Morphologic characteristics and functional significance of focal fibromuscular dysplasia of small coronary arteries

Fibromuscular dysplasia of the coronary arteries: An unusual case of sudden death and review of the literature

Fibromuscular dysplasia of the coronary is an uncommon coronary defect with a range of pathological alterations and unpredictable clinical description that can cause sudden death. We present an autopsy case of sudden cardiac death due to a rupture of a coronary artery aneurysm in a 59-year-old woman. Postmortem autopsy revealed two huge saccular aneurysms located at the right coronary artery, one of which was ruptured leading to a fatal hemopericardium. Histopathological examination revealed coronary artery fibromuscular dysplasia with fibromyxoid dissociation of the media causing saccular aneurysms. The involvement of coronary arteries in fibromuscular dysplasia with aneurysmal features has been rarely reported in the literature and is most likely an underdiagnosed finding. Due to the little number of published studies, the etiology is not fully understood and data on pathogenesis, risk factors, manifestation, disease course, and mortality are still unclear, which is a gap that needs to be filled in order to avoid under-diagnosis of the disease. Our case report aimed to discuss the mechanisms of sudden death attributed to coronary fibromuscular dysplasia.

Retinal Manifestations in Fibromuscular Dysplasia

Fibromuscular dysplasia of the arteries (FMD) is a segmental angiopathy which may produce obstruction of the carotid, cerebral, renal, mesenteric, coronary or iliac arteries. Except for lesions related to arterial hypertension, retinal manifestations have not yet been reported. This paper describes the case of a 10-year-old boy with progressive deafness, a history of an unexplained stroke and progressive occlusions of the retinal arterioles in the fundus periphery. This resulted in retinal neovascularization and recurrent retinal and vitreous hemorrhages. Despite repeated photo- and cryocoagulation the eyes progressed to a tractional retinal detachment which was successfully treated by vitrectomy and scleral buckling. The diagnosis of FMD was made on the basis of a histopathological examination of a temporal artery biopsy. The child also presented an asymptomatic but severe aneurysmal dilatation of the aorta and CT scan and MRI showed dilated cerebral arteries. The father of our patient had died at the age of 27 years either from myocardial infarction or rupture of a dissecting aortic aneurysm. He was highly myopic and had lost one eye from retinal detachment. The younger brother of our patient also presents aneurysmal dilatation of the aorta and tortuous cerebral vessels. Ocular examination is still normal. The findings in this family are compatible with an autosomal dominant inheritance with variable expression.

Age-related fibromuscular dysplasia in the human left ventricle papillary muscles arteries

We describe histologically cases of patients between 31 and 60 years of age who had fibromuscular dysplasia (FMD) in the tunica media (TM) of the left ventricle papillary muscles (PM) arteries. We also compared them with our previous findings in subjects younger than 30 years of age. We examined histologically samples taken from the tip of the anterior PM of the left ventricle in 200 healthy male hearts. In 33 cases (16.5 %), FMD was in the TM. We divided these cases into three subgroups (A, B, C) based on the degree of replacement of smooth muscle cells by fibrous tissue, and thus identified 17, 11 and 5 cases, respectively. Until the age of 41, the typical lesions were often localized within the TM. Beyond that age, the fibrous tissue increased in the TM wall and in the surrounding area of the vessels, causing dysfunction of the PM. Degenerative lesions, as well as inflammatory infiltration, were found after the age of 53. The findings of this study will be useful to cardiologists and cardiac surgeons, in pointing out that, after the age of 44 years old, some PM and their supporting valves may present a degree of dysfunction.

Sudden death due to coronary artery dissection associated with fibromuscular dysplasia revealed by postmortem selective computed tomography coronary angiography: A case report

We present an autopsy case of sudden death due to coronary artery dissection associated with fibromuscular dysplasia (FMD) in a young female patient. Postmortem selective coronary artery computed tomography (CT) angiography revealed dissections of the left anterior descending and left circumflex arteries. These findings were confirmed by subsequent autopsy. Histopathological examination revealed coronary artery FMD, which is considered a risk factor for dissection. To the best of our knowledge, this is the first postmortem radiology-pathology correlation of coronary artery dissection associated with FMD.

Coronary artery manifestations of fibromuscular dysplasia

Fibromuscular dysplasia (FMD) involving the coronary arteries is an uncommon but important condition that can present as acute coronary syndrome, left ventricular dysfunction, or potentially sudden cardiac death. Although the classic angiographic "string of beads" that may be observed in renal artery FMD does not occur in coronary arteries, potential manifestations include spontaneous coronary artery dissection, distal tapering or long, smooth narrowing that may represent dissection, intramural hematoma, spasm, or tortuosity. Importantly, FMD must be identified in at least one other noncoronary arterial territory to attribute any coronary findings to FMD. Although there is limited evidence to guide treatment, many lesions heal spontaneously; thus, a conservative approach is generally preferred. The etiology is poorly understood, but there are ongoing efforts to better characterize FMD and define its genetic and molecular basis. This report reviews the clinical course of FMD involving the coronary arteries and provides guidance for diagnosis and treatment strategies.

