围术期心肌缺血和心肌梗死研究进展

背景 围术期多种因素可能导致心肌缺血和心肌梗死,了解其发生机制,有效预防,可降低围术期心脏事件发生率.目的 探讨围术期心肌缺血和心肌梗死的发生机制及有效预防措施.内窖冠状动脉粥样硬化后冠脉内皮对交感神经、副交感神经兴奋的反应性发生改变以及围术期特殊的病理生理状态是围术期心肌缺血和心肌梗死发生的主要机制.对于冠心病患者加...     

远程预缺血的心肌保护机制

Remote myocardial preconditioning can protect myocardiuln. Some bioactive substances released from noncardiac tissues which suffer from ischemia and reperfusion protects the heart by neuronal and humoral paths. Preconditioning at a distance can attenuate myocardial intracellular acidosis and Ca^2＋ overload, reduce neutrophil and platelet infiltration, protect mitochondrial function and reduce free radicals. This method is simple to apply and have some clinical value. In order to safely apply this method to clinic, a further study on the remote myocardial preconditioning and its mechanism is necessary.     

围术期心肌缺血和心肌梗死研究进展

背景 围术期多种因素可能导致心肌缺血和心肌梗死,了解其发生机制,有效预防,可降低围术期心脏事件发生率.目的 探讨围术期心肌缺血和心肌梗死的发生机制及有效预防措施.内窖冠状动脉粥样硬化后冠脉内皮对交感神经、副交感神经兴奋的反应性发生改变以及围术期特殊的病理生理状态是围术期心肌缺血和心肌梗死发生的主要机制.对于冠心病患者加强围术期心肌缺血和心肌梗死的监测与诊断,加强围术期药物治疗维持斑块稳定性、维持氧供需平衡,并完善术后镇痛、加强保温、避免血糖过高可减少围术期心肌缺血和心肌梗死的发生.趋向 冠心病患者非心脏手术前常规预防性药物的治疗时间与获益的关系以及术前冠脉重建的价值尚需进一步探讨.     

Three-dimension structure of ventricular myocardial fibers after myocardial infarction

Background  

To explore the pathological changes of three-dimension structure of ventricular myocardial fibers after anterior myocardial infarction in dog heart.     

Traumatic myocardial dysfunction

Traumatic myocardial dysfunction is a frequently unsuspected, undiagnosed contributor to deaths from trauma. Electrocardiography, serum enzymes, and radionuclide myocardial scans are insensitive indicators of cardiac injury following blunt chest trauma. First-pass biventricular radionuclide angiography can accurately determine right and left ventricular ejection fractions and assess left ventricular segmental wall motion. Since August, 1980, we have evaluated 74 consecutive patients with blunt chest and multisystem trauma. Electrocardiograms and measurements of the myocardial band isoenzyme of creatine kinase were obtained at admission and repeated at 24 hour intervals for 3 days. Radionuclide angiography was performed 24 to 48 hours after admission. The electrocardiogram was abnormal in 21 patients (28%), levels of creatine kinase isoenzyme were elevated in six, and radionuclide angiographic abnormalities were present in 55 patients (74%). Electrocardiographic abnormalities correlated anatomically with angiographic abnormalities in 16 patients (76%). On follow-up radionuclide angiography, abnormalities had disappeared in nine of 12 patients restudied at 3 weeks. This study documents that the electrocardiogram and creatine kinase isoenzyme elevations are static, insensitive indicators of traumatic myocardial dysfunction. Radionuclide angiography with studies of left ventricular segmental wall motion demonstrate that traumatic myocardial dysfunction, although sometimes transitory, is a dynamic phenomenon that is more common than previously suspected. First-pass radionuclide angiography and wall motion studies are practical and valuable adjuncts to the management of the injured patient.     

Uneven myocardial hypothermia among cardiac chambers during hypothermic myocardial preservation

During the development of methods to protect the heart from ischaemic injury, attention has been focused on protection of the left ventricle. In an attempt to assess right heart preservation. 55 consecutive patients undergoing open heart surgery were studied. Mean aortic cross-clamp time was 59.3 +/- 29.4 min. Temperature probes were inserted into the right atrium (RA), right ventricle (RV), and left ventricle (LV). During cardioplegia, the mean myocardial temperatures of RA, RV and LV were 19.1 degrees +/- 4.1 degrees C, 12.7 degrees +/- 4.8 degrees C and 7.3 degrees +/- 3.4 degrees C, respectively. Of the LV temperature measurements, 67.2% were 10 degrees C or lower. By contrast, 94.1% of RA measurements and 58.5% of RV measurements were above 10 degrees C. The inhomogeneity of chamber temperatures was observed irrespective of the patient's disease or age and whether the atrium or right ventricle were open or not. Hearts with mitral regurgitation (MR), in contrast to mitral stenosis and stenoinsufficiency, had higher LV temperatures, similar to those in the RV. We conclude that there is uneven hypothermia among the three cardiac chambers during hypothermic cardioplegic arrest, regardless of disease states except MR and regardless of age and procedure performed.     

Does perioperative myocardial ischemia lead to postoperative myocardial infarction?

