Double potentials along the ablation line as a guide to radiofrequency ablation of typical atrial flutter.
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OBJECTIVES: The purpose of this study was to determine the characteristics of double potentials (DPs) that are helpful in guiding ablation within the cavo-tricuspid isthmus. BACKGROUND: Double potentials have been considered a reliable criterion of cavo-tricuspid isthmus block in patients undergoing radiofrequency ablation of typical atrial flutter (AFL). However, the minimal degree of separation of the two components of DPs needed to indicate complete block has not been well defined. METHODS: Radiofrequency ablation was performed in 30 patients with isthmus-dependent AFL. Bipolar electrograms were recorded along the ablation line during proximal coronary sinus pacing at sites at which radiofrequency ablation resulted in incomplete or complete isthmus block. RESULTS: Double potentials were observed at 42% of recording sites when there was incomplete isthmus block, compared with 100% of recording sites when the block was complete. The mean intervals separating the two components of DPs were 65 +/- 21 ms and 135 +/- 30 ms during incomplete and complete block, respectively (p < 0.001). An interval separating the two components of DPs (DP(1-2) interval) <90 ms was always associated with a local gap, whereas a DP(1-2) interval > or =110 ms was always associated with local block. When the DP(1-2) interval was between 90 and 110 ms, an isoelectric segment within the DP and a negative polarity in the second component of the DP were helpful in indicating local isthmus block. A DP(1-2) interval > or =90 ms with a maximal variation of 15 ms along the entire ablation line was an indicator of complete block in the cavo-tricuspid isthmus. CONCLUSIONS: Detailed analysis of DPs is helpful in identifying gaps in the ablation line and in distinguishing complete from incomplete isthmus block in patients undergoing radiofrequency ablation of typical AFL. (+info)
Single atriocaval cannulation is associated with increased incidence of hypercirculatory failure after cardiopulmonary bypass.
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Cardiopulmonary bypass (CPB) can lead to hypercirculatory cardiac failure (HCF). Despite the activation of inflammatory mediators, the infusion of cardioplegic solution into the systemic circulation may result in decreased systemic vascular resistance and thus may cause HCF. The present prospective study was conducted to investigate in cardiac surgical patients the effects of single atrial versus bi-caval venous drainage and intraoperative hemofiltration on the incidence of HCF. METHODS AND RESULTS: 120 patients undergoing coronary artery bypass surgery (CABG) were randomized in 3 groups: A- single atrial cannulation; B- single atrial cannulation and intraoperative zero fluid balance hemofiltration; C- bi-caval cannulation. Myocardial protection was performed using cold crystalloid cardioplegia (Bretschneider's HTK) administrated into the aortic root and moderate hypothermia (32 degree C). Hemodynamics, fluid balance, vasoactive drugs, body temperature, and hemoglobin/hematocrit ratio were recorded during and up to 12 hours after surgery. We noted a significantly increased incidence of HCF in-group A (32%, n=13) and B (40%, n=16) when compared to group C (10%, n=4, p<0.05), with significantly increased requirements for vasoactive medication in patients developing HCF. CONCLUSION: The present study results demonstrate that single atrial cannulation is associated with a significantly higher incidence of HCF. This is presumably caused by infusion of cardioplegic solution into the systemic circulation. (+info)
Syndromes of asplenia and polysplenia. A review of cardiac and non-cardiac malformations in 60 cases withspecial reference to diagnosis and prognosis.
