Right Ventricular Infarction

Right Ventricular Infarction Facts:

• Present in 30% of inferior AMIs.
• Isolated RV infarction is rare.
• Suggested by ST segment elevation >1 mm in V₄R.
• Adverse prognostic indicator.
• Reduced left sided filling pressures associated with systemic hypotension.

Right Ventricular Infarction Treatment:

• If patient is hypotensive - may require aggressive fluid resuscitation to maintain BP.
• RV end-diastolic pressure of 10-15 mm Hg has been associated with higher outputs than pressures lower or higher than this.[1]
• Inotropic therapy is indicated for RV failure when cardiogenic shock persists following optimization of RV end-diastolic pressure.[2]
• Persisting hypotension may warrant haemodynamic monitoring with a pulmonary artery catheter.
• Care must be taken passing a balloon catheter or pacing wire because of the increased risk of right ventricular perforation.
• Some evidence for the use of inhaled nitric oxide.[3]
• Obtaining early reperfusion - if patient presents within 6 hours of onset of inferior wall myocardial infarction with RV involvement there is a definite early survival benefit from thrombolytic therapy or coronary angioplasty.[4,5]

References:

• 1] - Claudia Dima et al. Right Ventricular Infarction (emedicine.medscape.com)
• 2] - Reynolds HR, Hochman JS. Cardiogenic shock: current concepts and improving outcomes. Circulation. Feb 5 2008;117(5):686-97.
• 3] - Inglessis I, Shin JT, Lepore JJ, Palacios IF, Zapol WM, Bloch KD, et al. Hemodynamic effects of inhaled nitric oxide in right ventricular myocardial infarction and cardiogenic shock. J Am Coll Cardiol. Aug 18 2004;44(4):793-8.
• 4] -Vesterby A, Steen M. Isolated right ventricular myocardial infarction. A case report. Acta Med Scand. 1984;216(2):233-5.
• 5] - Yoshino H, Udagawa H, Shimizu H. ST-segment elevation in right precordial leads implies depressed right ventricular function after acute inferior myocardial infarction. Am Heart J. Apr 1998;135(4):689-95.

Image: Right Ventricular Infarction (ECG)

Image Source: by Popfossa on flickr (cc)

Tags: AMI - Hypotension - Inferior MI - Nitric Oxide - Right Ventricular Infarction - RVEDP - V4R
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QTc Definition - Age and Sex Specific Criteria (Table)

QTc Definition - Age & Sex Specific Criteria (Table):

Reference: Ali A Sovari et al. (2010) Long QT Syndrome. (eMedicine Article)

Tags: Age - Definition - Long QT Syndrome - LQTS - QTc - Sex - Table

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Long QT Syndrome (LQTS) Diagnostic Criteria (1993) Table

Long QT Syndrome (LQTS) Diagnostic Criteria (1993) Table:

Legend:

* - In the absence of medications or disorders known to affect these electrocardiographic features.

† - QTc calculated by Bazett's formula where QTc=QT/RR(square root).

‡ - Mutually exclusive

§ - Resting heart rate below the second percentile for the age.

|| - Mutually exclusive

¶ - The same family member cannot be counted in A and B.

# - Definite LQTS is defined by an LQTS score of more than 3 (≥ 4).

Diagnostic Scoring:

• less than or equal to 1 point - low probability of LOTS.
• 2 to 3 points - intermediate probability of LOTS.
• > 4 points - high probability of LOTS.

Reference:

PJ Schwartz, AJ Moss, GM Vincent and RS Crampton. Diagnostic criteria for the long QT syndrome. An update. Circulation 1993;88;782-784

Tags: Bazett's formula - Congenital Deafness - Long QT Syndrome - LQTS - QTc - QT Interval - Stress - Sudden Cardiac Death - Sudden Death - Syncope - Torsade de Pointes - T-wave Alternans - Ventricular Tachyarrhythmias

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Romano-Ward Syndrome (LQT1 to LQT6)

Romano-Ward Syndrome Features:

• Major variant of long QT syndrome (abnormality on ECG - see opposite).
• Can lead to ventricular tachyarrhythmias.
• May lead to seizures, fainting, or sudden cardiac death.

Romano-Ward Syndrome Genetics:

• Inherited in an autosomal dominant pattern.
• Most common form of inherited long QT syndrome.
• Estimated to affect ~ 1 in 5,000 people, though may be more common than this because of non-symptomatic patients.
• 6 main forms noted (LQT1, LQT2, LQT3, LQT4, LQT5, LQT6).
• Associated with mutations in the ANK2, KCNE1, KCNE2, KCNH2, KCNQ1, and SCN5A genes.
• The proteins made by these genes lead to the proper formation of channels that transport positively-charged ions, such as potassium & sodium, in and out of cells.
• The ANK2 gene product has a function to ensure that proteins, particularly ion channels, are inserted into the cell membrane properly & appropriately.

