Position Paper

ECG phenomenon called the J wave: History, pathophysiology, and clinical significance1

The aim of this study was to compare hypothermia patients with and without an Osborn wave (OW) in terms of physical examination findings, laboratory results, and clinical survival.

The study was carried out retrospectively on hypothermic patients. The hypothermic patients were divided into two groups. Group 1 comprised patients with OW on electrocardiogram (ECG), and Group 2 comprised patients without OW on ECG. The Mann–Whitney U test was used to compare the two groups, and the relationships between the variables and the presence of OW and mortality were analyzed with ANOVA. A value of p < 0.05 was considered statistically significant.

OW was detected on ECG of 41.9% of the patients (Group 1). The mean body temperature was 30.8 ± 4.1 °C in Group 1 and 33.3 ± 1.6 °C in Group 2 (p = 0.106). The mean creatinine level was 1.01 ± 0.6 mg/dl in Group 1 and 0.73 ± 0.5 mg/dl in Group 2 (p = 0.046). The mean bicarbonate level was 15.9 ± 3.8 mmol/l in Group 1 and 18.6 ± 3.5 mmol/l in Group 2 (p = 0.038). A relationship was determined between the presence of OW and pH, bicarbonate, and creatinine levels (p = 0.026; 0.013; 0.042, respectively). The mortality rate was 69.2% in Group 1 and 77.8% in Group 2 (p = 0.689).

Although there is a relationship between the decrease in bicarbonate levels, changes in kidney functions that cause acidosis, and the presence of OW, it has no effect on mortality. The presence of OW in hypothermic patients is insufficient to make a decision regarding mortality.

Hypothermia occurs when the core body temperature falls below 35°C, which, in severe cases, can lead to electrocardiographic changes. Several conditions that occur in the psychiatric population increase the risk of hypothermia. This risk can be further increased by the use of several classes of medications such as antipsychotics, beta-adrenergic antagonists and benzodiazepines. We report on three psychiatric patients who were admitted for hypothermia and developed electrocardiographic manifestations (sinus bradycardia, QT prolongation and Osborn waves), which completely resolved after treatment.

To investigate the prevalence and amplitudes of the electrocardiographic J wave in the Petit Basset Griffon Vendéen compared to 10 other dog breeds.

Electrocardiograms from 206 healthy dogs representing 11 dog breeds were included in the study. Besides Petit Basset Griffon Vendéen (PBGV; n = 23) 10 other dog breeds were included.

An electrocardiogram ruler was used for measuring the amplitudes of the J waves. The definition of a J wave was a positive deflection at the J point of ≥0.1 mV in more than 1 lead of the bipolar standard limb leads (I, II, III) or the unipolar standard limb leads (aVL and aVF).

The prevalence of J waves in the PBGV (n = 23) was 91% (n = 21, standard error (SE) = 5.9%), which was significantly higher compared to seven other dog breeds (p < 0.05). The overall prevalence of J waves in all 11 dog breeds (n = 206) was 43% (n = 89, robust SE = 7.8%). There was no significant difference in the prevalence between male and female dogs (p = 0.79). Neither did age (p = 0.22) nor heart rate (p = 0.25) significantly affect the prevalence of J wave.

The PBGV had the highest prevalence of J waves and the highest amplitudes compared to 10 other dog breeds. However J waves were also seen in other breeds. Therefore, J waves may be considered a normal variant on the canine electrocardiogram and should not be interpreted as cardiac disease.

The purpose of this study was to comprehensively review the literature addressing the physiological effects of hypothermia and its association with the appropriate core body temperature for extubation following coronary artery bypass surgery.

The electronic databases MEDLINE, CINAHL and Web of Science via OVID were used to identify studies for the literature review. Search words used included ‘core temperature’, ‘arrhythmia’, ‘cardiac’, ‘cardiac surgery’, ‘hypothermia’, ‘extubation’, ‘temperature’, ‘rewarming’, and ‘shivering’.

The literature search yielded 55 articles that met our inclusion criteria. No studies specifically identified the benefit of extubation at 36.5 ° C. Although temperatures varied, arrhythmias resulting from hypothermia were not reported until core body temperature dropped below 33 ° C.

This comprehensive literature review suggests extubation at lower temperatures (between 34 ° C and 36 ° C) may be viable if shivering and other factors known to contribute to myocardial stress can be controlled. These findings offer the possibility of earlier extubation which may promote beneficial health outcomes.