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Archive for the ‘pregnancy and heart disease’ Category

Some of the questions  addressed  in this presentation

1.What happens to fetal blood pressure during maternal hypotension how good is fetal autoregulation?

2.Why is LSCS increasingly preferred mode of delivery in heart disease complicating pregnancy challenging the traditional scientific concept?

3.What is likely hood of patients with moderate mitral stenosis developing pulmonary edema during prolonged 2nd stage of labor?

3.What is the missing link between PIH and PPCM? How prepartum cardiomyopathy differs from postpartum?

4.Is Eisenemneger really an absolute contraindication for pregnancy?

5. How can we continue VKAs warfarin or Acitrom throughout pregnancy? What are the potential problems of double switching one at 6th week from VKA to Heparin and again from heparin to VKA  at  12th week?

Hope, the man-made hematological bridge in pregnancy has been finally liberated from confusion (Who is saying not yet?)

 

6. On what evidence base the safety margin of 5mg cutoff for Warfarin and 3mg for Acitorm was decided?

7. Who is insisting on us to do Anti-Xa monitoring for LMWH in pregnancy? Is it really needed? What does the American society of hematology say?  (ASH guidelines for VTE in pregancy 2018) Why we don’t insist on Xa estimation in acute coronary syndrome?

8. What is the inflection point of at which risk of termination is almost at equipoise with continuing pregnancy in various heart diseases.

A GIF run-through of the presentation.

PDF & video version will be posted

 

The ultimate reference 

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Have we ever wondered how six liters of blood in our body flows like a live stream, maintaining the fluidity life long, in spite of an active coagulation system in situ, ready to freeze at the slightest provocation (Invisible vascular wear & tear!) This housekeeping job, within the vast network of the human vascular tree, is silently accomplished by a less apparent system called fibrinolytic system. D-dimer is a physiological breakdown product of this system . D-dimer comes from fibrin monomer. The D in D-dimer stands for the domain. (See below) The ability to detect the D-dimer in the bedside has given us a good opportunity to monitor intravascular thrombus formation and subsequent dissolution in health and disease.

 

 

Formation of D-dimer from fully formed fibrin clot with the help of factor X111a and plasmin

Learning from a false alarm of pulmonary embolism

Recently I came across a pregnant woman in the third trimester with sudden onset dyspnea. Ongoing panic and a  hyper response  ER protocol ended up in D-dimer estimation. It was 2600μg/ml, which created a false alarm among obstetricians. She was started on heparin by then. Though her saturation was 95%, ECG was normal.An emergency bedside echo revealed normal right atrium and ventricle, no pulmonary HT. The diagnosis of PE was now rejected confidently. The much-dreaded dyspnea turned out to be some patient anxiety. Unnecessary exposure of a fragile pregnant lady to heparin was reverted with much difficulty as no one was willing to discount jacked-up D-dimer still. (Such is the power of sophisticated biomarkers and numbers! I asked them to report the elevated D-dimer as false-positive in bold letters in the case sheet and applied the break to bring the high voltage obstetrical -cardiac consult to a halt ) 

What is the normal D-dimer levels in blood?

In the strict sense, D- dimer can’t  have normality. It is flushed-out molecular debris from clots, levles of which fluctuates depending upon the fibrinolytic load on a given day. It is further limited by lab standardization issues and methodology. (ELISA vs latex ) Currently, a level of <500μg/ml is considered diagnostically useful to rule out DVT/PVE (Good sensitivity /low specificity)

What happens to D-dimer levels in pregnancy?

D-dimer levels are nornally high in pregnancy, and  can reach very high levels as well. 

What is this source of D-Dimer In pregnancy? 

