Severe Systemic Hypertension Research Articles

Mechanism of the pulmonary edema induced by intravenous injection of scorpion toxin in the rat.

The intravenous injection of purified scorpion toxin (tityustoxin, TsTX) into unanesthetized rats induces a severe systemic hypertension followed by a hemorrhagic edema of the lungs. The edema is focal or diffuse, whereas the hemorrhage is always focal and less prominent than the edema. Anesthesia of the rats prevents the appearance of pulmonary edema. It seems likely that this protective action of the anesthesia is due, at least in part, to an interference with the hypertension induced by TsTX. The pulmonary edema is prevented by bilateral adrenalectomy, guanethidine or phenoxybenzamine. It is suggested that the edema depends on a sympathetic-adrenal discharge and that catecholamines released by TsTX act on alpha adrenergic receptors. The mean kininogen content of the rat plasma, 1 h after TsTX injection, is not significantly different from that found in the control animals. The possible role played by kinins and other mediators in the early phases of the pulmonary edema induced by TsTX is under investigation.

Cardiac Toxicity of Clonidine

A 22-year-old woman with systemic lupus erythematosus complicated by mild renal insufficiency and severe systemic hypertension inadvertently received an excessive amount of clonidine hydrochloride. In association with a presumed toxic level of clonidine in the serum, the patient developed abnormalities of cardiac conduction, including 2:1 atrioventricular block, complete heart block, 3:2 Wenckebach block, and first-degree atrioventricular block. The transient nature of these abnormalities, with the return of normal conduction upon the cessation of therapy with clonidine, implicates this drug as being capable of producing high-grade atrioventricular block at toxic levels.

MEDICAL MANAGEMENT OF SEVERE SYSTEMIC HYPERTENSION IN INFANTS WITH COARCTATION OF THE THORACIC AORTA

16/56 infants (ages 2 wks to 6 mos) with isolated coarctation of the thoracic aorta presented with congestive heart failure and severe systemic hypertension ranging from 210/140 to 150/80 mmHg. Because of the surgical risks in symptomatic infants and the probability of recoarctation, conventional anticongestive medical management was instituted. The response to the anticongestive measures was markedly enhanced by diminishing after-load with chronic oral propranolol (.05-1.0 mg/kg/day) with maximal antihypertensive effects noted by 1-4 wks. Rebound hypertension was noted in 4 patients with propranolol withdrawal. This clinical response noted is consistent with high renin hypertension. No complications related to beta blockade have been seen in the infants treated. From this data we conclude that the antihypertensive effects from propranolol far outweigh the negative inotropic effects in the treatment of coarctation of the aorta. Further, thr treatment of severe hypertension in infants with coarctation of the aorta may allow deferral of surgery to a more optimal size and clinical status.

Letter: Haloperidol for acute amphetamine poisoning: a study in dogs.

To the Editor.— The accidental or suicidal consumption of large doses of amphetamine has been the cause of a number of fatalities in the past,1and it seems likely to continue because of the increasing abuse of this class of compounds. Several investigations have associated the stimulatory actions of amphetamine with an increased dopaminergic activity.2,3Therefore, we decided to test the effectiveness of haloperidol, a butyrophenone with a known antidopaminergic activity,4as a possible antidote. A previous study in this laboratory showed haloperidol to be effective in antagonizing dextroamphetamine intoxication in rats.5 The experiments were performed on unanesthetized mongrel dogs. A lethal dose (LD100) of dextroamphetamine sulfate (10 mg/kg) administered intravenously produced severe systemic and left ventricular hypertension, marked fluctuations in the central venous pressure, increases in cardiac output and heart rate, pronounced hyperthermia, elevations of the serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase,

Medical screening of patients with coronary artery disease: Criteria for entrance into exercise conditioning programs

Although considerable emphasis has been placed on stress testing and physical training of patients with coronary artery disease, data on safe and thorough preliminary medical evaluation are scarce. Because the routine history and physical examination are not sufficient to protect the exercising subject, medical screening attempts a thorough analysis of the patient's motivation, physical status, possible risk factors and the probability of benefit. Motivation is a critical factor since training for prolonged periods of time at high levels of heart rate and oxygen consumption may be required. Patients who have unstable angina or who may be harmed by increased myocardial oxygen requirements must be excluded. Concomitant influencing diseases and certain medications may also be causes for rejecting a patient. Valvular heart disease and severe systemic hypertension are not associated with benefit from exercise conditioning. The screening physician must exclude patients with certain abnormal electrocardiographic patterns, such as bilateral bundle branch block and type II second degree atrioventricular block, and he must be assured that he is dealing with coronary artery disease, not a pathologic process that mimics it. When these principles are applied, few persons in organized programs of exercise conditioning should suffer, and the yield of good results should be enhanced.

