Minutes Of Arrest Research Articles

Effect of nifedipine on cerebral high-energy phosphates after cardiac arrest and resuscitation in the rat

We studied the effect of nifedipine, a calcium entry blocker, on the recovery of cerebral adenosine triphosphate (ATP), creatine phosphate (CP), and lactate levels following resuscitation from cardiac arrest. Using the cardiac arrest and resuscitation model of de Garavilla, Babbs, and Tacker with an arrest time of eight minutes, 76% of the animals arrested were resuscitated with an average intermittent abdominal compression-CPR time of 3.3 minutes. Rats were assigned randomly to the following groups: nonischemic; eight minutes of arrest without resuscitation; and postresuscitation treatment with either IV normal saline; 3 micrograms/kg nifedipine; 10 micrograms/kg nifedipine; or 30 micrograms/kg nifedipine. Treated animals were sacrificed at either 20 or 120 minutes thereafter. As expected, after eight minutes of cardiac arrest, the levels of ATP and CP dropped to near 0 and rebounded in all resuscitated animals. By 120 minutes after resuscitation, rats given the 10-micrograms/kg dose of nifedipine had levels of ATP equivalent to nonischemic values. Return of CP values to nonischemic levels was seen only at the 3-micrograms/kg dose and was independent of time of measurement. The ATP and CP levels in these nifedipine-treated groups were significantly better when compared to saline-treated controls. There were no treatment-dependent differences in lactate levels. We conclude that clinically appropriate doses of nifedipine had a beneficial effect on the recovery of cerebral high-energy phosphates after cardiac arrest and resuscitation.

Manual open-chest cardiopulmonary resuscitation

Although the mechanistic differences between standard external cardiopulmonary resuscitation (SCPR) and open-chest CPR (OCCPR) are clear, it remains unclear when OCCPR offers a benefit over SCPR for nontraumatic cardiac arrest. Experimentally OCCPR has been shown to generate much higher arterial and much lower venous pressures, resulting in increased perfusion pressures across both heart and brain. Most studies have shown increased blood flow with OCCPR. Mechanical OCCPR has been shown to sustain electroencephalographic activity for up to one hour after up to four minutes of arrest. It has been shown in several studies that cardiac resuscitability is greater with OCCPR than with SCPR. Cerebral blood flow approaches normal with OCCPR; the best reported for SCPR is 50% of normal. After four minutes of cardiac arrest, OCCPR for 30 minutes does not yield a neurological deficit significantly different from immediate defibrillation; all animals studied returned to nearly normal by 24 hours postresuscitation. After the same arrest time, nearly all animals receiving either SCPR or simultaneous ventilation-compression CPR for 30 minutes were dead by 24 hours. Clinically early series reported up to 28% survivorship (patients discharged home) after OCCPR. Survivors after up to 2.5 hours of OCCPR and after successful restoration of spontaneous circulation by OCCPR after failure of SCPR for 75 minutes have been reported. Reported incidences of wound infection and iatrogenic cardiac injury range from 0 to 9.1% and 0 to 1.4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced myocardial protection during ischemic arrest: Oxygenation of a crystalloid cardioplegic solution

To determine if, during elective cardiac arrest, the myocardial protection afforded by a cold (4 degrees C) crystalloid potassium cardioplegic solution could be improved by oxygenation of the solution, we placed 16 dogs on cardiopulmonary bypass and subjected their hearts to 4 hours of cold cardioplegic arrest. Group 1 hearts (n = 8) received aerated crystalloid solution perfused through the aortic root every 20 minutes. Group 2 hearts (n = 8) were treated identically except that the crystalloid cardioplegic solution was fully oxygenated. Left ventricular function curves (ejecting heart) were generated before arrest (control) and after 45 minutes of reperfusion. A cardiac output of 1,000 ml/min could be attained in only two hearts of Group 1 after reperfusion, whereas all but one heart of Group 2 had excellent functional preservation. Mean postreperfusion adenosine triphosphate (ATP) levels in Group 1 and Group 2 hearts were 62% and 89% of control, respectively (p less than 0.01). Myocardial water content had increased significantly (p less than 0.002) after reperfusion in Group 1, but not in Group 2. During cardioplegic solution infusion, myocardial oxygen consumption (MVO2) was 1.42 +/- 0.15 ml O2/min/100 gm LV for Group 1 and 6.91 +/- 1.27 ml O2/min/100 gm LV for Group 2 (p less than 0.001). Oxygen consumed per minute of arrest was 0.027 +/- 0.003 ml O2/min/100 gm LV for Group 1 and 0.128 +/- 0.015 ml O2/min/100 gm LV for Group 2 (p less than 0.001). Postreperfusion ultrastructural evaluation of two of the Group 1 hearts revealed severe ischemic damage in contrast to the normal ultrastructural appearance of two of the Group 2 hearts. With careful attention given to maintenance of myocardial hypothermia and cardioplegic delivery methods, the myocardial protection afforded by an oxygenated crystalloid cardioplegic solution exceeds that provided by the aerated control and compares favorably with other methods of myocardial protection during ischemic arrest.

