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Nonlinear Summation of Depressor Effects of Carotid Sinus Pressure Changes and Aortic Nerve Stimulation in the Rabbit

Nonlinear Summation of Depressor Effects of Carotid Sinus Pressure Changes and Aortic Nerve Stimulation in the Rabbit

On the other hand, the decrease in the depressor effect of aortic nerve stimulation as carotid sinus pressure was further increased from the physiological to supraphysiological range sug[r]

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Cerebrospinal fluid absorption block at the vertex in chronic hydrocephalus: obstructed arachnoid granulations or elevated venous pressure?

Cerebrospinal fluid absorption block at the vertex in chronic hydrocephalus: obstructed arachnoid granulations or elevated venous pressure?

chronic hydrocephalus? The venous pressure is not rou- tinely measured in an infusion study and has been rarely measured in normal controls due to the invasive nature of retrograde manometry. Ekstedt’s finding that the sinus pressure does not change throughout life is also prob- lematic given that the blood flow through the sagittal sinus varies significantly throughout life. At 10 yrs the average flow is approximately 600 ml/min, at 45 years it is 400 ml/min and at 80 years about 250 ml/min [6]. Using Ohm’s law, where the pressure is dependent on the flow and outflow resistance, maintaining a constant sinus pressure throughout life would require a signifi- cant reduction in the cross-sectional area of the sinuses. Whilst we cannot directly study the sinus pressure in normal aging or during hydrocephalus due to the ethical constraints from the invasive nature of manometry, we can measure the blood flow through the sinuses and their cross-sectional areas using non-invasive MRI tech- niques. Using Poiseuille’s law, sinus pressure can be esti- mated if the constants in the equation can be calculated. We can calibrate the calculation of sinus pressure and obtain a figure for the constants in Poiseuille’s law by utilizing the limited available literature on normal sinus pressure at manometry and use the derived equation to study the changes in sinus pressure across normal aging and secondary to chronic hydrocephalus. Thus, the pur- pose of this study is to measure the venous sinus out- flow blood volume and the sinus cross-sectional area in a cohort of individuals with chronic hydrocephalus and
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Comparison between Diastolic Subendocardial Tissue Pressures Measured Directly  or Calculated from Pressure Flow  Relations

Comparison between Diastolic Subendocardial Tissue Pressures Measured Directly or Calculated from Pressure Flow Relations

The existence of tissue pressure gradients across the left ventricular wall dur- ing the cardiac cycle is well documented [4] [5] [6] [7]; intramyocardial pressure increases from subepicardium to subendocardium [6] [8] and during diastole is higher than intracavitary pressure [9]. Satoh et al. documented the marked de- pendence of intramyocardial tissue pressure on Pzf in transiently arrested canine hearts [10] [11]. These findings suggest that intramyocardial tissue pressure di- rectly affects perfusion across the ventricular wall. When autoregulatory reserve is exhausted, diastolic subendocardial tissue pressure is believed to be the effec- tive coronary back pressure, however, it must be greater than, or equal to, either left ventricular or coronary sinus pressure. During maximal pharmacologically- induced vasodilatation, the relation between coronary pressure and flow (PFR) is linear [12]. We already established in normal, in situ canine beating hearts that elevated coronary sinus pressure had no effect on subendocardial PFR; however at the same time the slope of the subepicardial PFR decreased [5]. These findings suggested that diastolic intramyocardial tissue pressure could be the effective back pressure in the subendocardium. As such, during diastole, subendocardial tissue pressure (measured with needle-tip transducers) and Pzf should be com- parable; we therefore examined this hypothesis in the present study after modu- lations of either left ventricular chamber, or coronary sinus, pressures in anes- thetized dogs.
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MR staging of acute dural sinus thrombosis: correlation with venous pressure measurements and implications for treatment and prognosis

MR staging of acute dural sinus thrombosis: correlation with venous pressure measurements and implications for treatment and prognosis

