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Anesthetic Outcome and Cardiopulmonary Resuscitation
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Myocardial stunning, a reversible phenomenon that happens early after global myocardial ischemia in which left and right ventricular ejection fractions decrease and end diastolic pressure increases, may contribute to the hemodynamic dysfunction. Patients suffering from this generally respond to inotropic therapy.
Anesthesia for Minimally Invasive Cardiac Surgery
Published in Theo Kofidis, Minimally Invasive Cardiac Surgery, 2021
Ti Lian Kah, Sophia Ang Bee Leng, Wei Zhang, Lalitha Manickam, Jai Ajitchandra Sule
The period of one-lung ventilation for hemostasis may be challenging. One-lung ventilation for MICS markedly reduces the PaO2/FiO2 ratio after termination of CPB [10]. Atelectasis, mechanotrauma from lung retraction and biotrauma from the inflammatory response to cardiopulmonary bypass all contribute to ventilation-perfusion imbalance, leading to desaturation [11]. The supine or minimally rotated position of the patient also accelerates the desaturation effect of one-lung ventilation. Acidosis, hypoxia and hypercarbia contribute to pulmonary hypertension and right heart strain. Myocardial stunning adds to right heart failure.
Biochemistry of Exercise Training and Mitigation of Cardiovascular Disease
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
Barry A. Franklin, John C. Quindry
Ischemic injury of the myocardium reflects the convergence of two fundamental tenets of cardiac physiology: (1) it is biologically necessary for the heart to beat continuously and (2) even a momentary oxygen supply–demand mismatch may be deleterious to the preservation of cardiac structure and function. The magnitude of the ischemic insult accrues in a time-dependent manner, and the injury process is evolutionary in nature (79). Upon a sufficiently reduced or occluded blood flow to a portion of the left ventricle, the earliest manifestation (1–5 minutes) of a supply–demand mismatch involves electrical abnormalities that are readily identifiable on an electrocardiogram (ECG). As the ischemic duration exceeds ∼5 minutes, the heart exhibits a temporary loss in ventricular contractility called myocardial stunning. Individual symptomology of myocardial stunning is highly variable, but may include light-headedness and fainting. Importantly, the ventricular arrhythmias and myocardial stunning that occur during the early phases of an ischemic cardiac event are considered reversible with appropriate medical attention, including restoration of coronary blood flow (e.g., emergent coronary revascularization). After ∼20 minutes, however, unremitting cardiac ischemia is marked by myocardial infarction and tissue death (25).
Complications associated with myocardial bridging in four children without underlying cardiac disease: a case series
Published in Paediatrics and International Child Health, 2021
Federica Brancato, Donato Rigante, Marco Piastra, Alessandro Gambacorta, Claudia Aurilia, Gabriella De Rosa
One of the most important triggers of symptomatic MB is intense physical activity which through tachycardia and increased contractility can facilitate myocardial ischaemia. During tachycardia, systole occupies a greater proportion of the cardiac cycle because of shortening of the diastolic filling period. Other pathophysiological factors that might reveal or exacerbate MB are age, left ventricular hypertrophy and coronary atherosclerosis, since all of these may worsen the supply-demand mismatch imposed by the bridge, reducing the coronary reserve [15]. Symptomatic patients may also present with clinical manifestations of myocardial ischaemia such as acute coronary syndrome, coronary spasm, exercise-induced dysrhythmias, myocardial stunning, transient ventricular dysfunction and syncope [15]. Only patients with symptomatic MB or those with objective signs of ischaemia require treatment. In most cases, beta-blockers, ivabradine and calcium channel blockers are effective in reducing symptoms [15]. In adults, myotomy, coronary artery by-pass surgery and stenting may be used to improve symptoms in patients with MB who are refractory to medical therapy [2,20,22,23]. MB is diagnosed by coronary or CT angiography, but it is sometimes established intra-operatively or at post-mortem examination. Another relevant diagnostic test is the stress ECG: the main objective of stress testing for myocardial ischaemia is to demonstrate the mismatch between myocardial oxygen demand and myocardial perfusion [22].
Survival and Rearrest in out-of-Hospital Cardiac Arrest Patients with Prehospital Return of Spontaneous Circulation: A Prospective Multi-Regional Observational Study
Published in Prehospital Emergency Care, 2021
Jae-Hyug Woo, Jin-Seong Cho, Choung Ah Lee, Gi Woon Kim, Yu Jin Kim, Hyung Jun Moon, Yong Jin Park, Kyoung Mi Lee, Won Jung Jeong, Il Kug Choi, Han Joo Choi, Hyuk Joong Choi
In addition to the occurrence of a more serious cardiac ischemia, more severe ischemic injuries to endocrine organs or target organs of catecholamines might induce more frequent rearrest. In our study, patients who experienced rearrest had lower blood pressure and slower heart rate after prehospital ROSC; moreover, non-survivors after rearrest also showed similar trends in blood pressure and heart rate. Although this hemodynamic instability might be caused by myocardial stunning, it may also occur from impaired function of target organs of catecholamines. In previous studies, after cardiac arrest, patients with relative adrenal insufficiency had poor outcomes and dogs with poor outcomes showed little response to exogenous catecholamines (14, 15). For the same reason, the rearrest (+) group that had a relatively poorer outcome might show this hemodynamic instability. As no previous study has evaluated the association between endocrinologic disturbance and the occurrence of rearrest, further studies are warranted.
High ultrafiltration rate induced intradialytic hypotension is a predictor for cardiac remodeling: a 5-year cohort study
Published in Renal Failure, 2021
Jinbo Yu, Xiaohong Chen, Yang Li, Yaqiong Wang, Zhonghua Liu, Bo Shen, Jie Teng, Jianzhou Zou, Xiaoqiang Ding
It is commonly recognized that the process of HD itself causes myocardial ischemia. IDH refers to intradialytic hemodynamic instability, linked to episodic myocardial stunning [22,23]. Repeated cardiac ischemia can result in myocardial hypertrophy and fibrosis, reduce the response to filling pressure, and increase the risk of hemodynamic compromise. Endothelial dysfunction, impaired calcium regulation, and reperfusion after IDH (the production of free radicals in the myocardium) bring about this phenomenon [24]. Myocardial stunning may cause LV dysfunction and structure alteration, leading to heart failure. In our study, we found no significant difference of LVEF in both groups of patients at baseline, while decreased LVEF was observed in the IDH group in long-term follow-up (p = .010). Repetitive ischemia episodes are cumulative, contributing to cardiac fibrosis and cardiac hypertrophy, causing systolic LV dysfunction and LVH. So IDH could cause cardiac dysfunction in the long term.