Clinical and hemodynamic characteristics of patients with inducible pulsus alternans

Pulsus alternans can be found in some patients with abnormal left ventricular function and also can develop after spontaneous premature beats. The purposes of this study were to: (1) determine the inducibility of pulsus alternans in a series of patients referred for routine cardiac catheterization and (2) define the clinical and hemodynamic characteristics of those who develop pulsus alternans. In 104 patients referred for right and left heart catheterization, atrial premature beats and rapid atrial pacing were used to try to provoke pulsus alternans. The 29 patients who developed pulsus alternans in response to these maneuvers were older (63 +/- 6 vs 59 +/- 10 years, p less than 0.01) and had a greater incidence of valvular heart disease (45% vs 23%, p less than 0.01) and congestive heart failure (38% vs 17%, p less than 0.05). Aortic stenosis was the most prevalent valve lesion found. Those who developed pulsus alternans in response to pacing were further characterized by higher left ventricular systolic (143 +/- 42 vs 121 +/- 23 mm Hg, p less than 0.02) and end-diastolic pressures (17 +/- 9 vs 13 +/- 6 mm Hg, p less than 0.05), higher pulmonary artery systolic pressure (35 +/- 14 vs 29 +/- 11 mm Hg, p less than 0.04), and lower left ventricular ejection fractions (0.42 +/- 0.13 vs 0.53 +/- 0.14, p less than 0.001). Eight patients (28%) with inducible pulsus alternans had a normal left ventricular ejection fraction (greater than 0.50) and left ventricular end-diastolic pressure (less than 13 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

A combined frontotemporal and lateral infratemporal fossa approach to the skull base

A variety of neoplasms involve both the infratemporal fossa and the base of the middle cranial fossa, in medial proximity to the cavernous sinus and orbital apex. To provide simultaneous access to both the intracranial and extracranial aspects of these tumors, a temporal or frontotemporal craniotomy may be combined with a lateral exposure of the infratemporal fossa. The approach, which is readily achieved by a neurosurgeon and an otolaryngologist acting as a team, involves a unilateral frontotemporal incision extended inferiorly onto the neck, a lateral facial flap reflected anteriorly, and transection of the zygoma followed by its reflection inferolaterally with the temporalis muscle. This exposure provides excellent visualization of both the intradural and extradural aspects of the anterior portion of the cavernous sinus, allowing for an aggressive resection of neoplasms involving this region. Experience with this procedure is reported here in the management of nine patients: three with nasopharyngeal angiofibromas, three with low-grade malignancies of the upper aerodigestive tract, and three with sphenoid ridge meningiomas.

Effect of increasing heart rate on left ventricular performance in patients with normal cardiac function

The influence of an increase in heart rate on left ventricular (LV) contractile performance was assessed in patients with normal LV function. In 19 patients (3 men, 16 women) ages 55 +/- 9 years (mean +/- standard deviation) with normal global and segmental LV function and normal coronary arteries, LV dP/dt max was measured at baseline heart rate and during atrial pacing at baseline +5, baseline +25 and baseline +45 beats/min. In 10 of the patients, intravascular volume was not altered during pacing and, as a result, echocardiographically measured LV end-diastolic dimension decreased (5.4 +/- 0.4 at baseline vs 4.9 +/- 0.5 cm at baseline +45 beats/min, p less than 0.05). In these patients, LV dP/dt max increased modestly (1,571 +/- 237 at baseline vs 1,760 +/- 199 mm Hg/s at baseline +45 beats/min, p less than 0.05). In the other 9 patients, intravascular volume was expanded rapidly (by saline infusion) during pacing and, as a result, LV end-diastolic dimension was held constant (5.2 +/- 0.6 at baseline vs 5.1 +/- 0.6 cm at baseline +45 beats/min, difference not significant). In these patients, LV dP/dt max increased substantially with pacing (1,505 +/- 228 at baseline vs 2,050 +/- 258 mm Hg/s at baseline +45 beats/min, p less than 0.05). Thus, an increase in heart rate induces a modest increase in LV dP/dt max in patients in whom LV preload (as reflected by end-diastolic dimension) is allowed to decrease; in contrast, it causes a marked increase in LV dP/dt max in those in whom LV preload is maintained constant.

