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Biomedical subjects

J M Atkins

Publications and source records attributed to J M Atkins.

At least 37 records · Page 2Linked to original sources
PubMed1980

Water and electrolyte movement and mucosal morphology in the jejunum of patients with portal hypertension.

Intestinal secretion and intercullular space dilatation can be induced in animal models by acute elevation of intravascular volume or portal pressure. We examined whether patients with increased portal venous pressure might represent a clinical counterpart to these animal models. Portal venous pressure, determined by hepatic wedge pressure measurement, was elevated to 10-55 mmHg (mean 29 mmHg) in 8 patients with chronic liver disease without diarrhea. Intestinal transport studies utilizing a steady-state perfusion technique revealed normal absorption of a plasmalike electrolyte solution. A solution dsigned to unmask intestinal secretion demonstrated no difference from control subjects in the movement of water, electrolytes, or protein into the intestional lumen. There was no correlation of absorption of secretion with hepatic wedge pressure. Jejunal biopsy revealed a significant increase in dilatation of intercellular spaces in patients compared to controls; this increase was not correlated with hepatic wedge pressure, but was significantly inversely correlated to plasma renin and aldosterone concentration. We conclude that patients with chronic liver disease and portal hypertension absorb water and electrolytes normally, but have mild morphologic alterations in the intestinal mucosa, possibly related to intravascular volume status.

Adult↗
PubMed1979

Self-administered analgesia with nitrous oxide. Adjunctive aid for emergency medical care systems.

Analgesia with a mixture containing 50% nitrous oxide and 50% oxygen (Nitronox) was evaluated in 47 patients with abdominal pain, chest pain, musculoskeletal trauma, and burns. Of these, 93.6% experienced either partial or complete relief of pain. There were no complications attributed to its application; the short duration of action makes its use suitable during emergency transportation.

Adolescent↗
PubMed1978

The clinical significance of bundle branch block complicating acute myocardial infarction. 1. Clinical characteristics, hospital mortality, and one-year follow-up.

To provide an understanding of the clinical characteristics of patients with acute myocardial infarction (MI) and bundle branch block, experience from five centers was accumulated. Patients in whom bundle branch block first appeared after the onset of cardiogenic shock were excluded. In 432 patients, the most common types of block were left (38%) and right with left anterior fascicular block (34%). In 42% of the patients, bundle branch block was new. Progression to high degree (second or third degree) atrioventricular (AV) block via a Type II pattern occurred in 22% of the patients. Hospital and first year follow-up mortality rates were 28% and 28%, respectively. Only 46% of the patients developed pulmonary edema or shock (Killip Class III or IV), and hospital mortality was related to the amount of heart failure (8%, 7%, 27%, 83% for Killip Classes I-IV, respectively). Patients with progression to second degree or third degree AV block via a Type II pattern had increased hospital mortality compared with patients without this complication (47% vs 23%, P less than 0.001). In the absence of pulmonary edema or shock, patients with Type II second degree or third degree AV block still had a higher mortality rate than patients without advanced AV block (31% vs 2%, P less than 0.005), with nearly all the deaths due to abrupt development of AV block. Thus, in many patients MI with bundle branch block is associated with severe heart failure. However, this was not true for a majority of the patients, in whom therapy aimed at preventing morbidity and mortality due to the bradyarrhythmia of advanced AV block might be beneficial.

Acute Disease↗
PubMed1978

The clinical significance of bundle branch block complicating acute myocardial infarction. 2. Indications for temporary and permanent pacemaker insertion.

