Neurogenic myocardial dysfunction post craniopharyngioma resection: A diagnostic dilemma.

Endoscopic transsphenoidal resection of craniopharyngioma is a commonly used technique. Cerebral vasospasm may occur in nearly 10% of cases leading to adverse neurological outcomes. Cardiopulmonary dysfunction may be seen in patients with severe vasospasm. The literature describing the occurrence of neurogenic stunned myocardium following craniopharyngioma resection in pediatric patients is very sparse. Here, we describe such a case managed with a combination of milrinone (to relieve vasospasm and improve cardiac pump function), noradrenaline (to obtain target blood pressure), and vasopressin (to control urine output). This case report proposes the treatment plan of neurogenic stunned myocardium following vasospasm in pediatric patients.

Recovery of hibernating myocardium using stem cell patch with coronary bypass surgery.

OBJECTIVE: This study aims to investigate the utility of mesenchymal stem cells (MSCs) applied as an epicardial patch during coronary artery bypass graft (CABG) to target hibernating myocardium; that is, tissue with persistently decreased myocardial function, in a large animal model. METHODS: Hibernating myocardium was induced in juvenile swine (n = 12) using a surgically placed constrictor on the left anterior descending artery, causing stenosis without infarction. After 12 weeks, single-vessel CABG was performed using left internal thoracic artery to left anterior descending artery graft. During CABG, an epicardial patch was applied to the hibernating myocardium region consisting either of MSCs grown onto a polyglactin mesh (n = 6), or sham polyglactin mesh without MSCs (n = 6). Four weeks after CABG and patch placement, cardiac magnetic resonance imaging was performed and cardiac tissue was examined by gross inspection, including coronary dilators for vessel stenosis and patency, electron microscopy, protein assays, and proteomic analysis. RESULTS: CABG + MSC myocardium showed improvement in contractile function (78.24% ± 19.6%) compared with sham patch (39.17% ± 5.57%) during inotropic stimulation (P < .05). Compared with sham patch control, electron microscopy of CABG + MSC myocardium showed improvement in mitochondrial size, number, and morphology; protein analysis similarly showed increases in expression of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor gamma coactivator 1-alpha (0.0022 ± 0.0009 vs 0.023 ± 0.009) (P < .01) along with key components of the electron transport chain, including succinate dehydrogenase (complex II) (0.06 ± 0.02 vs 0.14 ± 0.03) (P < .05) and adenosine triphosphate synthase (complex V) (2.7 ± 0.4 vs 4.2 ± 0.26) (P < .05). CONCLUSIONS: In hibernating myocardium, placement of a stem cell patch during CABG shows promise in improving myocardial function by improving mitochondrial morphology and function.

Myocardial Viability Testing to Guide Coronary Revascularization.

Left ventricular dysfunction remains one of the best prognostic determinants of survival in patients with coronary artery disease. Revascularization has been shown to improve survival compared with medical therapy alone. Viability testing can help direct patients who will benefit the most from revascularization. Single-photon emission computed tomography, dobutamine stress echo, cardiac MRI, and PET imaging with F18-fluorodeoxyglucose are the most common modalities for assessing myocardial viability. Viability testing can help differentiate which patients benefit most from chronic total occlusion interventions.

Cardiac Strain in a Swine Model of Regional Hibernating Myocardium: Effects of CoQ10 on Contractile Reserve Following Bypass Surgery.

There is conflicting clinical evidence whether administration of coenzyme Q10 (CoQ10) improves function following coronary artery bypass graft surgery (CABG). Using a swine model of hibernating myocardium, we tested whether daily CoQ10 would improve contractile function by MRI at 4-week post-CABG. Twelve pigs underwent a thoracotomy and had a constrictor placed on the left anterior descending (LAD). At 12 weeks, they underwent off-pump bypass and received daily dietary supplements of either CoQ10 (10 mg/kg/day) or placebo. At 4-week post-CABG, circumferential strain measurements in the hibernating LAD region from placebo and CoQ10 groups were not different and increased to a similar extent with dobutamine (-14.7 ± 0.6 versus -14.8 ± 0.1, respectively (NS)). Post-sacrifice, oxidant stress markers were obtained in the mitochondrial isolates and protein carbonyl in the placebo, and CoQ10 groups were 6.14 ± 0.36 and 5.05 ± 0.32 nmol/mg, respectively (NS). In summary, CoQ10 did not improve contractile reserve or reduce oxidant stress at 4-week post-CABG.

