Prognostic Value of Left Atrial Function in Dogs with Chronic Mitral Valvular Heart Disease

Background

A strong correlation between left atrial (LA) dysfunction and the severity of cardiac disease has been described in human patients with various cardiac diseases. The role of LA dysfunction in dogs with chronic mitral valvular heart disease (CMVHD) has not been addressed.

Objectives

To investigate the correlation between LA function and the prognosis of dogs with CMVHD.

Animals

Thirty‐eight client‐owned dogs with CMVHD.

Methods

Prospective clinical cohort study. Dogs were divided into 2 groups (survivors and nonsurvivors) based on the onset of cardiac‐related death within 1 year. Physical examination and echocardiographic variables were compared between the groups. For the assessment of the comparative accuracy in identifying patients with cardiac‐related death, receiver operating characteristic (ROC) curves and multivariate logistic analysis were used.

Results

The highest accuracy was obtained for the LA active fractional area change (LA‐FAC _act), with an area under the ROC curve (AUC) of 0.95, followed by the left atrial to aortic root ratio (LA/Ao), with an AUC of 0.94; peak early diastolic mitral inflow velocity (E), with an AUC of 0.85; and LA total fractional area change (LA‐FAC _total), with an AUC of 0.85. In the multivariate logistic regression analysis, LA‐FAC _act emerged as the only independent correlate of cardiac‐related death within 1 year (odds ratio = 1.401, P = .002).

Conclusions and Clinical Importance

Regarding both the size and function, the LA has a strong correlation with the prognosis of dogs with CMVHD. The most significant independent predictor of mortality in this study was LA‐FAC _act.     

Biochemistry and physiology of a family of eel natriuretic peptides

Three natriuretic peptides with similar structures were isolated from eels and their amino acid sequences determined; atrial natriuretic peptide (ANP) from atria, ventricular natriuretic peptide (VNP) from ventricles, and C-type natriuretic peptide (CNP) from brains. All three hormones were circulating in eel blood, and their plasma levels invariably decreased when eels were transferred from fresh water (FW) to seawater (SW). Eel ANP and VNP inhibited drinking in FW and SW eels. Eel ANP inhibited water and Na⁺ absorption by the intestine of SW eels. The potency of these ANP effects was 2–3 orders greater than those of other hormones which are known to have similar effects. Eel ANP and VNP induced antidiuresis but not antinatriuresis in FW eels. Eel ANP increased plasma cortisol level in SW eels but not in FW eels. The antidiuretic effect and the stimulation of cortisol secretion in eels are opposite to the ANP effects reported in mammals. These data suggest that ANP plays a complex role in the eel osmoregulation.

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Résumé Trois peptides natriurétiques présentant des structures similaires ont été isolés chez l'anguille et leurs séquences en acides aminés a été déterminées; le peptide atrial natriurétique (ANP) dans l'atria, le peptide ventriculaire natriurétique (VNP) dans les ventricules et le peptide natriurétique de type C dans le cerveau. Ces trois hormones sont présents dans le sang d'anguille et leur niveau plasmatique decroit invariablement quand les anguilles sont transférées d'eau douce en eau de mer. L'ANP et le VNP d'anguille inhibent l'action de boire chez les anguilles d'eau douce et d'eau de mer. L'ANP d'anguille inhibe l'absorption d'eau et de Na⁺ par l'intestin d'anguille en eau de mer. Ces effets de l'ANP sont 2 à 3 fois plus grands que ceux observés avec d'autres hormones qui sont connues pour avoir des effets similaires. L'ANP et le VNP d'anguille induisent l'antidiurèse mais pas l'antinatriurèse chez les anguilles d'eau douce. L'ANP d'anguille augmente chez ce poisson les niveaux de cortisol plasmatique en eau de mer mais pas en eau douce. L'effet antidiurétique et la stimulation de la sécrétion de cortisol chez l'anguille sont contraire aux effets de l'ANP observés chez les mammifères. Ces résultats suggèrent que l'ANP joue un role complexe dans l'osmorégulation de l'anguille.

     

Cx43 is involved in electrical remodeling of atrial myocytes through regulating L-type calcium current

AIM: To investigate whether the association of connexin 43(Cx43) and L-type calcium channel involved in the pathogenesis of atrial fibrillation (AF). METHODS: The biochemical assays and whole-cell patch-clamp technique were used to study the expression of Cx43 in human atrial tissue. The co-localization of Cx43 and L -type calcium channel, and the regulation of L-type calcium current in atrial myocytes were investigated. RESULTS: The expression of Cx43 at mRNA and protein levels was decreased in human atrial tissues of AF patients. In cultured atrium-derived myocytes (HL-1 cells), knockdown of Cx43 significantly inhibited the mRNA expression of L-type calcium channel α1c subunit, as well as L-type calcium current. Co-localization of Cx43 with L-type calcium channel α1c subunit in mouse atrial myocytes was observed. CONCLUSION: The decrease in Cx43 is involved in the pathogenesis of AF, probably through reducing the L-type calcium current in atrial myoctyes by co-localization with L-type calcium channel, thus representing the potential pathogenesis in atrial fibrillation.     