In vivo induction and reversal of nitroglycerin tolerance in human coronary arteries

The mechanism by which tolerance to the clinical effects of organic nitrates develops has not been elucidated. This study was done to determine whether an intravenous infusion of nitroglycerin induces tolerance in the coronary vascular bed and whether such tolerance is reversed by the sulfhydryl-group donor N-acetylcysteine. We studied 19 subjects--17 with coronary artery disease and 2 without it--who had a mean age (+/- SD) of 54 +/- 9 years. Coronary sinus blood flow, which approximates blood flow to the left ventricle, was measured before and during intracoronary injections of nitroglycerin (10, 25, 50, and 100 micrograms). The patients then received a 24-hour intravenous infusion of saline (n = 7) or of nitroglycerin, 45 +/- 13 micrograms per minute (n = 12), after which the responses of coronary sinus flow to the same doses of intracoronary nitroglycerin used earlier were measured. In the seven patients given saline, the four doses of intracoronary nitroglycerin caused similar percentage increases in coronary sinus flow before and after the saline infusion. In the 12 patients given intravenous nitroglycerin, the four intracoronary doses caused percentage increases in coronary flow before the infusion of 30 +/- 9, 35 +/- 14, 41 +/- 12, and 52 +/- 15, respectively. After the infusion, the same doses of nitroglycerin caused smaller (P less than 0.05) percentage increases (16 +/- 6, 21 +/- 11, 23 +/- 12, and 27 +/- 11, respectively), indicating the development of partial tolerance. Subsequently, 7 of the 12 patients received N-acetylcysteine, after which intracoronary nitroglycerin caused percentage increases in coronary sinus flow similar to the values measured before the intravenous nitroglycerin was given (34 +/- 13, 32 +/- 8, 38 +/- 11, and 44 +/- 16, respectively). We conclude that the coronary vasodilator effect of nitroglycerin is attenuated by an intravenous infusion of nitroglycerin (that is, partial tolerance develops) and that tolerance to the agent can be reversed by administration of the sulfhydryl-group donor N-acetylcysteine. The mechanism by which N-acetylcysteine reverses tolerance will require further investigation.

Even-echo rephasing and constant velocity flow

It has been shown previously that for constant magnetic field gradients, constant velocity flow leads to even-echo rephasing for all echo delay times. We show that for flow which is not pluglike, even-echo rephasing also occurs for the pulsed readout gradients used in magnetic resonance imaging if and only if the gradients begin at the time the 90 degrees pulse is applied. We also show for these gradients that even-echo rephasing for all echo delay times in the case of nonpluglike flow implies a constant flow velocity at the point considered. Furthermore, it suffices to assume the vanishing of the spin-echo phase for any even echo, since the vanishing of any even echo for all echo delay times implies that all other even echoes also vanish identically. The odd echoes are then all equal to each other and proportional to the flow velocity. If acceleration is present, it may then be seen that for nonpluglike flow, even-echo rephasing may only be present for some but not all echo delay times. However, for the typical slice selection gradients used in magnetic resonance imaging or for usual readout gradients starting after the 90 degrees pulse is applied, it is shown that for constant velocity flow the even-echo phases do not vanish identically. Hence, rephasing cannot always occur for nonpluglike flow in either of these situations. Furthermore, the spin-echo phases are proportional to the flow velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of spin-echo rephasing with pulsatile flow in 2D FT magnetic resonance imaging

The effects of pulsatile flow on spin phases in spin-echo magnetic resonance imaging are considered. General expressions for the spin phases of the first four echoes are derived in terms of the Fourier coefficients of flow. These expressions are valid for any time-dependent acceleration and, hence, are not restricted to constant acceleration. The derived expressions are then theoretically evaluated for aortic flow and examined at different points in the cardiac cycle. Our results show that rephasing may occur at certain points in the cardiac cycle for either even or odd echoes depending upon the particular Fourier coefficients of the velocity function and the spin-echo delay time. However, even-echo rephasing is not always necessarily valid. Furthermore, the possibility of determining the flow velocities in the body with an appropriate series of imaging studies is also discussed.