[MODERN STRATEGY FOR THE TREATMENT OF PATIENTS WITH "HIBERNATING MYOCARDIUM"].

The paper reports results of endovascular treatment of 66 patients with post-infarction cardiosclerosis. It was shown that normalization of coronary circulation in patients with viable hibernating myocardium in the zone of the affected artery not only eliminates the signs of chronic ischemia and slows down post-infarction heart remodeling but also restores the lost functions of hibernating myocardium which has beneficial influence on prognosis of the disease. Functioning of hibernating myocardium depends on the timely restoration of coronary circulation.

Mitochondrial fusion proteins in revascularized hibernating hearts.

BACKGROUND: Hibernating myocardium is characterized by viable yet dysfunctional myocardium secondary to chronic ischemia, with studies demonstrating incomplete early recovery after coronary artery bypass graft (CABG). We tested whether mitochondrial fusion proteins, an indicator of mitochondrial biogenesis, are increased in hibernating myocardium post-CABG. METHODS: A constrictor was placed on the left anterior descending (LAD) artery of nine pigs. Four of these pigs additionally underwent CABG 12 wk later with a left internal mammary artery graft to the LAD distal to the constrictor. Five pigs had a constrictor placed but did not undergo CABG (Hib). Five pigs did not have a constrictor placed (control). Computerized tomography angiography was used to confirm stenosis at the site of constrictor placement and patency of left internal mammary artery grafts. Regional blood flows were determined at baseline and during 40 µg/kg/min dobutamine infusion. Mitochondrial proteins were quantified by Western blot. RESULTS: Blood flow in the LAD region after CABG was lower than remote regions during dobutamine infusion (2.54 ± 0.24 versus 3.46 ± 0.33 mL/min/g; P < 0.05). Electron transport chain proteins were ∼70% lower in Hib compared with those in control and failed to normalize after CABG. Post-CABG, PGC1α nuclear-bound content was increased compared with Hib (9.02 ± 0.48 versus 5.54 ± 0.98 arbitrary units, respectively; P < 0.05), and expression of mitofusins-1 and 2 and optic atrophy-1 more than doubled. CONCLUSIONS: PGC1α and mitochondrial fusion proteins are increased 4 wk post-CABG in hibernating hearts, indicating mitochondrial fusion has begun to occur and signaling early mitochondrial recovery. Future studies should address changes in maximal myocardial oxygen consumption relative to mitochondrial protein expression.

Expression of uncoupling protein-2 remains increased within hibernating myocardium despite successful coronary artery bypass grafting at 4 wk post-revascularization.

BACKGROUND: We have previously shown that mitochondrial uncoupling protein-2 (UCP-2) is increased in a swine model of hibernating myocardium (HM). Although UCP-2 reduces oxidant stress, it can promote inefficiency of the electron transport chain. In this study, we tested whether UCP-2 remains increased in revascularized HM (RHM) after coronary artery bypass grafting (CABG). METHODS: Seven swine underwent thoracotomy with placement of a constrictor on the left anterior descending artery (LAD). Twelve weeks later, a left internal mammary artery graft was placed on the distal LAD. Four weeks post-CABG, computed tomography angiography documented patent grafts and function. At the terminal study, blood flow to the LAD and remote territories were assessed during high dose dobutamine and mitochondria isolated from both regions for analysis. Comparisons were made to a group of swine with HM who underwent constrictor placement without bypass grafting (n = 4). RESULTS: During dobutamine infusion, RHM demonstrated lower blood flows (2.44 ± 0.23 versus 3.43 ± 0.30 mL/min/g; P < 0.05) and reduced wall thickening (33 ± 9% versus 52 ± 13%; P < 0.05) compared with remote regions. RHM had lower respiratory control indices (3.7 ± 0.3 versus 4.3 ± 0.4; P < 0.05) with persistently increased UCP-2 content. CONCLUSIONS: Despite patent grafts, RHM demonstrates a submaximal response to dobutamine infusion and increased mitochondrial UCP-2 expression. These data support the notion that recovery of the mitochondria in RHM is delayed early post-CABG and may contribute to impaired oxygen consumption and contractile reserve during catecholamine challenges.

Recovery of hibernating myocardium: what is the role of surgical revascularization?

