Genetics, Syndromes & Miscellaneous

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Chapter 1: ECG J wave syndromes: hypothermia, early repolarization, hypercalcemia & Brugada syndrome

The J wave – also referred to as Osborn’s wave – is defined as a wave occurring at the J point (Figure 1). Conditions in which the J wave occurs may be referred to as J wave syndromes. J waves are typically most pronounced in the anterolateral (V3, V4, V5, V6) and inferior (II, aVF and III) leads. There are four principal causes of J waves, namely hypothermia, Brugada syndrome, early repolarization and hypercalcemia.

Figure 1. Osborn wave (J wave). These waves occur due to hypothermia, hypercalcemia, early repolarization and Brugada syndrome.

Early repolarization, Brugada syndrome and hypercalcemia are discussed separately. Please refer to these articles. ECG examples of each condition are presented below.

The ECG in Brugada syndrome

Brugada syndrome is a rare channelopathy (an electrical disorder caused by mutations in cardiac ion channels) which predisposes the individual to syncope, ventricular arrhythmias (ventricular tachycardia, ventricular fibrillation) and sudden cardiac death. There are three types of ECG manifestations, referred to as type 1, type 2 and type 3 Brugada syndrome. Refer to Figure 2 for ECG example of type 1 Brugada syndrome (note the large J waves in V2–V3).

Figure 2. Brugada syndrome. Note the gigantic J wave in V2 and V3. This may be confused with right bundle branch block. Paper speed 50 mm/s.

Type 1 Brugada syndrome reminds somewhat of right bundle branch block (RBBB) in leads V1–V3, but the QRS duration is not prolonged in leads V5–V6 (which is not consistent with RBBB, in which there must be wide QRS complexes). In type 1 Brugada syndrome, the ST segment elevation has a coved shape in V1, V2 or V3. The ST segment starts at the apex of the second R-wave and is downsloping. The T-wave is negative (inverted).

Early repolarization pattern

Early repolarization occurs in 5% to 10% of all males. It is less common among women (prevalence 2% to 4%). The condition has been recognized for decades, and it has been regarded as a benign form of ST segment elevation with slurring or notching at the J point. A notch at the J point is actually a J wave.

The term “early repolarization” was used to describe what appeared to be a premature repolarization on the ECG. As seen in Figures 3 and 4, the ST segment elevations are indeed associated with what appears to be an interruption in the QRS complex and initiation of repolarization. However, no study to date has been able to demonstrate that the repolarization is actually early and, moreover, this condition is associated with five times as great a risk of sudden cardiac death. The prefix “benign” must therefore not be used. The risk of sudden cardiac death is greatest if the early repolarization pattern occurs in the inferior limb leads (II, aVF and III).

ECG features of early repolarization

The ST segment elevations are concave and most pronounced in the chest leads. T-waves have high amplitude.

The hallmark of early repolarization is the end-QRS slurring or end-QRS notching (the notch is the J wave!).

Figure 3. Osborn waves (J waves) in a patient with early repolarization.

Figure 4. Osborn wave (J wave) in a patient with early repolarization. This patient was 31 years old when she died from sudden cardiac death.

References

An in-depth discussion regarding J wave syndromes is provided by Charles Antzelevitch. Note that Brugada syndrome and early repolarization are discussed separately here on ecgwaves.com.

Chapter 2: Brugada syndrome: ECG, clinical features and management

Pedro Brugada and his two brothers, Josep and Ramon, described this syndrome in 1992. The syndrome is characterized by a rather peculiar ECG and the patients experience syncope, life-threatening ventricular arrhythmias, cardiac arrest, or even sudden cardiac death. The Brugada brothers also noted that the syndrome – which was named the Brugada syndrome – appeared to be hereditary, since many patients reported a family history of the same symptoms and events. Perhaps the most distinguishing feature was the characteristic ST segment elevations in leads V1–V3.

Prevalence and genetics of Brugada syndrome

The prevalence of Brugada syndrome remains largely unknown. Available data suggest that it is most common in Asia, particularly Thailand. It is believed that the prevalence in Caucasian populations is approximately one in ten thousand individuals. Men are affected roughly ten times as often as women, and men also display the highest risk of experiencing malign ventricular arrhythmias.

