Evidence in support of the spasm of resistance vessel concept of ischemic heart disease: an update in 1993

Microvascular Alterations After Temporary Coronary Artery Occlusion: The No-Reflow Phenomenon

In experimental models of temporary coronary artery occlusion, tissue perfusion at the microvascular level remains incomplete even after patency of the infarct-related epicardial coronary artery is established, and distinct perfusion defects develop within the risk zone. This no-reflow phenomenon can be regarded as a basic cardiac response to ischemia-reperfusion. Perfusion defects observed in the clinical realm after reperfusion therapy for myocardial infarction may substantially be related to this mechanism in addition to microembolization and activation of platelets, as suggested in several recent studies. A major determinant of the amount of no-reflow seems to be infarct size itself. Reperfusion-related expansion of noreflow zones occurs within the first hours after the reopening of the coronary artery with a parallel reduction of regional myocardial flow, resulting in a potential therapeutic window. With various cardioprotective interventions, a close correlation between the size of the anatomic no-reflow and necrosis is a reproducible feature, which suggests a causal link between both entities of ischemic cardiac damage. Although vasodilating interventions failed to uncouple no-reflow zones from necrosis, the steps in the causal chain between microvascular and myocardial damage remain to be identified. On a long-term basis, tissue perfusion after ischemia-reperfusion remains markedly compromised for at least 4 weeks. Recent morphometric cardiac analyses suggested that the level of tissue perfusion after 4 weeks is a significant predictor of various indices of infarct healing, such as scar thickness, and infarct expansion index. As a consequence, improving tissue perfusion might concomitantly improve the healing process, which may provide the pathoanatomic basis for prognostic implications of no-reflow.

The altered homeostatic theory: A hypothesis proposed to be useful in understanding and preventing ischemic heart disease, hypertension, and diabetes – including reducing the risk of age and atherosclerosis

Evidence will be presented to support the usefulness of the altered homeostatic theory in understanding basic pathogenetic mechanisms of ischemic heart disease (IHD), hypertension, and diabetes, and in improving prevention of these disorders. The theory argues that: IHD, hypertension, and diabetes share the same basic pathogenesis; risk factors favor a sympathetic homeostatic shift; preventative factors favor a parasympathetic homeostatic shift; risk and preventative factors oppose each other through a dynamic risk/prevention balance; and prevention should be based on improving the risk/prevention balance. Prevention based on improving the risk/prevention balance should be more effective, as this method is regarded as reflecting more accurately basic pathogenetic mechanisms. As example, the theory argues that the risk of supposedly nonmodifiable risk factors as age and the risk of relatively nonmodifiable atherosclerosis can be reduced significantly. The possible validity of the altered homeostatic theory was tested by a study based on multiple associations. Findings support a common pathogenesis for IHD, hypertension, and diabetes based on a sympathetic homeostatic shift, and the usefulness of prevention based on improving the risk/prevention balance by using standard pharmaceutical and lifestyle preventative measures. The same set of multiple and diverse risk factors favored IHD, hypertension, and diabetes, and the same set of multiple and diverse pharmaceutical and lifestyle preventative measures prevented these disorders. Also, the same set of preventative agents generally improved cognitive function and bone density, and reduced the incidence of Alzheimer's disease, atrial fibrillation, and cancer. Unexpectedly, evidence was developed that four major attributes of sympathetic activation represent four major risk factors; attributes of sympathetic activation are a tendency toward thrombosis and vasoconstriction, lipidemia, inflammation, and hyperglycemia, and corresponding risk factors are endothelial dysfunction (which expresses thrombosis/vasoconstriction and epitomizes this tendency), dyslipidemia, inflammation, and insulin resistance. These findings, plus other information, provide evidence that dyslipidemia acts mainly as a marker of risk of IHD, rather than being the basic mechanism of this disorder. However, prevention generally is based solely on improvement of dyslipidemia; basing prevention on dyslipidemia relatively underemphasizes the importance of other significant risk factors and, by certifying its validity, discourages alternate pathogenetic approaches. Also, development of myocardial infarction is approached differently. It seems generally accepted that dyslipidemia results rather automatically in infarction through the sequence of atherosclerosis, atherosclerotic complications, and thrombosis. In contrast, distinction is made between development of atherosclerosis and acute induction of infarction--where atherosclerosis is only one of multiple risk factors.