The indication for prophylactic temporary and permanent pacing during acute myocardial infarction (MI) complicated by bundle branch block is high risk of progression via a Type II pattern to second or third degree (high degree) AV block during hospitalization or follow-up. In this study, determinants of high degree AV block during hospitalization and sudden death or recurrent high degree block during the first year of follow-up were examined in 432 patients with MI and bundle branch block. Timing of onset of bundle branch block, the involved fascicles, and the PR interval were examined as determinants of risk of progression to high degree AV block during MI. At highest risk were 186 patients with blocks involving the right bundle and at least one fascicle of the left bundle which were not documented on prior electrocardiograms. Risk was similar with (38%) or without (31%) accompanying first degree AV block. Patients with transient high degree AV block during MI had a 28% incidence of sudden death or recurrent high degree block during the first year of follow-up. Patients not continuously paced had a higher incidence of sudden death or recurrent high degree block than patients continuously paced (65% vs 10%, P less than 0.001). Sudden death during follow-up also occurred in 13% of patients without high degree block during MI. A subgroup with 1) documented prior MI, 2) anterior or indeterminant acute MI, and 3) no symptoms of cardiac failure had a 35% risk of sudden death. The role of permanent pacing in this group is unknown. Thus, patients at high risk of high degree AV block should receive prophylactic temporary pacing. Patients who survive high degree block with MI should receive temporary and then permanent pacing. Patients without high degree AV block during MI who nervertheless have a high risk of sudden death may benefit from permanent pacing.

Adult↗
PubMed1978

Late right ventricular failure after Mustard operation for transposition of the great arteries.

The clinical course and postmortem findings of an unusual case of complete transposition of the great arteries, in which the Mustard operation was not performed until the patient was 12 years of age, are documented with serial catheterizations showing adequate repair. The clinical course of the patient was uneventful for 8 years after surgery, when right (systemic) ventricular failure occurred, resulting in the patient's death at 20 years of age. Late cardiac failure, the cause of death, is not a commonly described problem after successful surgical repair of transposition of the great arteries.

Adolescent↗
PubMed1977

Increased pulmonary vascular resistance with systemic hypertension. Effect of minoxidil and other antihypertensive agents.

Recent case reports suggest that pulmonary hypertension could be caused by minoxidil, a new potent vasodilating antihypertensive drug. Therefore, we evaluated the incidence and severity of pulmonary hypertension in 110 patients with systemic hypertension. Fourteen patients were treated with minoxidil for 2 to 35 months (mean 19.9 months), 15 were treated with no drugs, and the remaining 81 patients received conventional antihypertensive agents of several types. Pulmonary vascular resistance correlated positively (P is less than 0.05) with systemic vascular resistance. Minoxidil-treated patients with hypertension previously refractory to conventional therapy had slightly lower pulmonary vascular resistance than other hypertensive subjects. There was no correlation between pulmonary vascular resistance and duration of minoxidil therapy or other types of antihypertensive regimens. The positive correlation between pulmonary and systemic vascular resistance suggests the possibility of a causal hypertension relation in the two vascular beds.

Adolescent↗
PubMed1977

Cardiac autonomic blockade in exercising dogs.

Pharmacological blockade of autonomic control of the heart was studied in dogs performing mild, moderate, and severe running exercise on a level treadmill. The dogs were studied without drugs, after atropine, after propranolol, and after both atropine and propranolol. As compared with results without drugs, cardiac denervation resulted in elevated resting heart rate (+45 beats/min) but reduced heart rate during moderate (-17 beats/min) and severe exercise (-47 beats/min); no change in cardiac output at rest or during mild exercise but decreases (-23% and -25%) during moderate and severe exercise; and reduced first derivatives of left ventricular pressure at rest (-24%) and during exercise (-35, -41, and -52% for mild, moderate, and severe loads, respectively). Cardiac denervation did not alter end-diastolic left ventricular diameter but significantly increased end-systolic diameter during exercise. It is concluded that blockade of autonomic control of the heart diminishes cardiac output during exercise by reducing heart rate and myocardial contractile force but does not alter cardiac output at rest.

Animals↗
PubMed1977

Effect of digitalis on left ventricular function in exercising dogs.

The effect of ouabain on left ventricular function in nonfailing hearts was assessed in 14 chronically instrumented dogs during graded treadmill exercise. At rest, ouabain increased the maximum first derivative of the left ventricular pressure (dp/dtmax) and stroke volume by 38% and 16%, respectively. No change occurred in end-diastolic left ventricular diameter or peak systolic left ventricular pressure. During exercise, ouabain reduced maximum running speed and limited the increments in heart rate and systolic pressure but did not alter dp/dtmax, stroke volume, or end-diastolic diameter. When atropine and ouabain were given and severe exercise was performed, there were no differences from controls in running speed, heart rate, dp/dtmax, or other parameters. When ouabain and propranolol were given dp/dtmax increased at rest and during exercise, compared with results with propranolol alone. It is concluded that the inotropic effect of ouabain is negligible during strenuous physical activity because of the presence of high levels of sympathetic stimulation. However, during exercise in the presence of beta-adrenergic blockade, increases in myocardial contractility do occur in response to ouabain.