Nuclear magnetic resonance imaging in Marfan's syndrome

Detection and evaluation of aortic root and other cardiovascular abnormalities in patients with Marfan's syndrome are important in determining appropriate therapy and preventing premature mortality. To evaluate the role of nuclear magnetic resonance imaging (NMR) in this syndrome, 10 patients were evaluated using a 0.35 tesla commercial nuclear magnetic resonance imaging system. Findings from these studies were compared with data from other noninvasive tests as well as surgical follow-up. Results from these examinations indicate that NMR-derived measurements of aortic root diameter agree closely with echocardiographic measurements. In addition, NMR provides more complete anatomic detail than does echocardiography and can be utilized to assess and follow up virtually all patients with this syndrome.

Magnetic resonance imaging findings and correlations in spasmodic dysphonia patients

A sample of 19 spasmodic dysphonia (SD) patients was selected from a larger population of such patients to undergo magnetic resonance imaging (MRI), auditory brain stem response (ABR) testing, speech analysis, and extensive physical examination. Six patients had abnormal spin-echo MRI findings, ranging from infarcts within the basal ganglia to demyelinating lesions within the supralateral angles of the lateral ventricles. A weakly positive correlation was noted between the abnormal MRI findings and an abnormal ABR. The lack of a significant correlation between the MRI findings and other predictors of brain stem and midbrain disease, and the current spatial resolution limitations of MRI, suggest that we are visualizing the associated lesions rather than the actual foci of SD. The range of MRI findings is consistent with the concept that SD is a voice disorder in a heterogeneous patient population.

Non-organic failure to thrive: a developmental perspective

Like other segments of the child's development, eating behavior follows a sequential pattern. To understand the infant's or child's feeding problems which can lead to failure to thrive or dwarfism we propose that a child's progression be studied through three stages of development: homeostasis, attachment and separation-individuation. Specific feeding problems can arise at each of these stages of development and consequently impede the child's weight gain. During the period of homeostasis the infant learns to regulate himself, to suck, to swallow and to time the onset and termination of feedings by giving signals of hunger and fullness. If he is unable to master these, he cannot be fed effectively. Failure to master these basic feeding skills interferes with the next developmental task of attachment and also impedes development of motor skills, language and affective engagement. During the period of attachment, the infant establishes distinct interactional patterns with his caretakers. Lack of engagement between mother and infant leads to lack of pleasure and lack of appetite or even to severe dysfunctional feeding patterns like vomiting and rumination. Feeding problems in the third developmental stage of separation and individuation can arise because of maladaption in the attachment phase or because of new difficulties which center around issues of autonomy vs. dependency. At this stage, the infant learns means-end differentiation and begins to understand that his actions elicit certain consequences. If the infant's struggle between autonomy and dependency gets caught in the feeding situation, the infant's emotional needs can dictate his eating behavior. The infant refuses to eat either to have his emotional hunger for mother's attention met or to assert his autonomy and to express his anger toward her. In order for the infant to learn to differentiate between his physiological feelings of hunger and his emotional need states, the caregiver needs to give contingent responses by offering food when the infant is hungry and comfort when the infant is distressed. Feeding problems which can create, co-exist with, or result from a growth problem must be considered within a developmental context. As the infant progresses through the developmental stages of homeostasis, attachment, and separation, he masters phase-appropriate feeding skills which help him to progress from reflex sucking to autonomous feeding. Early identification of maladaptive feeding behavior will assist the pediatrician in making timely interventions.

A prospective randomized trial of methotrexate versus cisplatin in the treatment of recurrent squamous cell carcinoma of the head and neck

A prospective randomized study was conducted to determine the relative effectiveness, toxicity and tolerance of methotrexate (MTX) versus cisplatin (DDP) in patients with recurrent head and neck squamous cell carcinoma. Forty-four patients were randomized to receive either MTX, 40 mg escalated to 60 mg/m2 IV push weekly, or DDP, 50 mg/m2 6 hour infusion days 1 and 8 every 4 weeks. All patients had objectively measurable disease and a performance status greater than 60% (Karnofsky scale). All had been treated with surgery and/or radiotherapy. No patients had prior chemotherapy. Prior treatment, performance status, and site of primary disease were comparable in both groups. Complete and partial objective responses were achieved in 23.5% of the MTX group and 28.6% of the DDP group (P = 0.51). Median duration of response was 84 days in the MTX group and 92 days in the DDP group. Median survival of patients was 6.1 months with MTX and 6.3 months with DDP. Mucositis was noted in 38% of patients in the MTX group (P = 0.001) compared to none in the DDP group. Vomiting occurred in 87% of patients in the DDP group (P less than .0001) compared to 10% of patients in the MTX group. This study demonstrates that in the treatment of recurrent head and neck squamous cell carcinoma, MTX and DDP are equally effective, although MTX appears to be better tolerated.