Acute dural sinus and cerebral venous throm- bosis may lead to various stages of parenchy- mal changes of venous infarction, with the de- gree of severity depending on the degree of venous congestion and elevated dural sinus pressure. The prognosis of venous thrombosis depends to a significant extent on the use of thrombolytics. Severe neurologic symptoms, including coma, may be reversible if treatment with thrombolytics is started before massive ce- rebral edema or hemorrhage has developed. Stage I may be treated with anticoagulants alone; however, if the patient deteriorates clini- cally, we recommend prompt thrombolysis. All other stages should be treated with thromboly- sis. A progression from mild brain swelling to severe cerebral edema and/or hemorrhage from increasing dural sinus pressure may occur if treatment is delayed.
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Intracranial Venous Sinus Stenting Improves Headaches and Cognitive Dysfunction Associated with Ehlers-Danlos Syndrome Type III

Intracranial Venous Sinus Stenting Improves Headaches and Cognitive Dysfunction Associated with Ehlers-Danlos Syndrome Type III

The most common subtype of Ehlers-Danlos syndrome (EDS) is type III, or hypermobility type (EDS-HT). A large proportion of this population suffers from debilitating headaches and cognitive dysfunction of unclear etiology. We hypothesize that a subset of these patients has underlying cerebral venous sinus outflow abnormalities contributing to these symptoms, and that outflow optimization with endovascular stenting may ameliorate these symptoms. In this study, consecutive EDS-HT patients presenting with headache and cognitive dysfunction were evaluated with intracranial venous manometry. Patients who were found to have a significant venous sinus pressure gradient and were treated with venous sinus stenting (VSS). A database of these cases was prospectively maintained and retrospectively reviewed for this study. The study cohort comprised 130 patients with EDS-HT, including 74 who underwent VSS. Technical success with resolution of the pressure gradient was achieved in 100%, with a 4% rate of significant procedural complications. Headaches and cognitive dysfunction significantly improved or completely resolved in 77% of patients, were unchanged in 11%, and worsened in 4%. 7% were lost to follow-up. Our results support the hypothesis that intracranial venous outflow abnormalities contribute to the underlying etiology of headache and cognitive symptoms in some patients with EDS-HT. Diagnostic venography with venous manometry is necessary to identify the population of EDS-HT patients who may benefit from VSS. VSS appears to have a favorable risk to benefit profile, and it may be considered as a minimally invasive treatment option for appropriately selected patients with this disorder.
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Differences in the Calculated Transvenous Pressure Drop between Chronic Hydrocephalus and Idiopathic Intracranial Hypertension

Differences in the Calculated Transvenous Pressure Drop between Chronic Hydrocephalus and Idiopathic Intracranial Hypertension

the wall thickness and fluid density are constants, the ratio of the elastic modulus to the internal radius of the sinus in hydroceph- alus must increase 5.8 times. The radius is reduced by 20% com- pared with that in controls. Therefore, the elastic modulus must be 4.6 times stiffer in hydrocephalus to account for the pulse wave velocity. The only way the sinus wall can be stiffer and yet still deflect further with a smaller pressure difference would be if the walls were irreversibly stretched. Note, post-shunt insertion, the sinuses greatly dilate with the CSF pressure set by the shunt valves in this cohort averaging 7.7 mm Hg. A normal sagittal sinus pres- sure is 7.5 mm Hg. 17 Thus, the sinus pressure post-shunt insertion
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Use of Phase Contrast MRA to Assess Intracranial Venous Sinus Resistance to Drainage in Healthy Individuals

Use of Phase Contrast MRA to Assess Intracranial Venous Sinus Resistance to Drainage in Healthy Individuals

also underline the importance of flow resistance in the regulation of cerebral blood outflow. Although our results are preliminary, they suggest that the cumulative effects of resistance to flow along vessel segments may have repercussions on the intracranial hy- drodynamics, insofar as cerebral blood outflow may be influenced by the venous sinus resistance to flow. It is also possible that an elevated Rd across the cerebral sinus pathways contributes to the elevation of blood pressure on the venous side of the cerebral vascular tree. An elevation in venous pressure makes the cortical veins stiffer and induces a decrease in craniospinal compliance. 33
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A Study on Clinical Spectrum of Cerebral Venous Thrombosis

A Study on Clinical Spectrum of Cerebral Venous Thrombosis

Recently, dynamic spiral CT techniques have been utilized to study the cerebral venous circulation. Spiral cerebral CT venography can be easily and rapidly performed in the acute setting, immediately following noncontrast CT.Filling defects within the affected sinuses, sinus wall enhancement and abnormal venous collaterals are the usual findings . This modality can be particularly useful in hospitals where timely access and availability of MRI or conventional angiography is limited. CTV images are not impaired by in-plane flow signal loss seen with MRV, and may be superior to MRV in visualizing sinuses or smaller veins with low flow 67 .
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Clinicoradiological Profile of Cerebral Venous
Sinus Thrombosis with Prognostic Evaluation Using
MR Sequences.

