The pathogenesis of reversible T-wave inversions or large upright peaked T-waves: Sympathetic T-waves. Int J Cardiol. 2015;191:237-243. [PMID: 25981361 DOI: 10.1016/j.ijcard.2015.04.233]

Left ventricular outflow tract obstruction/hypertrophic cardiomyopathy/takotsubo syndrome: A new hypothesis of takotsubo syndrome pathophysiology

The pathophysiology of TTS is still elusive. This viewpoint proposes that TTS is an acute coronary syndrome, engendered by an ASNS/catecholamine-induced LVOTO, which results in an enhanced wall stress and afterload-based supply/demand mismatch, culminating in a segmental myocardial ischemic injury state, in susceptible individuals. Such individuals are felt to be particularly women with chronic hypertension, known or latent HCM, or non-HCM segmental myocardial hypertrophy, and certain structural abnormalities involving the LV and the MV apparatus. Recommendations are provided to explore further this hypothesis, while maintaining our focus on all other advanced TTS pathophysiology hypotheses for all patients, or those who do not experience LVOTO, men, the young, and patients with reverse, mid-ventricular, or right ventricular TTS, in whom more prolonged hyperadrenergic stimulation and/or larger amounts of blood-ridden catecholamines, segmental particularities of cardiac innervation and/or density of α-, and β-adrenergic receptors, pheochromocytoma, neurological chronic or acute comorbidities/catastrophies, coronary epicardial/microvascular vasospasm, and CMD.

Takotsubo Syndrome in the Perioperative Period: A Case Report and a Comprehensive Review of Pertinent Literature

ABSTRACT

Stress-induced cardiomyopathy or takotsubo syndrome is a rare, nonischemic, heart condition resembling that of an acute coronary syndrome. Its distinctive feature is a transient wall motion abnormality occurring usually at the apical segment of the heart, with the degree of symptom manifestation and severity varying among patients. Although early data were supportive of a benign sequela and outcome, high degree of adverse events, such as acute heart failure and pulmonary edema, are anticipated, and the mortality rate approaches 5%. Hyperactivation of the sympathetic nervous system and adrenergic drugs have been pointed out as possible precipitators of the condition. Surgical procedures are a known cause of emotional and physical stress on patients, acting as an ideal substrate for the presentation of this syndrome. On occasion of a perioperative takotsubo syndrome case in a female patient during second-stage implant-based breast reconstruction, a review of the pertinent literature is presented. The acute onset and severity of the manifestations in this surgically uneventful procedure necessitated a multidisciplinary approach. Consequently, this report should raise awareness of the syndrome among plastic surgeons and anesthesiologists to promptly recognize and manage it effectively.

Electrocardiographic T-wave morphology and risk of mortality

BACKGROUND

Electrocardiographic T-wave morphology is used in drug safety studies as an adjunct to the QT_c interval, but few measurements of T-wave morphology can be interpreted in clinical practice. Morphology combination score (MCS) is a combination of T-wave flatness/peakedness, asymmetry, and notching, enabling easy visual assessment of T-wave morphology. We aimed to test the association between T-wave morphology, quantified by MCS, and mortality.

METHODS

We included electrocardiograms recorded in 2001-2011 from 342,294 primary care patients. Using Cox regression, we evaluated the association between MCS, cardiovascular death, and all-cause mortality, adjusting for heart rate, QT_c, QT-prolonging drugs, diabetes, ischemic heart disease, hypertension, and congestive heart failure.

RESULTS

270,039 individuals (44% men, median age 55 [inter-quartile range: 42-67 years]) were included and followed for a median of 9.3 years, during which time 13,489 (5.0%) died from cardiovascular causes and 50,481 (18.7%) from any cause. High values of MCS (i.e. asymmetric, flattened, and/or notched T waves) were associated with an adjusted mortality Hazard Ratio of 1.75 (95% CI 1.62-1.89) and 1.61 (1.43-1.92) for women and men, respectively. Low values of MCS (i.e. peaked and symmetric T waves) were associated with a Hazard Ratio of 1.18 (1.08-1.28) and 1.71 (1.48-1.98) for women and men, respectively.