  • Pregnancy is a procoagulant condition. (Estrogen Induced effect on fibrinogen and other clotting factors especially factor 2  & 7 ) We presume it is due to more  microthrombus activity in materno placental capillary circulation. When there is a pro-coagulant activity, fibrinolytic activity is also high hence elevating FDP and D dimers. 
  • Pregnancy-associated with diabetes /PIH/preeclampsia elevate it further due to subclinical  endothelial dysfunction 
  • Placental source for D-dimer is documented. (Might be a marker for partial abruption as well)
  • The role of the fetus in generating or triggering maternal procoagulant activity is possible with a reverse breach in the placental maternal barrier. (Many of stillbirth, Intrauterine deaths / DIC in mother could reflect  pathological faces of hypercoagulation states) 

Normality redefined in pregnancy 

This paper has something important. Didn’t  knew this till now. In the third trimester, D-Dimer can reach up to 4400 in diabetic mothers. It is also worthwhile to note the other common causes for high D- dimers sepsis,  autoimmune disorders* and occult malignancy,

*In fact, every normal pregnancy can be termed as a relative autoimmune disorder, as it is impossible for the mother to go through the pregnancy without  immunological modification of the host (by fetus or host itself)  

 

 

Final message 

Never rely on elevated D-dimer in isolation to diagnose DVT/Pulmonary embolism. This is especially true in pregnancy where even very high levels are physiological. The commonest cause for dyspnea in pregnancy will continue to be anxiety, anemia, PIH & physical deconditioning, and weight gain  (not the mitral valve stenosis /PE/or peripartum cardiomyopathy). Yes, It may appear rewarding to think  like a specialist, but please realize if we diagnose rare entities, we are “rarely likely” to be correct and the consequences of that are not always pleasant.   

Reference 

1.Siennicka A, Kłysz M, Chełstowski K, et al. Reference Values of D-Dimers and Fibrinogen in the Course of Physiological Pregnancy: the Potential Impact of Selected Risk Factors-A Pilot Study. Biomed Res Int. 2020;2020:3192350.

2.Gutiérrez García I, Pérez Cañadas P, Martínez Uriarte J, García Izquierdo O, Angeles Jódar Pérez M, García de Guadiana Romualdo L. D-dimer during pregnancy: establishing trimester-specific reference intervals. Scand J Clin Lab Invest. 2018 Oct;78(6):439-442. 

 

 

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cardiac output  during labor and postpartumcardiac output  during labor and postpartum 002

Cardiac output in pregnancy is increased by 30 %  physiologically . Hence  loss  of blood at the time of labor is  pregnancy is  sort of physiological correction .Cardiac patients do get a relief  with loss of about 500 ml of blood .

Stress of Labor

Each uterine contraction is a stress to the heart  and is akin to infusing 500 ml of saline into maternal circulation .This is further amplified in patients with severe mitral stenosis.

However , the maximum hemodynamic stress for the mother  occurs just after delivery  when about a 1 to 1.5 litre is auto transfused.One has to watch for deterioration at this point of time.

Why caeserian section is being preferred by many obstetricians  in cardiac disease complicating pregnancy ?

Traditional and modern text books clearly mention , natural delivery is best for both fetus and mother in cardiovascular disease .However it is  still  a debatable issue  in real world labor rooms, especially in obstetrical emergencies.These concepts are probably old when surgical risk were considered too high for LSCS .

My  current understanding of the issue ( Subjected to correction )

  • Normal  labor hemodynamics is unpredictable , even so in a women with critical valve obstruction
  • It is  a  “4 cornered obstetrical stress”  situation ,  almost equally distributed between  mother , fetus ,spouce  and the obstetrician !
  • A brief period of controlled stress is better than prolonged uncertainty of labor.
  • Since LSCS  is done  in the presence of an anesthetist in a monitored  and controlled setting, even a brief  high risk period is acceptable  till the baby is taken out.
  • Though technically LSCS may add a little risk to fetal life , It has been observed mothers are getting more rapid relief  from  post partum dyspnea who undergo LSCS.

*There is another reason for the heart  to feel comfortable with LSCS  in critical mitral stenosis,  which threatens  to precipitate  acute pulmonary edema .The post partum spike in cardiac output could theoretically be less if  blood loss in LSCS is accounted .(sort of venesection !)

http://www.ncbi.nlm.nih.gov/pubmed/4025461

hemodynamics of labor in  mitral stenosis

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