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This review presents the cardiac and non-cardiac malformations in 60 cases with asplenia and polysplenia with special reference to distinguishing factors which may be helpful in the clinical recognition of these syndromes. The asplenia cases were predominantly male and presented with cyanosis. They frequently had transposition of the great arteries (72%) with pulmonary stenosis or atresia (88%) and total anomalous pulmonary venous drainage (72%). Deaths were caused by cardiac failure and anoxia in 57 per cent of cases. Most of the patients died in the first year of life (79%), but longer survival is possible in the asplenia syndrome. The polysplenia cases were predominantly female and survived longer. The characteristic clinical findings were the relatively more benign presenting signs and the leftward or superiorly orientated P wave axis on the electrocardiogram. Conotruncal abnormalities were less common and total anomalous pulmonary venous drainage did not occur. On angiography the inferior vena caval drainage via the azygos system was clearly identified and this was present in all cases at surgery. Our study indicated that the cardiac anomalies in polysplenia were less severe than they were in asplenia and therefore the prognosis in the former syndrome is likely to be more favourable. Three families had two affects sibs but no single genetic factor could be identified. The aetiology of these syndromes remains undetermined. (+info)
Antithrombotic effects of controlled inhibition of factor VIII with a partially inhibitory human monoclonal antibody in a murine vena cava thrombosis model.
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The human monoclonal antibody mAb-LE2E9 partially inactivates human factor VIII (FVIII), leaving approximately 10% residual activity. The antithrombotic efficacy of the antibody was evaluated in mouse models of inferior vena cava thrombosis. Thrombi were induced in wild-type mice given either the antibody or saline. No thrombi occurred in any of 8 mice treated with mAb-LE2E9, whereas 6 of 8 control mice developed thrombi (P =.007). Treatment with mAb-LE2E9 did not result in a severe bleeding phenotype: a tail-cutting experiment that resulted in death of C57BL/6 FVIII-deficient (FVIII(-/-)) mice did not cause hemorrhagic death in mice treated with mAb-LE2E9. To evaluate the antithrombotic effect of mAb-LE2E9 in presence of human FVIII, thrombus formation was induced in FVIII(-/-) mice reconstituted intravenously with recombinant human FVIII (rhFVIII) or rhFVIII preincubated with mAb-LE2E9. Only 1 of 9 mice produced a thrombus in the rhFVIII/antibody complex-treated group, compared with 7 of 9 in the control group (P =.015). FVIII(-/-) mice were also reconstituted with rhFVIII and then injected with either mAb-LE2E9 or saline. One of 14 mice in the group treated with the antibody developed a thrombus, compared with 10 of 14 in the control group (P =.001). The thrombi occurring in antibody-treated animals were smaller than in controls (P <.01). All animals survived, and there were no bleeding complications. Thus, the mAb-LE2E9 antibody inhibits thrombosis without causing an overt bleeding tendency. (+info)
Phosphodiesterase type 4 inhibitor reduces the retention of polymorphonuclear leukocytes in the lung.
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Phosphodiesterase (PDE) type 4 is the predominant PDE isozyme in polymorphonuclear leukocytes (PMN) and plays a key role in the regulation of PMN activation. The aim of this study was to examine the effect of a PDE type 4 inhibitor, rolipram, on the functional changes and the retention of PMN in the lung. In vitro, F-actin content and L-selectin and CD11b expression of PMN stimulated by N-formyl-Met-Leu-Phe were measured by flow cytometry. PMN deformability was evaluated using silicon microchannels. Rolipram reduced the increase of F-actin and CD11b but did not change the decrease of L-selectin. Rolipram inhibited the increase of the transit time of PMN through the microchannel. We evaluated the retention of PMN in the lung in vivo by infusing labeled blood into the vena cava and examining the recovery into aortic root samples in rabbits. Rolipram inhibited the retention of stimulated PMN in the lung. In conclusion, a PDE type 4 inhibitor, rolipram, reduces the retention of PMN in the lung by reducing deformability change and CD11b upregulation of PMN. (+info)
Antithrombotic effect of Lonomia obliqua caterpillar bristle extract on experimental venous thrombosis.