Brugada syndrome is hereditary with an autosomal dominant inheritance pattern, meaning that only one mutated gene is necessary to develop the disorder. Till now (2016) more than 12 genetic mutations have been associated with the Brugada syndrome. These mutations are located in genes encoding potassium and calcium channels of the outer cell membrane.

Clinical presentation of Brugada syndrome

Most patients are asymptomatic until the age of 20 to 55 years. The disorder may manifest with any of the following symptoms:

Syncope, pre-syncope

Ventricular tachycardia

Ventricular fibrillation

Cardiac arrest with or without sudden cardiac death

Hence, the Brugada syndrome is a highly malignant disorder that must be recognized by any health care provider. A family history of any of the above-listed symptoms and manifestations must always raise suspicion of serious hereditary arrhythmias. Although clinicians are becoming increasingly aware of the Brugada syndrome, the diagnosis is still missed despite obvious clinical presentation.

It should be noted that the ECG features of Brugada syndrome are fairly specific to the disorder, provided that the clinical characteristics are in line with the disorder. There are however other disorders that may bring about similar ECG changes, and these are as follows:

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC/ARVD) – ARVC also tends to manifest in young adults and the most common symptoms are palpitations (prevalence 40%), syncope (30%), sudden cardiac death (15%), atypical chest pain (30%) and dyspnea (10%). The major ECG findings in ARVC are T-wave inversion in V1–V3 (in the absence of right bundle branch block); virtually all patients display this. The epsilon wave, which is much less common (one-third of patients), is defined as a wave occurring on the initial part of the ST segment.

Hyperkalaemia may cause ST segment elevations in V1–V3 that resemble those in Brugada syndrome. This disorder is easy to diagnose with a simple blood test and the ST segment elevations resolve after normalization of potassium levels.

Brugada-like ECG changes may occur transiently after electrical cardioversion.

Early repolarization also presents with J point elevation (as does Brugada syndrome, see below) and may also lead to syncope, ventricular arrhythmias, and even sudden cardiac death. However, the ECG changes in early repolarization are easy to separate from those in Brugada syndrome and the risk of ventricular arrhythmias and sudden cardiac death is considerably lower than the risk among patients with Brugada syndrome.

It follows that Brugada syndrome is a likely diagnosis in patients presenting with these symptoms and typical ST-segment elevations in V1–V3 (see below).

The characteristic ECG changes may be intermittent, which is why the diagnosis may be missed. For unknown reasons, the ECG changes, as well as arrhythmias and deaths, occur more frequently during rest, sleep, fever, and situations with high vagal tone. Interestingly, physical activity does not appear to provoke arrhythmias, which distinguishes Brugada syndrome from other channelopathies (e.g long QT syndrome (LQTS) and arrhythmogenic right ventricular dysplasia/cardiomyopathy (up to 80% may experience ventricular arrhythmias during physical exercise).

If Brugada syndrome is suspected, the ECG changes may be induced pharmacologically during controlled circumstances. Sodium channel blockers (ajmaline, flecainide) are administered intravenously, with defibrillator and resuscitation capabilities prepared, to produce the ECG changes. It should be noted that the list of drugs and disorders that may induce Brugada ECG (and thus the risk of arrhythmia) is much longer, and includes beta blockers, cocaine, hypercalcemia, etc. This list is continuously updated and maintained at www.brugadadrugs.org.

The ECG in Brugada syndrome

Figure 10. ECGs presenting Brugada syndrome type 1, type 2 and type 3, respectively.

Brugada syndrome ECG: criteria and definitions

The Brugada syndrome may present with three different ECG patterns, referred to as type 1, type 2, and type 2 Brugada syndrome ECG. The most typical, and diagnostic, is type 1 Brugada syndrome. It features large coved ST-segment elevations and T-wave inversions in leads V1–V3. The coved ST-segment elevations may resemble a shark tale. Refer to Figure 1, panel A. These ECG changes must not be confused with the right bundle branch block, as such a mistake may be devastating for the patient. Prospective studies show that type 1 Brugada syndrome has the strongest correlation with future risk of ventricular arrhythmias and cardiac arrest.

