[Spontaneous multivessel coronary dissection as a cause of acute myocardial infarct--case report]]. / Dissecção coronária multivasos espontânea como causa de enfarte agudo do miocárdio--a propósito de um caso.

The authors describe a case reported in a young female with antecedents of aortic pathology and renovascular hypertension submitted to renal artery surgery admitted to emergency with an extensive acute myocardial infarction, treated with thrombolysis. After coronariography we identify, as etiological factor, a spontaneous coronary dissection involving the descending anterior coronary artery and circumflex coronary artery with no affect on the left main coronary artery. About this case, the authors make a brief review of the literature emphasizing the therapeutic options.

[Diagnosis of paradoxal and concomitant pulmonary thromboembolism with transesophageal echocardiography: a clinical case]. / Diagnóstico de tromboembolismo paradoxal e pulmonar concomitante por ecocardiografia transesofágica: um caso clínico.

There is some controversy regarding the indications for transesophageal echocardiography in patients with suspected systemic embolism. The present case report refers to a 65 year old male admitted to the hospital for ischemic acute cerebrovascular accident, which was confirmed by cerebral computerized tomography. A transthoracic echocardiogram was performed showing right atrial and ventricular dilatation. A transesophageal echocardiogram was also performed to exclude thromboembolism and clarify dilatation of the right cavities. Mild spontaneous echocontrast was present in the left atrium without images of thrombus; an interatrial septal aneurysm with patent foramen ovale was found with right to left flow; an image compatible with a very mobile, large, proximal thrombus in the main pulmonary artery was observed. A venous duplex scan was performed, demonstrating venous thrombosis in the right popliteal and femoral veins. Pulmonary arteriography showed a large thrombus in the right pulmonary branch extending to the median lobe and a smaller thrombus in the left pulmonary branch. Apparently, the patient had no predisposing factors for thromboembolism. Full-dose heparin was started followed by oral anticoagulation. An inferior vena cava filter was implanted. At hospital discharge the pulmonary thrombus had disappeared and the right cardiac cavities had returned to normal size. The interatrial aneurysm had disappeared and foramen ovale was no longer patent. After 36 months of clinical follow up on oral anticoagulation, the patient remains asymptomatic without neurological sequelae nor respiratory distress.

[The metabolic-chronotropic relation in patients with heart failure--a correlation with functional capacity]. / Relação metabólica-cronotrópica em doentes com insuficiência cardíaca--correlação com a capacidade functional.

UNLABELLED: Previous studies on chronotropic incompetence (CI) in patients with congestive heart failure (CHF) have defined it as the inability to achieve > 80% of age predicted maximum heart rate (HR) (adequacy of HR response to submaximal exercise levels not being considered). The metabolic chronotropic relation (MCR) concept proposed by Wilkoff allows the assessment of the entire chronotropic function. The value of such an approach for the evaluation of CI in patients with CHF, and its relation to exercise capacity, is unclear at present. METHODS: We imposed maximal symptom-limited treadmill exercise testing while measuring breath-by-breath oxygen consumption, using CAEP protocol, in 25 patients (19 men), 49 +/- 10 years, all in sinus rhythm, with CHF secondary to dilated cardiomyopathy (17) or ischemic heart disease (8), NYHA class II-III. Anaerobic threshold (AT) was attained by all. No exercise was terminated due to arrhythmia or ischemia. MCR was calculated as the slope of the relation between the percentages of HR and metabolic reserves achieved at the end of each exercise stage. Using 2.0 standard deviations below the mean level of MCR in healthy controls, we defined an MCR value < 0.84 as abnormal. The parameters analysed were: age, drug therapy, fractional shortening (FS-%), resting HR (RHR-bpm), exercise duration (DUR-min), peak HR (HRp), peak oxygen consumption (VO2p-ml/kg/min), percentages of predicted maximal HR (% PMHR) and VO2 (% PMVO2), peak ventilatory equivalent for CO2 (VE/VCO2-L/min), time to AT (T-AT), and VO2 at AT (VO2-AT). RESULTS: MCR was normal (1.01 +/- 0.18-0.86 to 1.19) in 10 patients--Group I, and abnormal (0.66 +/- 0.13-0.42 to 0.81) in 15 (60%) patients--Group II. A similar proportion of patients in both groups were taking ACE inhibitors, digoxin and amiodarone. [table: see text] CI defined as an inability to achieve a % PMHR > 80% occurred only in 6 (24%) patients, all in Group 2 (p = 0.022 versus abnormal MCR). CONCLUSIONS: In CHF patients, CI assessed as an abnormal MCR is frequent, and relates to an impaired exercise capacity.

[The semiquantitative evaluation of systemic vascular resistances in heart failure via an analysis of Doppler aortic flow]. / Avaliação semiquantitativa das resistências vasculares sistémicas na insuficiência cardíaca a partir da análise do fluxo Doppler aórtico.

