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Biomedical subjects

J S Schroeder

Publications and source records attributed to J S Schroeder.

At least 37 records · Page 2Linked to original sources
PubMed1976

Effect of lithium on cardiovascular performance: report on extended ambulatory monitoring and exercise testing before and during lithium therapy.

To assess the effect of long-term lithium therapy on cardiac arrhythmias and cardiovascular performance, extended ambulatory electrocardiographic monitoring was performed in 12 patients, and rest and exercise electrocardiograms in 10 of 12, before and during lithium therapy. Lithium increased the frequency of premature ventricular contractions in three patients, decreased it in one, and produced no change in eight. Three of four patients with atrial arrhythmias showed improvement during lithium therapy. Exercise performance was unchanged. Although 7 of the 12 patients manifested T wave flattening in the resting electrocardiogram, none had S-T segment displacement at rest or on treadmill exercise. Before lithium therapy, arrhythmias on exercise included premature atrial contractions in four patients, ventricular arrhythmias in four (premature ventricular contractions in four, with couplets in two and with ventricular tachycardia in one). During lithium therapy, exercise did not provoke premature atrial contractions or ventricular tachycardia in any of the patients, but three patients had premature ventricular contractions (with couplets in one case). We conclude that lithium at therapeutic levels may precipitate or aggravate ventricular arrhythmias. When administered to patients with heart disease, factors that interfere with renal clearance of lithium (heart failure, salt restriction, long-term diuretic therapy) must be recognized and doses must be adjusted accordingly. Careful follow-up and electrocardiographic monitoring are advisable if lithium is to be used in the presence of ventricular arrhythmias. Cardiovascular performance as assessed by treadmill exercise testing was not affected by long-term lithium therapy.

Adult↗
PubMed1976

The cardiovascular effects of lithium in man. A review of the literature.

The medical literature since 1900 has been reviewed to determine the nature of lithium's cardiovascular effects. In therapeutic doses, lithium produces reversible T wave flattening and inversion in the electrocardiogram: rarely, it may cause sinus node dysfunction or ventricular arrhythmias. Patients with lithium toxicity almost always present with neurologic signs and symptoms. "Hypotension and cardiovascular collapse," alleged cardiotoxic manifestations of lithium, invariably follow days of coma. Given the possible cardiotoxic effect other psychopharmacologic agents and the hazards of withholding effective therapy in mania, it is concluded that lithium may be used safely in patients with cardiac disease if the dose is adjusted to the rate of lithium excretion and if serum levels of lithium are followed carefully. When used in patients with cardiac arrhythmias, frequent electrocardiographic monitoring is advised.

Adult↗
PubMed1976

Infections after cardiac transplantation: relation to rejection therapy.

We have analyzed the relation of the treatment of 76 acute graft rejection episodes in 45 late postoperative cardiac transplant patients to the 56 infections occurring in these patients. Intensification of immunosuppressive therapy for acute rejection greatly increased the occurrence of infection from a control incidence of 1.3 infections per 1000 patient-days to a posttreatment incidence of 3.6. Two modes of treatment, increased oral prednisone and high-dose methylprednisolone plus antithymocyte globulin, were further analyzed. Actuarial analysis of infections after these two treatment modes showed that the treatment-related increase in infection was nearly exclusively due to the latter form of therapy. Invasive cardiac procedures did not appear to be causally related to infections in these immunocompromised patients.

Antilymphocyte Serum↗
PubMed1976

Hemodynamics in sleep-induced apnea. Studies during wakefulness and sleep.

Twelve patients with predominantly obstructive type sleep apnea underwent cardiac catheterization, hemodynamic monitoring, and arterial blood gas analysis during wakefulness and sleep. Abnormalities during wakefulness included systemic hypertension in four of 12, exercise-induced mild pulmonary hypertension in five of 12, and alveolar hypoventilation in one. During sleep nine patients had cyclic elevations of arterial pressure with each apneic episode, exceeding 200 mm Hg systolic in three of 12. Pulmonary artery pressures increased in 10 of 12, exceeding 60 mm Hg systolic in five. Marked degrees of hypoxemia (arterial P02, less than 50 mm Hg in eight of 12) and moderate hypercapnia with respiratory acidosis were associated with these hemodynamic changes. Cyclic upper airway obstruction during sleep may result in hypercapnia, acidosis, and pronounced hypoxemia, which can lead to hemodynamic abnormalities during sleep. Sustained pulmonary hypertension and possibly systemic hypertension may follow. Tracheostomy is an effective therapy and is recommended to symptomatic patients who have predominantly obstructive apnea but no relievable anatomic cause of upper airway obstruction.

