Cardio-vascular Diseases (CVDs) are the leading cause of mortality worldwide and are likely to remain in that unenviable position for some time, despite the modifiable nature of several risk factors. Coronary Artery Disease (CAD) is the biggest killer amongst them, but it isn’t the only arterial disease that causes significant morbidity and mortality.
Accounting for more than 17.9 million deaths in 2016 alone, CVDs are the leading cause of mortality by a significant margin . Cancer comes in a distant second place, responsible for 9.6 million deaths in 2018 . Furthermore, CAD itself caused more than 9.43 million deaths in 2016 .
Another significant part of CVD-related mortality are strokes, which took the lives of 5.78 million individuals in the same year . They both account for nearly 85 % of all CVD-related deaths and what they both have in common is that they affect arterial beds and have a common underlying pathophysiology – atherosclerosis (in ischaemic strokes which accounts for 87 % of cases) . There are however other diseases that affect the arteries with varying degrees of morbidity and associated mortality and affect the life quality of those affected.
What is Arterial Assessment Used for?
Diagnosis of CVDs on the basis of symptoms alone is a nonsensical and difficult task, as many of them can often be asymptomatic until they are already in an advanced stage, or exhibit few symptoms, which can frequently be attributed to other lesser or non-serious medical conditions. Fortunately, there are many modern diagnostic methods and tools that can help clinicians identify and evaluate cardio-vascular issues in addition to well-established risk factors.
It should be noted that not all diagnostic approaches are the same, both from the perspective of their complexity, cost and patient-invasiveness. Angiographies are typically representative of invasive procedures as they usually entail the introduction of a contrast agent in the bloodstream prior to Computed Tomography (CT) or Magnetic Resonance (MR) imaging and, due to their versatility, they are suitable for the diagnosis of most arterial conditions. Although they are highly accurate, they are not without drawbacks, such as high cost (especially MR angiographies) and the possibility of adverse reactions to the contrast medium .
In contrast, there are many non-invasive techniques which are, under specific conditions, better options than (CT or MR) angiographies, examples of which include echocardiography and abdominal ultrasound (for diagnosis of abdominal aortic aneurysm, amongst others) and methods that use ultrasound. Included amongst these is the Ankle-brachial Index (ABI) and the Toe-brachial Index (TBI) measuring, which are used for the diagnosis of Peripheral Arterial Disease (PAD), a condition which may employ other techniques besides ultrasound.
Electrocardiography (ECG) can likewise yield valuable information, but is often supplemented by other diagnostic methods. On the other end of the spectrum, in terms of cost and potential negative effects (such as ionising radiation), are X-ray imaging (without contrast medium) and MRI. The latter has many advantages in comparison with both angiography and other non-invasive diagnostic methods, but is prohibitively expensive, limiting its usefulness for the general screening of potential patients.
Abdominal Aortic Aneurysm (AAA)
Localised enlargement of the abdominal aorta usually causes no symptoms unless the condition is already in more advanced state, i.e. the size of aneurysm is considerable and abdominal and/or back pain and, in some cases, pain radiating to the groin has developed. In 2010 the global prevalence was estimated to range between 7.88 (for the 40 to 44 years-old age group) and 2,274.82 (for the 75 to 79 years-old age group) per 100,000 inhabitants .
Mortality rates vary greatly by country and gender – aortic aneurysms (Sinus of Valsalva aneurysm (SOVA), AAA and TAA) in general accounted for approximately 168,200 deaths globally in 2015 . The most common diagnostic methods are physical examination, abdominal ultrasound, CT imaging and, less commonly, angiography and MRI.
Thoracic Aortic Aneurysm (TAA)
Aneurysm of the upper aspect of the aorta, i.e. above the diaphragm, is a less common condition (in comparison with AAA), but just as deadly in case of a rupture and has an extremely high mortality rate (due to untimely diagnosis and treatment) [8, 9]. As with AAA there are usually no symptoms until the aneurysm is particularly large, such as a pain in the chest or back, shortness of breath or difficulty swallowing.
Prevalence rates vary across countries and between both genders, and raise sharply with age: e.g. the incidence rate in Sweden was 16.3 for males and 9.1 for females per 100,000 per year in 2002 . Diagnostic methods include echocardiography, angiography, CT and MR imaging, and X-ray imaging (of the chest).
Arterial Thoracic Outlet Syndrome (ATOS)
This type of thoracic outlet syndrome is the rarest of them all (the other two being neurogenic thoracic outlet syndrome and venous thoracic outlet syndrome), accounting for less than 1 % of all cases . It is caused by the compression of the sub-clavian artery between the first rib, clavicle and scalene muscles. Common symptoms include a feeling of pulsating mass above the clavicle, numbness, pain, tingling and cold sensations in the hands or fingers and, in the most severe cases, ulceration and even gangrene of the fingertips.