CONCLUSIONS

In a large primary care population, we found that T-wave asymmetry, flatness, and notching provided prognostic information on mortality independent of heart rate, QTc, and baseline comorbidities.

Cardiovascular Manifestations and Complications of Pheochromocytomas and Paragangliomas

Pheochromocytomas and paragangliomas (PPGLs) are rare neuro-endocrine tumors. The catecholamine surge causes paroxysmal or chronic secondary hypertension. PPGLs may present as hypertensive- or PPGL-crisis with severe life-threatening cardiac and cerebrovascular complications. PPGLs-induced cardiac manifestations have been reported with diagnoses as PPGLs-induced electrocardiogram (ECG) changes “mimicking acute myocardial infarction”, arrhythmias, myocarditis, acute coronary syndrome, dilated cardiomyopathy, and lately as takotsubo syndrome. Critical analysis of these reports reveals that most of these cardiac manifestations have certain features in common. They have a dramatic clinical presentation and are reversible if the disease is treated with appropriate medical therapy and surgical resection of the PPGL tumor. They may have the same repolarization ECG changes irrespective of the clinical cardiac diagnosis, usually associated with mild to moderate elevations of myocardial biomarkers as troponins and normal coronary arteries. The histopathological findings are usually focal or multifocal in the form hypercontracted sarcomeres and contraction band necrosis (myofibrillar degeneration) with subsequent secondary mononuclear cell infiltration. Evidences argue the PPGL caused surge of catecholamines triggers hyperactivation of the sympathetic nervous system with cardiac sympathetic nerve terminal disruption with norepinephrine spillover causing the cardiac complications. A comprehensive review of various reported cardiovascular manifestations and complications of PPGLs are presented.

Autonomic neurocardiogenic syndrome is stonewalled by the universal definition of myocardial infarction

Myocardial infarction (MI) is defined as myocardial cell death due to prolonged myocardial ischemia. Clinically, troponin rise and/or fall have become the “defining feature of MI” according to the universal definition of MI (UD-MI). Takotsubo syndrome (TS) and TS-related disease conditions also cause troponin elevation with typical rise and/or fall pattern but through a mechanism other than coronary ischemia. By strict application of the clinical diagnostic criteria for type-1 MI, type-2 MI, type-3 MI, and MI with non-obstructive coronary arteries according to the UD-MI including the fourth one published recently, TS and most of the 26 other causes of troponin elevation mentioned in the fourth UD-MI may erroneously be classified as MI. The existing evidence argues for the case that TS by itself is not a MI. Hyper-activation of the autonomic-sympathetic nervous system including local cardiac sympathetic hyper-activation and disruption with nor-epinephrine churn and spillover is the most probable cause of TS. This autonomic neuro-cardiogenic (ANCA) mechanism results in myocardial “cramp” (stunning), the severity and duration of which depend on the degree of the sympathetic-hyperactivation and nor-epinephrine spillover. The myocardial cramp may squeeze the cytosolic free troponin pools causing mild to moderate troponin elevation in TS and TS-related disease conditions. This ANCA syndrome, which has hitherto been enveloped by the UD-MI over more than one decade, may occur in acute, recurrent, and chronic forms. In this critical review, the controversies of UD-MI, evidence for ANCA syndrome, and a hypothetical mechanism for the troponin elevation in ANCA syndrome are provided.

Autonomic nervous system in Takotsubo syndrome

Takotsubo syndrome (TTS) is an acute and usually reversible heart failure syndrome with symptoms resembling acute myocardial infarction, however, without obstruction of coronary arteries. In the majority of cases, TTS is preceded by emotional or physical stress and the disease concerns mainly postmenopausal women. Although several hypotheses have been introduced, the pathogenesis of TTS is controversial and still remains to be determined. As reported in recent studies, the role of the autonomic nervous system (ANS) seems to be pivotal in the pathogenesis of TTS. Therefore, the aim of this article is to summarize and discuss the current knowledge of the pathogenesis of TTS with a special focus on the ANS.

