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Archive for the ‘Cardiology’ Category

Disorders of lipid metabolism

Posted by iskanbasal on March 27, 2009

Or disorders of lipoprotein metabolism. I studied for this subject some chapters from important textbooks of medicine:

1. Chapter 350 from the Harrison’s principles of internal medicine. Clinically is the most comprehensive on the subject, either the description of  diseases of lipid metabolism or the approach to treatment.

2. Chapter 217 from Cecil medicine. Same as the above particularly when telling the physiopathology and the role of nuclear factors such as the PPARalpha, PPAR?, and PPARd in the regulation of lipids in the human body.

3. Chapter 21 “hyperlipidemias” from the Lippincott’s illustrated reviews: pharmacology 4th ed. a good rapid and concise review on the drugs used here.

4. Chapter 5 Tests of lipid metabolism from the Wallach interpretation of diagnostic tests. Excellent tables on this subject from the Adult Treatment Panel III guidelines.

One of the most useful paragraphs on the subject is that where the Harrison’s describes the diagnostic process. Now I should consider the lab results and divide them in categories. The critical first step in managing a lipid disorder is to determine the class or classes of lipoproteins that are increased or decreased in the patient. I might have Lab results showing only increased levels of tryglicerides or only increased levels of LDL-cholesterol and think about the differential diagnosis in each situation. But the most common error in the diagnosis and treatment of lipid disorders occurs in patients with a mixed hyperlipidemia without chylomicronemia. This occurs with increased levels of both cholesterol and tryglyceride which may indicate TypeIII (increased IDL levels) or Type IIb( increased LDL and VLDL) or TypeIV ( increased VLDL levels). Analysis of lab tests is very important to distinguish between the different situations. I also considered the secondary causes of lipid disorders: obesity, Diabetes mellitus, thyroid diseases, renal diseases, liver disorders, alcohol, and endocrine disorders but particularly the role of hyperlipidemia as a major risk for Coronary heart disease. Actually the tests of lipid metabolism ( my initial interest in this subject) has two important objectives:

1. to assess risk of atherosclerosis, especially Coronary heart disease

2. to classify hyperlipidemias.

I reviewed all the other risk factors for coronary heart disease(CHD) and understood the importance in calculating the atherogenic risk in a general practice setting. What I’m doing is to try to build the good and necessary clinical knowledge (CK) that one needs.

Posted in Cardiology, Lab | Tagged: , , , | Leave a Comment »

Variability is the law of life

Posted by iskanbasal on March 21, 2009

Sir William Osler said, “Variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions which we know as disease.”

This statement is cited in the article about the new , precise definition of acute myocardial infarction which I already posted below. The authors Shaun Senter MD and Gary S. Francis MD describe the wide variety of presentation of myocardial infarction and explain the need to make precise diagnosis before taking action. I read the article and learned new things in this subject. When studying a certain condition on my textbooks I try to keep in mind the most important clinical features that describe it and make a single picture of the disease but I should also be aware to the variability of presentation of a pathological condition. It might be that this variability depends on the extent to which tissues and organs are involved in a certain disease  or to the way a patient’s organism responds depending on their age, sex or other factors; I’m not sure but this what I think could be. The autors review the current criteria that is established by international cardiovascular societies for making diagnosis of MI:

“The cornerstone of diagnosis remains a high level of clinical suspicion, serial ECGs, and troponine” they say. Particulary the focus on the role of troponine. There is also a clinical classification of MI in five different types.

Read the article here.

Recently I studied some chapters on the Jacques Wallach Interpretation of diagnostic tests, 8th ed and I found very good tables for the interpretation  of biomarkers in this context, one about the characteristics of serum markers for MI is this :

Early appearance: Myoglobin, CK isoforms, glycogen phosphorylase isoenzyme BB, heart fatty acid-binding protein
High specificity: cTnI, cTnT, CK-MB, CK isoforms
Wide diagnostic window: cTnT, cTnI, LD, myosin hight and heavy chains
Risk stratification: cTnT, cTnI, CK-MB
Predicts reperfusion: Myoglobin, cTnI, cTnT, CK isoforms
Indicates reinfarction after 2–4 d: CK-MB

The Wallach’s textbook confirm the possibility of false-positive ECG in >10% to 20% of AMI cases in the ED and nondiagnostic in about 50%. But here there is an additional note about newer biomarkers being studied as independent predictors of cardiac risk which I did not know before such as The ischemia-modified albumin and others.