Myocardial responses to chronic ischemia represent a continuum of adaptations resulting, over time, in a stress-resistant phenotype. One such adaptation, hibernating myocardium (HM), has increased antioxidant capacity that protects against ischemia-induced oxidative stress. Studies have suggested that revascularization alone may not fully restore cardiac function, highlighting the need for targeted therapies to serve as adjuncts to the innate healing process following revascularization. In our review, we discuss current understanding of HM and the recovery process following surgical revascularization, focusing on animal models of HM to understand implications for human patients.

[Clinical research of safflower injection on hibernating myocardial revascularization].

Coronary artery disease (CAD) is one of the leading causes of death. Safflower attracts great attention owing to its anti-ischemia/reperfusion injury effect. Ninety-three patients with CAD were included and randomized into safflower treatment group, PCI group and control group. Low-dose dobutamine stress echocardiography (DSE) was performed to measure end-systolic volume (ESV), end-diastolic volume (EDV), left ventricular ejection fraction (LVEF) and wall motion score index (WMSI) to determine the recovery of hibernating myocardium and cardiac function in all patients before treatment and after 3-month follow-up. The study was to investigate the effects of safflower on hibernating myocardial revascularization and cardiac function. It was found that LVEF was significantly improved, while the ESV and WMSI were significantly reduced after 2-week treatment in safflower and PCI treatment groups. No significant differences were found between safflower and PCI treatment groups in ESV, EDV, WMSI and LVEF after treatment Safflower injection effectively improved hibernating myocardial function.

Stab wound of the heart with unusual sequelae.

A 31-year-old woman was admitted to the emergency department with a stab wound to the heart. She was initially stable but rapidly developed hypotension. While the operating room and staff were in preparation, she underwent pericardiocentesis. She was then rushed to the operating room by the general surgical trauma team, who performed a bilateral anterior thoracotomy to control the bleeding. In the recovery room, the patient was still hypotensive, so cardiothoracic surgery was consulted. An echocardiogram revealed severe hypokinesis of both ventricles. The cardiothoracic surgeons returned her to the operating room and discovered that the anterior pericardium had been completely removed by the trauma team. This had caused the posterior pericardium to form a "bowstring" that almost totally obstructed pulmonary venous return and restricted right ventricular outflow of blood, inducing right-sided heart failure. This pericardial string also strangulated the left atrium posteriorly, forming 2 compartments. We repositioned the patient's heart and implanted ventricular assist devices bilaterally to provide temporary circulatory support. The patient made a good recovery. We suggest that bilateral assist device placement can be beneficial in the recovery of a stunned but otherwise normal heart.

Predictors of post-stress LVEF drop 6 months after reperfused myocardial infarction: a gated myocardial perfusion SPECT study.

OBJECTIVE: To identify the predictive factors of myocardial stunning as assessed by the drop in post-stress Left Ventricular Ejection Fraction (LVEF) in patients with a recent history of myocardial infarction (MI). METHODS: We prospectively included 215 consecutive patients admitted for acute MI who underwent percutaneous coronary intervention with a greater than or equal to grade-3 TIMI flow in the culprit vessel. Six months after discharge, a post-stress/rest 99mTc-sestamibi gated SPECT was performed. The perfusion score was evaluated visually using a 17-segment model. The LVEF drop was considered significant if the post-stress LVEF was ≥ 5% below the rest LVEF (QGS® software). RESULTS: A post-stress LVEF drop was observed in 51 (24%) patients. Patients with an LVEF drop were more likely than patients with a stable post-stress LVEF to have diabetes (22% vs. 10%, p = 0.048), significant ischemia (SDS > 2) (51% vs. 28% p = 0.003) and higher rest LVEF [62% (56-69) vs. 56% (49-63) p < 0.001]. In contrast, summed rest score, related to infarct size, did not differ between the groups. Multivariate logistic regression analysis identified SDS > 2 (OR 3.78, 95% CI 1.8-7.92, p < 0.001), diabetes (OR 3.35, 95% CI 1.33-8.49; p = 0.011) and rest LVEF (OR 1.08, 95% CI 1.04-1.12, p < 0.001) as independent explanatory variables of an LVEF drop. CONCLUSION: In patients with recent MI and post-procedural grade-3 TIMI flow, ischemia and diabetes were independent predictive factors of myocardial stunning. The higher incidence of reversible perfusion abnormalities validates the model of myocardial stunning in the post-MI period, and excludes the potential involvement of myocardial necrosis.

Neurogenic stunned myocardium and cardiac transplantation: a case report.