Effects of Adenosine and Verapamil on Anatomic No-Reflow in a Rabbit Model of Coronary Artery Occlusion and Reperfusion

Adenosine and verapamil have successfully been used in the treatment of clinical no-reflow after direct angioplasty for acute myocardial infarction. However, their effects on anatomic perfusion defects in experimental myocardial ischemia/reperfusion are unknown. Thus the area of no-reflow (ANR), visualized after in-vivo staining of perfused tissue by thioflavin S (% of the risk area, RA, blue dye), and regional myocardial blood flow (radioactive microspheres) were determined in anesthetized open-chest rabbits after 30 minutes of occlusion and 120 minutes of reperfusion. Adenosine, administered intravenously during the entire reperfusion period, reduced vascular resistance in the RA at 120 minutes of reperfusion by 39% compared with controls (P < 0.053). However, in every animal, sizable perfusion defects developed and the ANR with adenosine treatment (29 +/- 3%) was not significantly different from saline controls (35 +/- 6%). Intravenous verapamil, given during the entire reperfusion period, reduced vascular resistance in the RA by 54% at 120 minutes of reperfusion (P < 0.03). But perfusion defects, visible in every animal, were similar in size between verapamil (38 +/- 5%) and saline (35 +/- 6%) groups. Therefore, neither treatment prevented or attenuated perfusion defects after ischemia/reperfusion despite reducing vascular resistance in the RA; hence vasospasm is not a major contributor to microvascular perfusion defects in this model.

Plaque rupture and consequent thromboses probably do not cause acute coronary syndromes

The objective of this communication is to provide evidence that the spasm of resistance vessel (S-RV) concept of ischemic heart disease (IHD) and other ischemic disorders provides a more consistent set of explanations for acute coronary syndromes than the accepted mechanism of plaque rupture and consequent thromboses. The concept avers that S-RV directly induces symptoms in the various syndromes of IHD, including acute coronary syndromes. The S-RV concept is considered to be an alternate paradigm to explain IHD, and interest only develops in such models when there is significant doubt about the validity of the accepted paradigm. This report is an update of a study reported in this Journal in 1999 and has 2 changes; evidence will be evaluated by formal verification/falsification (pass/fail) methods - the method used to evaluate paradigms, and this report focuses on the mechanism of acute coronary syndromes because of the importance of these syndromes. It is well accepted that acute coronary syndromes are due directly to plaque rupture/thromboses, and there is considerable evidence to support this obvious mechanism. In spite of the obviousness of this mechanism, the S-RV concept asserts that S-RV is a more rational mechanism to explain acute coronary syndromes. Consistent with this position, the results of the study favor the S-RV concept. The standard position was given 8 passes, 2 passes with associated possible limited failures, and 2 possible failures. In contrast, the S-RV concept was given 12 passes, and no failures. Hopefully, the results of this study, and other available information about the S-RV concept, will prompt interest in the concept - such as independent testing of its premises.

Can the premises of the altered homeostatic theory permit improvement in the prevention of ischemic heart disease?

In this communication, the altered homeostatic theory will be discussed and updated, and evidence will be presented that the premises of the theory might permit improvement of the prevention of ischemic heart disease (IHD). This hypothesis, first described in 1999, argues that IHD is due basically to an inappropriate shift of homeostasis, and the theory includes the position that S-RV directly induces symptoms. In contrast, the standard approach to IHD is based fundamentally on two principles: that atherosclerosis is due fundamentally to lipid abnormalities, and that symptoms in IHD are due to obstructive complications of atherosclerosis in epicardial coronary arteries. Suggestions for prevention stem from the altered homeostatic theory's different basic conceptualization of this disorder, and it seems reasonable that accepted basic pathogenetic mechanisms help shape measures to prevent IHD. Many of the theory's positions for preventing IHD parallel standard views, but the theory's basic premises have resulted in significant differences between the standard and the theory's overall approach to the prevention of IHD. Positions for the prevention of IHD include: the possibility that any preventative factor can improve any risk factor, the use of substitute preventative factors to counter unmodifiable or difficult to correct risk factors, underestimation of the risk of IHD by the standard position in individuals with normal lipid levels but multiple other risk factors, the probable relative overemphasis of the risk factor of cholesterol, the value of a national program to reduce the incidence of multiple disorders with similar risk factors, an alternate approach to the use of statins, and the value of an evolutionary approach to preventing IHD and other disorders.