Romano-Ward Syndrome Treatment:

• There is evidence that an imbalance between the right and left sides of the sympathetic nervous system may have a function in producing this symptomatic syndrome.
• A left stellate ganglion block, which shorten the QT interval, may redress this balance.
• In patients who respond to the stellate ganglion block may obtain lasting improvement with a surgical ganglionectomy.
• Drugs which prolong the QT interval should be avoided.
• Drugs which reduce serum potassium or magnesium should be avoided.
• Placement of an implantable cardioverter-defibrillator (ICD) is another treatment option in high risk patients.
• Competitive sport participation should be avoided for patients with the diagnosis established by means of genetic testing only.
• Beta-blocker therapy - ie propranolol or nadolol, reduce the risk or lethality of cardiac events.

Reference:

Ali A Sovari et al. (2010) Long QT Syndrome. eMedicine Article

Image: from Genotype and Severity of Long QT Syndrome. Jeffrey A. Towbin, Zhiqing Wang & Hua Li. © Drug Metabolism and Disposition (April 2001)

Tags: ANK2 - Beta-blocker - Ganglionectomy - ICD - KCNE1 - KCNE2 - KCNH2 - KCNQ1 - Long QT Syndrome - QT Interval - Romano-Ward Syndrome - SCN5A - Stellate Ganglion - Sympathetic Nervous System - Ventricular Tachyarrhythmias

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Continuous Positive Airways Pressure (CPAP) In Left Ventricular Dysfunction Acute Pulmonary Oedema

CPAP General Facts:

• Continuous positive airways pressure (CPAP).
• May be useful in the management of acute pulmonary oedema related to left ventricular failure.
• CPAP has both cardiac and pulmonary benefits.

CPAP Cardiac Benefits:

• Reduction in left ventricular (LV) preload.
• Reduction in mitral regurgitation.
• Improved ejection fraction.

CPAP Pulmonary Benefits:

• Increases functional residual capacity.
• Leading to an effective increase in alveolar surface area.
• Leading to improved oxygenation.
• Leading to reduced work of breathing.

CPAP Cautions:

• Hyperinflated chest
• Restrictive chest wall disease

Image: Acute Pulmonary Oedema by Jmh649 [CC-BY-SA-3.0)

Tags: Cardiac - CPAP - LV Dysfunction - Oxygenation - Pulmonary - Pulmonary Oedema
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Transient Constrictive Pericarditis

Transient Constrictive Pericarditis Clinical Features:

• Transient form of constrictive pericarditis lasting around 3 months.
• Approximately 2/rds of cases will have either a pericardial effusion or pericardial thinkening on echocardiography.
  

Epidemiology:

• Occurs in 10-20% of cases during the resolution of pericardial inflammation.

Investigation:

• Serial echocardiography.
• Inflammatory markers - ESR, CRP, WCC.
• ECG.
  

Pathophysiology & Aetiology:

• Occurring during or following acute pericarditis.
• May occur spontaneously.
• Commonly seen after empiric use of anti-inflammatory therapies.

Prognosis:

• Research evidence suggests that if constrictive findings are going to resolve, they will generally do so at an average time of three months.

Treatment & Management:

• Ensure there is absence of features suggesting chronicity - i.e. cachexia, atrial fibrillation (AF), liver dysfunction, or pericardial calcification).
• Assess for possible haemodynamic instability.
• If the patient is haemodynamically stable with no evidence of chronicity then a trial period (2-3 months) of conservative management with empiric anti-inflammatory therapy, or watchful waiting is recommended.
• Use NSAIDs for chest pain.
• Appropriate antibiotics for infection.
• Treat fluid retention with diuretics.
• Patients with worsening symptoms or clinical deterioration which is not responsive to medical treatment should be considered for early surgery (pericardiectomy).

References:
Haley, J. H. et al. Transient constrictive pericarditis: causes and natural history. J. Am. Coll. Cardiol. 43, 271-275 (2004).

Image: from Mystery To Medicine
Tags: Constrictive Pericarditis - Echocardiography - NSAID - Pericardiectomy - Pericarditis
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Open Heart Surgery Graphic

Open Heart Surgery Graphic:

Image: from TinyPic.com
Tags: Graphic - Heart - Open Heart Surgery - Pericardium - Retractor
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Medicalchemy Cardiology Blog

This Medicalchemy (TM) blog will be about Cardiology related topics.

Tags: Blog - Cardiology
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