Date Published: February 28, 2007
Publisher: BioMed Central
Author(s): Ragnvi Hagman, Anne-Sofie Lagerstedt, Boel A Fransson, Annika Bergström, Jens Häggström.
Myocardial injury may contribute to unexpected deaths due to pyometra. To detect myocardial damage, measurement of cardiac troponin I (cTnI) is currently the most sensitive and specific method. The aims of the present study were to evaluate presence of myocardial damage in canine pyometra by analysis of cTnI, to explore whether myocardial injury was associated with systemic inflammatory response syndrome (SIRS) and to evaluate whether other clinical or laboratory parameters were associated with cTnI increase.
Preoperative plasma levels of cTnI were investigated in 58 female dogs with pyometra and 9 controls. The value of physical examination findings, haematological, serum biochemical and pro-inflammatory (CRP and TNF-α) parameters as possible predictors of increased cTnI levels was also evaluated.
Seven dogs with pyometra (12%) and one control dog (11%) had increased levels of cTnI. In the pyometra group, the levels ranged between 0.3–0.9 μg l-1 and in the control dog the level was 0.3 μg l-1. The cTnI levels did not differ significantly between the two groups. No cardiac abnormalities were evident on preoperative physical examinations. Four of the pyometra patients died within two weeks of surgery, of which two were examined post mortem. In one of these cases (later diagnosed with myocarditis and disseminated bacterial infection) the cTnI levels increased from 0.9 μg l-1 preoperatively to 180 μg l-1 the following day when also heart arrhythmia was also detected. The other patient had cTnI levels of 0.7 μg l-1 with no detectable heart pathology post mortem. CTnI increase was not associated with presence of SIRS. There was a trend for the association of cTnI increase with increased mortality. No preoperative physical examination findings and few but unspecific laboratory parameters were associated with increased cTnI levels.
Increased cTnI levels were observed in 12% of the dogs with pyometra. The proportions of dogs with cTnI increase did not differ significantly in the pyometra group compared with the control group. CTnI increase was not associated with presence of SIRS. A trend for association of cTnI increase and mortality was observed. Preoperative physical examination findings and included laboratory parameters were poor predictors of increased cTnI levels.
Pyometra is a common reproductive disorder which affects nearly one fourth of all female dogs before they reach ten years of age . The disease generates clinical signs associated with infection and inflammation in the uterus and may induce endotoxaemia and systemic inflammation with multiorgan effects [2,3]. Despite modern treatment routines the mortality rate due to pyometra is about 4% . Myocardial injury secondary to endotoxaemia, inflammation, disseminated bacterial infection or infarcation, is suspected to be a contributing factor to unexpected deaths in female dogs with pyometra . In dogs where electrocardiography, thoracic radiography, ultrasonography and laboratory parameters are normal, myocardial necrosis and ischemia may be difficult to detect clinically . For definitive diagnosis heart muscle biopsy is often required, but it is not an acceptable procedure due to the risks and costs . Measurement of cardiac troponin can be useful as a non-invasive method to determine suspected myocardial injury, for example in cases presented with cardiac arrhythmia, severe depression or multi organ dysfunctions.
In the present study, 7 of the 58 dogs with pyometra had increased plasma levels of cTnI. The levels ranged between 0.3–0.9 μg l-1, which indicates minor myocardial damage. Even slight elevations of cardiac troponin are specific for myocyte injury . Unnoticed myocard injury, as measured by increased cTnI levels, is frequent in critically ill human patients and is associated with increased mortality rates . The analysis thus adds diagnostic and prognostic value to other clinical examinations in identifying patients at risk for cardiac events . In humans, events reported in the induction of myocard injury include reduction in oxygen supply in combination with increased myocard oxygen consumption or increasing wall stress, hypertension with left wall hypertrophy, tachycardia, infiltrative diseases, cardiac trauma, pulmonary embolism or myocardial toxins as a consequence of sepsis . It is probable that the same types of events may induce myocard damage also in dogs. Reference values for plasma cTnI in healthy dogs has (in two different studies using the same method as in the present study [13,14]) previously been determined to be < 0.5 μg l-1 and < 0.24 μg l-1. Four of the dogs with pyometra in the present study had cTnI levels over < 0.5 μg l-1, and all had cTnI levels above < 0.24 μg l-1. Minor myocardial injury was present in 12% of the female dogs with pyometra. The proportions of cases with increased cTnI levels did not differ significantly in the pyometra patient group when compared with healthy control dogs. Presence of SIRS was not associated with increased cTnI values. A trend for the association of detectable cTnI levels with increased mortality was apparent, as evaluated in the pyometra group. Findings at physical examination, haematological, biochemical and inflammatory parameters evaluated preoperatively in the present study, were all poor predictors of myocardial cell injury as determined by cTnI analysis. The author(s) declare that they have no competing interests. RH, ASL, BAF and AB were involved in the study design and collection of the samples. RH, AB and BAF were responsible for data acquisition. RH was responsible for data analysis and manuscript preparation. JH, ASL participated in the study design, and and revision of the manuscript. All authors read and approved the final manuscript. Source: http://doi.org/10.1186/1751-0147-49-6