Effects of anesthesia on echocardiographic assessment of left ventricular structure and function in rats

Abstract

Echocardiography is an essential diagnostic tool for accurate noninvasive assessment of cardiac structure and function in vivo. However, the use of anesthetic agents during echocardiographic studies is associated with alterations in cardiac anatomical and functional parameters. We sought to systematically compare the effects of three commonly used anesthetic agents on echocardiographic measurements of left ventricular (LV) systolic and diastolic function, LV dimensions, and LV mass in rats. Adult male Fischer 344 rats underwent echocardiographic studies under pentobarbital (PB, 25 mg/kg i.p.) (group I, n = 25), inhaled isoflurane (ISF, 1.5%) (group II, n = 25),or ketamine/xylazine (K/X, 37 mg/kg ketamine and 7 mg/kg xylazine i.p.) (group III, n = 25) anesthesia in a cross-over design. Echocardiography was also performed in an additional group of unanesthetized conscious rats (group IV, n = 5). Postmortem studies were performed to validate echocardiographic assessment of LV dimension and mass. Rats in group I exhibited significantly higher LV ejection fraction, fractional shortening, fractional area change, velocity of circumferential fiber shortening corrected for heart rate, and heart rate as compared with groups II and III. LV end-diastolic volume, end-diastolic diameter, and cross-sectional area in diastole were significantly smaller in group I compared with groups II and III. Cardiac output was significantly lower in group III compared with groups I and II. Postmortem LV mass measurements correlated well with echocardiographic estimation of LV mass for all anesthetic agents, and the correlation was best with PB anesthesia. Limited echocardiographic data obtained in conscious rats were similar to those obtained under PB anesthesia. We conclude that compared with ISF and K/X anesthesia, PB anesthesia at a lower dose yields echocardiographic LV structural and functional data similar to those obtained in conscious rats. In addition, PB anesthesia also facilitates more accurate estimation of LV mass.

MR study of postnatal development of myocardial structure and left ventricular function

“…However, the qualitative characteristics of the myocardial fiber structure assessed by DTI of formalin fixed heart are likely to remain true for intact myocardium. Lastly, the use of isoflurane during in vivo CMR study may affect cardiac function and result in lower EF and higher SV than those obtained in conscious rats (45). However, the trend of cardiac functional maturation may likely remain true.…”

Titin isoform switching is a major cardiac adaptive response in hibernating grizzly bears

“…are known to be affected by anesthetics (19,36). Even though the use of unanesthetized bears is challenging, it is clear that the echocardiography of conscious, well-adjusted subjects more accurately represents true cardiac physiology.…”

Increase in cardiac myosin heavy-chain (MyHC) alpha protein isoform in hibernating ground squirrels, with echocardiographic visualization of ventricular wall hypertrophy and prolonged contraction.

“…Prehibernation data were collected from the 24 squirrels in September 2009, but only 16 were subsequently sampled in January 2010 during hibernation because of investigator travel constraints (8 females, 8 males). These squirrels were used unanesthetized to avoid the potential confounding effects of anesthesia on in vivo assessment of cardiac function by echocardiography (Roth et al, 2002;Stein et al, 2007). Cardiac function thus was measured during the active phase of the year (September) and the hibernation period (January).…”

“…At a point approximately 3 months into hibernation, two hibernating states, deep torpor and early arousal, were compared with a pre-hibernating active period. Our study used unanesthetized ground squirrels to avoid the well-known confounding effects of drugs on cardiac function (Hellyer et al, 1988;Roth et al, 2002;Stein et al, 2007); this provided observations of more natural cardiac physiologic responses, and we feel any response to handling stress was minor.The deep torpor that ground squirrels utilize during hibernation presents considerable challenges to cardiovascular function. Cardiac cycle alterations in hibernators bear many similarities to human disease states.…”