53 year old man Flashcards
Monomorphic ventricular tachycardia vs polymorphic ventricular tachycardia
- Mono- single focus and single port of exit
- Poly- multiple focus and multiple exits
Causes of polymorphic VT
- Acute MI
- Abnormalities of ion channels
- Idiopathic ventricular fibrillation
- Structural disease: hypertrophy, recent infarction, cardiomyopathy
Causes of monomorphic VT
Scar-related reentry and Purkinje disease
What do GP 2b/3a antagonists do?
They block the final common pathway of platelet aggregation
After platelets are activated by local agonists, fibrinogen binds to the platelet surface glycoprotein 2b/3a receptor to link adjacent platelets and cause platelet aggregation. Intraluminal thrombus propagation follows platelet aggregation
What can antiarrhythmic drugs be divided into?
Four classes:
Class 1: Na+ channel blocker (e.g. lidocaine and quinidine)
Class 2: Beta blockers (e.g. propanolol and metoprolol
Class 3: K+ channel blocker (e..g. amiodarone)
Class 4: Ca2+ channel blocker (e.g. verapamil)
What is a right bundle branch block?
Electrical activity through the His-Purkinje system (responsible for the rapid electric conduction in the ventricles. It relays electrical impulses from the atrioventricular node to the muscle cells and, thus, coordinates the contraction of ventricles in order to ensure proper cardiac pump function.) is interrupted, especially through the right bundle
What can right bundle branch block be caused by?
- Structural heart disease
- Iatrogenic
- Athletes (incomplete)
What can disorders of myocarditis be divided into?
- Disorders that cause inflammatory myocarditis can be narrowed down to
infectious and autoimmune diseases. - Approximately 50% (82% in children) of the time, miocarditis is classified as idiopathic
Why is infectious myocarditis, in particular parasitic not likely in this patient?
- Echinococcus and T. solium may explain his recent diarrheal illness. However , myocarditis is due to a ruptured cyst that causes direct inflammation, and imaging studies in this patient did not show evidence of a cystic lesion.
- Strongyloides and ascaris also cause gastrointestinal symptoms. However,
myocarditis is due to a high parasitic burden resulting in a systemic eosinophilic
response that can then cause inflammation in distant organs. T he absence of a
clinically significant peripheral eosinophilia and the history of gastrointestinal
symptoms that spontaneously resolved make them an unlikely cause. - Giardia has been identified in some patients with acute myocarditis, although
its precise role in the pathogenesis has not been elucidated . Patients with
giardiasis may have indolent or relapsing gastrointestinal syndromes. Although
giardiasis has not been definitively ruled out in this patient, the absence of
ongoing gastrointestinal symptoms make this an unlikely diagnosis.
Why is autoimmune myocarditis not a possibility in this patient?
- Hyper-eosinophilic syndrome (in the absence of a parasitic infection)
should be considered. Typically the degree of organ involvement
parallels the severity of peripheral eosinophilia , but since Roy did not
have a significant eosinophilia, this diagnosis is unlikely - Celiac disease has an increased prevalence in patients with acute
myocarditis. Although the exact mechanism is not well understood,
celiac disease is presumed to cause myocarditis by means of bacterial
translocation and immune dysregulation . Celiac disease can cause
indolent or relapsing gastrointestinal symptoms. Although this diagnosis
cannot be ruled out, it is unlikely to cause myocarditis in the absence of
ongoing gastrointestinal symptoms or other systemic manifestations.
Which etiologies of myocarditis also show electrical instability?
Two distinct types of myocarditis show significant electrical instability:
1. giant cell myocarditis
2. cardiac sarcoidosis
Signs on patients of giant cell myocarditis and cardiac sarcoidosis on heart
Sarcoidosis: Rapid onset HF and ventricular tachyarrhythmia accompanied by conduction block
Giant cell myocarditis: Typically with rapidly progressive HF and ventricular tachycardia
What is giant cell myocarditis and cardiac sarcoidosis characterized by?