The incidence rate of thoracic outlet syndrome (all types) is quite low – about 1-2 % of population, making ATOS an extremely rare condition . Mortality is extremely rare if the disease is properly treated . Diagnosis is usually made on the basis of an angiogram and a CT/MR scan.
Vertebrobasilar Insufficiency (VBI)
This condition results from a decreased blood flow (through the vertebral and/or basilar arteries) in the posterior circulation of the brain and produces variable symptoms (depending upon which part of the brain is affected). The main cause of VBI is atherosclerosis. Symptoms range from vertigo, visual disturbances and slurred speech, to sudden falls (drop attack). It is estimated that Transient Ischaemic Attacks (TIAs) and strokes attributed to VBI account for approximately 20 % of all TIAs and stroke cases . Diagnosis of VBI is also associated with a significant mortality rate of up to 85 % . The disease is diagnosed through (CT or MR) angiography.
Sub-clavian Steal Syndrome (SSS)
As the name suggests this a syndrome of symptoms relating to arterial insufficiency in a branch of the sub-clavian artery stemming from flow reversal that can be attributed to an occlusion in a sub-clavian artery proximal to that branch. The most common cause is atherosclerosis . It is largely asymptomatic, but some patients may exhibit neurological symptoms such as headaches, blurred vision, diplopia, impairment of consciousness, dysarthria, and facial paraesthesia and arm claudication [17, 18]. Prevalence rates are fairly ambiguous, ranging from 0.6 to 6.4 % . In comparison with other arterial diseases and CVDs in general the mortality rate due to SSS is extremely low . Diagnosis is made with a (Doppler) ultrasound examination or a CT angiography.
Coronary Artery Disease (CAD)
The most common CVD and arterial medical condition needs no special introduction. The most common symptoms are chest pain and shortness of breath, but some patients can be entirely asymptomatic. Incidence rates greatly vary by country; it is estimated that, in 2016, about 15.5 million individuals had CAD in the United States alone . As was already mentioned, CAD is the main cause of mortality worldwide with death rates declining in the developed world (high-income countries), but rapidly growing in low- and middle-income countries . Commonly used diagnostic methods are ECG, exercise ECG (stress test), echocardiography (including stress echocardiography), (intravascular) ultrasound, (coronary) angiography and MRI.
Carotid Artery Stenosis
Carotid artery stenosis accounts for about 15 % of all stroke cases and has the same pathophysiology as many previously mentioned artery diseases, such as atherosclerosis . Common symptoms include dizziness, fainting and blurred vision and Transient Ischaemic Attacks (TIAs). The prevalence of (moderate, ≥50 %) stenosis in the general population is 4.2 % . Patients with only moderate carotid artery stenosis are at a significantly elevated risk of mortality, i.e. 23.6 % in the 5-year period after diagnosis . Diagnostic methods include (Doppler) ultrasound and CT and MR angiography.
Renal Artery Atenosis (RAS)
Stenosis of the renal arteries, most commonly due to atherosclerosis (90 % of all cases), is often asymptomatic until it presents in a more severe form . The most common symptom is persistent hypertension that doesn’t respond to standard treatment methods. The prevalence of ≥60 % stenosis in the general population is 6.8 % . It is associated with a high mortality rate that rises exponentially with time, even after successful treatment (stenting): one study found that, 10 years after the procedure, the mortality rate was more than 59 % . Methods of diagnosis include (Doppler) ultrasound of the kidneys and angiography.
Peripheral Arterial Disease (PAD)
It is also known as Lower Extremity Artery Disease (LEAD) as it most commonly affects the leg arteries (but can also involve other arteries). An often undiagnosed arterial disease, it is caused by atherosclerosis but, due to its asymptomatic nature, it is an important risk predictor for overall cardiovascular health and mortality . It is estimated that, in 2010, at least 202 million individuals worldwide had PAD – today that number is likely to be higher as the risk of the disease increases with age (the world’s population is ageing) .
Mortality is significant since PAD is indicative of possible atherosclerosis in other parts of vascular systems: those with PAD are three times more likely to die due to cardiovascular issues than those without the disease . Several diagnostic methods are used to identify PAD, including physical examination (pulse palpation), (Doppler) ultrasound and angiography and Toe Brachial Index or TBI measurement (used for patients with incompressible arteries), but the best method for fast and easy screening is an Ankle-brachial (pressure) Index (ABI) measurement utilising an oscillometric method .