hypertensive subjects perceived hypertension as less negative and more active, while myocardial infarction was perceived as more potent term than by normotensives. Women perceived myocardial infarction as less negative, and less potent term than men. Both groups perceived myocardial infarction as more negative, potent and active term than hypertension. Normotensive women evaluated hypertension as more negative, and perceived myocardial infarction as less potent than other subjects. Well-controlled hypertension was correlated with a lower potency of hypertension and lower activity of myocardial infarction. Both conditions are perceived as more "male" diseases. As perception of hypertension and myocardial infarction is correlated with blood pressure regulation in hypertensives, and hypertension is major risk factor for myocardial infarction, family doctors should put additional effort in changing perception of cardiovascular diseases in their patients, especially in women.     

急性下壁心肌梗死急诊PCI术中应用临时起搏器与阿托品的对比研究

目的：探讨临时起搏器与阿托品在急性下壁心肌梗死急诊经皮冠状动脉介入治疗（PCI）中应用的疗效。方法：入选2012 年2 月至2013 年8 月我院收治的发病12 小时内,诊断为急性下壁心肌梗死并接受急诊PCI治疗的患者92 例,依据治疗方法的不同 将病例分为临时起搏组和阿托品组,并对病例进行为期一年的追踪随访,收集患者平均住院天数、平均住院费用、再灌注心律失 常、心肌梗死后心绞痛、心肌梗死后心衰发生率资料。结果：临时起搏组的平均住院天数、平均住院费用、心肌梗死后心绞痛、心肌 梗死后心衰发生率均显著低于阿托品治疗组（P 均<0.05）,阿托品治疗组的再灌注心律失常发生率则明显低于临时起搏组（P<0. 05）。结论：急性下壁心肌梗死急诊PCI中应用临时起搏器,具有治疗成本低,降低心血管事件发生率的优点,而阿托品治疗在改 善再灌注心律失常的疗效上则显著优于临时起搏治疗。