Pseudoxanthoma elasticum with severe cardiovascular disease in a child.

A 13-year-old girl was hospitalized for a second episode of acute upper gastrointestinal hemorrhage. Acute inferior wall myocardial and diffuse subendocardial infarction was diagnosed on the fifth hospital day. Clinical and pathological evaluation established a diagnosis of pseudoxanthoma elasticum (PXE) with characteristic dermatological, ophthalmological, gastrointestinal, and peripheral vascular involvement. Recovery from the myocardial infarction was uneventful despite the development of severe systemic hypertension. Although PXE is a relatively uncommon disease and often seemingly benign, it may be responsible for acute catastrophic events such as gastrointestinal hemorrhage, myocardial infarction, and sudden death in the young.

Severe systemic hypertension and muscular subaortic stenosis

The case of a 15-year-old girl with severe systemic hypertension secondary to chronic pyelonephritis and muscular subaortic stenosis is reported. The severity of the obstruction of the left ventricular outflow tract varied according to the blood pressure levels. Uncontrolled hypertension attenuated the auscultatory signs indicative of stenosis. Augmentation of the obstruction, evidenced by intensification of the murmur, was present when antihypertensive drugs produced orthostatic hypotension. No adequate form of palliation could be offered to this patient because of the coexistence of end-stage renal failure and the severe cardiac disease which led to her death.

Late vascular manifestations of the rubella syndrome: A roentgenographic-pathologic study

Attention is called to the late development of complete aortic luminal occlusion with severe systemic hypertension in a seven year old boy with clinical features of the rubella syndrome. Necropsy showed that the aorta was occluded by fibrocalcific material, probably the result of organization of thrombus. The distal abdominal aorta and the branches arising from it were severely hypoplastic, as were the renal arteries. Aortic thrombosis and systemic arterial hypoplasia have not been described previously as complications of the rubella syndrome.

CURRENT CONCEPTS IN PEDIATRIC CARDIOVASCULAR SURGERY

AMONG the many interesting congenital cardiac malformations amenable to surgery today, four will be discussed, namely, coarctation of the aorta, ventricular septal defect, Tetralogy of Fallot, and transposition of the great vessels. Recommendations for surgical therapy are based on the experience at the Mayo Clinic. Coarctation of the aorta continues to be most satisfactorily treated by operation and the hospital mortality risk is extremely low. In general, the optimal age for surgery is about 10 to 12 years. Unusually severe systemic hypertension or cardiac enlargement constitute an indication for somewhat earlier surgery. When infants with isolated coarctation of the aorta show severe cardiac failure, and this certainly occurs although uncommonly, operation should be advised at that age. The risk even then is very low, but few cases may require reoperation at age 12 because of failure of adequate growth of the anastomosis. The indications for repair of ventricular septal defect must take into account the estimated size of the lesion and its hemodynamic effects. Patients with small ventricular septal defects who have normalsized hearts and normal electrocardiograms, that is, those without clinical evidence of significant hemodynamic derangement, are not advised by us to undergo repair of the defect at present. Patients with ventricular septal defect and mild or moderate pulmonary artery hypertension (that is, patients whose pulmonary artery pressure is less than 75% of systemic artery pressure) can be operated upon at essentially no hospital risk. Operation is clearly advisable in all of these patients. Patients with ventricular septal defect who have severe pulmonary artery hypertension associated with a large pulmonary blood flow (and thus with only mild elevation of pulmonary vascular resistance) can be operated upon with a low hospital mortality rate, in the neighborhood of 5%.

Role of anticoagulants in the treatment of cerebrovascular disease

Since 1955 a number of conflicting reports have appeared concerning the efficacy of anticoagulant agents against cerebrovascular disease. Some of the variation of opinion has been caused by different concepts of what may be accomplished by the treatment and by the fact that clinical categories of strokes may respond differently to therapy. The evidence accumulated to date suggests that anticoagulant therapy may favorably influence the natural history of (1) impending stroke (intermittent focal cerebrovascular insufficiency, transient ischemic attacks), (2) advancing stroke, particularly in the vertebrobasilar system, and (3) recurrent cerebral embolization from a cardiac source. In most reports it is said that anticoagulant therapy is of no benefit when completed stroke is present and under such a circumstance may be unduly dangerous. Hemorrhagic complications continue to be a problem. Careful control of the degree of anticoagulation must be maintained; it may reduce the incidence of complications. Severe systemic hypertension, which cannot be medically controlled, appears to be a contraindication to longterm therapy.