This is a controversial trial and further investigation is underway. Surgical revascularization of coronary stenosis with coronary artery bypass grafting is ideal for certain patients. Patients with diabetes or those with severe LV systolic dysfunction have improved outcomes with surgical revascularization compared with PCI. Also, when the left main coronary artery or a left main equivalent proximal left anterior descending and proximal circumflex is involved, CABG is recommended. Symptoms are that of typical stable angina, but no abnormality is detected on stress testing or angiography, and typical anginal therapies are not effective.
Similar symptoms are sometimes seen as a part of the mitral valve prolapse syndrome. This is somewhat different than syndrome X, which can indeed show signs of myocardial ischemia, even with normal coronary arteries and no inducible coronary vasospasm.
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This occurs when typical angina is present with ST segment depression upon exercise testing despite angiographically normal coronary arteries without inducible coronary vasospasm with ergonovine infusion. This is a controversial topic, as no clear etiology has been seen. Hibernating myocardium occurs when significantly reduced blood flow affects a segment of the myocardium, causing dysfunction on a chronic basis.
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If blood flow is restored via PCI or surgical bypass grafting, the function can return to normal. Viability testing can help determine if myocardium is hibernating or completely infarcted.
Chronic ischemic heart disease: an energy imbalance
This testing is best performed using magnetic resonance imaging, or MRI, but can also be achieved with positron emission tomography, or PET, scanning, thallium myocardial perfusion imaging and dobutamine stress echocardiography. Stunning of the myocardium occurs when transient ischemia resulting from total or subtotal coronary occlusion, such as during an ACS, results in segmental myocardial dysfunction. When blood flow is restored via coronary revascularization, the dysfunction persists. Segmental LV dysfunction can remain for days or even weeks after the ischemic insult, but eventually returns to normal.
In the setting of chronic ischemia, collateral circulation may develop to compensate for the reduced blood flow. These consist of small vessels that grow from sub-branches of a neighboring, non-occluded coronary vessel. Collateral circulation can sometimes be extensive and is increased by exercise. Some patients develop more extensive collateral circulation than others, and some therapies are under investigation to enhance the development of coronary collaterals. This occurs when angina is present with lower level of activity but is relieved when exercise is continued.
On treadmill testing, ST segment depression may be seen early on, then completely resolves. It is believed this is due to myocardial ischemia resulting in release of vasodilators, which help open collateral circulatory channels, eventually increasing the flow to the ischemic myocardial segment and relieving the symptoms of angina. When arterial tone is suddenly increased, coronary vasospasm can occur and result in angina.
Coronary arteries are angiographically normal, but vasospasm can be induced by ergonovine or acetylcholine infusion. The treatment is dihydropyridine calcium channel blockers. Circulating catecholamines will agonize alpha receptors more easily if the beta-receptors are occupied by a beta-blocker. The ECG during coronary vasospasm can be markedly abnormal mimicking ischemia or an ST segment elevation myocardial infarction.
The ECG changes quickly resolve once the angina and vasospasm are relieved. Coronary vasospasm is most common in middle-aged women. This occurs when a coronary vessel does not run along the epicardial surface of the heart, but instead dives deeply to run within the myocardial wall itself. During contraction, the coronary vessel can be compressed and is frequently seen on angiography.
Exercise exacerbates this due to increased contractility and faster heart rates, resulting in decreased time in diastole; recall that the coronary arteries fill in diastole. On rare occasions, myocardial bridging is thought to cause angina; however, the finding is benign and has no clinical significance a majority of times. Vasospasm has been more commonly found to be in patients with myocardial bridging.
When a coronary arterial wall becomes weakened, it can dilate and form a coronary artery aneurysm. This can occur as post-stenotic dilation during atheroslcerotic coronary disease or can occur as a part of a vasculitis. Many types of congenital variations of the coronary arteries exist.
Although most are benign, some anomalous coronary arteries can pass between the aorta and the pulmonary artery — known as an interarterial course — and cause compression, myocardial ischemia and angina. Coronary anomalies are the second leading cause of sudden cardiac death in young athletes, after HOCM.
Some examples include the left anterior descending originating from the right coronary cusp, the right coronary artery arising from the left main coronary artery, and the circumflex coronary artery arising from the right coronary cusp. References: 1. Abrams J. Clinical Practice: Chronic Stable Angina.