Note that the ECG changes are dynamic in patients with Brugada syndrome. Most patients have normal ECG during the majority of the time but they convert to the Brugada ECG patterns spontaneously. As noted above, certain drugs (www.brugadadrugs.org) and situations (sleeping, rest, fever) may also induce ECG changes. The patient may display all three types of Brugada ECG, even during the same ECG recording.

Type 1 Brugada syndrome: Coved ST segment elevation ≥2 mm which continues in T-wave inversion in lead V1 and/or V2. This pattern establishes a diagnosis of Brugada syndrome (i.e. no other examinations are warranted). Note that the electrodes to lead V1 and V2 may be placed in the second, third, or fourth intercostal space in the pursuit of these ECG changes. Refer to Figure 1.

Type 2 Brugada syndrome: Saddleback-shaped ST segment elevation with J point elevated ≥2 mm in leads V1 and/or V2. The terminal portion of the ST segment is elevated ≥1 mm.

Type 3 Brugada syndrome: Similar to type 2 criteria but the terminal portion of the ST segment is elevated <1 mm.

Note that it is allowed to record the 12-lead ECG with the electrodes of leads V1 and V2 placed in the second, third, or fourth intercostal space to maximize the probability of detecting the ECG changes. This maneuver is recommended in available consensus documents.

For type 2 and type 3 ECG patterns, a diagnosis of Brugada syndrome is only established if the patient converts to type 1 ECG pattern upon administration of class I antiarrhythmic drugs (this is tested in the electrophysiological laboratory, under controlled circumstances).

Screening for Brugada syndrome

It is motivated to screen family members of patients with Brugada syndrome. It is also motivated to acquire ECG in all patients whose clinical characteristics raise suspicion of Brugada syndrome. Currently, there are no other indications for screening.

Prognosis

The risk of syncope, life-threatening ventricular arrhythmias, cardiac arrest, and/or sudden cardiac death is very high in patients with Brugada syndrome. The risk is greatest during sleep, at rest, during fever, and in situations with high vagal tone. The ventricular tachycardia is polymorphic. Moreover, the risk is highest in patients displaying the type 1 ECG pattern. For unknown reasons, up to 20% of patients with Brugada syndrome develop supraventricular tachyarrhythmias, such as atrial fibrillation (AVNRT and WPW have also been described).

Treatment and management of Brugada syndrome

Some minor lifestyle changes are warranted. Excessive alcohol consumption is believed to be pro-arrhythmic and should therefore be avoided. The patient must not use any medication which may induce arrhythmias; the list of these drugs is extensive and a continuously updated list is available at www.brugadadrugs.org/drug-lists/.

ICD (Implantable Cardioverter Defibrillator) for Brugada syndrome

Prospective studies show that the use of ICD may be highly beneficial in selected cases of Brugada syndrome. The ICD prevents sudden cardiac death och thus increases survival. However, ICD is not indicated in individuals with asymptomatic Brugada syndrome (regardless of ECG pattern) because the risk of sudden cardiac arrest is very low.

An ICD should be considered in the following situations:

Patients who have survived cardiac arrest should have an ICD.

Patients with documented sustained ventricular tachycardia should have an ICD implanted.

Patients with type 1 Brugada ECG and a history of syncope may benefit from an ICD. An ICD should be considered.

Patients with inducible ventricular fibrillation during invasive provocation (stimulation during electrophysiological study) may benefit from an ICD. An ICD should be considered.

Hence, ICD is not indicated in asymptomatic individuals, regardless of ECG pattern. ICD is neither indicated based on the family history of events. However, when an ICD is under consideration, one should include family history in the risk stratification.

Quinidine (class I antiarrhythmic drug)

Quinidine reduces the incidence of ventricular arrhythmia in patients with Brugada syndrome. This drug may be considered in patients with 3 or more episodes of ventricular fibrillation or ventricular tachycardia within 24 hours. Quinidine should also be considered in patients who wish not to have an ICD or have contraindications for the use of an ICD.

References

Priori et al: Executive summary: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes.

Antzelevitch et al: Brugada Syndrome: Report of the Second Consensus Conference.

