Hemodynamic and physical performance during maximal exercise in patients with an aortic bioprosthetic valve Comparison of stentless versus stented bioprostheses

AbstractOBJECTIVESThe objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to their hemodynamic behavior during exercise.BACKGROUNDStentless aortic bioprostheses have better hemodynamic performances at rest than stented bioprostheses, but very few comparisons were performed during exercise.METHODSThirty-eight patients with normally functioning stentless (n = 19) or stented (n = 19) bioprostheses were submitted to a maximal ramp upright bicycle exercise test. Valve effective orifice area and mean transvalvular pressure gradient at rest and during peak exercise were successfully measured using Doppler echocardiography in 30 of the 38 patients.RESULTSAt peak exercise, the mean gradient increased significantly less in stentless than in stented bioprostheses (+5 ± 3 vs. +12 ± 8 mm Hg; p = 0.002) despite similar increases in mean flow rates (+137 ± 58 vs. +125 ± 65 ml/s; p = 0.58); valve area also increased but with no significant difference between groups. Despite this hemodynamic difference, exercise capacity was not significantly different, but left ventricular (LV) mass and function were closer to normal in stentless bioprostheses. Overall, there was a strong inverse relation between the mean gradient during peak exercise and the indexed valve area at rest (r = 0.90).CONCLUSIONSHemodynamics during exercise are better in stentless than stented bioprostheses due to the larger resting indexed valve area of stentless bioprostheses. This is associated with beneficial effects with regard to LV mass and function. The relation found between the resting indexed valve area and the gradient during exercise can be used to project the hemodynamic behavior of these bioprostheses at the time of operation. It should thus be useful to select the optimal prosthesis given the patient’s body surface area and level of physical activity

Dialogical self strategies of self-organization: psychotherapy and restructuring of internal management

A identidade tem sido um conceito central na literatura em psicologia e na forma como as diferentes abordagens terapêuticas têm concebido os processos de mudança. Entre as inúmeras perspectivas desenvolvidas sobre essa dimensão do ser humano, destacamos o paradigma dialógico que tem vindo a influenciar de forma crescente a teoria e prática em psicoterapia. Segundo esta perspectiva, a funcionalidade psicológica está relacionada com o modo como os indivíduos conseguem articular e colocar em diálogo produtivo as suas várias vozes ou posições de identidade. Neste artigo apresentamos uma revisão da literatura sobre as estratégias que subjazem a essa capacidade auto-organizadora do sistema identitário e sobre as diretrizes que poderão orientar uma intervenção terapêutica dialógica quando essa capacidade se torna disfuncional.Self-concept has been playing a crucial role in psychological literature and in the way the different therapeutic approaches conceive the processes of change. From the diverse perspectives developed about this human dimension, we emphasise the dialogical paradigm that has been increasingly influential in the psychotherapeutic theory and practice. According to the dialogical perspective the psychological well-being is dependent on the way individuals articulate and maintain productive dialogues between the different voices of the self or “I-Positions”. In this paper we present a review of the literature on the strategies that underlie this self-regulatory ability of the self-system and the guidelines of the dialogical therapeutic intervention that could be used when these self-regulatory strategies become dysfunctional.(undefined

Substitution of left ventricular outflow tract diameter with prosthesis size is inadequate for calculation of the aortic prosthetic valve area by the continuity equation.

It remains uncertain whether prosthetic ring size should be used interchangeably with measured left ventricular outflow tract (LVOT) diameter in the continuity equation to estimate the aortic prosthetic valve area by transthoracic Doppler echocardiography. To determine the difference in area caused by this substitution, the area of the prosthetic valve was calculated in 143 patients with aortic bioprostheses by use of the standard continuity equation with the measured LVOT diameter (LVOT method) and then with the bioprosthetic size (size method). Compared with known in vitro prosthetic valve areas, the LVOT method (r = 0.86; standard error of the estimate 9 0.16 cm2; p < 0.001) was more accurate than the size method (r = 0.74; standard error of the estimate _ 0.40 cm2; p < 0.001). The prosthetic valve area estimated by the size method overestimated the area estimated by the LVOT method by an average of 15% -4"- 23% (p < 0.001). This difference in area between the two methods has increased with the interval since implantation of the bioprosthesis (p = 0.01). It is concluded that prosthetic size should not be used instead of LVOT diameter during calculation of aortic prosthetic valve area. This restriction is partioalarly important in patients with older bioprosthese

The effect of prosthesis-patient mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status.

BACKGROUND: High pressure gradients occurring through normally functioning prosthetic valves appear to be related to a mismatch between the effective orifice area of the prosthesis and the patient's body surface area. OBJECTIVE: To determine whether prosthesis-patient mismatch affects clinical and hemodynamic status, a group of patients with a bioprosthetic heart valve in the aortic position was prospectively evaluated at 6.2+/-4.4 years after implantation by transthoracic Doppler echocardiography. METHODS: Manufacturer-derived in vitro valve areas were available in 61 patients allowing classification into two subgroups, with or without mismatch, based on a valve area at implantation indexed for body surface area 0.85 cm2/m2 or less, or greater than 0.85 cm2/m2. Clinical and hemodynamic parameters evaluated at follow-up included New York Heart Association (NYHA) class distribution, mean transprosthetic gradient, prosthetic valve area and cardiac index. RESULTS: Prosthesis-patient mismatch was present in 32 of 61 patients (52%). Although NYHA class of the patients was similar in both groups, hemo-dynamic performance of the aortic bioprostheses was worse in patients with mismatch than in patients with no mismatch, as indicated by a higher mean gradient (22+/-9 versus 15+/-8 mm Hg, P=0.002) and a lower cardiac index (3.0+/-0.7 versus 3.4+/-0.7 L/min/m2, P=0.04). The prevalence and severity of intrinsic prosthetic dysfunction were similar in both groups. Despite similar NYHA functional class distribution in both groups, the occurrence of syncope, acute pulmonary edema and angina pectoris was significantly higher in patients with mismatch (50% versus 21%, P=0.017). CONCLUSIONS: Prosthesis-patient mismatch is associated with worse hemodynamic performance and higher prevalence of adverse clinical events. However, mismatch did not promote accelerated hemodynamic or structural deterioration of the bioprosthesis