The Brain-Heart Connection in Takotsubo Syndrome: The Central Nervous System, Sympathetic Nervous System, and Catecholamine Overload

Takotsubo syndrome (TTS), also known as stress cardiomyopathy, is a type of acute heart failure syndrome triggered by intense psychological or physiological stress. TTS typically manifests as acute chest pain, dyspnea or syncope that mimics an acute myocardial infarction but does not involve coronary artery obstruction. The current understanding of the pathogenesis of TTS suggests that sympathetic nervous system (SNS) activation plays a central role. Specifically, stress can activate the SNS and lead to the over-release of catecholamine, which have toxic effects on myocardial tissue when present at excessive levels. However, the brain changes associated with TTS and the connection between the brain and the heart in patients with this disease remain unclear. In recent years, several published reports have revealed the role of this brain-heart connection in the pathogenesis of TTS. This review summarizes recent studies regarding SNS activation, catecholamine overload, and the brain-heart connection in patients with TTS from both pathophysiological and mechanistic aspects.

Takotsubo Cardiomyopathy-Acute Cardiac Dysfunction Associated With Neurological and Psychiatric Disorders

Takotsubo cardiomyopathy (TTC) is an acute and reversible cardiac wall motion abnormality of the left myocardium. Although many studies focused on etiology, diagnostic and treatment of TTC, precise clinical guidelines on TTC are not available. Research revealed emotional and physical triggering factors of TTC and emphasized the association of TTC with psychiatric and particularly acute neurological disorders. Similar clinical presentation of acute coronary syndrome (ACS) and TTC patients, makes an anamnestic screening for TTC risk factors necessary. In psychiatric anamnesis affective disorders and chronic anxiety disorders are presumably for TTC. Subarachnoid hemorrhages and status epilepticus are typical acute neurological associated with a higher risk for TTC. Moreover, magnetic resonance imaging (MRI) studies reveled brain alterations of the limbic system and reduced connectivity of central autonomic nervous system structures. Diagnosis of TTC is made by elevation of cardiac enzymes, electrocardiogram (ECG) and visualization of myocardial wall motion. Major differential diagnoses like acute coronary syndrome and myocarditis are hereby in synopsis with anamnesis with respect of possible emotional and physical triggering factors of TTC ruled out. In most cases the TTC typical wall motion abnormalities resolve in weeks and therapy is only necessary in hemodynamic instable patients and if rare complications, like cardiac wall ruptures occur. Recently, the two-parted International expert consensus document on Takotsubo syndrome was published, providing a detailed characterization of TTC and allows clinicians to understand this cardiac dysfunction with a multidisciplinary view.

Momentary giant T-waves hint the genesis of the electrocardiographic T-wave in human

T-wave morphology changes are linked to dispersion of ventricular repolarization. I encountered an 80-year-old man on hemodialysis manifesting momentary giant T-waves and QT prolongation on the 12-lead electrocardiogram, soon after initiating mechanical ventilation because of hypercapnic respiratory failure. A computed tomography of the brain showed no acute cerebrovascular accidents. An echocardiogram showed no left ventricular asynergy. Mechanisms that may be responsible for this phenomenon are discussed. Interpreting the giant T-waves with the concept of the three bipolar limb lead vectors, the Einthoven's triangle leads to recognize origin of the electrocardiographic T-wave.

"Lambda-wave" ST-elevation is associated with severe prognosis in stress (takotsubo) cardiomyopathy

BACKGROUND

Persistent ST-segment elevation in acute coronary syndrome is associated with both short and long-term complications. By contrast, there is limited information about ST-elevation and its evolution during takotsubo (stress) cardiomyopathy (TTC).