Chapter 3: Early repolarization pattern on ECG (early repolarization syndrome)

Although the early repolarization pattern has been recognized for almost 50 years, it is still one of the most frequently confused ECG findings. This is largely due to the fact that a universal definition of early repolarization is still lacking. Consequently, ECG criteria for early repolarization have varied over the years and across studies. This has lead to much confusion. In 2015 MacFarlane et al issued a consensus statement (refer to MacFarlane et al) and in 2016 Patton et al did likewise (refer to Patton et al). Surprisingly, the definition of early repolarization differs slightly in these two papers and the authors of this article decided to adopt the criteria from MacFarlane et al. However, the confusion actually extends beyond the ECG definition. For decades it was believed that early repolarization was a benign condition, which is why the term benign early repolarization was coined. This notion was overturned in 2008 when Haïssaguerre et al reported a strong association between the early repolarization pattern and sudden cardiac arrest due to idiopathic ventricular fibrillation. The combination of early repolarization pattern on ECG and ventricular fibrillation or sudden cardiac arrest is referred to as early repolarization syndrome.

Early repolarization pattern may actually not be due to early repolarization

The term “early repolarization” was used to describe the ECG pattern. Indeed, the ECG gives the impression that repolarization starts earlier than normal in these patients. However, it is still unknown whether that is actually the case; i.e repolarization may actually not start earlier than normal, despite the ECG appearance.

The epidemiology of the early repolarization pattern

The absence of a consensus definition of early repolarization has lead to variability in prevalence figures. Overall, prevalence estimates between 1% and 18% have been reported. In the consensus report by MacFarlane et al it was noted that roughly 5% to 13% of all individuals in a Western population display early repolarization pattern. It is more frequent among men, young individuals and blacks.

In a seminal paper published in 2008 by Haïssaguerre et al it was reported that early repolarization was associated with 3–5 times as great a risk of idiopathic ventricular fibrillation and sudden cardiac arrest. This is a rather large increase in relative risk, but the absolute risk is still very low among most patients with early repolarization.

Difference between relative and absolute risk

Readers not familiar with the terms absolute and relative risk may be confused by the previous paragraph. The absolute risk of an event (such as sudden cardiac arrest) is simply the number of individuals that experience the event divided by the number of individuals at risk. For example, if 3 individuals experience cardiac arrest in a population of 100 individuals, the absolute risk would be 3%. If 2 of those individuals were males and 1 was a female, then males would have two times as great a risk. Although two times the risk may seem very much, it only amounts to one extra case. So, even if the relative risk is high, the absolute risk can be low.

Mechanisms and pathogenesis of early repolarization

The biological mechanisms underlying the early repolarization pattern and the risk of ventricular fibrillation remain elusive. This is a rather complex topic that is only of relevance to researchers in electrophysiology and arrhythmology. Regarding the risk of ventricular fibrillation, it is believed that early repolarization is caused by altered ion channel function (alterations in sodium, potassium and calcium currents have been suggested). The altered ion channel function leads to regional dispersion in the refractoriness. This means that some myocardial regions will be refractory while others will be excitable at the same time. As previously discussed (refer to Reentry and arrhythmia mechanisms, as well as Mechanisms of atrial fibrillation) whenever there is varying excitability (conduction) in the myocardium, there is a risk fo re-entry occurring. Multiple re-entry circuits in the ventricles may cause ventricular fibrillation. Regarding the ECG hallmarks of early repolarization (ST segment elevation, notched or slurred end of the QRS), it is believed that these ECG changes are caused by voltage gradients between myocardial regions. Refer to Patton et al for details and references.

Genetic basis (heredity) of early repolarization

It is likely that the early repolarization pattern includes several subtypes, with varying heredity and risk of arrhythmia. The genetic basis of the condition proceeds from the fact that early repolarization pattern, as well as syndrome, is more frequent among relatives of individuals with early repolarization, as compared with control persons. Mutations in KCNJ8, SCN5A, among other genes, have been reported in patients with early repolarization. Yet, Sinner et al performed a meta-analysis that failed to identify any gene variants associated with early repolarization (Sinner et al). It is conceivable that the findings by Sinner et al are somewhat misleading because of the varying definitions of early repolarization in the data source used in the analysis. Genetic testing can currently only be recommended in selected cases with a presumed malignant form of early repolarization (i.e with very high risk of sudden cardiac arrest).

