Feeds:
Posts
Comments

Posts Tagged ‘sudden cardiac death’

Why is sudden cardiac death uncommon in women ?

Posted in Cardiology - Clinical, Cardiology - Electrophysiology -Pacemaker, cardiology -ECG, Cardiology-Arrhythmias, Cardiology-Coronary artery disese, Infrequently asked questions in cardiology (iFAQs), tagged , , , , , , , on March 17, 2009| Leave a Comment »

To further understand women's heart click on the title

SCD  continues to be  the major mode of  death of  our  population . Millions of men die every year instantly .The commonest mechanism is due to primary ventricular fibrillation following an abrupt closure of coronary artery due to a thrombus.Most die , within few minutes of the event, some  before reaching the hospital , few within the ambulance  and an  unlucky few die on the CCU bed  or cath lab table even after getting the best treatment.

If we analyse the data, there is a  surprising fact !  Men form the bulk of these SCD victims.In our experience , out of 100 cases of consecutive  in hospital primary VF only  6 were females , indicating  an important  biological phenomenon to be studied.The data for out of hospital primary VF is more difficult to get , but the  log records of EMRI and emergency rescue team consistently confirm the male preponderance of primary VF .

How  does the female heart enjoys this relative immunity from primary VF even as the blood supply is acutely compromised ?

The answer  is  not known . If we are able to  decode this , one can replicate the same  model in male .

The QT paradox and incidence of primary VF

QT interval represents a combination of  electrical depolarisation and repolarisation .It is a well established   scientific  fact  that  women have   relatively  prolonged QT interval .This  is determined by evolutionary biology and  inherited characteristics of  potassium channels  during myocardial repolarisation

In simple terms, the female heart  knows how to relax slowly and prolong the electrical relaxation time.(Not mechanical)

It is also a well known  fact ischemia mediated a prolonged  QT interval is a trigger for dangerous ventricular arrhythmia.This ischemia induced QT prolongation is less pronounced in females than males as the baseline QT itself is slightly longer in women.The percentage increment of QT interval during acute ischemia is significantly higher in male .This could be one reason for the preponderance of VF in men

The billion dolor question and a real challenge for the cardiologists is

How to make a heart electrically inert during ongoing ischemia ?

  • Pain is also trigger for primary VF due to high adrenergic tone.Prompt control of chest pain make VF less likely.
  • Lignoacaine a myocardial anesthetic if administered quickly can prevent many of the primary VF.

And now , shall we  think little wildly !

What if , if  we administer lignocaine spray straight over the (or sublingually ) in every patient with  chest pain

as like a sport injury and try calm down the heart electrically !

Also read

1.Lignocaine  the forgotten hero .

2.View this video -Ignorance based cardiology !

Reference

Arrhythmias and sex hormones


Read Full Post »

Why syncope is rarely fatal ?

Posted in Cardiology - Clinical, Infrequently asked questions in cardiology (iFAQs), Uncategorized, tagged , , , , , , , , , , , , , , , , , , , on September 30, 2008| 1 Comment »

                                                    

                                                             Syncope by definition is a transient loss of consciousness due to cerebral hypo perfusion and loss of muscular tone, and the patient falls but  recovers fully and gets up either assisted or spontaneous.The cardiac and vascular counter response to syncope is most often intact .This makes syncope characteristically transient . If a patient does not recover from syncope it could either be a prolonged loss of consciousness( Stroke etc)  or if he never gets up he will be called a victim of cardiac arrest or  a SCD ! (Sudden cardiac death ) . So technically by defintion ,  all  patients  will  have to  survive  the  syncopal episode.

But the following questions need to be answered   

  1. How prolonged  a syncope can be ?
  2. Can syncope lead onto  sudden cardiac death ?(SCD)  
  3. What are  life  threatening syncope and non life threatening syncope ?                           

What is the link between, syncope and SCD in patients with ventricular arrhythmia’s ?

Some case of long QT syndromes could be life threatening especially in children as they inherit sudden death. A patient with a non sustained VT  may develop syncope  if  the  VT  becomes sustained especially  if there is underlying heart disease and LV dysfunction . Among this  few , may degenerate into ventricular fibrillation and patient may die.  

How common is syncope in acute myocardial infarction ? 
 Syncope is a very  rare presentation of acute myocardial infarction. 
 
Can syncope precipitate  or precede a  cerebro vascular accident  ?   

 

Prolonged syncope , TIA,  stroke in evolution and completed stroke   can be a continuous spectrum in patients with carotid and cerebrovascular  disese . But when a syncope evolves in to a stroke the   patient is not considered to be a victim of syncope but  they enter the stroke protocol.

There is a big list for the causes of syncope

But to put it simply

A.Cardiac

  •    Purely electrical ( Arrhythmic- Brady, Tachycardia)
  •    Mechanical( Valvular obstruction, and other structural heart disease etc)

B. Non cardiac

  • Vasovagal (Commonest 90% of all syncope)

C. Metabolic*

  •  Anemia
  • Hypoglycemia
  • Hypoxia
*Metabolic causes  coupled with simple  vaso vagal(Neuro cardiogenic)  constitute the bulk of causes of syncope .Siezure disorders are very  common and a close  mimicker of syncope and need to be ruled out.

How to work up  a patient with syncope ?

                   First ,  one need to confirm  it is indeed a syncope . If the initial examination is not clearcut   one  need to  go back to the  history and ask for  circumstances under which the syncope occured  and  details of prodromal symptoms  if any . Patient’s  family members who witnessed the event can give useful information . It  is the most  cost effective ( Comes free of cost infact !)  investigative tool available .Cardiac syncopes are usually sudden, vasovagal often have environmental or emotional factor. Apart from routine investigations , ECG, Echocardiography, holter are done generally, head up tilt test, Loop, event recorders may be reuired in few.

Final message

                                          Syncope is one of the common symptoms in cardiology and  general medical practice. Many times the diagnosis is easy . Common syncope is  never fatal but , ruling out dangerous  tachy and bradyarrhythmias is a key aim.  In a significant number (20-30%) identifying the cause could be really  difficult and  may never be made in spite  of the modern diagnostic tools. These syncope of unknown origin is grouped along with the neurocardiogenic category.

The one,  positive thing about syncope is (unlike chest pain) , it is rarely fatal in it’s first episode ,  gives the physicians to  investigate and correct the underlying problem.

Read Full Post »