- Giant cell myocarditis is characterized by a mixed inflammatory infiltrate
that affects the heart alone, and it has been linked to infectious and
systemic autoimmune diseases. The characteristic pathological features
include multinucleated giant cells and myocyte necrosis. - Sarcoidosis is known to cause systemic manifestations , but it sometimes
affects the heart alone, as the sole manifestation. The pathological
features include multinucleated giant cells, but the hallmark features of
non caseating granulomas, fibrosis, and scarring are more prominent.
Treatment of giant cell myocarditis vs cardiac sarcoidosis
Parsing out these diseases is quite important, since giant cell
myocarditis require aggressive treatment with multiple
immunosuppressive medications, whereas cardiac sarcoidosis can be
treated with glucocorticoids alone.
Diagnosis of cardiac sarcoidosis and giant cell myocarditis historicaly
- These two entities are clinically indistinguishable.
- For many years, giant cell myocarditis and cardiac sarcoidosis were
considered to be the same disease, characterized by the presence of
multinucleated giant cells with or without granulomas. - They are now recognized as two pathologically distinct entities , but
distinguishing them clinically remains a challenge.
Differential diagnosis of giant cell myocarditis vs cardiac sarcoidosis
- Several features of this patient’s presentation point toward a diagnosis of
giant cell myocarditis rather than cardiac sarcoidosis , including his white
race and the rapidly progressive and fulminant course of the disease. - Giant cell myocarditis causes myocyte necrosis, which is the most likely
explanation for the aggressive nature; in contrast, sarcoidosis typically
causes fibrosis and is associated with a more indolent progression. - MRI findings may be helpful in distinguishing the two diseases.
Involvement of the right ventricular side of basal interventricular septum is
specific for sarcoidosis but was absent, whereas subendocardial cardiac
involvement is specific for giant cell myocarditis.
Definition and Microscopic pathology of giant cell myocarditis
- Widespread or serpiginous inflammation with myocyte necrosis in the absence of well formed granulomas of specific etiology
- Widespread or serpiginous inflammation with giant cells, lymphocytes and often eosinophils. Myocyte necrosis is always present. Poorly formed granulomas may be seen
Definition and Microscopic pathology of cardiac sarcoidosis
- Granulomatous myocarditis with no evidence of infectious or other specific cause
- Non necrotizing/caseating granulomas, fibrosis with few eosinophils. Myocyte necrosis is rare
T cells and eosinophils in myocarditis
- Sarcoidosis is typically associated with the presence of compact
granulomas, extensive scarring, and more CD4 expressing helper T cells
than CD8 expressing cytotoxic T cells. - In acute necrotizing eosinophilic myocarditis, eosinophils are numerous
and giant cells may be present but tend not to be located at the leading
edge of the inflammation, as are typically seen in giant cell myocarditis.
Treatment approach for giant cell myocarditis
- Immunosuppression with glucocorticoids alone does not increase
survival or decrease the likelihood of heart transplantation , although
combined treatment with glucocorticoids and agents as azathioprine ,
calcineurin inhibitors , antithymocyte globulin , mycophenolate mofetil , or
methotrexate may increase long term survival - Ventricular tachycardia commonly occurs in patients who do not undergo
heart transplantation , and thus , it is appropriate ICD implantation even
when left ventricular dysfunction is only mild to moderate - Mechanical circulatory support is often necessary during early treatment
and in patients for whom heart transplantation is indicated
Many patients have biventricular dysfunction , and extracorporeal
membrane oxygenation can provide lifesaving stability
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Short term treatment with extracorporeal membrane oxygenation may
be transitioned to more permanent treatment with a ventricular assist
device implanted on the left or right side of the heart (or both ), either as
destination therapy or as a bridge to heart transplantation - For patients who do not have a response to immunosuppressive therapy and receive mechanical circulatory support , heart transplantation is the
best long term therapeutic option.