Usefulness of the indexed effective orifice area at rest in predicting an increase in gradient during maximum exercise in patients with a bioprosthesis in the aortic valve position

This study examines the hemodynamic behavior of aortic bioprosthetic valves during maximum exercise. Nineteen patients with a normally functioning stented bioprosthetic valve and preserved left ventricular function were submitted to maximum ramp bicycle exercise. In 14 of the 19 patients, valve effective orifice area and mean gradient were measured at rest and during exercise using Doppler echocardiography. At peak exercise (mean maximal workload 118 ± 53 W), the cardiac index increased by 122 ± 34% (+3.18 ± 0.71 L/min/m2, p <0.001), whereas mean gradient increased by 94 ± 49% (+12 ± 8 mm Hg, p <0.001), and effective orifice area by 9 ± 13% (+0.15 ± 0.22 cm2, p = 0.02). A strong correlation was found between the increase in mean gradient during maximum exercise and the valve area at rest indexed for body surface area (r = 0.84, p <0.0001). Due to the increase in valve area, the increase in gradient was less (-9 ± 7 mm Hg, -41 ± 33%, p = 0.0006) than theoretically predicted assuming a fixed valve area. These results suggest that the effective orifice area of the bioprostheses has the capacity to increase during exercise; therefore, limiting the increase in gradient. The relation found between the indexed effective orifice area at rest and the increase in gradient during exercise should be useful in predicting the hemodynamic behavior of a stented bioprosthesis during exercise. Previous studies have shown that many patients with an aortic bioprosthesis can have a relatively high transprosthetic pressure gradient despite a normally functioning valve.1, 2, 3 and 4 This is most often due to prosthesis–patient mismatch, which is defined as a disproportion between the size of the prosthesis and the patient’s body surface area. Despite this adverse hemodynamic condition, these patients do relatively well clinically, and there are only small differences in the medium-term prognosis of these patients when compared with patients without evidence of mismatch.2, 3 and 5 To explain this apparent discrepancy, we hypothesized that the behavior of the bioprosthesis during exercise might be different from that predicted from theoretical models1 and 4 and in particular, that the increase in gradient occurring in bioprostheses during exercise might be less than expected. To investigate this hypothesis, we performed Doppler echocardiographic studies of patients with a stented bioprosthesis in the aortic position at rest and during exercise

The 2000 Canadian recommendations for the management of hypertension: Part one--therapy

&lt;b&gt;OBJECTIVE:&lt;/b&gt; To provide updated, evidence-based recommendations for the therapy of hypertension in adults.&lt;p&gt;&lt;/p&gt; &lt;b&gt;OPTIONS:&lt;/b&gt; For patients with hypertension, there are a number of lifestyle manoeuvres and antihypertensive agents that may control blood pressure. Randomized trials evaluating first- line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed.&lt;p&gt;&lt;/p&gt; &lt;b&gt;OUTCOMES:&lt;/b&gt; The health outcomes considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence.&lt;p&gt;&lt;/p&gt; &lt;b&gt;EVIDENCE:&lt;/b&gt; Medline searches were conducted from the period of the last revision of the Canadian Recommendations for the Management of Hypertension (May 1998 to October 2000). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts.&lt;p&gt;&lt;/p&gt; &lt;b&gt;VALUES:&lt;/b&gt; A high value was placed on the avoidance of cardiovascular morbidity and mortality.&lt;p&gt;&lt;/p&gt; &lt;b&gt;BENEFITS, HARMS, AND COSTS:&lt;/b&gt; Various lifestyle manoeuvres and antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality.&lt;p&gt;&lt;/p&gt; &lt;b&gt;RECOMMENDATIONS:&lt;/b&gt; The present document contains detailed recommendations pertaining to all aspects of the therapy of patients with hypertension, including lifestyle modifications proven to lower blood pressure, treatment thresholds, target blood pressures, choice of agents in various settings and strategies to enhance adherence. Lower thresholds for blood pressure treatment are advocated for people with other cardiovascular risk factors or established hypertensive target organ damage. Implicit in the recommendations for therapy is the principle that treatment should be individualized for each patient and the choice of agent should be dictated by coexistent conditions. For the treatment of uncomplicated essential hypertension, thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors or calcium channel blockers may be appropriate, depending on individual circumstances.&lt;p&gt;&lt;/p&gt; &lt;b&gt;VALIDATION:&lt;/b&gt; All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported here. These guidelines will be updated annually

The 2001 Canadian recommendations for the management of hypertension: Part one--Assessment for diagnosis, cardiovascular risk, causes and lifestyle modification

All recommendations were graded according to the strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported. These guidelines will be updated annually. ENDORSEMENT: These guidelines are endorsed by the Canadian Hypertension Society, The Canadian Coalition for High Blood Pressure Prevention and Control, The College of Family Physicians of Canada, The Heart and Stroke Foundation of Canada, The Adult Disease Division and Bureau of Cardio-Respiratory Diseases and Diabetes at the Centre for Chronic Disease Prevention and Control, Health Canada