Clinicoradiological Profile of Cerebral Venous Sinus Thrombosis with Prognostic Evaluation Using MR Sequences.

This is to certify that this dissertation entitled "THE CLINICORADIOLOGICAL PROFILE OF CEREBRAL VENOUS SINUS THROMBOSIS WITH PROGNOSTIC EVALUATION USING MR SEQUENCES" submitted by Dr.G.SATHYAN, appearing for Part II M.D. Branch VIII - Radiodiagnosis degree examination in September 2006 is a bonafide record of work done by him under my direct guidance and supervision in partial fulfilment of regulations of The Tamil Nadu Dr.M.G.R. Medical University, Chennai. I forward this to The Tamil Nadu Dr.M.G.R. Medical University, Chennai.

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Endoscopic sinus surgery for maxillary sinus mucoceles

Endoscopic sinus surgery for maxillary sinus mucoceles

Results: There were eight males and six females with an age range of 14 to 65. Ten patients complained of nasal obstruction, five of nasal drainage, five of cheek pressure or pain and one of proptosis of the eye and cheek swelling. The maxillary sinus and ipsilateral ethmoid sinus involvement on computed tomographic studies was seen in 4 patients. Four patients had history of endoscopic ethmoidectomy surgery for ethmoid sinusitis and one had Caldwell-Luc operation in the past. Ethmoidectomy with middle meatal antrostomy and marsupialization of the mucocele was performed in all patients. Postoperative follow-up ranged between 8 to 48 months. All patients had a patent middle meatal antrostomy and healthy maxillary sinus mucosa. No patients need revision surgery.
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Does Your Headache Treatment Plan Include Targeted Thermal Therapy?

Does Your Headache Treatment Plan Include Targeted Thermal Therapy?

Thermal therapy has been studied scientifically and validated as a method for primary or adjunctive headache relief for patients who have had a complete evaluation and diagno- sis by a physician. This therapy is administered easily and safely outside of the physicians’ office and allows for patient directed modulation of the heating and cooling mechanism for maximum pain relief, without adverse side effects. Ideally the thermal therapy would be delivered through an inte- grated mechanism that allows for patient directed modula- tion of the heating and cooling affect. Thermal and pressure therapy mitigates pain for multiple types of headaches. This therapy is safe and effective for the many patients who prefer non-pharmacological treatment or desire adjunctive relief, including pregnant and nursing women, children, and those sensitive or refractory to medications. A low cost, self-admin- istered, integrated thermal therapy system can help reduce the financial burden and disability associated with acute and chronic headaches with its low cost, self-administered system, restoring headache sufferers to function quicker and reducing the frequency of headaches in some of the nearly 45 million afflicted in the United States.
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Prevalence of anatomical variations and incidental pathologies in Antrum of Highmore detected by cone beam computed tomography

Prevalence of anatomical variations and incidental pathologies in Antrum of Highmore detected by cone beam computed tomography

Mucous retention cyst results from the accumulation of mucous within the soft tissue that lines the sinus as a result of obstruction of the duct or gland within the epithelial layer which appears as a dome shaped radio opacity. The reported incidence is 13% in earlier CT and MRI studies conducted by Hoang, (2000). Anitha Raghunathan et al. (2016) in her CBCT study found only 4% whereas in our study the prevalence of mucous retention cyst was very much higher than the earlier studies which was recorded to be 16.42%. Antral polyps are inflammatory conditions of paranasal sinus mucosa that leads to a typical polypoid appearance. Cystic fibrosis and Kartagener’s syndrome were found to predispose the polyp formation. Chandramani B. More et al., (2016) concluded that 93.10% of participants had bilateral polyp and 6.90% had unilateral polyp in their retrospective CT study which included images which had only mucosal polyp. Anitha Raghunathan et al. (2016) reported only 4% of the prevalence of antral polyps whereas our study had a higher incidence of 9.28% of antral polyps.
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Compression of Left Main Coronary Artery in Patients with Pulmonary Artery Aneurysm and Pulmonary Hypertension

