Saturday, September 1, 2012

Hypertension and abnormal differences in blood pressure between the right and left arms (1)

 

Simply put, hypertension is the abnormal elevation of blood pressure beyond what is accepted as normal for an individual’s age gender and race.  Further, hypertension can be said to imply the elevation of one or two components of blood pressure two(2) standard deviations(2SD) above the accepted mean, taking into consideration, variables like age, gender, ethnicity, occupation  etc, Many of us can’t remember when last we went to a clinic for simple blood pressure check .  A good number of Nigerians who own Electronic blood pressure monitors don’t know
how to use them and don’t bother about their accuracy.  Most people who check their blood pressure regularly are satisfied with the measurement done with one arm, and in the sitting position. 
Risk Factors  associated with hypertension  are no longer news, and include being an African and male, high  intake of salt ,seasoned food, carbohydrate, proteins fats, and oils. Frequent patronage of fast food restaurants, and diets low in vegetables, fiber, fruits and water. Others are sluggish and sedentary lifestyle, obesity, smoking, excessive alcohol intake, presence of  a disease condition in an organ whose activity indirectly affects the heart  and its vessels, such as in kidney disease, thyroid over activity, and adrenal hyperplasia.
Studies have shown marked reduction in libido amongst married couples, after the age of 45 years, and a direct relationship between low sexual activity, truncal (android) obesity and hypertension has been suggested.
An adult may live with hypertension for five to ten years without the affected individual knowing it ; and a hypertensive patient may decide regrettably  to avoid or stop taking prescribed medicines and  resort to other means. Over time, slow damage will have occurred in body organs known as hypertension target organs. Some of these organs are the brain, kidneys, the heart and the lungs. Much of what has been discussed is common knowledge and many of us are quite familiar with the comments. Perhaps what has not been emphasized , but very  relevant to  physicians and patients is the matter of different blood pressure readings between the right and left arms, and large pressure differences between the two arms and between the arms and legs. When small, these differences can be ignored, but when higher than 10mmhg for systole (number placed at the top) and 20mmhg diastole(number placed at the bottom), it becomes a health issue that must be taken very seriously, for the rest of the life of an affected individual
How often do physicians see patients with abnormal differences in blood pressure between the arms?   Not very easy to answer the question. In a very busy clinic as seen in Teaching Hospitals, a Cardiologist  will see only cases that require specialist attention, and unless specific instructions are given, other members of his team are not likely to spend much time bothering about issues which concern only a minority of cases. Says Dr Uvie  . J . Ajugah, a family physician with the University of Port Harcourt Teaching Hospital (UPTH).  When cases of IABPD are discovered, the potential for complications are indeed very real and should not be ignored; there is need to follow up such patients with comprehensive family history, basic laboratory Studies and advanced  imaging techniques to better understand the problem
Experts put the prevalence of abnormal differences in inter arm blood pressure in the developed countries at a little over 10%. These are places where diagnostic health facilities are readily available and people have access to essential medicines.   In resource limited countries like Nigeria, the prevalence is likely to be very much higher. Part of the problem has to do with the Doctor Population ratio here, which currently is about one qualified Medical Doctor to Ten thousand Nigerians.  Poverty and lack of transparency in the operation of various streams of the health insurance scheme have made it difficult for  many families to enjoy  good health. On the other hand awareness of this condition is unremarkable; 
What do the ordinary people know about abnormal inter arm blood pressure differences (IABPD) What do experts in the different  fields of medical practice know and  What challenges do  the cardiologists, radiologists cardiothoracic surgeons  family physicians  and others face in the detection, management  and evaluation of  IABPD.
The very recent report released by the world health organization (WHO) in may 2012,  came with a  warning that  chronic non communicable diseases like hypertension have begun to spread from Western nations to poorer regions like Africa . Data from  the United Nations, the UN and Ties Boerma, the WHO’s director of  Health statistics indicate that  1 in 3 adults worldwide has raised elevated  blood pressure, and half a billion people  have obesity”, a major  issue  in the development of hypertension in children and adults . Contrary to the previous  assessment,  the report  endorsed by the director, Margaret Chan suggest that Women in all parts of the world are more likely to be obese than men with a  higher risk of developing diabetes, mellitus, heart disease , stroke, and even cancers, particularly after the age of 50 years. According to  the report  40-50%  of  adults in Africa n countries have  high blood pressure 
In Nigeria statistics are difficult to come by, because of  religious, ethnic and geographical problems amongst others but experts believe about 8 million people representing  about 10% of the Nigerian population may be living with hypertension with as high as   30 to 40 %  not knowing they have the condition. This scenario may persist in the setting where  the routine use of one and the same arm to measure an individual’s blood pressure  rules out the presence of the disease whereas  it is actually waiting to be revealed when the other arm is used for measurement. This is because for patients in whom IABPD has been established, it is instructive that treatment update rely on  the higher of the two readings obtained, irrespective of whether it is the right or left .
No one is sure how and why differences in interim blood pressure arise but the following have been suggested. 

CONGENITAL:  
In Taussig –Bing malformation, the Aorta is transposed, with the pulmonary trunk receiving blood from the right ventricle instead of the left ventricle, and with associated large ventricular septal defects. Similarly in Sinus inversus totalis, regarded as a walking medical curiosity, viscera such as appendix and gall bladder are on the left side of the body instead of the right as seen in normal individuals. Abnormal positioning of the major vessels of the heart results in unequal distribution blood pressure elevation
Post ductal coarctation (narrowing )of the aorta may remain  silent for years until  adult hood when large pressure differences, between the upper limbs and between the upper arms and legs become manifest. 
Another predisposing congenital abnormality is Rogers disease, in which truncus arteriosus coexists  with right to left ventricular septal defects .Patients survive with septal defects with small diameters, about 0.5cm, 
Similar conditions occur in Steal phenomena —Subclavian, and Coronary artery fistula.
Anomalous origin of the coronary artery from a region between the pulmonary artery and the aorta gives rise to  abnormalities of perfusion and aortic insufficiency 
William syndrome of supra valvular aortic stenosis is another condition associated with abnormal interarm blood pressure differences.
A single coronary artery infrequently exists with various coronary insufficiency and distal vascular anomalies.
The presence of one congenital abnormality should encourage search for others.

ACQUIRED : 
Lutten baches syndrome acquired rheumatic mitral stenosis leads long standing hypertension.
Most cases  of Hypertension  in Africa remain  undiagnosed but, even amongst those found to have symptoms associated with hypertension  Here in Nigeria, Blood pressure readings up to 320/160  have been recorded in patients dying a few minutes after  sudden collapse; to the sorrow and shock of  close family members.

- Dr Mike Oyakire

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