Stability of AV conduction in sick sinus node syndrome patients with implanted atrial pacemakers

Single-chamber atrial pacing is effective in the management of sinus node dysfunction, subject to the uncertainty of long-term atrioventricular conduction. Despite the accepted observation that many patients with sinus node dysfunction also have atrioventricular conduction disease, data do not exist on the development of atrioventricular block in those patients with permanent single-chamber atrial pacing. Of 70 patients who received single-chamber atrial pacing from 1967 to 1982 (mean duration of pacing was 33 months), only two patients of 58 (3.4%) of those with sinus node dysfunction developed atrioventricular (AV) block—after 14 months in one patient and after 23 months of successful atrial pacing in the other. None of the 12 patients paced for tachyarrhythmia management developed AV block. Of the 70 patients, 37 had assessment of AV conduction by incremental atrial pacing at the time of implant and 20 patients underwent atrial pacing on the basis of surface ECG and clinical judgment. Electrophysiologic studies were conducted only in those patients being paced for control of supraventricular arrhythmias. Only 5 of the 70 patients required conversion to ventricular pacing for technical difficulties; three of these conversions occurred in the early 1970's before the advent of atrial tined or J leads; one was for irreparable lead fracture and only one occurred in a patient with a newer design atrial lead. In conclusion, progression to AV block in patients with permanent atrial pacing is uncommon; formal electrophysiologic studies are necessary mainly in patients with supraventricular arrhythmias; and in the majority of patients, AV conduction can be assessed at the time of implant. Continued improvement in atrial leads should make atrial pacing even more successful.     

Relation between functional response to nitroglycerin and extent of myocardial necrosis in dogs: mapping of the left ventricle by 2-dimensional echocardiography

The relation between functional response to brief nitroglycerin infusions and extent of myocardial damage was studied sequentially in closed-chest dogs with acute occlusion of the left anterior descending coronary artery. Two-dimensional echocardiography was used to derive segmental left ventricular (LV) function (systolic fractional area change and systolic wall thickening), and this function was compared with the extent of necrosis measured 5 hours after occlusion in equivalent segments of corresponding pathologic slabs. Two-dimensional echocardiographic study before the dogs were killed indicated that remote nonnecrotic segments always responded to nitroglycerin by significant augmentation of segmental LV function. Segments in which necrosis was less than 40% showed a significant nitroglycerin-induced potentiation in segmental LV function. In contrast, segments in which necrosis was greater than 60% had no potentiation with nitroglycerin. In those segments in which eventual necrosis was 60 to 80%, significant nitroglycerin-induced augmentation in segmental LV function was observed only before and 30 minutes after the coronary occlusion. When the degree of necrosis was greater than 80%, no significant potentiation of segmental LV function was observed even as early as 30 minutes after occlusion. Thus, the degree of nitroglycerin-induced potentiation of segmental cardiac function is closely associated with the extent of myocardial necrosis in the particular ventricular segment. Two-dimensional echocardiography coupled with a nitroglycerin potentiation test might be useful for assessment of the viability of ischemic myocardium.     

Supraventricular tachycardia dependent upon accessory pathways in the absence of ventricular preexcitation

Paroxysmal supraventricular tachycardia is a common disorder of cardiac rhythm, generally thought to be due to reentry within the atrioventrlcular (A-V) node. The possibility that this disorder may be a manifestation of the Wolff-Parkinson-White syndrome should always be considered, but this etiology is usually rejected if the electrocardiogram in sinus rhythm falls to demonstrate a delta wave (i.e., ventricular preexcitatlon). Several recent reports have demonstrated that an accessory A-V pathway may conduct impulses only in the retrograde or ventriculo-atrial direction. Hence, reentrant tachycardia based on a mechanism identical to that observed in patients with classic Wolff-Parkinson-White syndrome may occur, and the electrocardiogram in sinus rhythm fail to show a delta wave. This report describes 11 patients who presented with paroxysmal supraventricular tachycardia without QRS changes in sinus rhythm that suggested the Wolff-Parkinson-White syndrome. Electrophysiologic studies demonstrated that an accessory pathway participated in the mechanism of the tachycardia. Eight of these 11 patients were successfully treated by surgical interruption of either the accessory pathway or the bundle of His. Accessory pathways are not rare among patients with paroxysmal supraventricular tachycardia; and it follows that this variant of the Wolff-ParkinsonWhite syndrome is more common than would be suspected if the Wolff-Parkinson-White syndrome is considered only when delta waves are observed on the electrocardiogram.     