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Pathophysiology – CAD - Stable Angina
Visit Healio. Three main factors determine myocardial oxygen demand. Etiology — CAD - Stable Angina Atherosclerosis of the coronary arteries is the most common cause of ischemic heart disease. Physical Examination — CAD - Stable Angina Physical examination findings are relatively non-specific and usually only present during the anginal episode, making this a less helpful means of diagnosis. Diagnosis — CAD - Stable Angina Diagnosing coronary disease in the absence of an ACS can be difficult as the clinical presentation varies and, as previously mentioned, physical examination is non-specific.
Exertional angina of new onset even if relieved with rest and requiring a consistent amount of exertion to produce symptoms, angina is considered unstable when it first occurs Exertional angina that was previously stable and now occurs with less physical exertion Anginal symptoms at rest without physical exertion In unstable angina, the cardiac enzymes remain normal or are only very minimally elevated. Reducing Disease Progression Risk Once a CAD diagnosis is made, treatment directed at the known CV risk factors should be aggressively undertaken to prevent progression of disease.
Antiplatelet Therapy Usually given in the form of aspirin, all patients with documented CAD should be taking antiplatelet therapy for the prevention of ACS. TOS levels were significantly higher in the patient compared to the control group [2. TAC levels were comparable in both groups [1.
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The OSI ratio was significantly higher in the patient than in the control group [2. However, uric acid 6. In the present study, OSI levels, a marker of oxidative status, were significantly higher in the patients with nonischemic HF compared to the control subjects; uric acid and the TOS level were also higher in nonischemic HF patients compared to the control group.
Oxidative stress results from an imbalance between ROS generation and antioxidant defensive mechanisms. ROS play a key role in the pathogenesis of a variety of cardiovascular diseases; the generation of increased levels of ROS has been shown to contribute directly to the progression of atherosclerosis, hypertension, reperfusion injury due to acute myocardial infarction and HF [ 18 , 19 ].
A number of experimental and clinical studies have demonstrated an increased generation of ROS in HF patients [ 4 , 5 , 6 , 7 ]; hence, the activity of antioxidants may be reduced [ 20 ]. The importance of oxidative stress in HF patients may be associated with the process underlying LV hypertrophy, adverse LV remodeling and HF [ 21 , 22 , 23 ]. The most widely recognized effects of increased oxidative stress in the heart that cause cellular dysfunction, protein and lipid peroxidation, and DNA damage, leading to irreversible cell damage and death, have been implicated in a wide range of pathological cardiovascular conditions [ 3 , 24 ].
The role of oxidative stress is increasingly emerging with respect to a pathophysiological mechanism of cardiac remodeling responsible for the development and progression of HF [ 3 , 24 ]. Plasma lipid peroxidation, an indicator of oxidative stress, is increased in patients with dilated cardiomyopathy and positively correlates with the severity of symptoms [ 25 , 26 ]. Also, similar to our study, there is an inverse correlation between lipid peroxidation parameters and cardiac performance EF, exercise capacity [ 25 ].
These results may be associated with the effect of increased oxidative stress on LV remodeling and disease progression. As in our study, Demirbag et al. However, the TAC levels of plasma were significantly lower in the control subjects. Previous studies by Hill and Singal [ 6 ] demonstrated that HF subsequent to myocardial infarction was associated with an antioxidant capacity deficit as well as with increased oxidative stress. However, unlike these studies, we excluded HF due to ischemic etiology. In addition, the uric acid level was moderately positively correlated with OSI fig.
Similarly to our study, Demirbag et al. Diraman et al. A previous study has shown that in children with idiopathic dilated cardiomyopathy undergoing standard treatment, abnormal antioxidant enzyme activity was found [ 28 ].
Sezgin et al. In addition, Erdogan et al. Based on the aforementioned data, we suggest that antioxidant treatment could be used widely in HF patients.
The limitations of this study include the small number of patients with nonischemic HF. In addition, the analysis was based on a simple baseline determination at a single time point, which might not reflect patient status over long periods. The present study showed that OSI levels were significantly increased in patients with nonischemic HF compared to control participants. This may be associated with increased cardiovascular risk. Our findings also suggest that antioxidant treatment might be helpful for these patients. However, further prospective studies are needed to establish the pathophysiological and clinical significance of increased oxidative status in patients with HF.