We present the case of a 46-year-old woman referred to our center for urgent heart transplantation assessment, initially diagnosed as having cardiogenic shock of uncertain etiology. Some hours before she had suffered syncope without regaining consciousness. When she arrived at our hospital, the objective examination revealed bilateral unreactive mydriasis and absent brain-stem reflexes, and echocardiography showed global left ventricle wall hypokinesis sparing the apex. An urgent computed tomography (CT) imaging of the head was performed, which showed a massive subarachnoid hemorrhage and extensive cerebral edema. In the following hours, she fulfilled the criteria of brain-stem death and indeed became a multiorgan donor. The heart was rejected for transplantation because of the existence of left ventricle wall motion abnormalities associated with neurogenic stunned myocardium. Neurogenic stunned myocardium is a stress-related cardiomyopathy that occurs after an acute brain injury. It is especially frequent in subarachnoid hemorrhage, where it reaches an incidence of up to 40% of patients. It is characterized by acute electrocardiographic changes and regional hypokinesis of the left ventricle wall not consistent with the coronary artery distribution, and is thought to be a transient condition. For this reason it should not constitute an absolute contraindication to cardiac donation in young donors with no previous cardiac disease. In our hospital during the last year one third of the potential heart donors had regional left ventricle wall motion abnormalities compatible with neurogenic stunned myocardium. With the aim of improving the number of cardiac donors, several strategies have been described to try to demonstrate the reversibility of this entity, such as dobutamine stress echocardiography.

[Revascularization of the hibernated myocardium: a clinical problem still unsolved]. / Rivascolarizzazione del miocardio ibernato: un problema clinico ancora irrisolto.

The mid- and long-term outcome of revascularization procedures is still uncertain in patients with chronic left ventricular systolic dysfunction due to coronary artery disease. The identification of dysfunctional myocardial segments with residual viability that can improve after revascularization is pivotal for further patient management. Hibernating myocardium (chronically dysfunctional but still viable tissue) can be identified by positron emission tomography and cardiac magnetic resonance and its presence and extent can predict functional recovery after revascularization. Before beta-blockers were introduced as routine care for heart failure, surgical revascularization appeared to improve survival in these patients. Nowadays, novel medical treatments and devices such as cardiac resynchronization therapy and implantable cardioverter-defibrillators have improved prognosis of these patients and their use is supported by a number of clinical trials. A recently concluded randomized trial, the STICH (Surgical Treatment for Ischemic Heart Failure) trial, has assessed the prognostic benefit derived from revascularization added to optimal medical therapy in patients with ischemic left ventricular dysfunction. This is an overview of the pathophysiological mechanisms as well as the main clinical studies and meta-analyses that have addressed this issue in the past four decades. Furthermore, a brief proposal for a randomized trial to assess effect on prognosis of revascularization of hibernating myocardium will be presented.

Improvement of myocardial performance (Tei) index closely reflects intrinsic improvement of cardiac function: assessment in revascularized hibernating myocardium.

BACKGROUND: Myocardial performance index (MPI), or Tei index, is an indicator of systolic and diastolic myocardial function. MPI increases in case of cardiac dysfunction; however, whether reversal of left ventricular dysfunction is also reflected by concomitant improvement (i.e., decrease) of MPI is unknown. METHODS: Fifty-two patients with chronic ischemic cardiomyopathy and viable myocardium by dobutamine stress echocardiography were studied by echocardiography before and more than 4 months after cardiac revascularization. Patients were in optimal medical therapy, which remained unchanged following revascularization. RESULTS: At baseline, ejection fraction (EF: 32 ± 6%) and wall motion score index (WMSI: 2.37 ± 0.32) were impaired, and MPI averaged 0.71 ± 0.19. Revascularization markedly improved EF (44 ± 10%, P < 0.0001) and WMSI (1.77 ± 0.44, P < 0.0001). MPI also improved (0.59 ± 0.26, P < 0.0001), and its decrease was significantly correlated with the improvement in EF (r =-0.68, P < 0.0001) and to the extent of viable myocardium (r =-0.45, P = 0.0007). Responders to revascularization (≥5% increase in EF at follow-up, n = 40% and 77%) achieved a significant improvement in MPI at follow-up in contrast with nonresponders (-23 ± 25% vs. 0.02 ± 0.18%, P = 0.001). Improvement in MPI was largely driven by a significant reduction in isovolumic contraction time (P < 0.001) with consequent prolongation of the ejection phase. CONCLUSION: In patients with chronic ischemic cardiomyopathy, MPI improves along with recovery of function, reflecting the intrinsic improvement of viable segments induced by revascularization.