UNLABELLED: In patients with advanced heart failure (HF) submitted to tailored therapy, monitoring of systemic vascular resistance (SVR) is essential to establish an adequate hemodynamic response, being one of the end-points to achieve SVR < 18 Wood U (WU). PURPOSE: To correlate SVR value with parameters derived from the analysis of echo-Doppler aortic flow in patients with HF on tailored therapy, in order to allow a non-invasive semiquantitative evaluation of this hemodynamic end-point. METHODS: In 13 patients with dilated cardiomyopathy (eight idiopathic, five ischemic) and advanced HF (mean age 60 +/- 10 years, 10 male, all in sinus rhythm, NYHA class IV), admitted in the ICU and submitted to tailored therapy, serial simultaneous hemodynamic and echocardiographic studies were performed (2 to 5 per patient, overall 43 evaluations). The following parameters derived from the analysis of continuous wave aortic Doppler flow were analysed: peak velocity, acceleration, deacceleration and ejection times, systolic time intervals ratio, mean acceleration, mean deacceleration, acceleration, deacceleration and overall systolic flow velocity time integrals. RESULTS: SVR ranged from 10.4 to 41.9 WU (mean = 21.7, SD = 6.9). A significant correlation was found only with mean deacceleration (MnDc)-r = -0.60. MnDc ranged from 362 to 1162 cm/s2 (mean = 667, SD = 188) and proved to be independent from heart rate, systolic, diastolic and mean blood pressure, capillary wedge pressure, cardiac output, cardiac index and ejection volume. MnDc < 700 cm.s2 occurred in 25/28 evaluations with SVR > 18 WU and only in 3/15 evaluations with SVR < 18 WU-p = 0.00003. A MnDc value < 700 cm.s2 showed sensitivity = 89%, specificity = 80%, and predictive value = 89% for SVR > 18 WU (Kappa index = 0.693). CONCLUSION: Mean deacceleration of aortic continuous wave flow is reliable for semiquantitative evaluation of systemic vascular resistance and can be particularly useful for patients with advanced heart failure submitted to tailored therapy.

[Therapeutic exhaustion in patients with an implantable cardioverter-defibrillator. Are there predisposing factors?]. / Exaustão terapêutica em doentes com cardioversor-desfibrilhador implantável. Há factores predisponentes?

UNLABELLED: In patients (pts) with implantable cardioverter-defibrillators (ICD), antitachycardia pacing (ATP) schemes may be used followed by a limited number of endocavitary shocks in the same episode of ventricular tachycardia (VT) with the potential risk of therapeutic exhaustion. OBJECTIVE: To assess the incidence of episodes of therapeutic exhaustion in a population of ICD carriers with ATP programmes and to attempt to determine their correlation with clinical variables. METHODS: Study of the episodes of VT treated by ICD in 8 patients (6 male; 2 female) with an average age of 56 +/- 17 years with a follow-up > 6 months. The underlying pathology was: ischemic heart disease-5 patients; arrhythmogenic dysplasia of the right ventricle-1 patient; hypertrophic cardiomyopathy-1 patient; and operated pulmonary valve stenosis-1 patient. The authors considered therapeutic exhaustion to be the occurrence of episodes in which VT persisted after the application of ATP and the maximum number of shocks. The patients with episodes of therapeutic exhaustion (group A-3 patients) were compared with the remaining patients (group B-5 patients) with regard to the following parameters: age; ejection fraction; previous myocardial infarction (pMI; cardiac frequency during VT (cfVT); number of episodes of non-maintained VT (NMVT) without therapeutic intervention; > 20% reduction of the VT cycle after ATP (VTATP); intensity of programmable shocks (Icho); and medication with anti-arrhythmia drugs (AA). RESULTS: In a total of 262 VT records (duration > 2.5 sec. after detection) with treatment by ICD during an average follow-up of 11 months, 6 episodes (2.3%) of therapeutic exhaustion were detected in 3 patients. Four of the episodes occurred in the same patient in a period of 4 hours, hospitalisation being necessary following syncope. In the other two cases, there were complaints of dizziness which subsided spontaneously a short time after the application of the last shock by the ICD. [table: see text] CONCLUSION: Therapeutic exhaustion occurred in about 2% of the VT treated with this population. The possibility of a high number of non maintained VT episodes being associated to a greater possibility of therapeutic exhaustion may have implications on ICD programming.

Porcine class pi glutathione S-transferase: anionic ligand binding and conformational analysis.

The equilibrium binding of the non-substrate ligands 8-anilino-1-naphthalene sulfonate and bromosulfophthalein to porcine class pi glutathione S-transferase (pGSTP1-1) was studied using a variety of techniques (size-exclusion HPLC, steady-state fluorescence, second-derivative spectroscopy, and chemical modification of cysteines). Both ligands share the same binding site which has a highly hydrophobic surface. Occupation of the site inhibits catalytic function with glutathione and 1-chloro-2,4-dinitrobenzene in a non-competitive manner. Data obtained from different structural probes either located at strategic regions of pGSTP1-1 (Trp-28, Trp-38 and Cys-45) or distributed throughout the protein molecule (tyrosine residues) suggest that binding induces a microstructural change that impacts on the functional conformation of the active site.

Class pi glutathione S-transferase: Meisenheimer complex formation.

The enzyme-catalysed formation of the dead-end Meisenheimer complex, 1-(S-glutathionyl)-2,4,6-trinitrocyclohexadienate, between glutathione and 1,3,5-trinitrobenzene by two class pi glutathione S-transferases was studied under equilibrium conditions. The apparent formation constant of the complex at pH6.5, is 1.21 x 10(3) M-1 and 1.47 x 10(3) M-1 for isoenzyme pGSTP1-1 from porcine lung and hGSTP1-1 the human recombinant orthologue, respectively. These values are about 40- to 50-times larger than that determined for the nonenzymatic reaction in solution. Competitive inhibitors in the form of glutathione analogues that bind the G-site (glutathione sulphonate) or both the G-site and the H-site (S-hexylglutathione) regions of the active site markedly diminish complex formation. Comparison of kinetic data for glutathione S-transferase isoenzymes from the pi and mu gene classes suggests that the catalytic efficiencies for nucleophilic aromatic substitution reactions correspond with the ability of the enzyme's active site to stabilise the Meisenheimer complex. Formation of the red-coloured complex in orthorhombic crystals of pGSTP1-1 demonstrated that the crystallized protein retains its catalytically functional conformation in the crystal lattice.