Adult↗
PubMed1976

Does cardiac transplantation prolong life and improve its quality? An updated report.

The current status of the human cardiac transplant experience at Stanford University Medical Center is presented in order to reassess its role in the treatment of end-stage cardiac disease. Of 109 patients undergoing transplantation at Stanford between January 1968 and August 1976, 44 were still alive as of August 1, 1976. The overall 1- and 2-year survival rates for the series are 52% and 43%, respectively. Sixty-nine patients have survived more than 3 months, and their overall 1- and 2-year survival rates are 80% and 66%, respectively. Of the 3-month survivors, 62 (90%) returned to functional Class I New York Heart Association cardiac status and most of these returned to their pre-illness activities. Of 40 patients selected for transplantation for whom a donor did not become available, 38 were dead in less than 6 months. Complications related to immunosuppression with steroids are currently the major barrier to longer survival and improved rehabilitation postransplantation. On the basis of these data we conclude that cardiac transplantation not only prolongs survival, but can return carefully selected recipients to an active life.

Adolescent↗
PubMed1976

Cardiac transplantation: review of seven years' experience.

Over the past 7 years, the feasibility of human cardiac transplantation has been documented and proved to prolong useful human life. Ideal candidates are characterized by the relatively young vigorous patient who is otherwise healthy and optimistic about his long-term chances of survival. Survival statistics indicate over a 75% 1-year survival if the patient survived the first 3 months following transplantation, at which time the most severe rejection episodes occur. Allograft rejection in both acute and chronic form remain the single most challenging problem limiting the success of the transplant program. Despite this, there has been gradual improvement in survival statistics characterized by a 57% 1-year survival for the past 1 year. The early diagnosis of cardiac rejection has been facilitated by routine serial percutaneous transvenous endomyocardial biopsies of the right ventricle to confirm clinical evidence of rejection. Over 88% of patients have been vocationally and actively rehabilitated and the remaining 12% are not limited by cardiovascular function but by complications of immunosuppresive therapy. In conclusion, it appears that human cardiac transplantation has been successful and can be used to treat selected patients with end-stage cardiac disease.

Azathioprine↗
PubMed1975

Diagnosis and quantification of arrhythmias in ambulatory patients using an improved R-R interval plotting system.

An improved technique for identification, diagnosis and quantification of arrhythmias during rest or ambulatory electrocardiographic recording is described. With simultaneous plotting of the R-R interval and the QRS duration and QRS vector measurement of each beat versus time, all periods of arrhythmias or abnormal complexes can be identified and characterized. Analog electrocardiographic samplings are used to confirm the diagnosis of the arrhythmia and to exclude artifact. The availability of a permanent record for the characterization of each QRS complex enables the physician to check the technician's analysis of the recording and to relate all events to the patient's heart rate and clinical symptoms. This technique also provides data for quantification of ventricular arrhythmias.

Ambulatory Care↗
PubMed1975

Cardiac amyloidosis. Diagnosis by transvenous endomyocardial biopsy.

Endomyocardial tissue, obtained from two patients presenting with restrictive cardiomyopathies, demonstrated amyloid infiltration. The percutaneous transvenous cardiac biopsy technic, using a modified Konno-Sakakibara cardiac bioptome, was safe and quick. Physical examination and catheterization data may not provide a definite differential diagnosis between restrictive and constrictive myocardial disease. Confirmation by biopsy of the cardiac amyloidosis assisted in providing optimum diagnostic and therapeutic care for these patients.

Aged↗
PubMed1975

Coronary bypass surgery for unstable angina pectoris. Clinical follow-up and results of postoperative treadmill electrocardiograms.