Sudden Death in 14 Month Old Due to Fibromuscular Dysplasia of Atrioventricular Nodal Artery

Fibromuscular dysplasia is a non-atherosclerotic, non-inflammatory vascular disease that is most commonly found in the renal arteries of pre-menopausal women. However, this disease entity has rarely been described in the coronary arteries and small cardiac conduction arteries. To our knowledge, there is no recorded case of fibromuscular dysplasia in small cardiac conduction arteries in infants/children. In this report, we present a case of unexplained death of a 14 month old wherein routine histologic examination failed to reveal a cause of death, but subsequent submission of the cardiac conduction system (atrioventricular [AV] and sinoatrial [SA] node regions) demonstrated the presence of isolated AV nodal artery fibromuscular dysplasia, which was considered the cause of death. The case serves to emphasize the potential importance of evaluating the cardiac conduction system in cases where routine gross and microscopic autopsy fails to reveal an adequate explanation for death.

Multiple episodes of ventricular tachycardia induced by silent coronary vasospasm

We present a 46-year-old patient who suffered from cardiac arrest and subsequently underwent placement of an implantable cardioverter defibrillator (ICD). The patient underwent a cardiac catheterization which revealed no significant coronary artery disease. About 1 year later he experienced appropriated and frequent ICD discharges due to monomorphic ventricular tachycardia (VT) with left bundle branch block morphology. His prodromal symptoms were mild dizziness and lightheadedness with no chest pain. Amiodarone, mexiletine, sotalol and dofetilide as well as ablation of two inducible ventricular tachycardias in the electrophysiology studies were unsuccessful in controlling the arrhythmias and ICD discharges. During the last episode, he experienced a mild burning sensation in his chest and was given nitroglycerin 0.4 mg sublingually, which relived his symptoms and aborted the VT. This led to a second cardiac catheterization to investigate whether the VT was being induced by myocardial ischemia. This second coronary angiogram spontaneously revealed significant coronary vasospasm and simultaneously, the patient's cardiac rhythm showed short runs of VT with left bundle branch block morphology. Intracoronary nitroglycerine relieved the coronary vasospasm and terminated the arrhythmia. The patient was treated with isosorbide mononitrate and diltiazem. He remained symptom free with no ICD discharges and no VT in ICD interrogations for more than 2 years. Coronary vasospasm may be silent and with no chest pain which creates a difficult clinical situation particularly if it is associated with ventricular tachycardia and sudden cardiac death. The mechanisms of VT in the setting of coronary vasospasm are not known and increased automaticity, focal discharges, functional unidirectional block with reentry, or a combination of these mechanisms may contribute to inducing the VT during the transient ischemia or rarely in the reperfusion phase. It is important to perform provocative tests to diagnose silent coronary vasospasm in unexplained sudden cardiac arrests.

Case report and review: epicardial coronary artery fibromuscular dysplasia

Fibromuscular dysplasia (FMD) of the epicardial coronary arteries is an uncommon entity. We describe the first published case of this condition presenting as a transient ischaemic attack due to thromboembolism from intracardiac thrombus secondary to silent myocardial infarction. We also present the first published case of epicardial coronary FMD with sparing of the renal arteries. This case provides further evidence that FMD of the epicardial coronary arteries frequently involves the mid to distal segments of the left anterior descending artery. A brief review of the literature on FMD is presented.

Post-mortem angiographic and histologic findings of coronary artery fibromuscular dysplasia

The present report highlights on exceptional angiographic and histologic features of coronary artery fibromuscular dysplasia in a young man complaining of chest discomfort during strenuous exercise. The striking features of fibromuscular dysplasia were the relative proximal localization of the lesion in left anterior descending coronary artery, the extensive length of the lesion, and the exclusive involvement of the intima producing a diffuse regular narrowing lesion. An eccentric intimal proliferation of the small left anterior descending coronary artery branches along their epicardial and intramural course was additionally demonstrated. No involvement of other coronary arteries or arteries of any other organs was observed.

Fibromuscular dysplasia of the coronary and renal arteries?