AIM

To evaluate whether persistent downsloping ST-elevation in the early stages of TTC might correlate with short and long-term clinical events.

METHODS

One-hundred fifty-eight consecutive subjects with TTC were prospectively enrolled and assessed by electrocardiogram. Patients were classified in two groups according to the presence of downsloping ST-elevation ≥5 mm lasting at least 24 hr ("lambda-wave" ST-elevation group vs. without downsloping ST-elevation) in at least one/two contiguous leads.

RESULTS

Five (3.2%) patients, all female with a mean left ventricular ejection fraction 32 ± 5%, were included in the lambda-wave ST-elevation group. These patients were characterized by a higher prevalence of physical stressor (100% vs. 49%, p = 0.04) and higher admission and peak levels of troponin-I levels during hospitalization. Peak of ST-elevation in the lambda-wave ST-elevation group was reached 6 hr after admission and gradually decreased after 24 hr. In-hospital complications were observed in all the patients presenting lambda ST-elevation (100% vs. 23%, p = 0.03, OR: 29.1, p = 0.04); one patient presented endoventricular thrombosis and two died of cardiogenic shock. At long-term follow-up (mean 443 days), adverse events were observed in 80% of patients with lambda-wave ST-elevation (RR of adverse events at follow-up 32, p < 0.01).

CONCLUSION

Persistent downsloping lambda-wave ST-elevation during the acute phase of stress cardiomyopathy may be associated with a higher risk of adverse events at short and long-term follow-up.

Pseudo-Wellens' syndrome secondary to concurrent cannabis and phencyclidine intoxication

Wellens' syndrome is an electrocardiographic pattern of T-wave changes associated with critical stenosis of the proximal left anterior descending artery, signifying imminent risk of an anterior-wall myocardial infarction. The Wellens' electrocardiographic pattern can also be noted in several cardiac and non-cardiac diseases. We chronicle here a unique case of a patient who presented with atypical left chest pain and dizziness for 6 hours. His pain started after he smoked phencyclidine-laced cannabis. Cardiac panel demonstrated normal troponin T levels. Electrocardiogram showed sinus rhythm with new deep biphasic T-wave inversions in anterolateral leads. Coronary angiography showed no pathological processes. Subsequently, ECG changes resolved coincidentally with the resolution of chest pain. He was eventually diagnosed with pseudo-Wellens' syndrome. This paper illustrates that physicians should be vigilant for Wellens' syndrome mimicked by acute phencyclidine and cannabis intoxication. Additionally, we present a review of various aetiologies of pseudo-Wellens' syndrome, especially in patients with substance abuse.

Cocaine-induced pseudo-Wellens' syndrome: a Wellens' phenocopy

Wellens' syndrome represents critical occlusion of the proximal left anterior descending coronary artery. Electrocardiographic changes similar to Wellens' wave are not exceptional to acute coronary occlusion and can also be seen in cardiac and non-cardiac conditions, such as left ventricular hypertrophy, persistent juvenile T wave, bundle branch blocks, cerebral haemorrhage, pulmonary oedema, pulmonary embolism, pheochromocytoma, Takotsubo syndrome, digitalis and cocaine-induced coronary vasospasm. Cocaine-induced pseudo-Wellens' syndrome should be considered as one of the differentials, since cocaine is used frequently by young adults and can cause left anterior descending coronary vasospasm mimicking Wellens' syndrome. Initiation of the beta-blocking agent in pseudo-Wellens' syndrome as a part of acute coronary syndrome management can be disastrous. We illustrated a case of cocaine-induced pseudo-Wellens' syndrome presented with typical chest pain associated with Wellenoid ECG.