Fatal disseminated herpesvirus hominis type 2 infection in an adult with associated thymic dysplasia

Disseminated herpesvirus hominis (HVH) type 2 infection, proved by viral isolation, is described in a previously healthy young woman. The clinical course was characterized by rapidly progressive hepatic failure leading to death 1 week after hospitalization. Postmortem examination showed involvement of many organs by HVH, most severe in the liver. The thymus gland showed dysplasia. It is suggested that this thymic alteration was congenital and was associated with a partial deficiency in cellular immunity, which permitted the patient's relatively long survival but ultimately rendered her susceptible to overwhelming viremia. Six adults with disseminated HVH infection, type unspecified but proved by viral isolation, were found in a review of the literature; predisposing factors (steroids, burns, Hodgkin's disease, malnutrition) existed in five patients. The thymus gland was not described, however, in the autopsy reports on any of the five patients who died.It is concluded that in order to initiate early antiviral therapy, HVH should be a diagnostic consideration in adults with hepatitis, particularly if skin or mucosal lesions are present. Furthermore, the central and peripheral lymphoid system of any patient who dies of a disseminated viral infection should be thoroughly examined.     

Dissociation between sleep-related and TRH-induced prolactin secretion in seminiferous tubule failure

Prolactin (PRL) secretion has been measured during sleep and following TRH administration in 8 patients aged 24-39 yr with seminiferous tubule failure and 36 controls. Basal LH levels were 25.7 +/- 14.7 mIU/ml in the patients compared to 11.5 +/- 4.2 mIU/ml in the controls (p less than 0.01) Corresponding FSH levels were 26.2 +/- 10.7 mIU/ml and 5.9 +/- 2.1 mIU/ml (p less than 0.001) Mean estradiol 17B and testosterone levels were similar in the 2 groups. The mean PRL secretion during sleep was 16.5 +/- 11.7 ng/ml in the patients and not different in 11 of the controls (12.4 +/- 3.2 ng/ml). One patient had a mean nocturnal PRL concentration of 44.1 ng/ml. In both groups, the mean sleep related PRL concentration was greater than that during waking hours. The average number of peaks in the 2 groups was similar. In the same patients, the peak PRL response to TRH (200 ug IV) was 81.9 +/- 18.8 ng/ml as compared to 32.1 +/- 10.7 ng/ml in the controls (p less than 0.001). It is concluded that PRL concentrations following pharmacological stimulation are increased in seminiferous tubule failure, whereas levels are normal in relation to the physiological stimulus of sleep.     

Direct inhibition of rat leydig cell function by tamoxifen

The effects of tamoxifen on rat testicular steroidogenesis were studied using dispersed interstitial cells. Tamoxifen significantly inhibited LH-, and 8-bromo-adenosine 3′,5′-monophosphate (8-bromo-cyclic AMP)-stimulated testosterone synthesis in a dose-dependent manner. Tamoxifen (10^?5M) also reduced LH-stimulated cyclic AMP formation. The addition of equimolar concentrations of 17β-estradiol or tamoxifen separately to interstitial cells resulted in similar inhibition of LH-stimulated testosterone synthesis. When equimolar concentrations of 17β-estradiol and tamoxifen were added concomitantly to interstitial cells, the inhibition was additive. Present studies demonstrate that tamoxifen has direct inhibitory effects on testicular steroidogenesis: both at the plasma membrane resulting in decreased cyclic AMP formation and also at steps subsequent to cyclic AMP.     

