View source for Effects of clinical disorders on ECG

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==Medication==
===Digoxin===

ECG changes typical for digoxin intoxication (digoxin = Lanoxin) are:
*odd shaped ST-depression. 
*T-wave flat, negative or biphasic
*Short QT interval
*Increased u-wave amplitude
*Prolonged PR-interval
*Brady-arrhytmias:
**Sinus bradycardia
**AV block. Including complete AV block and Wenkebach.
*Tachyarrhythmias:
**Junctional tachycardia
**Atrialtachycardia
**Ventricular ectopia, bigemini, monomorphic ventricular tachycardia, bidirectional ventricular tachycardia

Intoxication can lead to a SA-block or AV-block, sometimes in combination with a tachycardia. '''NB''' these effects are increased by hypokaliemia. In extreme high concentrations rhythmdisturbances (''ventricular tachycardia, ventricular fibrillation, atrial fibrillation'') may develop.
[[Image:Digitalis Toxicity1.jpg|thumb|250 px| center|Digitalis toxicity - Irregular heart rate, Absent P waves; ST depression in lateral leads V<sub>5</sub> V<sub>6</sub> with T wave inversions]]

===Anti-arhythmics===
* '''anti-arhythmics:''' These may lead to several ECG-changes;
**broad and irregulair P-wave
**broad QRS-complex
**prolonged QT-interval (brady-, tachycardia, AV-block, ventricular tachycardia)
**prominent U-wave
**In case of intoxication, the above mentioned characteristics are more prominent

Additionally, several arrhtythmias can be seen.

=== Nortriptyline intoxication ===
[[Image:ECG_nortr_intox.png|thumb| An example of severe nortriptyline intoxication. The inhibitory effect of the sodiumchannel manifests as a broadened QRS complex and a prolonged QT interval.]]
[[Image:ECG_TCA_intox.jpg|thumb| Another example of severe nortriptyline intoxication.]]
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=== Amitriptyline intoxication ===
[[Image:ECG_amitr_OD_during.jpg|thumb| An example of a severe amitriptylin intoxication. The inhibitory effect of the sodiumchannel manifests as a broadened QRS complex.]]
[[Image:ECG_amitr_OD_before.jpg|thumb| An ECG of the same patient before the intoxication.]]

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==Pericarditis==
[[Pericarditis]]

==Myocarditis==

[[w:Myocarditis|Myocarditis]] is an inflammation of the myocardium and the interstitium. The symptoms are faint chestpain, abnormal heartrate and progressive heartfailure. It can be caused by several factors: viral, bacterial, fungi, parasites, spirochaet, auto-immune, borreliosis (Lyme's disease) and HIV/AIDS. 

Acute peri/myocarditis causes aspecific ST changes. These can be accompanied with supraventricular and ventricular rhythmdisturbances and T-wave abnormalities.

==Pulmonary embolism==
See the chapter [[Pulmonary Embolism]]

==Chronic pulmonary disease pattern==
The ECG shows low voltaged QRS-complexes in leads I, II, and III and a right axisdeviation. This is caused by the increased pressure on the right chamber. This leads to right ventricular hypertrophy.

==Pacemaker==
See the chapter [[Pacemaker]]

==Tamponade==
[[Image:PulsusAlternans.jpg|thumb]]
In case of a tamponade, fluid collects in the pericardium. As the pericardium is stiff, the heart is compressed resulting in relaxation, and thus, filling difficulties. This is a potential life-threatening situation and should be treated with pericardiocenteses, which is drainage of the fluid. Tamponade can be the results of pericarditis or myocarditis. Also, after a myocardial infarction a tamponade may develop, this is called Dresslers' Syndrome. In case of cancer, pericardial fluid may develop. This is usually caused by a Pericarditis carcinomatosa, meaning that the cancer has spread to the pericardium

The ECG shows:
*Sinus tachycardia
*Low-voltaged QRS complexes [[microvoltages]]
*Alternation of the QRS complexes, usually in a 2:1 ratio. Electrical alternans can also be seen in myocardial ischemia, acute pulmonary embolism, and tachyarrhythmias
*PR segment depression (this can also be observed in an [[Ischemia#Atriaal_.2F_boezem_infarct|atrial infarction]])
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==Ventricular Aneurysm==
The ECG pattern suggests an acute MI. All classical signs of MI may occur:; Q-waves, ST-elevations (>1mm, >4 weeks present)and T-wave inversions are present. To exclude an acute MI, comparison with old ECG's is compulsory (MI has occurred years before).