The first 81 patients who underwent coronary artery bypass surgery at Stanford University Hospital for unstable angina pectoris have been followed up for an average of 18 months. The over-all surgical mortality was 8.6 per cent (seven patients). There have been no operative deaths in last 32 patients, which may be due to over 75 per cent of these patients being stabilized on intensive medical therapy from 24 to 72 hours before study or surgery. There was a 16 per cent (13 patients) perioperative and 15 per cent (12 patients) late incidence of myocardial infarction. Of 74 patients who survived the initial operation 2 died 2 and 3 months postoperatively. Good or complete relief from pain was obtained in 94 per cent (70 patients) of the survivors. Of 57 longterm survivors tested, 49 per cent (28 patients) had a definite ischemic response to treadmill exercise testing. This may reflect the severe nature of the occlusive coronary disease or mechanisms other than increased coronary flow being responsible for the relief of pain. Although coronary bypass surgery appears to be effective in relieving the pain of patients with unstable angina pectoris, the 18 month average follow-up indicates that the incidence of myocardial infarction in surgically treated patients is comparable to that in medically treated patients.

Adult↗
PubMed1975

Perioperative myocardial infarction during cardiac surgery. Diagnosis, ECG and enzyme testing.

The detection of perioperative myocardial infarction is complicated by the variety of electrocardiographic changes normally seen concomitantly with cardiac surgery. Unequivocal electrocardiographic diagnoses based on new Q wave development and evolution of ST and T segments are virtually always confirmed by inappropriately high postoperative enzyme test results. For those patients exhibiting nondiagnostic but suggestive electrocardiographic changes, enzyme testing provides a valuable adjunct in determining whether infarction has indeed taken place. Enzyme testing, similarly, in and of itself, cannot provide the dichotomous situation between those patients experiencing infarction and those who are not. SGOT and LDH appear the most reliable indicators of infarction. CPK is quite volatile with sporadic occurrences of high enzyme elevations without obvious clinical or electrocardiographic explanation. The Ck isoenzymes provide a highly specific test for myocardial damage. However, their sensitivity is sufficiently great that a relatively minor cardiac manipulation may result in uninterpretable results.

Angina Pectoris↗
PubMed1975

Arrhythmias in patients with mitral valve prolapse.

Resting ECGs, exercise treadmill tests and 24-hour ambulatory ECGs were recorded and analyzed in 24 unselected patients with mitral valve prolapse. Arrhythmias were frequent. There were three distinct groups of patients, defined on the basis of total number of premature ventricular contractions (PVCs) during the 24 hours; there were no PVCs in 25%, and frequent PVCs in 50%. Complex ventricular arrhythmias, including ventricular tachycardia in five patients, were found almost exclusively in the group with frequent PVCs. Fifteen of the 24 patients demonstrated atrial premature contractions (APCs) during the 24 hours. Complex atrial arrhythmias were found among patients with infrequent, as well as those with frequent, APCs. Supraventricular tachycardia was detected in seven of these patients. The incidence of ACPs decreased during sleep in 67% of the patients and showed no change during sleep in 33%. A poor correlation was found between symptoms recorded in patient diaries and changes noted on 24-hour ECG recordings. The peak PVCs/15 min and peak ACPs/15 min during a 24-hour period of monitoring was found to be an excellent guide to the total number of PVCs and APCs occurring during that period. This permits an accurate prediction of the total number of PVCs in 24 hours after performing an exact PVC count on only 15 minutes of ECG data. Finally, the 24-hour ambulatory ECG was sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.

Adult↗
PubMed1975

The status of cardiac transplantation, 1975.

Since December 1967, 263 human cardiac transplant operations have been performed throughout the world. Eighty-two of these were performed at Stanford University Medical Center, In 1974, 27 such operations were performed, 15 at Stanford Survival rates for the entire Standford series are 48% at one year and 25% at three years; survival rates at one and three years for patients surviving the first three critical months after transplantation are 77% and 42%, respectively. Recipients under the age of 55 years, with New York Heart Association Class IV cardiac disability, are selected for transplant procedures according to criteria dictated by experience over the past seven years. A routine immunsuppressive regimen for organ transplantation, incorporating prednisone, azathioprine, and antithymocyte globulin is employed early postoperatively, and prednisone and azathioprine are used for indefinite maintenance therapy. Acute cardiac graft rejection in nearly all recipients is diagnosed by clinical signs, electrocardiographic changes, and percutaneous transvenous endomyocardial biopsy. Ninety-five percent of acute rejection episodes are reversible with appropriate immunosuppressive treatment, but infectious complications are common and have accounted for 56% of all postoperative deaths. The Stanford experience in cardiac transplantation has demonstrated the potential therapeutic value of this procedure. Maximum survival now extends beyond five years. Satisfactory graft function has been documented in long-term surviving patients, the majority of whom have enjoyed a high degree of social and physical rehabilitation.