Effects of serum from patients with atrial fibrillation on chemotaxis of cardiac fibroblasts

AIM: To investigate the effects of the serum from the patients with atrial fibrillation (AF) on the chemotaxis of rat cardiac fibroblasts.METHODS: Cardiac fibroblasts were isolated from the ventricles of neonatal Sprague-Dawley rats and primarily cultured with digestion and differential adhesion. The cells in 3 to 4 passages were used for Transwell chamber assay to determine the chemotatic effects of the sera.RESULTS: Compared with control group, the cells that migrated through the polycarbonate membrane were obviously increased in AF group. The strongest chemotaxis was induced by the serum from the patients with persistent atrial fibrillation(pers-AF).The number of migrated cells in non-AF atrial arrhythmia(AA) group was higher than that in paroxysmal atrial fibrillation(paro-AF) group, and that in control group was the lowest. The results of multiple Logistic regression analysis showed that the migrated cells were related to AF and left atrial diameter.CONCLUSION: The chemotactic effect of AF serum is obviously higher than that of control serum. The differences of AF sera among groups show that myocardial fibrosis is a chronic, insidious and delayed process. The migration and infiltration of cardiac fibroblasts indirectly reflect the presence, severity and extent of the myocardial damage. The changes of migrated cells precede the changes of left atrial diameter, indicating that the cause of fibrosis is more important, and the positive correlation between AF and left atrial diameter may not be the direct causality.     

Atrioventricular septal defects: Natural history,echocardiographic, electrocardiographic,and radiographic findings in 26 cats

ObjectivesTo evaluate signalment, echocardiographic, electrocardiographic, and radiographic findings as well as natural history in a group of cats with atrioventricular septal defects (AVSD).Animals26 client owned cats.MethodsMedical records were reviewed retrospectively for signalment, morphologic type of AVSD, presence of concurrent congenital heart disease (ConcCHD), diagnostic findings, and natural history.ResultsSeventeen cats had an isolated AVSD; 13/17 had a partial and 4/17 had a complete AVSD. Double outlet right atrium (DORA) was diagnosed in 4/17 cats. Of those with a partial AVSD, 7/13 had an atrial communication while 6/13 had a ventricular communication. Congestive heart failure (CHF) developed in 5/17 cats; all 3 cats diagnosed with a DORA not lost to follow-up developed pulmonary edema. Sudden death was documented in 4/17 (23.5%). The 5 year survival was 53.0% (9/17). Concurrent congenital heart disease was identified in 9/26 cats with 7/9 having a conotruncal abnormality. Electrocardiography was performed in 14 cats with 11/14 diagnosed with a conduction disturbance.ConclusionsOverall the echocardiographic and electrocardiographic findings with AVSD are similar to that seen in humans. Cats may have a higher prevalence than humans of partial AVSD with ventricular communication only as well as a higher prevalence of DORA. Cats with an AVSD have an overall guarded prognosis although some can live for a protracted time.     

Avoiding medical error during electrical cardioversion of atrial fibrillation: Prevention of unsynchronized shock delivery

Electrical cardioversion of atrial fibrillation is now commonly performed in veterinary medicine. Successful timing of the delivery of energy is important in order to avoid ventricular fibrillation. This brief communication describes how to ensure that proper energy delivery is performed.     

胺碘酮、普罗帕酮、西地兰治疗阵发性房颤的效果比较

目的 比较静脉应用胺碘酮、普罗帕酮、西地兰治疗阵发性房颤的效果。方法70例阵发性房颤患者随机分成胺碘酮组（n=26）、普罗帕酮组（n=20）、西地兰组（n=24）,分别静脉推注胺碘酮150～600mg、普罗帕酮70～210mg、西地兰0．2～0．6mg,观察各组房颤的转复情况、复律时间、心室率变化及药物不良反应。结果胺碘酮组转复有效率优于普罗帕酮组和西地兰组（P〈0．05或0,01）。普罗帕酮组和胺碘酮组转复成功时间短于西地兰组（P〈0．01）,其中普罗帕酮组最短。每组治疗前、后的平均心室率差异均有统计学意义（P〈0．01）,胺碘酮组和普罗帕酮组治疗后的平均心室率优于西地兰组（P〈0．01）。结论胺碘酮转复心律的效果优于普罗帕酮和西地兰。     

氯沙坦与胺碘酮联合应用对减少原发性高血压合并心房颤动复发的临床观察

目的探讨血管紧张素Ⅱ受体拈抗剂氯沙坦与抗心律失常药物胺碘酮联合应用是否可以减少原发性高血压合并心房颤动的复发。方法将原发性高血压合并持续性或阵发性房颤经电转复或药物恢复窦性心律的178例患者随机分为氯沙坦组与氨氯地平组,每组89例。两组恢复窦律后均选用胺碘酮维持窦律,氯沙坦组以氯沙坦100～150mg／d作为基础用药,氨氯地平组以氨氯地平5～10mg／d作为基础用药,疗程为1a。观察两组患者1a内的房颤复发率并比较治疗前后左心房内径（LAD）、左房舒张末期容量（LAEDV）、左房收缩末期容量（LAESV）及左心房射血分数（LAEF）。结果氯沙坦组房颤复发率比氨氯地平组明显降低（16．9％哪32．6％,P〈0．05）。治疗后氯沙坦组LAD、LAEDV及LAESV较治疗前有明显下降（P〈0．01）;氨氯地平组则无明显改善。两组治疗后的LAEF均明显增加,且以氯沙坦组增加更为显著（P〈0．01）。结论氯沙坦能够逆转原发性高血压引起的左室肥厚,可以延缓左心房扩大,进而改善心房的电重塑与结构重塑,从而减少原发性高血压合并房颤的复发。     

Left atrial volume and function in dogs with naturally occurring myxomatous mitral valve disease

Objective

Myxomatous mitral valve disease (MMVD) induces progressive left atrial (LA) enlargement. The LA modulates left ventricular filling and performance through its reservoir, conduit, and contractile function. Assessment of LA size and function may provide valuable information on the level of cardiac compensation. Left atrial function in dogs with naturally occurring MMVD remains largely unexplored. The objective of this study was to evaluate LA volume and function in dogs with naturally occurring MMVD.