suitable bradycardic agents for the practice of the invention have been disclosed hereinbefore . pharmaceutically acceptable salts or esters of these agents may also be employed . the pharmaceutically acceptable salts of some bradycardic agents suitable for the practice of the invention have been disclosed hereinbefore . the preparation of the bradycardic agents or their pharmaceutically acceptable salts or esters suitable for the practice of the invention is known per se . for example , for the preparation of cilobradine or its pharmaceutically acceptable salts , reference is made to the aforementioned literature ep - b - 0 224 794 and its us counterpart u . s . pat . no . 5 , 175 , 157 , which describes the chemical synthesis of these compounds . for the preparation of zatebradine or its pharmaceutically acceptable salts , reference is made to the aforementioned literature ep - b - 0 065 229 and its us counterpart u . s . pat . no . 5 , 516 , 773 , which describes the chemical synthesis of these compounds . for the preparation of ivabradine or its pharmaceutically acceptable salts , reference is made to the aforementioned literature ep - b - 0 534 859 , which describes the chemical synthesis of these compounds . for the practice of the invention , the bradycardic agent may be administered to patients in any medically or veterinary acceptable manner . hence , the composition comprising the bradycardic agent may be formulated as liquid formulation or lyophilised powder for oral or parenteral administration . powders may be reconstituted by addition of a suitable diluent or other pharmaceutically acceptable carrier prior to use . the liquid formulation is generally an aqueous solution . such formulation is especially suitable for oral administration , but may also be used for parenteral administration or contained in a metered dose inhaler or nebulizer for insufflation . it may be desirable to add excipients such as polyvinylpyrrolidone or hydroxycellulose to the composition . the liquid formulation may be administered directly per orally or filled into a soft capsule . alternatively , the ingredients may be encapsulated , tableted or prepared in a syrup for oral administration . pharmaceutically acceptable solid or liquid carriers may be added to enhance or stabilise the composition , or to facilitate the preparation of the composition . the carrier may also include a sustained release material . the compositions are prepared following the conventional techniques of pharmacy involving milling , mixing , granulating , and compressing , when necessary , for tablet forms , or milling , mixing and filling for capsule forms . for the purposes of practicing the current invention it is however preferred that the bradycardic agent be administered orally or via injection , the oral route being preferred . suitable compositions for the oral administration of the aforementioned agents are known per se . for example , a suitable composition for the administration of alinidine and ivabradine is disclosed in wo 02 / 45693 , to which reference is made . for the preparation of compositions comprising cilobradine or its pharmaceutically acceptable salts , reference is made in particular to ep - b - 0 224 794 and its us counterpart u . s . pat . no . 5 , 175 , 157 , to wo 01 / 78699 and to ep - b - 1 362 590 , which describe examples of injectable , oral liquid , tablet , capsule and suppository formulations of cilobradine or its pharmaceutically acceptable salts . in order to achieve the effect according to the invention it is expedient to use the dosages known from the literature for the treatment of elevated heart rate for the individual bradycardiac agents , dosages which are known to those of ordinary skill in the medical or veterinary art and to which reference is made , or the dosages evaluated in appropriate studies for each of these bradycardic agents . for cilobradine , the single dose is 0 . 1 to 0 . 5 mg / kg per os , preferably 0 . 2 to 0 . 4 mg / kg , 1 to 3 × daily ; for zatebradine , the single dose is 0 . 2 to 1 mg / kg 2 × daily ; and for alinidine , the single dose is 0 . 5 to 5 mg / kg 2 × daily . for example , the following dosages relevant for practicing the present invention with the bradycardic agent cilobradine in cats and dogs , have been determined in appropriate pharmacokinetic studies performed by the inventors . the single oral dose of cilobradine for potent heart rate reduction in cats is 0 . 2 - 0 . 4 mg / kg . the single oral dose of cilobradine for potent heart rate reduction in dogs is 0 . 3 mg / kg . absolute bioavailabilities of oral formulations of cilobradine are 22 . 6 % in cats and 26 - 43 % in dogs . peak plasma levels are reached 0 . 5 hours after oral administration in cats and after 1 to 2 hours in dogs . within the meaning of the present invention , the following dosage ranges are preferred for the bradycardic agent cilobradine : 0 . 05 to 5 mg / kg body weight , 0 . 1 to 2 . 5 mg / kg body weight , 0 . 1 to 1 mg / kg body weight , and 0 . 1 to 0 . 75 mg / kg body weight . the invention will now be described in more detail with reference to the following experiment . the use according to the invention of an i f channel blocker , namely cilobradine , was investigated in a clinical field study with cats suffering from asymptomatic hcm . four cats diagnosed as suffering from asymptomatic hcm by means of motion mode ecg ( left ventricular wall thickness & gt ; 6 mm ), received cilobradine orally once daily for 5 consecutive days . detailed clinical examinations were conducted at baseline and on days 1 , 2 , 3 , 6 and 9 . ecg measurements were performed at baseline and on days 3 and 6 of the study . oral solution containing 2 mg / ml cilobradine active ingredient added to 0 . 9 % nacl solution the results of the experiment , measuring the left ventricular e to a ratios obtained at baseline and under cilobradine treatment , are shown in enclosed fig1 . these results show that calculation of left ventricular e / a ratios was not possible in 2 of 4 cats at baseline , thus before treatment with cilobradine . during treatment with cilobradine , at days 3 and 6 , calculation of left ventricular e / a ratios was possible in all cats . from this study , it can be concluded that treatment with the i f channel blocker cilobradine facilitates and improves the quality of ecg diagnosis .
the present invention provides a method for improving diagnostic quality in echocardiography , especially for patients having an elevated heart rate .