Acute Disease↗
PubMed1975

Ostium primum defect in the adult: postoperative follow-up studies.

Twelve adult patients with ostium primum atrial septal defects (incomplete endocardial cushion defect) who underwent surgical repair of their lesions were evaluated in the late postoperative period. All had closure of the low-lying atrial septal defect, with suturing of the mitral valve cleft in 11 patients. Although the patients benefited symptomatically from the surgery, all had residual cardiac murmurs. Postoperative cardiac catheterization and left ventriculography in eight revealed successful closure of the atrial septla defect, but three demonstrated residual mitral insufficiency. In spite of the successful surgical repair in these patients, bacterial indocarditis prophylaxis should be continued in view of the residual murmurs and valvular abnormalities.

Adolescent↗
PubMed1975

Comparison of 24 versus 12 hours of ambulatory ECG monitoring.

In order to assess the additional information obtained from 24 hours compared to 12 hours of ambulatory ECG (electrocardiogram) recording, we analyzed 72 ambulatory ECG monitoring tapes in which arrhythmias were present. In all cases the second 12 hours included the entire period of sleep. Only 38 of 233 (16 percent) episodes of arrhythmias, frequent premature ventricular contractions (PVC's), two or more PVC's in a row, multiform PVC's, ventricular bigeminy, trigeminy, premature atrial contractions (PAC's), and supraventricular tachyarrhythmias occurred for the first time in the second 12-hour period. New ventricular arrhythmias were detected during the second 12-hour period in 13 percent of the arrhythmic episodes. Although sleep resulted in a marked decrease in PVC frequency in 63 percent of 30 recordings, with frequent PVC's while awake, 8 percent had a significant increase during sleep. In contrast, short runs of supraventricular tachyarrhythmias occurred during the second 12 hours in 48 percent of cases, 66 percent of these while asleep. These data suggest that a 24-hour ambulatory ECG tape recording be utilized initially to characterize the occurrence and frquency of the patients' ambulatory arrhythmias during awake and sleep periods. Thereafter, additional ECG recordings for monitoring antiarrhythmic drug therapy can be accomplished with a 12-hour recording in more than 80 percent of patients

Adolescent↗
PubMed1975

Hemodynamic effects of procainamide and quinidine and the influence of beta-blockade before and after experimental myocardial infarction.

The use of antiarrhythmie drugs in combination has been limited because of possible side effects secondary to myocardial depression in the acute myocardial infarction patient. Therefore, we investigated in intact dogs (group I) the hemodynamic interaction of propranolol plus procainamide (subgroup A) or quinidine (subgroup B) and in dogs after experimental myocardial infarction produced by coronary artery ligation (group II). Infusion of procainamide (30 mg/kg over 5 min) in animals of group IA produced a significant (P less than 0.05) decrease of 30% in mean aortic pressure, a decrease of 40% in left ventricular dp/dt and 29% in cardiac output. When procainamide was reinfuse after propranolol (1 mg/kg), its hemodynamic effects were not significantly different from those observed before propranolol in both groups IA and IIA. Infusion of quinidine (10 mg/kg over 5 min) in animals of group IB (intact dogs) also produced significant decreases of 24% in mean aortic pressure and 38% in dp/dt while cardiac output was unchanged. However, these hemodynamic changes were seen only after beta-blockade and were significantly different from those obtained before propranolol, where heart rate increased by 14%, dp/dt by 30%, and cardiac output by 35%. These changes occurred despite a similar reduction in mean aortic pressure. This drug combination produced similar response in animals after coronary artery ligation (group IIB). In conclusion, we feel that the administration of propranolol does not prevent the depressive circulatory effects of procainamide. The combined use of quinidine and propranolol also has a negative circulatory effect although not as marked as the effects observed after procainamide with propranolol.

Adrenergic beta-Antagonists↗