Epidemiology, pathogenesis, and management of takotsubo syndrome

Takotsubo syndrome is a recently recognized acute cardiac disease entity with a clinical presentation resembling that of an acute coronary syndrome. The typical takotsubo syndrome patient has a unique circumferential left (bi-) ventricular contraction abnormality profile that extends beyond a coronary artery supply territory and appears to follow the anatomical cardiac sympathetic innervation. The syndrome predominantly affects postmenopausal women and is often preceded by emotional or physical stress. Patients with predisposing factors such as malignancy and other chronic comorbidities are more prone to suffer from takotsubo syndrome. The pathogenesis of takotsubo syndrome is elusive. Several pathophysiological mechanisms involving myocardial ischemia (multivessel coronary artery spasm, microvascular dysfunction, aborted myocardial infarction), left ventricular outlet tract obstruction, blood-borne catecholamine myocardial toxicity, epinephrine-induced switch in signal trafficking, and autonomic nervous system dysfunction have been proposed. The syndrome is usually reversible; nevertheless, during the acute stage, a substantial number of patients develop severe complications such as arrhythmias, heart failure including pulmonary edema and cardiogenic shock, thromboembolism, cardiac arrest, and rupture. Treatment of precipitating factors, predisposing diseases, and complications is fundamental during the acute stage of the disease. The epidemiology, pathogenesis, and management of takotsubo syndrome are reviewed in this paper.

Contemporary review on the pathogenesis of takotsubo syndrome: The heart shedding tears: Norepinephrine churn and foam at the cardiac sympathetic nerve terminals

Takotsubo syndrome (TS), an increasingly recognized acute cardiac disease entity, is characterized by a unique pattern of circumferential and typically regional left ventricular wall motion abnormality resulting in a conspicuous transient ballooning of the left ventricle during systole. The mechanism of the disease remains elusive. However, the sudden onset of acute myocardial stunning in a systematic pattern extending beyond a coronary artery territory; the history of a preceding emotional or physical stress factor in two thirds of cases; the signs of sympathetic denervation at the regions of left ventricular dysfunction on sympathetic scintigraphy; the finding of myocardial edema and other signs consistent with (catecholamine-induced) myocarditis shown by cardiac magnetic resonance imaging; and the contraction band necrosis on histopathological examination all argue strongly for the involvement of the cardiac sympathetic nervous system in the pathogenesis of TS. In this narrative review, extensive evidence in support of local cardiac sympathetic nerve hyperactivation, disruption and norepinephrine spillover causing TS in predisposed patients is provided.

The Role of Transmural Repolarization Gradient in the Inversion of Cardiac Electric Field: Model Study of ECG in Hypothermia

BACKGROUND

The changes in ventricular repolarization gradients lead to significant alterations of the electrocardiographic body surface T waves up to the T wave inversion. However, the contribution of a specific gradient remains to be elucidated. The objective of the present investigation was to study the role of the transmural repolarization gradient in the inversion of the body surface T wave with a mathematical model of the hypothermia-induced changes of ventricular repolarization.

METHODS

By means of mathematical simulation, we set the hypothermic action potential duration (APD) distribution on the rabbit ventricular epicardium as it was previously experimentally documented. Then the parameters of the body surface potential distribution were tested with the introduction of different scenarios of the endocardial and epicardial APD behavior in hypothermia resulting in the unchanged, reversed or enlarged transmural repolarization gradient.

RESULTS

The reversal of epicardial repolarization gradients (apicobasal, anterior-posterior and interventricular) caused the inversion of the T waves regardless of the direction of the transmural repolarization gradient. However, the most realistic body surface potentials were obtained when the endocardial APDs were not changed under hypothermia while the epicardial APDs prolonged. This produced the reversed and increased transmural repolarization gradient in absolute magnitude. The body surface potentials simulated under the unchanged transmural gradient were reduced in comparison to those simulated under the reversed transmural gradient.

CONCLUSIONS

The simulations demonstrated that the transmural repolarization gradient did not play a crucial role in the cardiac electric field inversion under hypothermia, but its magnitude and direction contribute to the T wave amplitude.