Compression of Left Main Coronary Artery in Patients with Pulmonary Artery Aneurysm and Pulmonary Hypertension

Background: Pulmonary artery aneurysm (PAA) is an unusual finding and its association with left main coronary (LMCA) compression is even more infrequent. Cardiac CT evaluates of presence and size of PAA and the degree of LMCA compression. The aim of this study is to describe two cases of adults with compression of LMCA with PAA associated with PDA and pul- monary hypertension. Case presentation: The first case is a 27-year-old man with PAA (78 mm diameter) and LMCA compression of 70% between the aortic sinus and the PAA. He presented angina as a manifestation of the LMCA compression. During follow-up the patient died. The second case is a 28-year-old man with PAA (110 mm diameter) that compresses LMCA in 55%, he rejected surgical treatment, but he is in close follow-up with medical treatment. Conclusion: Cardiac computed tomography played an important role both in the diagnosis and identification of high-risk PAA patients.
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Vol 8 (2016)

Vol 8 (2016)

The given explanation of microrhythmic findings by heterometric autoregulation presumes that duorhythm is somewhat unrelated to a pathological condition known as pulsus alternans. Such Figure 4. Ten–minutes autocorrelation in left–ventricular pressure curves of isolated guinea pig (GPig, N=20 at 37°C, 10 at 31°C) and Sprague–Dawley rat hearts (Rat, N=64 at 37°C, 34 at 31°C), working at standard conditions (see Table 1 for BI lengths). Upper panels: Time–course of the peak coefficients (r) of autocorrelation by moving an initial 2s–window. Curves are medians from 1s each, at 37°C (white) with 95 per cent interval of confidence (gray, clipped downwards at GPig) of the median, and at 31°C (black ). Bottom panels: Occurrence of similar beats as a Poisson process. Window of autocorrelation is one beat interval (BI), those ten per cent of following BIs presenting with the highest r values are qualified as “very similar”; black bars, distribution of the periods free from similar beats (number of BIs to wait), given as percentage of the total number, n, of waiting periods; gray curves, best fitting exponentials with λ, expected number of BIs to wait. Black exponential curves (having λ=9) would be predicted by a Poisson process with neither microrhythms nor fade-out.
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Occlusion of Posterior Fossa Dural Sinuses in Vein of Galen Malformation

Occlusion of Posterior Fossa Dural Sinuses in Vein of Galen Malformation

Twenty patients (32.8%) demon- strated occlusion of the posterior fossa dural sinuses. In the neonate group, si- nus occlusion was considerably less likely to occur compared with the other groups. All 19 neonates demonstrated well-developed sigmoid sinuses and internal jugular veins on the initial angiograms. Oc- cipital sinuses were also observed in all neonates. Only 2 (cases 16 and 19) of them, who had been referred late to our center owing to previous complications after early treatment, developed sinus oc- clusion during their infancy.

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Cerebral sinus venous thrombosis.

Cerebral sinus venous thrombosis.

Dural sinuses are divided classically into posterior superior (P-S) and anterior inferior groups (A-I). P-S comprises the SSS, ISS, LS, straight sinus, and occipital sinus. The A-I group comprises the superior and inferior petrosal sinuses and the cavernous sinus. Inside of dural sinuses are found the Pacchioni’s or arachnoid granulations, which play an essential role in the cerebrospinal fluid (CSF) physiology. SSS is located anatomically in the attached margin of falxcerebri, and drains almost all cerebral cortex.