Can the premises of the spasm of resistance vessel concept permit improvement in the treatment and prevention of ischemic heart disease?

In this communication, the spasm of resistance vessel (S-RV) concept of ischemic heart disease (IHD) and other ischemic will be reviewed and updated, and evidence will be presented that principles of the hypothesis might improve the treatment and prevention of IHD. The S-RV concept provides a different basic pathogenetic framework for IHD, and suggestions for treatment and prevention stem from its different basic conceptualization of this disorder. The concept asserts that S-RV directly induces symptoms in IHD, and this position challenges the accepted pathogenetic mechanism for this disorder, i.e., that symptoms in IHD are due directly to obstructive occlusions of epicardial arteries secondary to coronary artery disease. The S-RV concept avers that ischemia-induced S-RV is a major factor in IHD, and evidence supporting this position is provided. Another major position of the hypothesis is that no-reflow (reduced flow after infarction and severe myocardial ischemia in the absence of infarction) is due to ischemic injury-induced S-RV, and a variety of evidences to support this position are offered.Proposed improvement in the treatment of IHD is based mainly on treating ischemia-induced S-RV. alpha-Adrenergic sympathetic blockade reverses ischemia-induced S-RV, and alpha-adrenergic blockade is suggested as therapy for acute coronary syndromes and to prevent complications of percutaneous coronary interventions. Also, angiotensin-converting enzyme inhibition, which has actions similar to alpha-adrenergic blockade, is also suggested. Proposals for the prevention of IHD are based the prevention of S-RV, and special emphasis is given to preventing exercise- and stress-related IHD.

Microvascular reperfusion injury: rapid expansion of anatomic no reflow during reperfusion in the rabbit

The aim was to define the degree and time course of reperfusion-related expansion of no reflow. In five groups of anesthetized, open-chest rabbits (30-min coronary occlusion and different durations of reperfusion), anatomic no reflow was determined by injection of thioflavin S at the end of reperfusion and compared with regional myocardial blood flow (RMBF; radioactive microspheres) and infarct size (triphenyltetrazolium). The area of no reflow progressively increased from 12.2 +/- 4.2% of the risk area after 2 min of reperfusion to 30.8 +/- 3.1% after 2 h and 34.9 +/- 3.3% after 8 h and significantly correlated with infarct size after 1 h of reperfusion (r = 0.88-0.97). This rapid expansion of no reflow predominantly occurred during the first 2 h, finally encompassing approximately 80% of the infarct size, and was accompanied by a decrease of RMBF within the risk area, being hyperemic after 2 min of reperfusion (3.78 +/- 0.75 ml x min(-1) x g(-1)) and plateauing at a level of approximately 0.9 ml x min(-1) x g(-1) by 2 and 8 h of reperfusion (preischemic RMBF: 2.06 +/- 0.01 ml x min(-1) x g(-1)). The development of macroscopic hemorrhage lagged behind no reflow, was closely correlated with it, and may be the consequence of microvascular damage.

Occlusions of epicardial arteries might not directly induce symptoms in ischemic heart disease

It is accepted that primary occlusions of epicardial arteries by thromboses, stenotic coronary artery disease (CAD), and spasm directly induce symptoms in ischemic heart disease (IHD). Because of this acceptance, there has been little interest in alternate mechanisms for IHD--as the spasm of resistance vessel (S-RV) concept of IHD, which asserts that S-RV directly induces symptoms in IHD. To stimulate interest in the S-RV concept, evidence against the primacy of occlusions of epicardial arteries was presented, as well as evidence for this position to provide a balanced discussion; while the evidence was mixed, overall findings appeared to weigh significantly against the primacy of occlusions of epicardial arteries. Also, the S-RV concept was discussed; the discussion included presenting the theory's explanations for events in epicardial arteries, with the aim of demonstrating that the concept provides more consistent explanations than the standard position. It is suggested that there is sufficient information to warrant renewed consideration of the S-RV concept.