Fibromuscular dysplasia (FMD) involving the coronary arteries has been described pathologically as a cause of myocardial infarction but has not been described antemortem. Unlike renal artery FMD, its clinical manifestations remain poorly characterized. We describe demographic, clinical, and coronary angiographic characteristics of seven women with acute coronary syndromes and unusual coronary anatomy who also had renal artery FMD. All subjects were female caucasians, age 42-56, who presented with prolonged chest pain and positive troponin tests. Two were smokers, two had hypertension, and one had hypercholesterolemia. None was diabetic. There were distinctive angiographic features common to all seven patients. The left anterior descending artery was involved in six, the right posterior descending artery in one. In each case, the proximal vessel appeared normal but in the middle or distal segment there was a well-demarcated abrupt transition to diffuse obliterative disease. In six of the cases, this continued distally for the remainder of the epicardial vessel. In no case was revascularization feasible. Unlike severe diffuse atherosclerotic disease, all other coronary segments were angiographically normal. Ventricular dysfunction, if present, was mild. All seven patients had typical angiographic features of renal FMD, three bilaterally. We have observed a characteristic pattern of well-demarcated obliterative coronary artery disease associated with FMD of the renal arteries. All cases presented as acute coronary syndromes in patients at relatively low risk of coronary artery disease. We propose that these appearances in the epicardial arteries, previously undescribed ante-mortem represent coronary artery fibromuscular dysplasia.

Multiple spontaneous coronary artery dissections in association with anomalous origin of right coronary and intramural coronary artery dysplasia

We present a case of sudden death due to spontaneous acute coronary artery dissection. In addition, there was a healing spontaneous coronary dissection, intramural coronary artery dysplasia, and an anomalous origin of the right coronary artery from the pulmonary trunk. The coincidence of multiple spontaneous coronary dissections, coronary arterial dysplasia, and anomalous origin of the right coronary artery is unique.

Intramyocardial arterial narrowing in dogs with subaortic stenosis

Earlier studies have described intramyocardial arterial narrowing based on hyperplasia and hypertrophy of the vessel wall in dogs with subaortic stenosis (SAS). In theory, such changes might increase the risk of sudden death, as they seem to do in heart disease in other species. This retrospective pathological study describes and quantifies intramyocardial arterial narrowing in 44 dogs with naturally occurring SAS and in eight control dogs. The majority of the dogs with SAS died suddenly (n=27); nine had died or been euthanased with signs of heart failure and eight were euthanased without clinical signs. Dogs with SAS had significantly narrower intramyocardial arteries (P<0.001) and more myocardial fibrosis (P<0.001) than control dogs. Male dogs and those with more severe hypertrophy had more vessel narrowing (P=0.02 and P=0.02, respectively), whereas dogs with dilated hearts had slightly less pronounced arterial thickening (P=0.01). Arterial narrowing was not related to age, but fibrosis increased with age (P=0.047). Dogs that died suddenly did not have a greater number of arterial changes than other dogs with SAS. This study suggests that most dogs with SAS have intramyocardial arterial narrowing and that the risk of dying suddenly is not significantly related to the overall degree of vessel obliteration.

Coronary flow reserve measurements in hypertension

Taken together, the diagnostic algorithm is leaded by a simple ECG stress test. In case of ST-segment depression the preferred image test should be stress ECG to bring patients at high risk for significant epicardial coronary artery stenosis to coronary angiography (and revascularization). In case of the lack of wall motion abnormalities (during stress-echo test) or absence of epicardial stenosis one may further assess coronary flow reserve with noninvasive Doppler harmonic echocardiography. For ultimate quantitative assessment invasive procedures, such as argon dilution or intracoronary Doppler techniques, represent the appropriate approach. Treatment of microvascular disease may be followed-up by these new noninvasive diagnostic approaches in future and also, at present, by monitoring ST-segment depression.

Idiopathic intimal hyperplasia of small arteries and arterioles affecting intestines and myocardium

We report the case of a 52-year-old woman dying from a noninflammatory, occlusive vasculopathy. Histology showed marked intimal hyperplasia of small arteries of the intestines and myocardium with subsequent infarction of myocardium, large intestine and gallbladder. A comprehensive work up including laboratory studies, clinical investigations and postmortem failed to assign this condition to any of the known vascular diseases.

Genetics of leukoaraiosis

Computed tomography and magnetic resonance imaging of the brains of elderly individuals frequently show areas of altered signal intensity in the periventricular and subcortical white matter, referred to as leukoaraiosis. Although mildly affected individuals appear asymptomatic, larger burdens of leukoaraiosis are associated with deficits of cognition and gait. Histopathologically, areas of leukoaraiosis invariably show sclerosis, luminal narrowing, and tortuosity of small arteries and arterioles, accompanied by variable degrees of gliosis, demyelination, and axonal loss resulting from ischemia. Genetic variation plays a substantial role in interindividual differences in the volume of leukoaraiosis and its associated adverse clinical outcomes. Characterizing genetic factors contributing to interindividual differences in leukoaraiosis has the potential to enhance understanding of molecular determinants of ischemic brain injury and lead to new approaches to the diagnosis, evaluation, treatment, and prevention of this common form of vascular dementia.