Effect of afterload reduction on plasma volume during acute heart failure

Previous investigations in our unit indicated that acute cardiogenic pulmonary edema is associated not only with an increase in left ventricular end-diastolic pressure and pulmonary arterial wedge pressure but also with a relative increase in colloid osmotic (oncotic) pressure and peripheral hemoglobin concentration. This combination of changes suggested that acute congestive heart failure with pulmonary edema, unlike chronic congestive heart failure, is associated with a contraction of intravascular blood volume. In this study, plasma volume changes were measured before and during the treatment of acute cardiogenic pulmonary edema in 14 patients with arteriosclerotic heart disease. The plasma volume measurement in all 14 patients before the initiation of treatment was either normal or decreased. After treatment with the alpha adrenergic blocking agent phentolamine, the plasma volume increased rather than decreased when measured 4 and 12 hours after the initiation of treatment. During this time colloid osmotic pressure and peripheral hemoglobin concentration progressively decreased. These findings suggest that acute cardiogenic pulmonary edema is associated with the extravasation of large quantities of plasma water from the intravascular compartment into the interstitial compartment and contraction of the intravascular plasma volume. The treatment of acute cardiogenic pulmonary edema is associated with the return of hypo-oncotic fluid from the interstitial compartment back into the intravascular compartment with expansion of plasma volume and reduction of colloid osmotic pressure and hemoglobin concentration.     

Atherosclerotic ulcerative disease and associated aneurysms of the coronary arteries.

Abnormal cardiac muscle function has been reported in experimental diabetes mellitus from this laboratory. To examine left ventricular performance in diabetic patients without clinical evidence of myocardial ischemia or other cardiovascular disease, a noninvasive measurement of the systolic time intervals was carried out. Simultaneous recordings of the electrocardiogram, heart sounds, and carotid pulse were made in 25 diabetic subjects, 20 to 56 years of age, and compared with 37 normal subjects. The diabetic subjects had a shorter left ventricular ejection time, longer pre-ejection period, and a higher ratio of pre-ejection period/left ventricular ejection time (P < 0.001). The isovolumic time was prolonged (P < 0.001), while heart rate and arterial pressure were within normal limits. Abnormal function was independent of apparent duration and treatment by diet alone, insulin, or hypoglycemic agents. On the basis of available morphologic data in human and canine diabetes, an alteration of the myocardial interstitium may be the basis for this preclinical abnormality in diabetic patients.     

Variant angina pectoris: Investigation of indexes of sympathetic nervous system function

One thousand forty-five spontaneous episodes of S-T segment elevation were observed in three patients over a total of 72 days of continuous electrocardiographic monitoring. Eighty-nine percent of episodes were asymptomatic; chest pain tended to occur with episodes longer than 3 minutes, and ventricular ectopy occurred almost exclusively with symptomatic episodes. Nitroglycerin regularly relieved angina or S-T elevation, or both.

Plasma and urinary catecholamines and their metabolites were normal. Episodes of variant angina were not associated with a generalized increase in sympathetic outflow because serum catecholamine levels at the onset and termination of the S-T abnormalities were not elevated. Controlled trials of propranolol showed no significant beneficial effect. Propranolol significantly increased the length of episodes of S-T elevation in one patient, increasing ventricular irritability. The overall course of variant angina was quite variable, with spontaneous and long-lasting remissions, necessitating cautious interpretation of clinical trials.     

Radiological review of rhinocerebral mucormycosis cases during the COVID-19 Pandemic: A single-center experience

Mucormycosis is caused by the fungi belonging to the order Mucorales and class Zygomycetes. The incidence of mucormycosis has increased with the onset of the severe acute respiratory syndrome coronavirus 2 infections leading to the coronavirus disease 2019 (COVID-19) pandemic. This rise is attributed to the use of immunosuppressive medication to treat COVID-19 infections. Authors have retrospectively collected data of our cases of mucormycosis diagnosed from April 2020 to April 2021 at our institute. A total of 20 patients with rhinocerebral mucormycosis were studied. Most of the study subjects were male patients (90%) and were of the age group 41-50 years. Most patients in the review had comorbidities (85%) with diabetes being the most common comorbidity. Para nasal sinuses were involved in all the cases. Involvement of the neck spaces was present in 60% of the cases. Involvement of the central nervous system was present in 80% of the cases. Orbital involvement was present in 90% of the cases. The authors reviewed the various imaging findings of mucormycosis on computed tomography and magnetic resonance imaging in this article.