Pregnancy, MS and changes to the veins

March 9, 2012 at 3:53pm

Naturally, there is lot of discussion on how the immune system is modulated while carrying a fetus...something the body sees as "other" and how this might affect MS.  And many people have mentioned hormones, especially estrogen.

But I wanted to discuss the vascular changes that happen while a woman is pregnant, because I never see this discussed, and I hope to encourage the ISNVD and other MS researchers to look into this correlation.

During pregnancy, a woman's blood volume increases by 50%.   This is to nourish the placenta and growing fetus, and also to compensate for blood loss during delivery.  If the blood vessels remained the same, with more blood volume, blood pressure would become dangerously high....so, the veins become more pliant, open and relaxed.  This is why many women develop varicose veins or hemorrhoids during preganancy.  

Venous Distension increases approximately to 150% during the course of gestation and the venous ends of capillaries become dilated.  Hormonal factors cause the veins to become more compliant. Together with the increased venous pressure that occurs later in pregnancy, these factors cause significant venous distension. Venous distendibility follows the rise in the hormones progesterone and relaxin.   Relaxin works by softening collagen and elastin in the tissues. It loosens the strong, cord-like fibers until they are super-pliable.

The hormone Relaxin is now being studied in cardiovascular disease, for its affects on the endothelium, via nitric oxide mechanisms.

The ovarian peptide hormone, relaxin, circulates during pregnancy, contributing to profound maternal vasodilation through endothelial and nitric oxide (NO)–dependent mechanisms. To conclude, relaxin is a novel regulator of BMDECs number and function, which has implications for angiogenesis and vascular remodeling in pregnancy, as well as therapeutic potential in vascular disease.

http://bloodjournal.hematologylibrary.org/content/119/2/629.abstract

Cerebral bloodflow increases during pregnancy:

Internal carotid artery blood flow volume increased during pregnancy from 318 mL/min ± 40.6 mL/min in the first trimester to 382.1 mL/min ± 50.0 mL/min during the third trimester, corresponding to CBF values of 44.4 and 51.8 mL/min(-1)/100 g(-1), respectively (P < .0001). CBF changes were associated with progressive decrease in cerebral vascular resistance and moderate increase in ICA diameter.

CONCLUSION:

Maternal CBF is gradually increasing during normal pregnancy. Vasorelaxing impact of estrogens and other factors on cerebral vessels may explain the changes in CBF during pregnancy.

http://www.ncbi.nlm.nih.gov/pubmed/20599183

 Could the hormonal relaxation of the jugular and azygos veins and increased blood volume during pregnancy account for better cerebral/spinal bloodflow?  Could this be why MS symptoms are less during pregnancy,  why pregnancy appears to "protect" women from MS?

more questions to ask, and to be answered--

Joan

Hydration, your Heart and Blood Flow

December 26, 2010 at 2:12pm

Did you know that when you are not drinking enough water, you are straining your heart and vascular system, and depriving your brain of good blood flow?

Dehydration causes strain on your heart. The amount of blood circulating through your body, or blood volume, decreases when you are dehydrated. To compensate, your heart beats faster, increasing your heart rate and causing you to feel palpitations. link

When we do not get enough hydration from water, our blood volume decreases. Water is essential for our vascular system.

Hypovolemia means low blood volume. This condition can be very serious and can be due to blood loss from injury.  It can also happen in a body that is dehydrated or inactive, or not functioning well. Hypovolemia occurs often to the elderly and disabled.

Low blood volume can cause orthostatic hypotension. This is when there isn't enough blood getting to the brain when you change position from lying down to upright. This can lead to dizziness, confusion and falls, and often happens in the elderly. But it can happen in people with MS, too. Orthostatic hypotension is well-documented in MS and has been a mystery for researchers.

For many women, pregnancy offers a time of blessed relief of MS symptoms. This has lead to studies of hormones and MS, and a clinical trial of estrogen in MS patients. But looking at pregnancy from the vascular paradigm, what else can we learn?

When women are pregnant, their blood volume increases dramatically. This sends blood pumping throughout the body.

Perhaps the most striking maternal physiologic alteration occurring during pregnancy is the increase in the blood volume. The magnitude of the increases varies according to the size of woman, the number of pregnancies she has had, the number of infants she has delivered, and whether there is one or multiple fetuses.The increases in blood volume progress until term;the average increase in volume at term is 45-50%. The increase is needed for extra blood flow to the uterus, extra metabolic needs of fetus, and increased perfusion of others organs, especially kidneys. Extra volume also compensate for maternal blood loss during delivery. 
link

After delivery is the time during which many women report having exacerbations in their MS, or a return of MS symptoms. Yes, hormone levels are fluctuating, but so are blood volume levels. Pondering this fact has lead me to do more reading on blood volume, and I am finding some interesting things to consider.

Thinking about blood volume in terms of CCSVI treatment and restenosis of veins has been very interesting to me. If angioplasty is returning good, open routes of flow, but the body is not able to compensate by providing adequate blood volume, then these opened vessels will not have the necessary pressure to remain opened. And the areas of prior stenosis might re-collapse, just like an old garden hose with low flow.

I hope to bring this avenue of discussion to the doctors. Perhaps aftercare needs to include additional hydration, salt intake, maybe even intravenous fluids--all to keep blood levels adequate. Inactivity and remaining in the supine position increase hypovolemia--therefore, movement, exercise and upright activities would encourage blood flow and blood volume. Something to think about as we move forward with CCSVI research in 2011.

With wishes for good flow in the New Year!

Joan