The altered homeostatic theory: a holistic approach to multiple diseases, including atherosclerosis, ischemic diseases, and hypertension

The altered homeostatic theory proposes that multiple acquired and genetic factors (risk factors) move the basic homeostatic balance in an 'action' direction which 'inappropriately' activates defense mechanisms and thus favors multiple diseases; factors which improve these disorders move the homeostatic balance in the opposite 'rest' direction. Diseases include hypertension, atherosclerosis, and ischemic disorders as ischemic heart disease (IHD), stroke, migraine, and Raynaud's disease. The theory has its origins in the premises of the spasm-of-resistance-vessel (S-RV) concept of ischemic diseases (which attributes symptoms in ischemic diseases to S-RV), and in a study designed to provide more evidence for this concept. The study showed that multiple risk factors for IHD express the combination of S-RV and a tendency toward thrombosis, and are risk factors for hypertension, migraine, Raynaud's disease, and stroke; factors which ameliorate IHD express vasodilation of resistance vessels and are anti-thrombotic, and ameliorate the other disorders.

New evidence for the spasm-of-resistance-vessel concept of ischemic diseases

The spasm of resistance vessel (S-RV) concept of ischemic diseases avers that S-RV representing vascular autoregulatory dysfunction directly induces symptoms in ischemic diseases. The most important ischemic diseases, ischemic heart disease (IHD) and stroke, generally are not attributed to S-RV, and new evidence will be provided in this communication that S-RV induces IHD and stroke. Hypertension and the ischemic disorders of migraine and Raynaud's disease have been attributed to S-RV and to vascular dysregulation, and this information was used to help structure the study. It was found that these disorders are closely associated with IHD and stroke, and this is consistent with S-RV and vascular dysregulation as the mechanism for IHD and stroke. Also, it was found that multiple risk factors for IHD foster S-RV and are risk factors for hypertension, migraine, Raynaud's disease, and stroke, and this supports S-RV as the mechanism for IHD and stroke.

A case that biomedicine is unduly negative to radical hypotheses and to theorizing--evidence based on cardiology's reaction to the spasm of resistance vessel concept and on the nature of scientific research

This communication will attempt to make a case that biomedicine is unduly negative to radical hypotheses and to theorizing. Evidence will be based on a proposed undue negativity by cardiology to a radical hypothesis I first described two and a half decades ago--the spasm of resistance vessel (S-RV) concept of ischemic heart disease (IHD). The theory is regarded as an alternate paradigm and deals with basic pathogenetic mechanisms of IHD, the most significant disorder of Western civilization. The concept, if valid, might help in reducing the impact of this disorder, and I believe that the evidence for the theory and the importance of IHD support a more open minded attitude toward the idea. Cardiology's negativity is attributed to the nature of research; the most important factor is considered to be the Kuhnian negativity of scientific communities to hypotheses which are destructive of conventional wisdom, and a second factor is the special nature of biomedical research. Biomedicine is regarded as special because a low level of specific information about complex biomedical processes has fostered an essentially total study-based approach. Such an approach is assumed to have resulted in biomedicine's use of induction as 'the' method of scientific inquiry, and prompted negativity towards the hypothetico-deductive method used to develop and test the theory. Also, the study-based nature of biomedicine appears to have fostered an intuitive reliance on only newly performed studies to test hypotheses, which led to ignoring evidence for the concept derived from known information about IHD. Biomedicine is also regarded as special because its infrequent use of paradigm-change has resulted in unfamiliarity with this method, and because the practical method of training in biomedical research has worsened the general unfamiliarity of scientists with theoretical aspects of science. Because of these factors, the S-RV concept has not yet been properly evaluated--a quarter of a century after it was first created.