The early repolarization pattern on ECG

Early repolarization is frequently confused with other common causes of ST segment elevation and J wave syndromes. Because early repolarization is common and studies suggest that it is associated with an increased risk of sudden cardiac death, it is important that health care providers are able to recognize the ECG pattern. Failure to do so may lead to unnecessary referrals, examinations and interventions. Early repolarization manifests in the inferolateral leads (II, III, aVF, aVL, I, –aVR, V4, V5, V6) and it appears that the risk of ventricular fibrillation is highest when ECG changes are evident in the inferior leads.

Early repolarization are characterized by the following ECG changes:

ST segment elevations with concave ST segment. The ST elevations are most pronounced in the chest leads and they are accompanied by prominent T-waves. Virtually all patients with early repolarization display ST segment elevation.

The hallmark of early repolarization is the end-QRS notch (a notch in the J point) or the end-QRS slur (the final slurring part of the R-wave). Refer to Figure 1.

Figure 1. Early repolarization pattern on ECG. Note the end-QRS notches and slurs, as well as the ST segment elevations.

The end-QRS notch is located above the baseline and the end-QRS slur starts before the baseline is reached. As seen in Figure 1, the terms Jonset, Jpeak, Jtermination are used to describe the notch/slurring. However, these terms lack clinical significance. In the case of ST segment elevation, the magnitude of the ST segment elevation is always measured in Jtermination.

ECG criteria for early repolarization

According to MacFarlane et al:

Notch or slur in transition between R-wave and ST segment. ST-segment is virtually almost evident.

Jpeak ≥1 mm in at least two anatomically contiguous leads (V1–V3 are not considered).

QRS duration <120 ms.

Figure 2. Chest (precordial) leads showing early repolarization pattern. This patient’s brother died from sudden cardiac arrest at the age of 29. Note the incomplete right bundle branch block (RBBB).

Figure 2. Limb leads showing early repolarization pattern. This patient’s brother died from sudden cardiac arrest at the age of 29.

Risk stratification

The strongest risk factor of ventricular fibrillation is signs of early repolarization in leads II, III and aVF (i.e inferior limb leads). It also appears that the higher the J point the greater the risk of ventricular fibrillation. Some studies also suggest that the slope of the ST segment may be of relevance; a horizontal or downsloping ST segment has been associated with a greater risk of ventricular fibrillation, as compared with an upsloping ST segment.

Management and available treatments

Early repolarization pattern on ECG does not require any treatment. Treatment with ICD (implantable cardioverter-defibrillator) may be considered in patients who have experienced ventricular fibrillation or sudden cardiac arrest.

Chapter 4: Takotsubo cardiomyopathy (broken heart syndrome, stress induced cardiomyopathy)

Takotsubo cardiomyopathy (broken heart syndrome) is a rather peculiar and certainly acute condition. Much research has been devoted to it in recent years. Most cases (70%) of takotsubo cardiomyopathy occur in situations with extreme stress, such as car accidents, gun violence, threats, or any situation in which the individual’s life is (or perceived as it is) in danger. Takotsubo cardiomyopathy is much more common in women (70% are women) and elderly individuals.

Clinical characteristics and ECG changes in takotsubo cardiomyopathy

The typical patient presents with severe chest pain, dyspnea and occasionally hemodynamic compromise. The ECG shows localized ST segment elevations, T-wave inversions and occasionally pathological Q-waves. Troponin levels are often mildly elevated. Hence, takotsubo cardiomyopathy cannot be differentiated from ST segment elevation myocardial infarction.

Due to their clinical presentation, these patients are immediately referred to angiography but no coronary artery occlusion can be identified. Injection of contrast media into the ventricle will instead reveal that the apical portion of the left ventricle is dilated (hence the term apical ballooning syndrome). This syndrome was first descried in 1991 in Japan and the authors termed it takotsubo, which is the Japanese word for a kind of octopus trap (the left ventricle takes the shape of that octopus trap). Refer to Figure 1 and Figure 2.

