Dynamic left ventricular outflow obstruction during lumbar laminectomy as an unexpected cause of intraoperative hypotension

Can epinephrine therapy be detrimental to patients with hypertrophic cardiomyopathy with hypotension or cardiac arrest? A systematic review

Approximately 10% of sudden cardiac deaths among patients under 35 years of age is owing to hypertrophic cardiomyopathy (HCM)-related cardiac arrest (CA). CA is often associated with pre-arrest or peri-arrest hypotension and is treated by a set of interventions, including the administration of epinephrine. It is debated whether epinephrine increases or decreases survival to discharge following CA. HCM is associated with septal hypertrophy with a dynamic left ventricular outflow tract obstruction and impaired peripheral vasoconstriction in response to α1-adrenergic stimulation, both of which could cause epinephrine to have a different effect than in the general population. This systematic review of the literature aimed to investigate if patients with HCM in CA have a detrimental hemodynamic response to epinephrine. A literature search was performed in October 2016 using Medline (OVID), Embase (Elsevier), and Cochrane Library (Wiley). The initial search generated 2429 articles, of which 22 articles were found to meet inclusion criteria: four physiology studies, 13 case reports of hypotensive HCM patients, and five case reports of HCM patients in CA. The reviewed studies demonstrate that epinephrine effect varies in patients with HCM: in some cases, the expected hypertensive effect was obtained, but in others, a paradoxical hypotensive effect, or no effect, was observed. The probable mechanism of this effect is an increased left ventricular outflow tract obstruction. Other drugs were considered in several of these cases. In summary, the retrieved studies jointly suggest that patients with HCM may respond differently to epinephrine than patients without HCM. The suitability of epinephrine in HCM-associated CA is questionable.

Perioperative cardiopulmonary complications after cervical spine surgery in the prone position: the relationship between age and preoperative testing

BACKGROUND

Cardiac arrest during spine surgery in the prone position is difficult to manage as poor access makes cardiopulmonary resuscitation and defibrillation difficult. Advanced age is the maximal risk factor for cardiac arrest. Therefore, we wanted to determine the relationship between age and cardiac risk factors/pre-operating tests for cervical spine surgery in the prone position.

METHODS

The inclusion criteria for this study specified 88 patients scheduled should undergo cervical spine surgery in the prone position. The patients were divided into two groups: Paients in group A (50 patients) were aged 69 and under, Group B (38 patients) 70 and above. All patients responded to a medical interview about eight cardiac risk factors including past history, chest symptoms, diabetes mellitus, hypertension, hyperlipidemia, obesity, smoking, and family history. All patients underwent physical examination and 24-h Holter ECG and echocardiography performed by two cardiologists before surgery. We analyzed relationships between cardiac risk factors and ECG/echocardiography and investigated intra- and postoperative cardiovascular complications.

RESULTS

Although there were no significant differences in the number of cardiac risk factors between the two groups, the frequency of hypertension was significantly greater in Group B than in Group A. The frequency of abnormal ECG and echocardiography findings especially was significantly greater in Group B than in Group A. In ECG and echocardiography, three patients in Group B who had no cardiac risk factors before surgery showed abnormal findings, and one of the three patients had the amalgamation of arrhythmia after the operation. Also, in Group B, cardiovascular complications occurred in one case during operation.

CONCLUSION

These results suggested that patients aged 70 and above should undergo ECG and echocardiography examination before cervical spine surgery in the prone position whether they have cardiac risk factors or not . A prospective, randomized multi-center study with a larger patient sample is warranted to ultimately demonstrate how patients should be tested before spine surgery in the prone position.