Assessing Myocardial Architecture: The Challenges and Controversies

In recent decades, investigators have strived to describe and quantify the orientation of the cardiac myocytes in an attempt to classify their arrangement in healthy and diseased hearts. There are, however, striking differences between the investigations from both a technical and methodological standpoint, thus limiting their comparability and impeding the drawing of appropriate physiological conclusions from the structural assessments. This review aims to elucidate these differences, and to propose guidance to establish methodological consensus in the field. The review outlines the theory behind myocyte orientation analysis, and importantly has identified pronounced differences in the definitions of otherwise widely accepted concepts of myocytic orientation. Based on the findings, recommendations are made for the future design of studies in the field of myocardial morphology. It is emphasised that projection of myocyte orientations, before quantification of their angulation, introduces considerable bias, and that angles should be assessed relative to the epicardial curvature. The transmural orientation of the cardiomyocytes should also not be neglected, as it is an important determinant of cardiac function. Finally, there is considerable disagreement in the literature as to how the orientation of myocardial aggregates should be assessed, but to do so in a mathematically meaningful way, the normal vector of the aggregate plane should be utilised.

Cardioprotective activity of Piper betle juice in isoproterenol induced hypertrophic rat models

Impaired electrolytes (preferably Na+, K+, Cl-, HCO3-) is one of the key fundamental complications associated with cardiac hypertrophy (enlarged heart) mediated heart failure. Piper betle (P. betle - family Piperaceae) due to its potent antioxidant activity is used in various pharmacological applications. The present study evaluates the cardioprotective (anti-hypertrophic) potential of aqueous (juice) extract of P. betle in restoring electrolyte homeostasis, thereby its ability to curb the fundamental progression of hypertrophy. Isoproterenol (ISO - 10 mg/kg b.w., i.p., 7 days) induced cardiac hypertrophic rats were developed that were simultaneously treated with the standard drug losartan (50mg/kg b.w., orally., 7days) and aqueous juice extract of P. betle (30mg/kg b.w., orally., 7 days). The biochemical estimation of glucose, protein, cholesterol, cardiac marker enzymes like SGOT, SGPT, LDH, enzymatic antioxidants namely SOD, catalase, GPx and electrolytes (Na+, K+, Cl- and bicarbonate) in serum were statistically performed along with the histopathological analysis of left ventricles (H&E stain). The present study showed increased levels of glucose, protein, cholesterol, cardiac marker enzymes, reduced enzymatic antioxidants with reduced electrolytes during cardiac hypertrophy (ISO) that were reflected in a histopathological analysis by thickened abnormal myocardial architecture which was reversed similar to normal in plant juice administered rats. Hence, this study demonstrated the beneficial effect of P. betle (aqueous juice) on electrolytes (Na+, K+, Cl-, HCO3-), thereby imposing an interventional effect against cardiac hypertrophy.

P5703The anterior interventricular crux: anatomic basis for ablation below the left sinus of valsalva (LSOV) of varied ECG morphology PVCs

Background Outflow tract premature ventricular complexes (PVCs) may be ablated at sites where the local electrogram is early. We describe ablation of PVCs of varying morphology at a cruciate structure extending from the inflection of the great cardiac vein to the junction of the distal RVOT and from the left ventricular (LV) inflow myocardium through the aortic mitral continuity (AMC) to the right coronary sinus of Valsalva centered below LSOV, termed the LV crux. Purpose Evaluate a novel target for ablation of PVCs with varied QRS morphologies. Methods A series of 51 patients undergoing ablation for PVCs between 2013–2018 was identified. In all cases, ICE-guided ablation occurred at the center of the LV crux. Results All patients had high PVC burden >20% (28±8%); EF<50% in 40/51 (78%). QRS morphology of PVCs is summarized in Table 1. 50% had prior ablation attempted at early sites. Mapping and ICE-guided ablation at the LV crux (Figure 1 A-B) revealed early activation with near-field ventricular or fascicular signal in 31 (61%), while others had early sites at extensions of the crux. PVCs were eliminated in 50/51 (98%) with continued suppression at 3-months. EF normalized in all 51. Table 1. ECG charactaeristics ECG characteristics Number of patients (%) Inferior morphology 51/51 (100%) Lead I morphology Monophasic R 8/51 (16%) Rs 9/51 (18%) rS 34/51 (66%) Precordial transition Positive across precordium 40 (78%) V2 transition 7 (14%) V3 transition 4 (8%) Maximum deflection index <0.55 37 (73%) >0.55 14 (27%) Figure 1. Mapping and ablation Conclusions A cruciate interventricular multidimensional crux centered below the LSOV is a site for successful ablation of varied PVC morphologies and should be considered for detailed mapping and ablation, particularly when multiple morphologies are present or prior ablation at early sites is unsuccessful. Ventricular myocardial architecture along with conduction system remnants may be the basis for this phenomenon.