Figure 1. Echocardiogram showing takotsubo cardiomyopathy in acute phase (A) and resolution phase (B). Note the apical ballooning of the apical portion fo the left ventricle (A). Source.

Figure 2. Left ventriculography during systole showing apical ballooning akinesis with basal hyperkinesis in a characteristic takotsubo ventricle.

Studies from the US and Japan has estimated that up to 2% of patients referred to PCI with a suspicion of STE-ACS/STEMI, actually have takotsubo. Previous studies reported that 98 out of 100 cases had full recovery. More recent studies has reported mortality rates reaching 4%.

ECG in takotsubo cardiomyopathy (broken heart syndrome)

80% of patients have localized ST segment elevations (mostly in the chest leads). The morphology of the ST segment elevations cannot be differentiated from those seen in STEMI/STE-ACS.

64 % have T-wave changes (mostly inversions) accompanying the ST segment elevations.

32% have pathological Q-waves.

Although several criteria has been suggested, the ECG cannot distinguish takotsubo cardiomyopathy from STE-ACS/STEMI (Johnsson et al Int J Cardiol, 2011). Therefore, these patients must be managed as STE-ACS/STEMI until angiography has been performed. Note that troponins may be elevated but the elevation is typically discrete and not on a par with the degree of left ventricular impairment.

Pathophysiology of takotsubo cardiomyopathy (broken heart syndrome)

This topic is still under investigation. A number of plausible mechanisms have been suggested. Among them are coronary artery vasospasm, dysfunctional capillary function and catecholamine toxicity. The latter theory is corroborated by the finding that 75% of patients have increased plasma levels of catecholamines.

References

A recent consensus document has been issued by the European Society for Cardiology:

Lyon et al: Current state of knowledge on Takotsubo syndrome: a Position Statement from the Taskforce on Takotsubo Syndrome of the Heart Failure Association of the European Society of Cardiology.

Chapter 5: Pericarditis, myocarditis & perimyocarditis: ECG, criteria & treatment

The pericardium is a double-walled sac in which the heart and the roots of the great vessels are contained (Figure 1). The pericardial sac encloses the pericardial cavity which contains pericardial fluid. Numerous conditions may cause inflammation in the pericardium, the pericardial cavity and/or the myocardium. Pericarditis refers to inflammation of the pericardium, and myocarditis refers to inflammation of the myocardial (muscle) tissue. However, it is often difficult to differentiate pericarditis and myocarditis, and they tend to accompany each other. Therefore, the term perimyocarditis is often used in clinical practice (this article will use all three terms interchangeably). The etiology, clinical characteristics and ECG features of pericarditis will be discussed here. From a clinical point of view, clinicians must be able to separate pericarditis from ST elevation myocardial infarction (STEMI). This may not always be simple, because both conditions bring about severe chest pain and ST elevations on the ECG. However, as we will discuss below, it is actually rather straightforward to distinguish these two conditions.

Figure 1. The pericardial sac and the myocardium. Note that pericarditis (inflammation of the pericardial sac) is difficult to discern from myocarditis (inflammation of the myocardial tissue) and because they tend to accompany each other, the term perimyocarditis is often used. Image by Bruce Blausen, Blausen Gallery 2014.

Causes of acute pericarditis/myocarditis

The most frequent cause of pericarditis is infections, in particular viral infections. This explains why pericarditis may affect individuals of all ages. However, a wide range of local and systemic conditions may cause pericarditis. The most common causes are as follows:

Rheumatoid arthritis (RA)

Systemic Lupus Erythematosus (SLE)

Acute myocardial infarction (AMI)

Post-infarction (including Dressler syndrome)

Uremia

Radiation to the heart

Trauma

Tuberculousis

Neoplasms (cancer)

Post cardiac surgery (hemorrhagic pericarditis).

Symptoms of acute pericarditis/myocarditis

There are two forms of pericarditis: acute and chronic. This article will focus on the former, as it has implications for all clinicians and the ECG.