Ct air-contrast scanning of the internal auditory canal

Two hundred and four patients with audiometric and vestibular findings suggestive of a retrocochlear lesion were studied prospectively by computed tomographic scan with air contrast of the internal auditory canal. With this technique tumor limits are clearly defined. In the absence of disease the internal auditory canal has been completely air-filled in over 97% of cases. Soft tissue masses occluding the internal auditory canal were demonstrated in 11 patients. Four studies were inconclusive and there was one false positive. Headaches have been the only side effect and there have been no complications. In reporting their results the authors examined the indications, accuracy and limitations of this technique. This study demonstrates that computed tomographic scan with air contrast of the internal auditory canal should be considered as the radiologic procedure of choice for the evaluation of small acoustic tumors.

Computerized axial tomography with air contrast of the cerebellopontine angle and internal auditory canal

The introduction of computerized axial tomography (C.T.) in 1973 completely changed the diagnostic evaluation of acoustic neuromas. Seventy to eighty percent of all acoustic neuromas can be diagnosed with intravenous enhanced C.T. scan. Acoustic tumors with a diameter of less than 1.5 cm, however, are not consistently seen on C.T. scan. Twenty-six consecutive patients were evaluated by C.T. scan with air contrast posterior fossa myelography (C.T. air cisternography). Nineteen studies were normal, with complete air filling of the internal auditory canal. Surgically verified acoustic neuromas were demonstrated in four patients. Two studies were inconclusive and there was one false positive. Other than headaches, there is no morbidity associated with this technique. C.T. air cisternography should be considered as the definitive study for evaluating patients for acoustic neuromas who have normal intravenous contrast enhanced C.T. scans. This study reports the first intracanalicular tumor diagnosed with this technique.

Operant control of autonomic functions: biofeedback bibliography

280 references to studies on instrumental or operant learning of autonomically controlled responses in humans and animals are grouped into category: books, review articles and theoretical discussions; cortical activity; electromyogram; cardiovascular activity; electrodermal activity; remaining autonomic functions; therapeutical applications; instrumentation and methodology; and miscellaneous.

Mediators of inflammation in leukocyte lysosomes. II. Mechanism of action of lysosomal cationic protein upon vascular permeability in the rat

The vascular permeability-increasing action of rabbit PMNL lysosomes has been studied in skin and cremaster muscle of the rat. Both an extract of frozen-thawed granules and a cathepsin-free cationic protein fraction of the granules (which had previously been demonstrated to cause leukocyte adhesion and emigration in vivo) induce increased vascular permeability in skin and muscle which resembles that produced by histamine or histamine-liberators with respect to the timing of the response and the predominant type of microvessel affected. Extracts of frozen-thawed lysosomes and the inflammatory lysosomal cationic protein both cause disruption of rat mesenteric mast cells in vitro, whereas a granule-free cytoplasmic fraction of PMN leukocytes and a non-inflammatory cationic protein fraction of the granules do not do so under identical test conditions. The mastocytolytic action of lysosomal materials in vitro is not inhibited in the presence of 10 kallikrein-inhibiting units of trasylol per ml. The mast cell rupturing fraction of PMNL granules (cationic protein) possesses no detectable peroxidase activity or acid-mucopolysaccharase activity. When compared with compound 48/80 on the basis of estimated molecular weight, the lysosomal cationic protein appears to be at least as active as the latter compound with respect to in vitro mastocytolytic potency. Chronic pretreatment of rats with an agent known to reduce tissue mast cell numbers causes marked suppression of the vascular permeability change normally induced in skin and muscle by lysosomal extracts and cationic protein. Similar results are obtained if lysosomal materials are tested in rats pretreated with an antihistaminic. These observations are discussed with respect to the mode of action of PMNL lysosomes in the early and late phases of local tissue-injury reactions.