Syncope in hypertrophic cardiomyopathy: mechanisms and consequences for treatment.

Hypertrophic cardiomyopathy (HCM) is an inherited disease with marked phenotypic variability that includes the extent of hypertrophy, the presence and severity of symptoms, and the natural history of the disease. Symptoms of impaired consciousness (syncope and pre-syncope) occur in approximately 15-25% of patients with hypertrophic cardiomyopathy (HCM). In young patients a history of recurrent syncope is associated with an increased risk of sudden death. Detailed investigations identify a probable mechanism in a minority of these, usually paroxysmal atrial fibrillation or ventricular tachycardia. In the majority, however, no likely mechanism is found despite extensive investigation. Although this may be the case, it is still of vital importance to exclude potentially treatable causes of syncope.     

Diagnostic and therapeutic pitfalls associated with primaquine-tolerant Plasmodium vivax

We describe a U.S. Army Ranger returning from duty in Afghanistan and Iraq with life-threatening infection due to Plasmodium vivax. Morphological variants were observed in blood films prepared using samples collected by venipuncture. The patient's multiple relapses indicate infection with primaquine-tolerant P. vivax. Strategies for relapse prevention using primaquine are reviewed.     

Evaluation of a real-time polymerase chain reaction assay for the diagnosis of malaria in patients from Thailand

We compared the diagnosis of malaria in 297 patients from Thailand by a real-time polymerase chain reaction (PCR) assay using the LightCycler with conventional microscopy using Giemsa-stained thick and thin blood films. The PCR assay can be completed in one hour and has the potential to detect and identify four species of Plasmodium in a single reaction by use of melting temperature curve analysis (however, we did not detect Plasmodium ovale in this study). Blood was collected, stored, and transported on IsoCode STIX, which provide a stable matrix for the archiving and rapid simple extraction of DNA. A genus-specific primer set corresponding to the 18S ribosomal RNA was used to amplify the target sequence. Fluorescence resonance energy technology hybridization probes were designed for P. falciparum over a region containing basepair mismatches, which allowed differentiation of the other Plasmodium species. The PCR results correlated with the microscopic results in 282 (95%) of 297 patient specimens. Most of these were single-species infections caused by P. vivax (150) and P. falciparum (120), along with 5 P. malariae, 2 mixed infections (P. falciparum and P. vivax), and 5 negative specimens. No negative microscopy specimens were positive by PCR (100% specificity for detection of any Plasmodium). The 15 discrepant results could not be resolved, but given the subjective nature of microscopy and the analytical objectivity of the PCR, the PCR results may be correct. The ability of the PCR method to detect mixed infections or to detect P. ovale could not be determined in this study. Within the limitations of initial equipment costs, this real-time PCR assay is a rapid, accurate, and efficient method for the specific diagnosis of malaria. It may have application in clinical laboratories, as well as in epidemiologic studies and antimalarial efficacy trials.     

Reversal of inappropriate peripheral vascular responses in hypertrophic cardiomyopathy

OBJECTIVES: We assessed the frequency of abnormal forearm vasodilator responses during lower body negative pressure (LBNP) in 21 non-obstructive hypertrophic cardiomyopathy (HCM) patients (31 +/- 8 [20 to 43] years) with abnormal blood pressure response (ABPR) to exercise and the effects of three drugs used to treat vasovagal syncope (propranolol, clonidine, and paroxetine) in a double-blind crossover study. BACKGROUND: Some HCM patients have an ABPR to exercise, which may be due to paradoxical peripheral vasodilatation. A similar proportion has paradoxical forearm vasodilatation during central volume unloading using LBNP. These abnormal reflexes may be caused by left ventricular mechanoreceptor activation. Similar mechanisms may also contribute to some cases of vasovagal syncope. METHODS: Blood pressure changes were assessed during exercise, and forearm vascular responses and baroreceptor sensitivity were assessed during LBNP using plethysmography. RESULTS: Nine (43%) patients (group A) had paradoxical vasodilator responses (forearm vascular resistance [FVR] fell by 7.5 +/- 4.6 U), and 12 (57%) patients (group B) had normal vasoconstrictor responses during LBNP (FVR increased by 7.7 +/- 4.9 U). Paroxetine augmented systolic blood pressure (SBP) during exercise in group A (21 +/- 6 mm Hg vs. 14 +/- 11 mm Hg at baseline, p = 0.02); no effect was detected in group B. Paroxetine reversed paradoxical vascular responses during LBNP in seven (78%) patients from group A. Propranolol and clonidine had no significant effect on SBP during exercise but reversed paradoxical vascular responses in some patients from group A (n = 5 and n = 3). CONCLUSIONS: Paradoxical vasodilatation during LBNP occurs in 40% of patients with ABPR during exercise and is reversed by propranolol, clonidine, and paroxetine. Paroxetine also improved SBP response to exercise.     

