The Canadian journal of cardiology
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A large number of patients suspected of having congestive heart failure have normal left ventricular systolic function and may, therefore, have primary diastolic heart failure. This diagnosis, however, should not be made unless there is also objective evidence of diastolic dysfunction, ie, signs of abnormal left ventricular relaxation and/or diastolic distensibility. The most useful noninvasive diagnostic approaches are the measurement of transmitral and pulmonary venous flow velocities by pulsed wave Doppler, and mitral annulus velocities by tissue Doppler echocardiography. ⋯ Furthermore, left ventricular filling patterns, in particular, the deceleration time of early transmitral filling, are powerful predictors of patient prognosis. It is probably not cost effective to perform a comprehensive assessment of diastolic filling in every patient undergoing an echocardiographic examination. However, in selected patients, the assessment of diastolic filling provides information that is important for patient management.
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Case Reports
Resection of renal cell carcinomas with inferior vena caval extension using deep hypothermic circulatory arrest.
Renal cell carcinoma with tumour thrombus extension into the inferior vena cava presents a difficult surgical challenge. The conventional surgical approach, which involves isolating the inferior vena cava, incising its wall and removing the thrombus, can have high incidences of perioperative mortality and embolization of the tumour thrombus compounded by severe hemorrhage. ⋯ The technique allowed the surgeon to operate in a bloodless field, thereby improving visibility and allowing complete tumour excision without significantly prolonging operative time. It is believed that this technique has improved the safety and technical feasibility of what had previously been a complicated and risky surgical procedure.
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In recent years, extensive studies have expanded the knowledge of the role of preconditioning (PC) for cardiac protection against ischemia reperfusion (I/R) injury. These studies are reviewed, and their relevance to the early and late phases of cardiac protection is discussed. ⋯ First, there is strong evidence that the L-arginine-nitric oxide pathway plays a major role in PC. Second, early and late phase protection are probably distinct phenomena with similar effects induced by different mechanisms. Third, nitric oxide appears to be causally involved in both mechanisms. Fourth, nitric oxide produced by endothelial nitric oxide synthase (eNOS) in the early seconds of ischemia induces reactive hyperemia. It is proposed that reactive hyperemia provides the short-lived protection of early phase PC. It is unlikely that heat shock protein 72 (HSP72) or antioxidants have a role in early phase protection--both have a time lag of 12 to 24 h after PC before gene expression occurs. Fifth, late phase PC appears to depend on HSP72 gene expression mediated by the L-arginine-nitric-oxide pathway; during late phase PC, the inducible nitric oxide synthase (iNOS) content is increased while the eNOS content is unchanged. There is good evidence for an obligatory role of iNOS in cardiac protection afforded by the late phase of I/R protection in vivo. Sixth, the results of studies on the role of endogenous antioxidants in late phase protection are contradictory and further study is required. Seventh, studies on the signalling and transduction processes associated with preconditioning provide important information that may be helpful in the development of drugs protective against I/R injury. Finally, until such drugs are developed, PC by heat shock may be an effective alternative. A recent study in a human subject reported that HSP72 is upregulated by induction of hyperthermia within a range of moderate fever levels--oral temperatures between 38.6 degrees C and 39.5 degrees C. If this is confirmed, it seems plausible that inducing hyperthermia 24 h before major cardiac surgery may be an effective therapeutic strategy for protection against I/R.