Acute pericarditis causes chest pain, which may be very difficult to discern from pain caused by acute myocardial infarction. The chest pain in acute pericarditis may be severe and the patient may also experience cold sweats, tachycardia and anxiety; all of which are common in acute myocardial infarction. Clinical examination may reveal pericardial friction rub and the echocardiogram may show increased fluid in the pericardial cavity (pericardial effusion). Hemodynamic compromise may occur if accumulation of fluid in the pericardial sac compromises the relaxation and/or contraction of the ventricles and atria. This situation is referred to as cardiac tamponade, which has been discussed earlier.

Differentiating acute pericarditis and acute ST elevation myocardial infarction (STEMI)

The retrosternal chest pain caused by acute pericarditis may be very similar to that seen in patients with STEMI. Moreover, the pain in acute pericarditis may also, as in STEMI, radiate to the neck, shoulders or back. However, acute pericarditis is more likely if inspiration and supine position worsens the chest pain, and sitting upright and leaning forward alleviates the chest pain; the pain in STEMI is unaffected by position. Nevertheless, the retrosternal chest pain in acute pericarditis is very similar to that in STEMI.

The combination of retrosternal chest pain and ST elevation on ECG explains why clinicians often confuse acute pericarditis and STEMI. This is further complicated by the fact that acute myocarditis may cause elevated troponin levels (myocardial cells may die as a result of inflammation).

Note two differences regarding the clinical presentation of STEMI and acute pericarditis:

Acute pericarditis tends to affect younger individuals.

The most common cause of pericarditis is infections, which is why many patients may report symptoms consistent with viral infections (particularly in the preceding days).

The ECG in acute pericarditis (myocarditis)

The ECG is highly effective in differentiating pericarditis from STEMI. Figure 2 displays an example of perimyocarditis. ECG features are discussed below.

Figure 2. The ECG in acute pericarditis (myocarditis, perimyocarditis). As evident there are generalized ST segment elevations. There are no reciprocal ST segment depressions and no simultaneous T-wave inversions (negative T-waves).

ECG changes in acute pericarditis, myocarditis, perimyocarditis

The ECG is used to diagnose acute pericarditis. One must always rule out the most serious differential diagnosis, which is ST elevation myocardial infarction (STEM). In order to provide the reader with knowledge on this matter, we will now discuss the characteristics of all ECG changes seen in acute pericarditis, and contrast them to ECG changes seen in STEMI.

ST elevations in acute pericarditis

ST elevations in acute pericarditis are generalized, which implies that they occur in most ECG leads (both limb leads and chest leads). Indeed, whenever a patient presents with chest pain and generalized ST elevations, one must always suspect acute pericarditis.

Lead V1 is typically spared from ST elevation (i.e lead V1 does usually not show any ST elevation).

The ST segment is typically concave (read about ST segment elevations). There may be a notch in the J-point (which can be seen in leads V4 and V5 in Figure 2).

The magnitude of the ST elevation is typically <4 mm high.

There are no reciprocal ST depressions.

ST elevations and T-wave inversions do not occur simultaneously.

ECG changes in pericarditis are rather static and changes slowly over the course of several days to weeks.

Characteristics of ST elevations in STEMI

ST elevation myocardial infarction (STEMI) causes localized ST elevations, meaning that there are ST elevations in a few leads which are anatomically neighbouring (so called contiguous leads). For example, inferior STEMI causes ST elevations in leads II, III and aVF.

The ST segment is typically straight or convex (read about ST segment elevations).

Reciprocal ST segment depressions are very typical of STEMI.

ST elevations and T-wave inversions may occur simultaneously in STEMI.

The magnitude of the ST elevation may be considerably higher than 4 mm.

ECG changes are dynamic in STEMI. For example development of pathological Q-waves, changes in the magnitude of the ST elevation, T-wave inversion etc, may change within minutes to hours.

Note, however, that in some (rare) cases of acute myocarditis, ST elevations may be localized. This results in a situation in which it is very difficult to rule out STEMI on basis of the ECG.

T-wave inversions (negative T-waves)

ST elevations are normalized slowly in pericarditis. It may take weeks for the ST elevations to resolve. Thereafter, T-wave inversion typically ensues. The T-wave inversion may be discrete and lasts for one month. As mentioned above, ST elevations and T-wave inversions do not occur simultaneously in pericarditis. More: Inverted (negative) T-waves.