-Selectin is required for the development of airway hyperresponsiveness but not airway inflammation in a murine model of asthma

Background: Airway inflammation and airway hyperresponsiveness (AHR) are fundamental features of asthma. Migration of inflammatory cells from the circulation into the lungs is dependent on adhesion molecule interactions. The cell surface adhesion molecule -selectin has been demonstrated to mediate leukocyte rolling on inflamed and noninflamed pulmonary endothelium. However, its role in the development of airway inflammation and AHR in asthma has not been examined. Objective: We sought to characterize the role of -selectin in the recruitment of inflammatory cells to the airway-lung and the development of AHR in a murine model of asthma. Methods: An ovalbumin (OVA)-induced allergic airway disease model of asthma was applied to -selectin–deficient (LKO) mice and C57BL/6 wild-type (WT) control mice. The development of airway inflammation was assessed by examining leukocyte influx into bronchoalveolar lavage (BAL) fluid and the lung. Total and differential BAL leukocyte counts were determined, and the immunophenotype of BAL lymphocytes was assessed by means of flow cytometry. The development of AHR was assessed by means of whole-body plethysmography. Results: Airway-lung inflammation was equivalent in LKO and WT mice sensitized-challenged with OVA, as measured by total and differential BAL cell counts and histologic analysis of lung tissue. Numbers of eosinophils, neutrophils, lymphocytes, and monocytes in BAL fluid were equivalent in LKO and WT mice. However, phenotypic analysis of BAL lymphocytes demonstrated significantly reduced CD3⁺ populations and increased B220⁺ populations in LKO compared with WT mice (P < .05). Remarkably, despite a fulminant inflammatory response in the airway-lung in LKO mice sensitized-challenged with OVA, AHR was completely abrogated. Conclusion: -Selectin plays a crucial role in the development of AHR but not allergic inflammation in an animal model of asthma. -Selectin represents a potential target for novel asthma therapies specifically aimed at controlling AHR. (J Allergy Clin Immunol 2001;107:1019-24.)     

Effect of sitting vs. standing on perception of provider time at bedside: a pilot study

Objective

Patients commonly perceive that a provider has spent more time at their bedside when the provider sits rather than stands. This study provides empirical evidence for this perception.

Methods

We conducted a prospective, randomized, controlled study with 120 adult post-operative inpatients admitted for elective spine surgery. The actual lengths of the interactions were compared to patients’ estimations of the time of those interactions.

Results

Patients perceived the provider as present at their bedside longer when he sat, even though the actual time the physician spent at the bedside did not change significantly whether he sat or stood. Patients with whom the physician sat reported a more positive interaction and a better understanding of their condition.

Conclusion

Simply sitting instead of standing at a patient's bedside can have a significant impact on patient satisfaction, patient compliance, and provider-patient rapport, all of which are known factors in decreased litigation, decreased lengths of stay, decreased costs, and improved clinical outcomes.

Practice implications

Any healthcare provider may have a positive effect on doctor-patient interaction by sitting as opposed to standing during a hospital follow-up visit.