To determine if a relationship exists between perioperative myocardial ischemia (ST segment depression greater than or equal to 0.1 mV) and postoperative myocardial infarction (PMI), nonparticipating observers recorded all ECG, hemodynamic, and other events between arrival of patients in the operating room and onset of cardiopulmonary bypass during 1,023 elective coronary artery bypass operations (CABG). The roles of preoperative patient characteristics, quality of the operation limited by disease as rated by the surgeon and duration of ischemic cardiac arrest as risk factors for PMI also were quantified. ECG ischemia occurred in 36.9% of all patients, with almost half the episodes occurring before induction of anesthesia. PMI was almost three times as frequent in patients with ischemia (6.9% vs. 2.5%) and was independent of when ischemia occurred. Ischemia was related significantly to tachycardia but not hypertension nor hypotension and was frequent in the absence of any hemodynamic abnormalities. The anesthesiologist whose patients had the highest rate of tachycardia and ischemia had the highest rate of PMI. Although neither single nor multiple preoperative patient characteristics related to PMI, suboptimal quality of operation and prolonged ischemic cardiac arrest increased the likelihood of PMI independent of the occurrence of myocardial ischemia. The authors conclude that perioperative myocardial ischemia is common in patients undergoing CABG, occurs randomly as well as in response to hemodynamic abnormalities, and is one of three independent risk factors the authors identified as related to PMI. PMI is unrelated to preoperative patient characteristics such as ejection fraction and left main coronary artery disease, and its frequency will relate primarily to perioperative management rather than patient selection.     

Perioperative myocardial ischaemia

Canadian Journal of Anesthesia/Journal canadien d'anesthésie - Techniques which detect the mechanical and electrical manifestations of ischaemia are defining the incidence and temporal...     

Laser myocardial revascularization

A significant number of patients with ischemic heart disease are not candidates for coronary artery bypass or percutaneous transluminal angioplasty and do not respond to medical management. This group includes those who have diffuse coronary artery disease, those with poor ventricular function, and those who have had poor results from previous surgery. Developing a method to directly revascularize the myocardium by creating channels through the ventricular wall has challenged many investigators. Early methods, including needle acupuncture, were successful in the acute phase, but long-term patency could not be achieved. Closure of the channels was due to fibrosis and scarring. Experiments in our laboratory demonstrated that myocardial channels, made with the CO2 laser, remained patent up to five years. Histopathologic examination of the channels showed minimal damage to the surrounding cells in the acute phase. Studies at intervals of two months to two years showed patent endothelialized channels, with no evidence of fibrosis. Channels created in the myocardium protected the ventricle against an ischemic event when the left anterior descending branch of the coronary artery was ligated. Clinical experience with direct myocardial revascularization by CO2 laser indicates it may be a viable method of treating those patients with ischemic heart disease who are not candidates for other forms of management. The treatment and early postoperative follow-up in one patient are described.     

Metastatic myocardial calcification

A case of metastatic myocardial calcification is reported in a patient with chronic renal failure. The characteristic features are failure to take phosphate-binding antacids on a regular basis, intractable congestive heart failure, atrioventricular block, a calcium phosphate product consistently greater than 60, and sudden irreversible cardiac arrest. Arteriovenous fistulae created for haemodialysis appear to be an unlikely cause of cardiac failure.     

Hybrid myocardial revascularization

Background

In patients with advanced coronary artery disease (CAD), coronary artery bypass grafting (CABG) is associated with improved long-term outcomes while percutaneous coronary intervention (PCI) is associated with lower periprocedural complications. A new approach has emerged in the last decade that attempts to reap the benefits of bypass surgery and stenting while minimizing the shortcomings of each approach, hybrid myocardial revascularization (HMR).Three strategies for timing of the hybrid revascularization exists, each with their own inherent advantages and shortcomings: (1) CABG followed by PCI, (2) PCI followed by CABG, or (3) simultaneous CABG + PCI in a hybrid suite.

Studies

The results of the first randomized control trial comparing HMR (CABG first) and standard CABG, POL-MIDES (Prospective Randomized PilOt Study EvaLuating the Safety and Efficacy of Hybrid Revascularization in MultIvessel Coronary Artery DisEaSe), show HMR was feasible for 93.9% of patients whereas conversion to standard CABG was required for 6.1%. At 1 year, both groups had similar all-cause mortality (CABG 2.9% vs. HMR 2%) and major adverse clinical event (MACE)-free survival rates (CABG 92.2% vs. HMR 89.8%). Results of observational and comparative studies show that minimally invasive HMR procedures in patients with multivessel CAD carry minimal perioperative mortality risk and low morbidity and do not increase the risk of postoperative bleeding. The advantage they offer in comparison to classical surgical revascularization is indeed faster rehabilitation and patient’s return to normal life.

Conclusion

Hybrid myocardial revascularization has been developed as a promising technique for the treatment of high-risk patients with CAD. Hybrid revascularization using minimally invasive surgical techniques combined with PCI offers to a part of patients an advantage of optimal revascularization of the most important artery of the heart, together with adequate myocardial revascularization in a relatively delicate way. Indeed, to patients with high operative risk of standard surgery, it offers an alternative which should be considered carefully.