Recurrence of cardiac sarcoidosis and giant cell myocarditis in heart transplant patients
- Sufficient data about the recurrence of cardiac sarcoidosis in the transplanted heart, which has been well described. The good news about it is that, with or augmentation of immunosuppression it usually resolves
- We have less information about the recurrence of giant cell myocarditis, because not many patients have undergone transplantation. In general, recurrence rate is very low. Similar to sarcoidosis, recurrent giant-cell myocarditis is usually effectively treated with enhance immunosuppression
Cause of giant cell myocarditis
- The cause is generally unknown, and the disease is limited to the heart.
- Autoimmune disorders (e.g., IBD, fibromyalgia , Hashimoto’s thyroiditis )
may occur in up to 20% of patients - In addition, giant cell myocarditis may be part of a systemic giant cell
polymyositis , which occurs as a paraneoplastic syndrome in thymoma - On rare occasions, drug reactions can result in a pattern of inflammatory
response similar to that of giant cell myocarditis.
Prognosis of giant cell myocarditis
- Giant cell myocarditis is aggressive and often fatal , with a rate of death
or heart transplantation of 89% and a median survival of only 6 months
after symptom onset - The disease can progress rapidly , leading to cardiogenic shock or intractable ventricular arrhythmias as in this patient
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When do patients usually present and what are the clinical features of giant cell myocarditis
- Patients typically present in the fourth or fifth decade
- The clinical presentation can include:
heart failure or new onset cardiomyopathy in 75% of patients
syncope
sudden death due to ventricular tachycardia in 15%
heart block (in 5%) - An initial electrocardiogram frequently shows evidence of bifascicular
block (as in this patient) or left bundle branch block.
Cardiac MRI usefulness in giant cell myocarditis diagnosis
Cardiac MRI is useful in detecting acute inflammation in all forms of
acute myocarditis but cannot be used to differentiate between fulminant
lymphocytic myocarditis and giant cell disease
What is essential in the diagnosis of giant cell myocarditis
Endomyocardial biopsy is essential and should be performed promptly
Positive inotropic agents in giant cell myocarditis
Positive inotropic agents often exacerbate underlying ventricular
arrhythmias and are generally avoided
Risk of acute transplant rejection in giant cell myocarditis
The risk of acute rejection is higher with giant cell myocarditis than with dilated cardiomyopathy 16% vs. 5%), but no substantial difference in survival has been reported
What is myocarditis?
Inflammatory disease of the myocardium occuring in the absence of ischemia
How is myocarditis diagnosed
Diagnosed by established histological/immunological, and immunohistochemical criteria
Inflammatory cardiomyopathy definition
Myocarditis in association with cardiac dysfunction
Dallas criteria
WHO Marburg classification for acute myocarditis
Necrosis or degeneration is compulsory
Acute myocarditis epidemiology
- Age is around 20-51 years
- Slight preponderance in men
Laboratory studies to be performed in patients with myocarditis
- CBC to check for leukocytosis (may demonstrate eosinophilia)
- Elevated ESR or other APR such as CRP
- Rheumatological screening to rule out systemic inflammatory diseases
- Enzymes for cardiac myonecrosis (I or T and CKMB)
Troponin and CKM elevation in myocarditis
- Cardiac troponin I or T is elevated in at least 50% of patients with biopsy proven myocarditis
- CKMB is are elevated in only 5.7% of patients with biopsy proven myocarditis
Sensitivity and features of ECG for myocarditis
Sinus tachycardia with non specific ST segment and T wave abnormalities
Sensitivity Low at around 47%
Presence of Q waves or LBBB block is associated with higher rates of death or cardiac transplantation
Tissue characteristics of myocarditis on Cardiac MRI
- Edema
- Hyperemia and capillary leak (if done with myocardial early gadolinium enhancement)
- Necrosis and fibrosis (late gadolinium enhancement)
Myocarditis treatment
Viruses in myocarditis