Sudden death related to small coronary artery disease

Two cases of sudden death of young people in apparently good health are reported. The only pathologic change found was a fibromuscular dysplasia of the artery supplying the conduction system of the heart with an important narrowing of the lumen and strong thickening of the arterial wall. The first case was of a 12-year-old girl who died suddenly while skiing; the second was of a 32-year-old man who died while talking to his wife. No other pathologic changes were found at autopsy, and the results of toxicologic analysis were negative. There was no individual or family history of cardiac diseases. These cases illustrate the importance of an analysis of the conduction system, including examination of the intramural coronary arteries supplying the conduction system.

Sudden unexpected death with dysplastic change in the atrioventricular node artery

We report an autopsy case of a 19-year-old male who died suddenly. Death happened while he was sleeping after drinking alcoholic beverages. His heart revealed concentric hypertrophy of the left ventricle without asymmetric septal hypertrophy or mitral regurgitation. Upon microscopic examination, the epicardial atrioventricular (AV) node artery revealed stenosis with intimal thickening before it entered the ventricular septum and acute ischemic change was observed beneath the conduction system in the upper ventricular septum. This finding suggests that death occurred after some preceding localized ischemic event within the ventricular septum. We therefore consider that the cause of death was fatal arrhythmia due to dysplastic change to the AV node artery.

Ischaemic heart disease in the dog: a review of 65 cases

Sixty-five dogs are reviewed with histopathologically confirmed intramural arteriosclerosis. Clinical data (clinical signs, electrocardiographic findings and ultrasound parameters) on these animals were collected from nine small animal clinics in Sweden: 16 dogs had died suddenly, with few or no previous clinical signs; 13 dogs died or were euthanased during or shortly after general anaesthesia or sedation; 30 dogs developed acute (14) or chronic (16) congestive heart failure; and six dogs died or were euthanased for causes unrelated to cardiac disease. Electrocardiography of 23 of the dogs revealed several types of arrhythmias, with atrial fibrillation and sinus tachycardia being most commonly detected. Ultrasonographic examinations of 24 dogs found a relatively high number (19) with decreased indices of contractility. Dogs that had died suddenly and in relation to general anaesthesia or sedation had a higher incidence (25 of 29) of purely arteriosclerotic changes in the myocardial vessels, whereas just over half the dogs with congestive heart failure (16 of 30) had other concomitant heart lesions (in most cases endocardiosis). The incidence of myocardial infarcts was high (51 of 65 cases). It is postulated that arteriosclerosis in the dog may be an important reason for sudden death and death during general anaesthesia. Coronary arterial disease should also be a consideration in the clinical evaluation of dilated cardiomyopathy and may contribute to the decreased myocardial contractility when it is present in dogs with mitral regurgitation.

Fibromuscular dysplasia

Fibromuscular dysplasia is an uncommon angiopathy that occurs in young to middle-aged, predominately female individuals. The disease consists of a heterogeneous group of histologic changes, which ultimately lead to arterial narrowing. Clinical manifestations reflect the arterial bed involved, most commonly hypertension (renal) and stroke (carotid). Fibromuscular dysplasia is a pathologic diagnosis, but the characteristic changes seen on an angiogram can be used to make the diagnosis in the appropriate clinical setting. This noninflammatory disease is a common mimic of vasculitis. A very limited amount of new literature has been published in the past year about this relatively uncommon condition.

Pathologic and electrocardiographic findings in sudden cardiac death in racehorses

Five racehorses in apparently normal condition succumbed to sudden cardiac death (SCD) during or shortly after intensive training exercise. Cardiopathologic examination was performed. In 1 of the 5 horses, the use of an electrocardiogram (ECG) recording taken continuously for 440 sec enabled us to analyze some of the arrhythmias in the terminal event of SCD. The ECG tracing exhibited the R-on-T phenomenon following a pair of ventricular premature contractions (VPCs). The phenomenon rapidly degenerated into ventricular fibrillation, which led to cardiac arrest. In all 5 horses cardiopathologic examination revealed the following lesions: (i) foci of myocardial fibrosis in the right atrium located close to the sinoatrial (SA) node, (ii) fibrotic and/or fibroplastic changes in the upper portion of the interventricular septum, including the atrioventricular (AV) conduction system, and (iii) arterio- and arteriolosclerosis of the SA and AV node vessels. Pathogenetically, the process by which the focal lesions of myocardial ischemia secondary to vascular sclerosis progressed into fibrosis and/or fibroplasia could play a major role in the genesis of arrhythmias. Presumably the fibrotic and/or fibroplastic changes in the area of the AV bundle and its bundle branches are closely related to the onset of fatal ventricular arrhythmias such as VPCs, deteriorating into ventricular fibrillation. SCD in training and racing Thoroughbred horses appears to be due to arrhythmia.

