The Analysis Of Right Cardiac Structural And Functional Parameters In Canine With Hyperkalemia By Doppler Eechocadiography

Whether it?s in clinical veterinary medicine or human clincal medicine,the record of right heart function is far from the left heart.Probabaly the reason is that people lack sufficient understanding of right heart function and used to believe that the right heart is only a conduit to eject blood in hemodynamics.Studies have found that the right ventricle is quite critical to maintain adequate pulmonary perfusion pressure and low systemic venous pressure.The morphology and function of the right ventricle are often impaired in the left heart lesion involving the right heart or in the pre-capillary pulmonary hypertension caused by primary right heart disease.The reason is that right heart function is an vital factor in the prognosis of animal heart disease and respiratory disease,and it is critial important to evaluate the right heart dysfunction accurately by non-invasive device.Hyperkalemia is a common electrolyte disorder in small animals.The ardiomyocytes show high sensitivity to blood potassium levels,as a result,hyperkalemia may causes damage to the heart function of diseased animals.Studies have shown that ECG change with different serem potassium levels,so we can make diagnosis of hyperkalemia by ECG.In this experiment,52 healthy adult beagle dogs were recruited and divided into two groups randomly.There is 26 dogs in each group（half male and half female）and were fed routely.We establish a modle of acute hyperkalemia of dog through inject KCL solution and monitor the serum potassium concentration and changes in ECG at the same time.We aim to supply the technological evidence for the diagonosis of hyperkalemia in canine and medicine tests by Doppler echocadiography to evaluate the right ventricular?s stuctrue and function of dogs with hypekalemia.The tested dog was connected with an electrocardiogram,each dogs were adminstered with 1%KCl solution（150 ml of solution contains 5g of potassium）by5.6×10^-3mmol per minute and per kilogram,and closely monitored the P wave in ECG at the same time.When the amplitude of the P wave drops to 1/2 of the original P wave,stop injecting.Then test the serun potassium concentration and assess the RV?s stucture and function by echocardiograph.Then continue the infusion until the P wave in the electrocardiogram drops to 1/4 of the original and test the serumpotassium and assess the RV?s stucture and function again.In order to observe the influence of infusion on the assessment of the echocardiographic parmeters,the control group was intravenously adminstered with 0.9%NaCl solution with the same speed of injection,and serum potassium concentration and echocardiagraphic assessment of the right heart were detected at the same time as the test group.The right heart structure parameters include the right ventricular long-axisdimension（RVLD）,the right ventricular short-axis dimension（RVXD）,and the right atrial area（RRA）and pulmonary artery（PA）diameter.The right heart systolic parameters include tricuspid annular systolic excursion（TAPSE）,two-dimensional right ventricular ejection fraction（RVEF）,right ventricular myocardial function index（RVMPI）,tricuspid annulus systolic velocity（S_m）,right ventricular area change fraction（RVFA）,pulmonary artery maximumblood flow velocity（V）,pulmonary blood flow velocity time integral（VTI）and ejection time（ET）.Right ventricular diastolic parameters include tricuspid blood flow diastolic early peak velocity E,tricuspid blood flow diastolic lately peak velocity A,E/A ratio and E wave deceleration time（EDT）,early diastolic velocity E_m of the tricuspid annulus,late diastolic velocity A_m of the tricuspid annulus and the E_m/A_m ratio.The test results and analysis are as follows:The right heart structural parameters,systolic parameters and diastolic function parameters of the healthy group were not significantly different from the pre-test results,indicating that the intravenous infusion had no effect on the echocardiographic assessment of the right heart.The normal range of right ventricular systolic parameters of dogs such as TAPSE,RVFAC,Sm,MPI and Vp is 3.75±3.41cm,46.50±6.57%,13.42±3.97cm/s,0.224±0.099,0.84±0.17m/s and 0.015±0.010s.The others is not recorded in veterinarin yet.The normal range of right ventricular diastolic parameters E,A,E/A,E_m,A_m,and E_m/A_m is 0.86±0.20 m/s,0.58±0.16cm/s,1.60±0.56,12.5±3.2cm/s,10.3±2.6cm/s,6.7±1.8cm/s,and 1.6±0.6.The normal range of right ventricular diastolic parameters E,A,E/A,E_m,A_m,and E_m/A_m is 0.8±0.20m/s,0.58±0.16cm/s,1.60±0.56,12.5±3.2 m/s,10.3±2.6cm/s,6.7±1.8cm/s and 1.6±0.6.The right ventricular parameters of the healthy group and the trial group?s right ventricular parameters before the test group were within the range.When the P wave of the electrocardiogram decreased to 1/2 of the original,the serum potassium concentration of the hyperkalemia group was 6.68±0.30 mmol/L.At this point,the right heart systolic function parameter MPI increased by1.0%±0.3%（P<0.05）,RVFAC decreased by 3.0%±0.0%（P<0.01）,other parameters were not significantly different（P>0.05）.Right diastolic function parameters A,A_m increased by 5.14±3.75cm/s（P<0.01）,2.02±0.72cm/s（P<0.01）,E/A,Em and Em/Am respectively decreased by 0.43±0.08（P<0.01）,1.71±0.55（P<0.01）and 0.42±0.11（P<0.01）.There was no significant difference in other parameters（P>0.05）;there was no significant difference between right and left structural parameters before and after the test（P>0.05）.When the P wave of the electrocardiogram decreased to 1/4 of the original,the serum potassium concentration was 7.91±0.55mmol/L.At this time,the right systolic function parameters TAPSE,Sm and RVFAC decreased by 0.06±0.03mm（P<0.01）,7.62±1.52cm/s（P<0.01）,6.0%±2%（P<0.01）,no significant difference in other parameters（P>0.05）;right heart diastolic function parameters E,A E/A,E_m,A_m and E_m/A_m decreased by 16.45±4.26cm/s（P<0.01）,22.43±3.26cm/s（P<0.01）and 0.49±0.12respectively（P<0.01）,2.49±0.86cm/s（P<0.01）,1.01±0.98cm/s（P<0.01）,0.40±0.13（P<0.01）;there was no significant difference between right heart structure parameters before and after the test（P>0.05）.Correlation analysis between right ventricular ultrasound parameters and serum potassium concentration showed that MPI was positively correlated with serum potassium concentration（r=0.52）,S_m（r=-0.65）,RVFAC（r=-0.66）and serum potassium.There was a moderate negative correlation between TAPSE and serum potassium concentration（r=-0.33）;right heart diastolic parameters A（r=-0.54）,EDT（r=-0.57）,E_m（r=-0.55）.And E_m/A_m（r=-0.84）showed a moderate negative correlation with serum potassium concentration,A_m（r=0.36）was positively correlated with serum potassium concentration,E/A（r=0.51）was moderately positive correlation with serum potassium concentration,other parameters have no correlation with serum potassium concentration.Conclusion:The systolic function and diastolic function of the right ventricular in the hyperkalemia group were severely impaired and aggravated with the degree of hyperkalemia.There was no significant difference in the right heart structure.And the right heart systolic function parameters such as MPI,S_m,RVFAC and TAPSE is a sensitive indicator of hyperkalemia and can be used to evaluate right systolic function in dogs.Right heart diastolic parameters such as E,A,E/A,E_m,A_m,and E_m/A_m are sensitive,can be used as the right diastolic function parameters in the canine.