The Journal of thoracic and cardiovascular surgery
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J. Thorac. Cardiovasc. Surg. · May 1988
Comparative StudyA physiologic comparison of external cardiac massage techniques.
On the basis of recent investigation, controversy has arisen regarding which of several cardiopulmonary resuscitation methods optimizes hemodynamics. The present study was designed to compare five recently described chest compression techniques: high-impulse manual chest compression at 150/min, mechanical compression at 60/min with simultaneous ventilation, mechanical compression at 60/min with simultaneous ventilation and either systolic or diastolic abdominal compression, and pneumatic vest compression at 60/min. Eight dogs were chronically instrumented with electromagnetic flow probes in the ascending and descending aorta while matched micromanometers measured aortic, left ventricular, and pleural pressures. ⋯ Brachiocephalic blood flow generally followed cardiac output and was statistically the greatest with high-impulse manual compression at 273 +/- 47 ml/min (p less than 0.05). Finally, high-impulse manual compression provided the highest coronary perfusion pressure of 31 +/- 4 mm Hg (p less than 0.05) compared to 23 +/- 2 mm Hg for mechanical compression and simultaneous ventilation, 23 +/- 2 mm Hg for mechanical compression and simultaneous ventilation with systolic abdominal compression, 23 +/- 3 mm Hg for mechanical compression and simultaneous ventilation with diastolic abdominal compression, and 11 +/- 2 mm Hg for vest resuscitation. These data demonstrate that high-impulse manual compression generated physiologically and statistically superior hemodynamics when compared with other methods in this model of cardiopulmonary resuscitation.
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J. Thorac. Cardiovasc. Surg. · May 1988
Relationship between cerebrospinal fluid dynamics and reversible spinal cord ischemia during experimental thoracic aortic occlusion.
This study was designed to assess the effects of hemodynamic changes and cerebrospinal fluid dynamics on spinal cord function during experimental thoracic aortic occlusion. We investigated the effects of dopamine, sodium nitroprusside, and sodium thiopental in this model. ⋯ By multiple regression analysis, the degree of spinal cord ischemia was positively related to the cerebrospinal fluid pressure (p = 0.0092) and negatively related to the percent change in cerebrospinal fluid pressure (p = 0.028); there were no significant drug effects on cerebrospinal fluid pressure or on the degree of spinal cord ischemia. This study indicates that cerebrospinal fluid pressure is an important factor in determining the degree of spinal cord ischemia during aortic occlusion and suggests that measures to reduce cerebrospinal fluid pressure will mitigate the degree of spinal cord ischemia.
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J. Thorac. Cardiovasc. Surg. · May 1988
Enhancement of crystalloid cardioplegic protection against global normothermic ischemia by superoxide dismutase plus catalase but not diltiazem in the isolated, working rat heart.
Oxygen-derived free radicals and intracellular calcium overload have been implicated as mediators of myocardial ischemia/reperfusion injury. We hypothesized that free radical scavengers or calcium channel blockers could enhance the protection afforded the isolated, working rat heart by crystalloid cardioplegia against this type of injury at 37 degrees C. Hearts from 42 male rats in seven groups (n = 6) were studied in an isolated, working heart preparation measuring aortic flow (ml/min/gm dry wt), peak systolic pressure (mm Hg), coronary artery flow (ml/min/gm dry wt), and calculated coronary vascular resistance (dyne.sec.cm-5/gm dry wt). ⋯ We conclude that the addition of superoxide dismutase and catalase but not diltiazem to St. Thomas' Hospital cardioplegic solution can significantly enhance myocardial protection against normothermic ischemia/reperfusion injury. This implicates oxygen-derived free radicals as mediators of this type of injury.
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J. Thorac. Cardiovasc. Surg. · Apr 1988
Right atrial isolation: a new surgical treatment for supraventricular tachycardia. II. Hemodynamic effects.
Surgical isolation of the body of the right atrium presents a unique hemodynamic situation in which the synchronous right atrial contraction (kick) is lost but the synchronous left atrial contraction is preserved. The hemodynamic effects of this procedure were evaluated by pacing at selected atrial sites postoperatively to simulate (1) sinus rhythm with a synchronous right atrial kick, (2) sinus rhythm without a synchronous right atrial kick, (3) right atrial tachycardia propagated to the entire heart (propagated right atrial tachycardia), and (4) right atrial tachycardia confined to the isolated right atrium with sinus rhythm in the rest of the heart (confined right atrial tachycardia). ⋯ Moreover, cardiac hemodynamic performance remained within normal limits for up to 14 weeks. Thus the right atrial isolation procedure does not adversely affect cardiac hemodynamics despite the loss of synchronous right atrial contraction during sinus rhythm, and the procedure prevents hemodynamic deterioration during right atrial tachycardia.
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J. Thorac. Cardiovasc. Surg. · Apr 1988
Right atrial isolation: a new surgical treatment for supraventricular tachycardia. I. Surgical technique and electrophysiologic effects.
This study describes the surgical technique and electrophysiologic effects of isolating the right atrium while preserving normal function and continuity of the sinoatrial node with the remainder of the heart. Thirteen adult mongrel dogs underwent normothermic cardiopulmonary bypass. A posterorlateral right atriotomy was performed that encircled the upper right atrium but excluded the atrial pacemaker complex. ⋯ Moreover, the simulated tachycardia did not affect normal sinus rhythm or normal atrioventricular conduction. It is concluded that isolation of the right atrium with preservation of normal sinoatrial node function and continuity is feasible. This technique offers an alternative to the current surgical approaches for management of refractory supraventricular tachycardias that arise in the right atrium.