Atrioventricular node fetal dispersion and His bundle fragmentation of the cardiac conduction system in sudden cardiac death

OBJECTIVES

This study sought to examine the frequency of persistent fetal dispersion of the atrioventricular (AV) node and fragmentation of the atrioventricular bundle (His) bundle in the cardiac conduction system of sudden cardiac death cases and control subjects to establish their importance as the cause of death.

BACKGROUND

These are two of the most frequent lesions reported in published reports in the cardiac conduction system in unexplained sudden deaths.

METHODS

We have studied the conduction system of 347 hearts: 249 hearts from sudden cardiac death cases and 98 control hearts. The sudden cardiac death cases were divided, according to the pathology found, in three groups: group I: ischemic heart disease, 137 cases; group II: nonischemic heart disease, 48 cases, and group III: unexplained sudden cardiac deaths, 64 cases. The control group (group IV) consisted of patients with unnatural deaths and extracardiac natural deaths.

RESULTS

Persistent fetal dispersion of the AV node was observed in 70 cases (20.17%) of all groups with a frequency (40.81%) statistically higher in the control group. Fragmentation of the His bundle was observed in 95 cases (31.77%), and the frequency was statistically higher in the control group, too (47.67%).

CONCLUSIONS

Persistent fetal dispersion of the AV node and fragmentation of the His bundle can be a normal variation present during many years in life and must not be considered the anatomic substrate for arrhythmias and sudden death without electrocardiographic abnormalities.

Intramural coronary artery dysplasia of the ventricular septum and sudden death

We report four cases of sudden unexpected death in three males and one female aged 12 to 31 years. Death occurred during exercise in three of four cases, and there was no history of sudden death or previous cardiac history in any patient. At autopsy, there was marked intramural coronary artery dysplasia of the ventricular septum, accompanied in three of the four cases by myocardial fibrosis. The arterial dysplasia was characterized by severe medial thickening with smooth muscle cell disorganization and marked luminal narrowing. There was no evidence of myofiber disarray or asymmetric septal hypertrophy to suggest hypertrophic cardiomyopathy. Other than an ostium secundum type atrial septal defect in one case, there were no associated cardiac or extracardiac lesions found at complete autopsy of these individuals. We conclude that small vessel disease of intramural coronary arteries of the ventricular septum may be an isolated finding leading to sudden cardiac death in young adults.

Assessing the coronary circulation in hypertension

Systemic arterial hypertension is one of the major risk factors for coronary artery disease, coronary microangiopathy, and left ventricular hypertrophy, all of which can potentially lead to cardiac failure and sudden cardiac death. Coronary flow reserve is defined as the maximal increase in coronary flow above its resting, autoregulated level for a given perfusion pressure. In arterial hypertension functional and structural alterations are observed at the level of epicardial vessels as well as in resistive vessels requiring sophisticated approaches to assess coronary flow reserve and thus myocardial perfusion. Electrocardiographic tests and echocardiography can be regarded as monitoring and screening methods. Myocardial scintography is useful to semiquantitatively estimate hypertension-associated perfusion abnormalities, whereas positron emission tomography provides the only quantitative approach of a non-invasive technique for myocardial blood flow measurement. Invasive methods for the assessment of coronary blood flow need cardiac catheterization procedures, such as techniques requiring catheterization of the coronary sinus, angiographic methods, and guidewire based methods. Thermodilution and venous oxymetry in the coronary sinus systematically underestimate coronary flow reserve and are thus considered as only semiquantitative approaches. In contrast, the gas chromatographic argon method allows a quantitative measurement of coronary blood flow at baseline and during maximum vasodilation; thus it is possible to distinguish between an altered autoregulated and maximal flow as the major cause of a reduced coronary flow reserve and to evaluate long-term therapeutic interventions in hypertensive hearts. Videodensitometric and angiographic methods should be restricted only to patients with coronary microangiopathy or with coronary single-vessel disease. Guidewire-based Doppler techniques are suitable to semiquantitatively assess coronary flow reserve with a considerable spatial and time resolution. Myocardial biopsies may gain insight into hypertension-associated structural alterations in small arterioles. Long-term treatment of hypertensive heart disease aims to normalize blood pressure, to reduce left ventricular hypertrophy and to achieve cardioreparation including reversal of the abnormal structure and function of coronary circulation. Based on the different methods for assessment of coronary circulation the therapeutic value of different classes of antihypertensive therapeutics will be evaluated in this overview.