==Dilated Cardiomyopathy==
Often, a LBBB or broadened QRS-complex can be seen. Additionally, aspecific ST changes are present with signs of left atrial enlargement.

==Hypertrophic Obstructive Cardiomyopathy==
A HOCM is an heditary illness.
On the ECG there are signs of [[hypertrophy|left ventricular hypertrophy]] and [[P wave morphology|left atrial enlargement]].

==Electrolyte disturbances==
See chapter: [[electrolyte disturbances]]

==Hypothermia==
In hypothermia a number of specific changes can be seen;<cite>hypoth</cite>
* sinubradycardia
* prolonged QTc-interval
* ST-elevation (inferior and left precordial leads)
* Osborne-waves (slow deflexions at the end of the QRS-complex)

[[Image:osborne.gif|thumb| An Osborne J wave]]
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==ECG changes after neurologic events==
[[Image:ECG_SAB.png|thumb| ECG of a 74 year old patient with a subarachnoid hemorrhage. Note the negative T-waves and the prolonged QT interval.]]
In 1938, Aschenbrenner <cite>Aschenbrenner</cite> noted that repolarisation abnormalities may occur after increased intracranial pressure. Since then, many publications have occurred discribing ECG changes after acute neurological events.

De ECG changes that may occur are: 
*q-waves
*ST-elevations, 
*ST-depressions, 
*T-wave changes. Large negative T waves over the precordial leads are observed frequently.
*prolonged QT-interval.
*prominent u-waves.

These abnormalites are frequently seen after [[w:Subarachnoid_hemorrhage|subarachnoid_hemorrhage (SAH)]] (if measured serially, almost every SAH patients has at least one abnormal ECG.), but also in [[w:Subdural_haematoma|subdural haematoma]], ischemic [[w:Cerebrovascular_accident|CVA]]'s, [[w:Brain_tumor|brain Tumors]], [[w:Guillain-Barre|Guillain BarrÃ©]], [[w:Epilepsy|epilepsy]] and [[w:Migraine|migraine]]. The ECG changes are generally reversible and have linited prognostic value. However, the ECG changes can be accompanied with myocardial damage and echocardiographic changes. The cause of the ECG changes is not yet cl;ear. The most common hypothesis is that of a neurotramittor "catecholaminestorm" caused by sympathtic stimulation.

==Cardiac contusion==
Cardiac contusion (in latin: contusio cordis or commotio cordis) is caused by a blunt trauma to the chest, often caused by a car- or motorbikeaccident or in martial arts<cite>Maron</cite>. Rhythmdisturbances may occur and even heartfailure. Diagnosis is made using echocardiography and laboratorytesting for cardiac enzymes. 
Possible ECG changes are:<cite>Sybrandy</cite>

'''Not-specific changes'''
*Pericarditis-like ST elevation or PTa depression
*Prolonged QT interval
'''Myocardial damage'''
*New Q waves
*ST-T segment elevation or depression
'''Conduction delay'''
*Right bundelbranchblok
*Fascicular blok
*AV delay(1st, 2nd, and 3rd degree AV blok)
'''Arrhythmias'''
*Sinustachycardia
*Atrial and ventricular extrasystoles
*Atrial fibrillation
*Ventricular tachycardia
*[[Arrhythmias#Ventricular fibrillation|Ventricular fibrillation]]
*Sinusbradycardia
*Atriala tachycardia

==Lown Ganong Levine Syndrome==
The Lown Ganong Levine Syndrome is a pre-excitation syndrome in which the atria are connected to the lower part of the AV node or bundle of His. On the ECG:
* short PR interval, < 120 ms
* normal QRS complex
* no delta wave
==Left and right bundle branch block==
See: [[Conduction_delay|Conduction delay]]

==References==
<biblio>
#Sybrandy pmid=12695446
#Rodger pmid=11018210
#Ferrari pmid=9118684
#Aschenbrenner Aschenbrenner R, Bodechtel G, ''Ãber Ekg.-VerÃ¤nderungen bei Hirntumorkranken''. Journal of Molecular Medicine, 17, 9, 2/1/1938, Pages 298-302, http://dx.doi.org/10.1007/BF01778563
#Maron pmid=14681516
#hypoth pmid=2738372
</biblio>

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