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The venom of Lonomia obliqua caterpillar may induce a hemorrhagic syndrome in humans, and blood incoagulability by afibrinogenemia when intravenously injected in laboratory animals. The possible antithrombotic and thrombolytic activities of L. obliqua caterpillar bristle extract (LOCBE) were evaluated in this study. The minimal intravenous dose of the extract necessary to induce afibrinogenemia and anticoagulation was 3.0 and 10.0 microg protein/kg body weight for rabbits and rats, respectively. In rabbits, this dose induced total blood incoagulability for at least 10 h and did not reduce the weight of preformed venous thrombi, in contrast to streptokinase (30,000 IU/kg). In rats, pretreatment with 5.0 and 10.0 microg/kg LOCBE prevented the formation of thrombi induced by venous stasis or by injury to the venous endothelium. The dose of 5.0 microg/kg LOCBE did not modify blood coagulation assay parameters but increased bleeding time and decreased plasma factor XIII concentration. When the extract was administered to rats at the dose of 10.0 microg/kg, the blood was totally incoagulable for 6 h. These data show that LOCBE was effective in preventing experimental venous thrombosis in rats, justifying further studies using purified fractions of the extract to clarify the mechanisms of this effect. (+info)
Is percutaneous vertebroplasty without pretreatment venography safe? Evaluation of 205 consecutives procedures.
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BACKGROUND AND PURPOSE: Vertebral venography has been advocated before bone cement injection when performing percutaneous vertebroplasty (PV) for benign or malignant lesions of the spine. Although venography can document sites of potential leakage during subsequent cement application, stagnant contrast agent renders the cement injection more difficult to monitor, and an allergic reaction to contrast agent remains a potential risk. We evaluated our experience with PV without prior venographic evaluation. METHODS: Two hundred five consecutive PV procedures performed in 137 patients without pretreatment venography were evaluated for complications linked to bone cement injection. Treated lesions were 172 benign compression fractures, 27 metastases, two hemangiomas, and four multiple myelomas. PV was performed with a single-pedicle technique in 146 cases and a two-pedicle technique in 59 cases. RESULTS: No major complication occurred in our series. Three minor complications (1.5%) were documented: One patient had a transient episode of arterial hypotension during cement injection, without cement leak; one patient had a spontaneously resolving patch of cutaneous hypoesthesia at the puncture site; and one patient had a radiculopathy four levels above the treated level, not caused by cement deposition, and successfully treated with a nerve block. None of these three minor complications were related to cement leakage. CONCLUSION: PV can, in our experience, be performed safely without prior angiographic evaluation of the vertebral venous system. (+info)
Nitric oxide synthase activity in hyperthyroid and hypothyroid rats.
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OBJECTIVE: Thyroid disorders are accompanied by important changes in haemodynamic and cardiac functions and renal sodium handling. Since nitric oxide (NO) plays a crucial role in regulating vascular tone and renal sodium excretion, the present paper was designed to determine whether changes in the activity of NO synthase (NOS) participate in the cardiovascular and renal manifestations of thyroid disorders. METHODS: We measured NOS activity in the heart (left and right ventricles), vessels (aorta and cava) and kidney (cortex and medulla) of euthyroid, hyperthyroid and hypothyroid rats after 6 weeks of treatment. NOS activity was determined by measuring the conversion of L-[(3)H]-arginine to L-[(3)H]-citruline. RESULTS: NOS activity was higher in all tissues from hyperthyroid rats when compared with controls, except in the right ventricle. In the hypothyroid group, NOS activity showed a more heterogeneous pattern, with significant increases in both ventricles but significant reduction in the aorta, while in the vena cava, renal cortex and medulla the enzyme activity also tended to be higher, but significance was not reached. CONCLUSIONS: These data indicated that NOS activity was upregulated in tissues primarily related to blood pressure control in hyperthyroid rats, suggesting that an increased NO production may contribute to the hyperdynamic circulation in hyperthyroidism and may have a protective homeostatic effect in the target organs of the hypertension that accompanies this endocrine disease. The aortic and renal findings in hypothyroid rats suggested a possible role for NOS in the increased peripheral resistance and the normal pressure-diuresis-natriuresis response of these hypotensive animals, although hypothyroidism produced a heterogeneous tissue response in NOS activity. (+info)