Familial syndrome of progressive arterial occlusive disease consistent with fibromuscular dysplasia, hypertension, congenital cardiac defects, bone fragility, brachysyndactyly, and learning disabilities

We report on 4 of 9 sibs with a syndrome of stenosis of the renal arteries and chronic hypertension, variable stenosis or occlusion of cerebral, abdominal and probably coronary arteries due to suspected fibromuscular dysplasia, congenital cardiac abnormalities, brachydactyly and syndactyly of the hands and feet, and increased bone fragility consistent with a mild form of osteogenesis imperfecta. Three affected individuals have had mild to moderate learning disabilities. The parents and the remaining 5 sibs have normal hands and feet and no history of excessive fractures. Individual components of this syndrome may appear as isolated conditions, including fibromuscular dysplasia, brachydactyly, syndactyly, and osteogenesis imperfecta, and are autosomal dominant traits in many cases. Explanations for this familial occurrence include autosomal recessive inheritance, autosomal dominant inheritance with decreased penetrance, or parental gonadal mosaicism for a mutation involving a single gene or several contiguous genes.

Fibromuscular dysplasia of small coronary arteries and fibrosis in the basilar ventricular septum in mitral valve prolapse

The mechanism of sudden cardiac death in patients with mitral valve prolapse is poorly understood. Twenty-four hearts from patients with mitral valve prolapse who suddenly died (mean age 34 +/- 8 years) and 16 trauma control hearts (mean age 30 +/- 7 years) were histologically studied. Dysplasia of the atrioventricular nodal artery was present in 18 of 24 hearts with mitral valve prolapse and four of 16 controls hearts (p = 0.003). The degree of luminal narrowing, as morphometrically measured, was significantly greater in hearts with mitral valve prolapse (p = 0.003). The degree of fibrosis in the base of the ventricular septum, as calculated by computerized morphometry, was greater in hearts with mitral valve prolapse (p = 0.0002) and independent of age, sex, and heart weight (p = 0.005). We conclude that arterial dysplasia in mitral valve prolapse may contribute to sudden cardiac death mediated by ventricular fibrosis.

Cardiac disease in chronic uremia: pathogenesis

Cardiomyopathy in chronic uremia results from pressure and volume overload. The former causes concentric left ventricular [LV] hypertrophy, results from hypertension and aortic stenosis, and is also associated with diabetes mellitus and anemia. Volume overload causes LV dilatation, results from arteriovenous shunting, salt and water overload, and anemia, and is also associated with ischemic heart disease, hypertension, and hypoalbuminemia. Decreased major arterial compliance and an early return of arterial wave reflections are also associated with the extent of LV hypertrophy. Cardiomyopathy predisposes to diastolic and systolic dysfunction. The latter results from myocyte death, and predisposing factors include ischemic heart disease and the uremic environment. Ischemic heart disease may be atherosclerotic or nonatherosclerotic in origin. Multiple factors contribute to the vascular pathology of chronic uremia, including injury to the vessel wall, dyslipidemia, prothrombotic factors, increased oxidant stress, and hyperhomocysteinemia. Ischemic risk factors include hypertension, LV hypertrophy, hypoalbuminemia, and perhaps hyperparathyroidism. The clinical consequences of cardiomyopathy include heart failure, ischemic heart disease, dialysis hypotension, and arrhythmias. The adverse impact of ischemic heart disease is probably mediated through the development of cardiac failure.

Spontaneous changes of heart rate, blood pressure, and ischemia-type ST-segment depressions in patients with hypertension without significant coronary artery disease: beneficial effects of beta-blockade

In hypertensives, a reduced coronary flow reserve is observed and may contribute to angina pectoris and silent (painless) myocardial ischemia, which frequently occur in these patients even in the absence of coronary artery disease (CAD). To assess the frequency of ischemia-type ST-segment depressions in these patients and the influence of heart rate (HR) and blood pressure (BP) as major determinants of myocardial oxygen demand and to test the effects of beta-blocker therapy (10-20 mg betaxolol/day for 4 weeks) on these variables, simultaneous 24-h Holter and 24-h ambulatory BP monitoring was performed in 19 patients with hypertension (age, 43-71 years; nine women, 10 men) without CAD (stenosis < 50% in angiography). Before treatment, 25 periods of significant ST-segment depressions with a total duration of 470 min were observed in nine patients. ST-segment depressions were significantly correlated with preceding increases in HR and the rate-pressure product. The majority (79%) of episodes with ST-segment depression were clinically painless. In this open study, beta-blockade significantly decreased the number of episodes with ST-segment depressions to six in four of 15 patients and the total duration to 38 min (p < 0.05). The data demonstrate that HR seems to be associated with the development of ischemic ST-segment deviations in patients with hypertension without CAD. Antihypertensive therapy in these patients should target not only sufficient BP control, but also reduction of ischemic events.

