The influence of hyperkalemia on the central nervous system and cardiac toxicity of bupivacaine and lidocaine was studied in open-chested mechanically ventilated dogs. The seizure and cardiotoxic doses of intravenously administered lidocaine and bupivacaine were determined in two separate groups of normokalemic (2.7 +/- 0.05 SEM mEq/1) dogs. In the case of both anesthetics, the cardiotoxic dose was found to be approximately four times the seizure dose. Under conditions of hyperkalemia (5.4 +/- 0.08 SEM mEq/1), however, the cardiotoxic doses of both anesthetics were decreased significantly to approximately two times the seizure dose. Hyperkalemia did not change the seizure dose for either anesthetic. The cardiac to seizure dose ratio was decreased significantly for bupivacaine but not for lidocaine. The results of this study suggest that hyperkalemia enhances the cardiotoxic effects of both lidocaine and bupivacaine, with this enhancement being more pronounced in the case of bupivacaine.

The Influence of Serum Potassium on the Cerebral and Cardiac Toxicity of Bupivacaine and Lidocaine

Hyperkalemia is a common electrolyte abnormality and has well-recognized early electrocardiographic manifestations including PR prolongation and symmetric T wave peaking. With severe increase in serum potassium, dysrhythmias and atrioventricular and bundle branch blocks can be seen on electrocardiogram. Although cardiac arrest is a worrisome consequence of untreated hyperkalemia, rarely does hyperkalemia electrocardiographically manifest as acute ischemia. We present a case of acute renal failure complicated by malignant hyperkalemia and eventual ventricular fibrillation cardiac arrest. Recognition of this disorder was delayed secondary to an initial ECG pattern suggesting an acute ST segment elevation myocardial infarction (STEMI). Emergent coronary angiography performed showed no evidence of coronary artery disease. Pseudo-STEMI patterns are rarely seen in association with acute hyperkalemia and are most commonly described with patient without acute cardiac symptomatology. This is the first such case presenting concurrently with cardiac arrest. A brief review of this rare pseudo-infarct pattern is also given.

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Hyperkalemia masked by pseudo-stemi infarct pattern and cardiac arrest.

Equilibrium radionuclide ventriculography is often restricted to the left anterior oblique projection. The differential sensitivity of left anterior oblique amplitude and phase images for anterior and inferior infarction was evaluated using quantitative analysis, and the role of left posterior oblique images assessed. Twenty anterior infarcts, 20 inferior infarcts and 20 normal controls were studied. Left anterior oblique amplitude and phase abnormalities were seen in 100% (20) and 85% (17) of anterior infarcts but only 55% (11) and 50% (10) of inferior infarcts. Left posterior oblique amplitude and phase abnormalities were seen in 95% (19) of anterior infarcts and 75% (15) and 85% (17) of inferior infarcts. Left anterior oblique standard deviation of phase differed from normal only for anterior infarction (P < 0.01); both anterior and inferior (P < 0.05) infarction differed from normal in the left posterior oblique projection. Left anterior oblique images are therefore insensitive for inferior infarction. An accurate description of regional ventricular wall motion requires biplane radionuclide ventriculography.

Improved assessment of inferior left ventricular wall motion using biplane equilibrium radionuclide ventriculography

A case report of fatal asystole associated with use of lidocaine in a hyperkalemic patient is presented The patient was a 61–year-old man with a rapidly increasing serum potassium level related to acute renal failure Ventricular tachycardia with a pulse developed twice, for which lidocaine was administered according to the American Heart Association's ACLS protocol Both episodes were immediately followed by asystole, the second of which was terminal Available information suggests that this phenomenon can be explained by a synergistic effect on membrane responsiveness and conduction velocity Thus, extreme caution should be exercised in the use of lidocaine when ventricular tachycardia complicates severe hyperkalemia

Asystole Associated with Lidocaine Use in a Hyperkalemic Patient during Advanced Cardiac Life Support

This report is a prospective study of 33 male patients who underwent both contrast ventriculography (CVG) and radionuclide ventriculography (RVG) within a 24-hour period. Expert, blinded observers graded the left ventricle's regional wall motion (RWM) in the left anterior descending (LAD), left circumflex (LCx), and posterior descending arterial (PDA) distributions on right anterior oblique (RAO), and left anterior oblique (LAO) CVGs, and on anterior (ANT), LAO, 70 degrees left anterior oblique (LAO70), and left posterior oblique (LPO) RVGs. When statistically compared with CVG RWM standard data, RVG studies composed of LAO and LPO views were equal to the RVG studies composed of ANT, LAO, and LAO70 views in assessment of the LAD and LCx distributions. The RVG with LAO and LPO views was superior to the RVG with ANT, LAO, LAO70 in the detection of the posterior descending artery RWM. The authors conclude that accurate assessment of RWM is efficiently performed with the RVG composed of LAO and LPO views.

Bruce K. Shively

Papers

Asystole Associated with Lidocaine Use in a Hyperkalemic Patient during Advanced Cardiac Life Support

The two-view radionuclide ventriculogram. Advantages of the LPO view.