I’d like, here below, to summarize  only the clinical features of MI which describe the clinical variability of the condition cited in the article  above:

.

  • the presentation of myocardial infarction varies from 25% of patients with no symptoms to patients with severe, crushing chest pain.
  • Discomfort may occur in the upper back, neck, jaw, teeth, arms, wrist, and epigastrium and it build up in a crescendo manner. It can lessen in the standing position. A pressure sensation, air hunger, or gas “building up” can be described.
  • Shortness of breath, diaphoresis, nausea, vomiting and even syncope may occur.
  • The only symptoms may be shortness of breath and diaphoresis
  • symptoms last from minutes to hours and can be releived by sublingual nitroglycerin.
  • Atypical presentaion or less prominent symptoms may make the diagnosis difficult in the elderly and in patients with diabetes, and in women.
  • On physical exam the patient may appear pale and diaphoretic and the skin cool. Heart sounds are soft and a fourth heart sound may be audible. BP may be low and tachycardia and pulmonary edema are poor diagnostic features.

Posted in Cardiology | Tagged: , , , | Leave a Comment »

Primary Prevention Of Atherosclerotic Heart Disease: New Data from the AHA

Posted by iskanbasal on March 12, 2009

Thanks to KevinMd where I got information about reachMd radio. Actually it is a good educational site, there are many prog to follow and I just finished my first act of listening to an interesting program on the primary prevention of atherosclerotic heart disease and got a CME 0.25 credit. As only a medical student I only wanted to listen and develop a little my english and also get new important information directed to general practice. The clinical researcher discussed in this activity the results of a trial  in which patients with a normal level of cholesterol= 130mg/dL but with high levels of C reactive protein called CRP (which is considered an important risk factor for CAD) took a statin to prevent the occurence of cardiac events. The trial resulted in a 44% reduction in cardiovascular events and was stopped early because the benefits were very evident.   

Primary Prevention Of Atherosclerotic Heart Disease: New Data from the AHA

Listen here.

Posted in Cardiology | Tagged: , , , | Leave a Comment »

A new, precise definition of acute myocardial infarction

Posted by iskanbasal on March 5, 2009

This article from the Cleveland clinic journal of medicine discusses very important issues in the diagnosis and differential diagnosis of Myocardial infarction.

Read the article here

“Several international cardiovascular societies have revised their diagnostic criteria for acute myocardial infarction (MI) (J Am Coll Cardiol 2007; 50:2173–2188). The cornerstone of diagnosis remains a high level of clinical suspicion, serial electrocardiograms, and troponin levels. This article reviews the new definition and the appropriate clinical tools necessary to diagnose acute MI accurately”

KEY POINTS The clinical presentation of acute MI varies considerably from patient to patient. Therefore, one must consider the symptoms, serial electrocardiographic findings, and serial biomarker results in concert.

KEY POINTS Troponin I or T is now the preferred biomarker of myocardial necrosis. Still, troponin can be elevated in many conditions other than ischemic heart disease.

KEY POINTS Electrocardiographic signs of acute ischemia have been precisely defined, but electrocardiography can give false-positive or false-negative results in a number of conditions.

KEY POINTS MI is now categorized into five types depending on cause.

Posted in Cardiology | Tagged: , , | 2 Comments »

When high is low: Raising low levels of high-density lipoprotein cholesterol

Posted by iskanbasal on January 21, 2009

This is an interersting article to read on this subject, low levels of HDL-C as a risk factor for cardiovascular disease and how to raise them. Thanks to MDLinks.

Low serum levels of high-density lipoprotein cholesterol (HDL-C) are highly prevalent and are recognized as an independent risk factor for cardiovascular morbidity (myocardial infarction, stroke, peripheral arterial disease, and restenosis after coronary stenting) and mortality. HDL plays an important role in modulating atherogenesis, although its functions are varied and complex and the mechanisms for its antiatherogenic effects have not been completely elucidated. The inverse relationship between HDL-C and cardiovascular risk is well established, and epidemiologic studies and clinical trials have provided ample evidence that higher levels of HDL-C are vasculoprotective. Although considerable interest exists in the development of novel approaches to raise serum HDL-C and to augment HDL functionality, this article discusses currently available therapies to raise suboptimal levels of this important lipoprotein.