Animals↗
PubMed1976

Permanent pacing in patients with transient trifascicular block during acute myocardial infarction.

Patients with acute myocardial infarction and transient complete atrioventricular (A-V) block in association with right bundle branch block and left anterior hemiblock have a high incidence rate of late sudden death presumably due to recurrent A-V block. Over a 5 year period, 18 patients demonstrated right bundle branch block and left anterior hemiblock and had transient complete block during an acute myocardial infarction and survived to hospital discharge. Of six patients who did not have permanent pacing, five died suddenly (one was lost to follow-up) with a mean survival time of 2.4 months after hospital discharge. Twelve subsequent patients received permanent demand pacemakers and had a significantly improved prognosis with a mean survival time of 18 months (P less than 0.001). Six patients were still alive at an average follow-up time of 20 months. Prophylactic permanent pacing significantly improves the prognosis after acute myocardial infarction in this select subgroup of patients.

Acute Disease↗
PubMed1976

Incidence of arrhythmias induced by isometric and dynamic exercise.

The incidence of arrhythmias during isometric sustained handgrip exercise and during dynamic graded bicycle exercise was compared in a group of 45 patients with various forms of heart disease on no antiarrhythmic therapy. Atrial arrhythmias were equally common during handgrip and bicycle exercise but ventricular arrhythmias were more frequent during handgrip exercise. Of the 45 patients, 38 per cent developed ventricular arrhythmias during isometric exercise, with ventricular tachycardia occurring in 15 per cent. During dynamic exercise 22 per cent of the 45 patients developed ventricular arrhythmias, with ventricular tachycardia occurring in 2 per cent. Patients with coronary artery disease and/or depressed left ventricular function developed twice the incidence of ventricular arrhythmias with isometric than with dynamic exercise. Thus, isometric exercise testing is of more value than dynamic exercise testing in unmasking latent ventricular arrhythmias in patients with heart disease.

Adult↗
PubMed1976

Blood flow to respiratory, cardiac, and limb muscles in dogs during graded exercise.

The distribution of cardiac output was analyzed in six dogs, with the animals at rest and running on a level treadmill for 3 min at 3-4 mph (mild exercise) and 3 min at 6-8 mph (moderate exercise). Organ flows were measured using 25-mug-diam radioactive microspheres. Cardiac output averaged 2.5, 4.6, and 5.7 liters/min, for rest, mild exercise, and moderate exercise, respectively. The greatest change was in diaphragmatic flow which increased by 275% with mild exercise and 500% with moderate exercise. Flow to intercostal muscles increased by 160 and 186%, to the exercising gastrocnemius muscle by 153 and 224%, and to cardiac muscle by 57 and 109% during mild and moderate exercise, respectively. Renal and cerebral flows did not change significantly. Significant decreases in flow occurred in the small and large intestines during moderate exercise. It is concluded that the increase in cardiac output during submaximal exercise was redistributed in a manner which limited flow to the brain, intestines, and kidneys and increased flow flow to the diaphragm, heart, and limb muscles.

Animals↗
PubMed1976

Prognosis of patients permanently paced for sick sinus syndrome.

In 39 patients (mean age, 66 years) treated for sick sinus syndrome (SSS) with pacemaker insertion, the long-term prognosis was studied. Fifteen patients (42%) died during the follow-up period of 6 to 59 months (mean, 25 months). Three patients were unavailable for follow-up. Eleven of the 15 deaths (73%) were cardiac-related, yet none could be associated with either an arrhythmia or pacemaker failure. Symptoms recurred or persisted after pacemaker insertion in 14 patients (mean age, 71 years), nine of whom died (31 deaths per 100 patient follow-up years). Twenty-two patients (mean age, 63 years) were asymptomatic after pacer insertion, six of whom died (11 deaths per 100 patient follow-up years). These follow-up results demonstrate a poor long-term prognosis in patients with SSS and persistent symptoms following permanent pacing.

Aged↗