Outcome and risk factors of ischemic heart disease in chronic uremia

To determine the prognosis and risk factors for ischemic heart disease in chronic uremia, a cohort of 432 dialysis patients were followed prospectively from start of dialysis therapy until death or renal transplantation. Baseline demographic, clinical and echocardiographic data were obtained. After the initiation of dialysis laboratory data were collected at monthly intervals, and clinical and echocardiographic data at yearly intervals. Twenty-two percent of patients (N = 95) had either a history of angina pectoris or myocardial infarction on starting dialysis therapy. Median time to onset of heart failure was 24 months in those with ischemic heart disease on initiation of dialysis, compared to 55 months in those without (P < 0.0001). This effect was independent of age, diabetes and underlying cardiomyopathy. Median survival was 44 months in those with ischemic disease compared to 56 months in those without (P = 0.0001). This adverse impact was independent of age and diabetes mellitus but, when cardiac failure was added to the Cox's model, ischemic heart disease was no longer an independent predictor of survival. De novo ischemic heart disease, not evident on starting dialysis therapy, occurred in 41 (9%) patients. When compared to patients who never developed ischemic disease (N = 296; 69%), significant and independent predictors of de novo disease were older age (P = 0.0007), diabetes mellitus (P = 0.0001), high blood pressure during follow up on dialysis (P = 0.02) and hypoalbuminemia (P = 0.03), whereas anemia was not an independent predictor. LV mass index was 174 +/- 7 g/m2 in those who developed de novo ischemic disease compared to 155 +/- 3 g/m2 (P < 0.001) in those who did not. Concentric LV hypertrophy, LV dilation and systolic dysfunction were independent risk factors for de novo ischemic heart disease. We conclude that ischemic heart disease occurs frequently in dialysis patients, that its adverse impact is mediated through the development of heart failure, and that the most important, potentially reversible risk factors are hypertension, hypoalbuminemia, and underlying cardiomyopathy.

Normal and abnormal consequences of apoptosis in the human heart. From postnatal morphogenesis to paroxysmal arrhythmias

Apoptosis and necrosis are two distinctly different forms of cell death, and both occur in the human heart. In contrast to necrosis, apoptosis is not associated with inflammation for two reasons. First, the apoptotic cell does not swell or rupture before it is engulfed by either a macrophage or even a neighboring like cell. Second, the phagocytosis occurs with unusual rapidity. Apoptosis, also thought of as cell suicide, is a tidy way of removing cells no longer useful, in essence a form of selective deletion. These features make apoptosis a valuable component of morphogenesis, mediation of hormonal and immunologic responses, and the homeostatic balance between hypertrophy and atrophy or involution. In the human heart apoptosis has been found in the sinus node of patients with the long QT syndrome. It most likely participates in the important postnatal morphogenesis of the sinus node, AV node, and His bundle. Apoptosis may also participate in the genesis and pathophysiology of cardiomyopathy, paroxysmal arrhythmias, or conduction disturbances (some of which may be responsible for sudden death), focal fibromuscular dysplasia of small coronary arteries, hereditary medial degeneration of the tunica media of coronary arteries, and arrhythmogenic right ventricular dysplasia. The possible role apoptosis in numerous other changes in the human heart, among them the pathogenesis of atherosclerosis and mechanisms of aging in the myocardium, merits future investigation.

Congenital disorders of cardiac rhythm and conduction

Electrical instability of the heart has numerous congenital origins. This review approaches the problems from a morphological standpoint, utilizing selected examples from my own studies of the human cardiac conduction system performed during the last three decades. Subjects discussed include multifocal Purkinje cell tumors, benign congenital polycystic tumors of the AV node, several types of congenital heart block, postnatal morphogenesis of the AV node and His bundle (including considerations of persistent fetal dispersion and crib death), the Wolff-Parkinson-White syndrome, left superior vena cava, focal fibromuscular dysplasia of small coronary arteries, hereditary neuromuscular or musculoskeletal diseases, familial atrial fibrillation, long QT syndrome, and apoptosis of the heart. In many congenital disorders of cardiac electrical activity, both arrhythmias and conduction disturbances may occur. How the abnormal anatomy may relate to cardiac electrical instability is discussed, including certain clinical matters to be considered.

Nonatherosclerotic narrowing of the atrioventricular node artery and sudden death

OBJECTIVES

This study was undertaken to determine whether thickening of the atrioventricular (AV) node artery is a cause of sudden cardiac death.