The article is cited:

Journal Title  – Current Cardiology Reports
Article Title  – When high is low: Raising low levels of high-density lipoprotein cholesterol
Volume  – Volume 10
Issue  – 6
First Page  – 488
Last Page  – 496
Issue Cover Date  – 2008-11-01

Author  – Peter P. Toth
DOI  – 10.1007/s11886-008-0077-2
Link  – http://www.metapress.com/content/b7xk865071252854

Posted in Cardiology | Tagged: , | Leave a Comment »

Concepts in Cardiovascular Physiology

Posted by iskanbasal on December 23, 2008

From Cardiovascular Physiology by David  E. Mohrman:

“A common misconception in cardiovascular physiology is that the systolic pressure alone or the diastolic pressure alone indicates the status of a specific cardiovascular variable. For example, high diastolic pressure is often taken to indicate high total peripheral resistance. This is not necessarily so since high diastolic pressure can exist with normal (or even reduced) total peripheral resistance if heart rate and cardiac output are high. Both systolic pressure and diastolic pressure are influenced by heart rate, stroke volume, total peripheral resistance, and CA ( compliance). The student should not attempt to interpret systolic and diastolic pressure values independently. Interpretation is much more straightforward when the focus is on mean arterial pressure:

PA = CO x TPR and arterial pulse pressure: Pp= SV/CA.”

I really always thought the diastolic pressure as indicator of the total peripheral resistances, which is a specific cardiovascular variable, without thinking about it in the way the author is explaining it in the above piece.

Some more concepts:

“Turbulent blood flow is abnormal and makes noise (murmurs and bruits)”.

(the normal blood flow is the laminar one)

“Veins contain most of the total blood volume”.

“Because arteries are elastic, the intermittent flow from the heart is converted to continuous flow through capillaries.”

“Mean systemic arterial pressure is determined by the product of cardiac output and total peripheral resistance.”

“Changes in arterial pulse pressure reflect changes in stroke volume and/or the compliance of the arterial space.”

I’m now going to review an another chapter in the same book: the “Vascular Control” and “the central venous pressure” which was my aim of reviewing.

Posted in Cardiology, Medical education | Tagged: , , | Leave a Comment »

PFO Closure has significant impact on Migraine

Posted by iskanbasal on July 19, 2007

I have forgotten it completely, this  association between Migraine and the Patent foramen ovale, PFO. In migraineurs there is a higher probability to find PFO, a cardiac defect or a flap-like opening in the atrial septal wall which is also present in 27% of the general population. I’m aware about the association of PFO and ischemic stroke; PFO cause right to left shunting of venous blood in the heart between the right and left atrium bypassing the lungs. See the opened foramen in this image from the cleveland clinic, see the flux of blood through it. Now the closure of the defect is associated with a more than 50% reduction of migraine headache episodes in patients suffering of migrain. These are results of the trial MIST. PFO closure is performed using the STARFlex septal repair, a catheter-based minimally invasive interventional cardiology procedure.

I have some  interesting reference I got from the primary care neurology society which I would like to keep here for any future interest.

(escuse me english errors).

References

1. Wilmshurst P, Bryson P. Relationship between the clinical features of neurological decompression illness and its causes. Clinical Science 2000; 99:65-75.

2. Post MC, Thijs V, Herroelen L et al. Closure of a patent foramen ovale is associated with a decrease in prevalence of migraine. Neurology 2004;62:1439–40.

3. Schwerzmann M, Wiher S, Nedeltchev K et al. Percutaneous closure of patent foramen ovale reduces the frequency of migraine attacks.Neurology 2004;62:1399–401.

4. Wilmshurst PT, Nightingale S, Walsh KP et al. Effect on migraine of closure of cardiac right-to-left shunts to prevent recurrence of decompression illness or stroke or for haemodynamic reasons. Lancet 2000;356:1648–51.

5. Morandi E, Anzola GP, Angeli S et al. Transcatheter closure of patent foramen ovale: a new migraine treatment? J Intervent Cardiol 2003;16:39–42.

6. Reisman M, Jesurum J, Spencer M et al. Migraine relief following transcatheter closure of patent foramen ovale. American College of Cardiology Abstract. JACC 2004 March 3;43(5) Supplement A:376A.

7. Azarbal B, Tobis J et al. Association of interatrial shunts and migraine headaches. JACC 45(4) 2005; 489–92.

8. Reisman M, Christofferson RD, Jesurum J et al. Migraine headache relief after transcatheter closure of patent foramen ovale. JACC 45 2005: 493–5.

9. Wilmshurst P, Pearson M, Nightingale S. Reevaluation of the relationship between migraine and persistent foramen ovale and other right-to-left shunts. Clinical Science2005;108:365–367.

Posted in Cardiology, Headache, neurology | Tagged: | 1 Comment »

 
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