The PR segment elevation and depression

The PR segment is not affected in STEMI, whereas acute pericarditis often causes PR segment depression. Such depressions occur in most leads, except from lead V1, which often shows PR segment elevation.

Troponin leakage in acute pericarditis

Elevated troponins are common in acute pericarditis. M. Imazio et al (Cardiac troponin I in acute pericarditis; JACC 2003) showed that one third of patients had troponin elevations; in total, 8% had significantly elevated troponin levels. However, there was no association between troponin level and survival.

Below follows an ECG example of a patient with acute pericarditis. Note that the ECG changes are rather subtle.

Figure 3. Chest leads of patient with acute pericarditis. Note the ST segment elevations, concave ST segments.

Figure 4. Limb leads of patient with acute pericarditis. Note the very discrete, but generalized, ST segment elevations, concave ST segments.

Chapter 6: Eletrical alternans: the ECG in pericardial effusion & cardiac tamponade

The pericardial space (cavity) always contains a small amount of serous fluid which acts as a lubricant that prevents friction during ventricular contraction and relaxation. Pericardial effusion is the presence of an abnormal amount of fluid in the pericardial space. It can be caused by numerous local and systemic disorders. Accumulation of fluid in the pericardial space may lead to increased intrapericardial pressure, which in turn affects ventricular relaxation (and thus ventricular filling). This may even lead to compression of the ventricles during diastole; cardiac tamponade occurs if excess pericardial fluid causes hemodynamic effects. Electrical alternans – i.e the beat-to-beat variation i electrical amplitude – is the ECG hallmark of cardiac tamponade.

Causes of pericardial effusion and cardiac tamponade

The most common cause of pericardial effusion is infections, such as viral, bacterial, and tuberculous infections.

Post-pericardiotomy syndrome.

Acute transmural myocardial infarction.

Rupture of the free ventricular wall.

Neoplasms (particularly breast and lung cancer).

Inflammatory conditions, such as rheumatoid arthritis, systemic lupus erythematosus, scleroderma, and rheumatic fever.

Aortic dissection rupturing into the pericardium.

Idiopathic pericardial effusion.

Renal failure, hypothyroidism, and hypercholesterolemia.

Dressler syndrome.

Iatrogenic damage to the pericardium.

Irradiation.

Trauma.

The most common cause of pericardial effusion is pericarditis. Because it is difficult to determine if there is also myocarditis (which is frequent), it is common to use the term perimyocarditis.

Hemodynamic effects of pericardial effusion and cardiac tamponade

Intrapericardial pressure increases as fluid accumulates in the pericardial space. Intrapericardial pressure may reach the point where the ventricles and atria can no longer relax normally, and the ventricles may even be compressed during diastole. This causes adverse hemodynamic effects, and the condition is classified as cardiac tamponade. The classical signs of cardiac tamponade are hypotension, muffled heart sounds and jugular venous distention. Other frequent symptoms are pulsus paradoxus, pericardial friction sounds, tachycardia, tachypnea, weakened peripheral pulses, edema, cyanosis. Cardiac tamponade is seen in Video 1.

Video 1. Cardiac tamponade. The heart is surrounded by fluid (black) and swings back and forth in the fluid. One can also note that the right ventricular free wall is being compressed by the fluid. Video source.

ECG changes caused by pericardial effusion and cardiac tamponade

Small amounts of pericardial effusion may not cause any ECG changes. Significant pericardial effusion may bring about the following ECG changes.:

Low voltage: large amounts of pericardial effusion will diminish the QRS amplitudes.

Electrical alternans: The amplitude of the QRS complexes vary from one beat to another (in the same lead). This is due to the swinging back and forth of the heart in the pericardial space. Note that tachycardia, pulmonary embolism and ischemia may also cause electrical alternans.

PQ segment depression.

Sinus tachycardia.

Refer to Figure 1.

Figure 1. Electrical alternans in patient with cardiac tamponade. The ECG shows varying QRS and T-wave amplitudes.

Chapter 7: Long QT Syndrome (LQTS)

Please refer to the previous chapter: LQTS (Long QT Syndrome)

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