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Hemodynamics, coronary blood flow, and myocardial metabolism in coronary shock; response to l norepinephrine and isoproterenol

Hemodynamics, coronary blood flow, and myocardial metabolism in coronary shock; response to l norepinephrine and isoproterenol

Hemodynamics and myocardial metabolism were evaluated in 18 patients in cardiogenic shock following acute myocardial infarction. The response to l-norepinephrine was studied in seven cases and the response to isoproterenol in four cases. Cardiac index (CI) was markedly reduced, averaging 1.35 liters/min per m 2 . Mean arterial pressure ranged from 40 to 65 mm Hg while systemic vascular resistance varied widely, averaging 1575 dyne-sec- cm -5 . Coronary blood flow (CBF) was decreased in all but three patients (range 60-95, mean 71 ml/100 g per min). Myocardial oxygen consumption (MV O 2 ) was normal or
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Distribution of Flow and Plasma Skimming In Isolated Perfused Gills of Three Teleosts

Distribution of Flow and Plasma Skimming In Isolated Perfused Gills of Three Teleosts

Effects of red cells and vasoactive drugs on percent efferent outflow efferent artery outflow/efferent artery outflow + central sinus outflow at constant efferent artery pressure lOmmHg [r]

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Pit excision with phenolisation of the sinus tract versus radical excision in sacrococcygeal pilonidal sinus disease: study protocol for a single centre randomized controlled trial

Pit excision with phenolisation of the sinus tract versus radical excision in sacrococcygeal pilonidal sinus disease: study protocol for a single centre randomized controlled trial

In the past, radical surgical excision was the treatment of choice for SPSD. Since 2010, however, pit excision and phenolisation of the sinus tract has increasingly been applied as treatment for SPSD. This treatment seems to have some advantages compared to radical ex- cision; it is performed under local anaesthesia with a relatively small surgical wound, less postoperative pain and minor risk of complications of the wound (that is, SSI) and long-lasting wound healing. All these advan- tages potentially lead to a reduction in days unable to perform normal activity. The recurrence rate is, at 13%, somewhat higher for the phenolisation technique. How- ever, as far as we know it seems unlikely that this treat- ment does compromise or negatively influence radical surgical excision if necessary in the future due to recur- rence after phenolisation. Currently, no randomised controlled trials have been performed comparing both treatment modalities. Therefore, the abovementioned advantages of the phenolisation technique over radical excision are not evidence-based. The study described in this research protocol is potentially able to provide evi- dence of the advantages of the phenolisation technique. The primary endpoint in this study is the number of days unable to perform patient’s normal activity. This was chosen as all the advantages of the phenolisation technique (that is, local anaesthesia and less pain and wound complication) contribute to this primary end- point. As stated in the research protocol, a more con- servative estimation of the primary endpoint was considered for sample size calculation, as the results from the previous observational studies showed a rela- tively broad SD [2,5,13]. Moreover, this more conser- vative estimation requires the inclusion of more patients into each study group, leading to the advan- tage of a more powerful randomised trial. The sample size could also be calculated based on the difference in recurrence rate between both interventions. Although the recurrence rate of surgical excision seems to be favourable, the difference with the phenolisation tech- nique is quite small as reported in previous studies [5,13]. Therefore, it would require an inclusion of over 4,000 patients in each group to reach statistical
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Prevalence of Cardiac Arrhythmias among Chronic
Obstructive Pulmonary Disease Patients Admitted
to Jimma University Medical Center

Prevalence of Cardiac Arrhythmias among Chronic Obstructive Pulmonary Disease Patients Admitted to Jimma University Medical Center

the study of Kleiger et al. [14] and Shih et al. [32], H Zaghla et al. [33] was higher than the present finding. This difference might be because they involved only patients with severe stage of COPD, but the present study involved COPD patients from all stages. The 50% prevalence of cardiac arrhythmia diagnosed in the present study was also against the finding of Curkendall et al. [4] with lowest prevalence of 21.1%, Cazzola et al. [34] with prevalence of 15.9% due to possible sample size difference, difference in severity of the disease, difference in design method, they exclude also sinus origin arrhythmias like sinus tachycardia and bradycardia which is actually diagnosed in the present study as sinus origin arrhythmia. Though, the arrhythmogenic mechanisms involved in COPD are complex and seem to have diversity across the different types of arrhythmias, the common causes for the occurrence of arrhythmias in COPD are P-wave duration and PQ interval, oxidative stress, inflammation, hypoxia, hypercapnia, pulmonary hypertension, β-adrenergic effects of bronchodilators, diastolic dysfunction, changes in atrial size by altered respiratory physiology, increased arrhythmogenicity from no pulmonary vein foci of right atrium, autonomic dysfunction, QTc dispersion, concomitant CAD and HF [24,35,36].
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