BACKGROUND

Thickening of the AV node artery has been implicated as a cause of sudden death primarily on the basis of case reports. Few pathologic studies have compared subjects who died of sudden cardiac death with normal control subjects who died traumatically.

METHODS

The AV node artery in 27 patients with unexplained sudden cardiac death (mean age 24.8 +/- 7.4 years) was compared with that in 17 control subjects who died traumatically (mean age 25.6 +/- 7.0 years). No anatomic cause of death was found at autopsy in the subjects with sudden death, all of whom died of presumed cardiac arrhythmias. The conduction system of all hearts was studied by semiserial sections and Movat pentachrome stains. At the point of greatest narrowing of the AV node artery, the outer circumference and lumen outline were traced by computerized morphometry, the ratio of outer vessel area to lumen area was calculated and the histopathologic changes were noted.

RESULTS

The rank-sum of ratios was significantly greater in the sudden death group than in the control group (p = 0.031, Wilcoxon rank-sum/Mann-Whitney statistic). A dysplastic AV node artery with significant acid mucopolysaccharide deposition was seen almost exclusively in the sudden death group (12 of 27 vs. 1 of 17, p = 0.006). In 10 subjects with sudden death a dysplastic AV node artery was narrowed > 2 SD over the control value; half of this subgroup died during exercise and one third had a family history of sudden unexplained cardiac death.

CONCLUSIONS

Dysplasia of the AV node artery may contribute to death in a substantial portion of patients with unexplained sudden death, and such death is often associated with exercise and a family history of unexplained sudden death.

Coronary microcirculation in hypertensive heart disease: functional significance and therapeutic implications

In arterial hypertension left ventricular hypertrophy comprises myocyte hypertrophy, interstitial fibrosis and structural alterations of the coronary microcirculation. This leads to an impairment of diastolic function of the left ventricle and coronary flow reserve despite normal epicardial arteries. Consequently, antihypertensive treatment should aim at [13] reversing myocyte hypertrophy, [14] restoring myocardial structure and [8] improving coronary flow reserve along with blood pressure normalization.

Causative role of coronary microvessels for the development and progression of chronic myocardial lesions in spontaneously hypertensive rats (SHR)

The pathomechanisms responsible for the development and progression of myocardial alterations in hypertensive heart disease are largely unknown. Using newly developed preparation and measuring procedures in 78 SHR and 82 controls aged 3-78 weeks, topological relations were detected between focal morphological appearances of chronic myocardial ischemia (fml.) and pathological microvessel (mv.) reactions characterized by morphometric signs of chronic contractions. The smallest ramifications are of particular pathogenic importance. A generalized peak of pathological mv. reactions between the 16th and 24th weeks is responsible for the development of first fml. The further progression of the area density of fml. from 1.26 +/- 0.85% (24th week) to 31.82 +/- 8.60% (78th week) is attributable to the further increase in pathological mv. reactions caused by organ-specific influences. The histological and morphometric findings suggest that the pathological mv. reactions are aggravated by their own effects at the local level.

Histologic abnormalities of large and small coronary arteries, neural structures, and the conduction system of the heart found in postmortem studies of individuals dying from the toxic oil syndrome

Hundreds died and thousands were poisoned by rapeseed oil adulterated with aniline and sold illegally in Spain in 1981. The clinical manifestations, now known as the toxic oil syndrome, include pulmonary hypertension and right ventricular hypertrophy plus widespread vascular and neural lesions in other organs. Many of the late deaths ended with a scleroderma-like illness. Because scleroderma involves the heart, in this study we examined the small and large coronary arteries, neural structures, and conduction system from eight victims dying with the toxic oil syndrome. Dense fibrosis of the sinus node in two hearts resembled changes found in scleroderma. Atrionodal junctional hemorrhages and cystic degeneration of the sinus node present in the other six hearts resembled changes found in lupus erythematosus. Small and large coronary arteries exhibited focal fibromuscular dysplasia and a proliferative cystic myointimal degeneration. This latter abnormality was associated with sloughing of the inner wall and embolization of the detached fragment downstream in the same coronary artery. Every heart had many degenerative lesions within nerves, ganglia, and the coronary chemoreceptor. Both the arterial and neural abnormalities prominently involved the conduction system. Based upon observations by others with experimental feeding of rapeseed oil containing either high or low erucic acid, we suggest that this oil must remain a major suspected cause of the toxic oil syndrome, particularly in conjunction with some as yet unexplained facilitative influence by oleoanilids. If this is so, it is important to reconsider the widely recommended use of any rapeseed oil product as a suitable food for man or other animals.