Safety of prolonged ischemic arrest using hypothermic cardioplegia

An evaluation was carried out of 200 consecutive patients undergoing elective cardiac operations. Hypothermic potassium (25 mEq/L) crystalloid cardioplegia was used for myocardial preservation during ischemic arrest. The purpose of this study was to determine if the length of cardioplegic arrest correlated with any parameter of myocardial injury, operative morbidity, or mortality. There were 154 patients undergoing coronary revascularization (CBG) and 46 valve replacement of repair (VR/R). The duration of cardioplegic arrest varied from 17 to 187 minutes. Eighteen patients (12%) in the CBG group and 11 (24%) in the VR/R group had arrest times of greater than 2 hours. In the CBG group, serum enzyme measurements, the incidence of inotropic support, perioperative myocardial infarction, and operative mortality rate did not correlate with the duration of ischemic arrest. In the VR/R group, however, the CPK-MB level increased in proportion to the duration of ischemia; none of the other parameters changed significantly. Myocardial infarction was diagnosed in 3.7% of the coronary bypass (CBG) patients having cardioplegic arrest times of less than 120 minutes and in none of the 18 patients having longer arrest times. Three operative infarcts occurred in the VR/R group, two between 60 and 90 minutes of arrest and one between 120 and 150 minutes. The only clinical manifestation of prolonged cardioplegic arrest in the CBG patients was an increase in the incidence of postoperative arrhythmias. The results of this study support the safety of prolonged (3 hour) cardioplegic arrest under appropriate hypothermic conditions in the CBG group, but not necessarily in the VR/R group, where increased myocardial enzyme generation was noted. The proper reduction of myocardial temperature in the use of multidose cardioplegia is considered essential for optimal preservation.

SURGICAL TREATMENT OF BASILAR ARTERY ANEURYSMS ELECTIVE CIRCULATORY ARREST WITH THORACOTOMY IN 12 CASES

✓ The authors report a technique to aid in the surgical treatment of patients with basilar artery aneurysms. Under moderate hypothermia a nondominant temporal craniotomy and small anterior temporal lobectomy are performed. After median sternotomy is done and ventricular fibrillation is induced, microscopic dissection around the aneurysm proceeds for 4 minutes. If more time is needed, manual cardiac systole is performed for 60 seconds. This has been repeated for as long as 28 minutes, with an average of 9 minutes of arrest. After the aneurysm has been treated, normal sinus rhythm is restored in the heart. The operative technique and 12 case histories are presented. There were two deaths among the early cases. All others have done well.

Surgical treatment of basilar artery aneurysms. Elective circulatory arrest with thoracotomy in 12 cases.

✓ The authors report a technique to aid in the surgical treatment of patients with basilar artery aneurysms. Under moderate hypothermia a nondominant temporal craniotomy and small anterior temporal lobectomy are performed. After median sternotomy is done and ventricular fibrillation is induced, microscopic dissection around the aneurysm proceeds for 4 minutes. If more time is needed, manual cardiac systole is performed for 60 seconds. This has been repeated for as long as 28 minutes, with an average of 9 minutes of arrest. After the aneurysm has been treated, normal sinus rhythm is restored in the heart. The operative technique and 12 case histories are presented. There were two deaths among the early cases. All others have done well.

Retroperfusion of the heart with a solution of glucose, insulin, and potassium during anoxic arrest

Retroperfusion of the coronary circulation with a solution containing glucose, insulin, and potassium was evaluated experimentally during anoxic cardiac arrest under normothermic conditions. The solution was composed of approximately 2 L. of 5 per cent dextrose in water, containing insulin (100 μ per liter) and potassium chloride (20 mEq. per liter), and was buffered with sodium bicarbonate. Gravity perfusion of the coronary circulation during 30 minutes of arrest resulted in greater perfusion of the Thebesian-sinusoidal system than the capillary system, as indicated by a right ventricular-coronary artery effluent ratio of 3:1. Significant utilization of glucose was observed with capillary perfusion but not with Thebesian-sinusoidal perfusion. Cardiac function was significantly better in the group with retroperfusion than in a control group, which had no perfusion, as evidenced by cardiac output, left ventricular contractility, and cardiac rhythm. The present study corroborrates previous observations, which suggested that the availability of glucose as an energy substrate during cardiac anoxia offers a protective effect upon the heart. This study also demonstrates that retroperfusion through the coronary sinus during anoxia is one technique of supplying energy substrate.

BUTLER WF MALOY WC, ROSSI JH, HALL DP: Role of hypothermia in the protection of myocardial metabolism during cardiopulmonary by-pass and elective cardiac arrest.

It is recognized that present-day techniques of intracardiacsurgery demand a satisfactory method of elective cardiac arrest. Potassium citrate, acetylcholineand hypoxic arrest have allbeen used with varying degrees of success.Each of these methods has its limitations and with each, difficulties in resuscitationare encountered. In general,because of the greater ease of resuscitation,hypoxic arrest seems preferableto potassium citrateor acetyicholine.Our previous studies’suggest that hypothermia offerssome degree of protection to myocardial metabolism by preserving sources of energy for myocardial contraction. It was demonstrated that when the dog’s heart was permanently arrested at normothermia with potassium citrate, myocardial glycogen values decreased by 78 per cent, ATP by 60 per cent and lactic acid increased by 500 per cent by the end of 90 minutes of arrest. When animals were placed on cardiopulmonary by-pass and arrest produced with potassium citrate or hypoxia for 30 minutes these changes were of the same order. When total body hypothermia was utilized with by-pass, however, with myocardial temperature reduced below 20CC., glycogen values were essentially unaltered and lactic acid increased to a less degree. Adenosine triphosphate and phosphocreatine values were less consistent, but some degree of protection by hypothermia was suggested. These results are similar to those recently presented by Gott.’ Cardiac resuscitation after arrest with potassium citrate or hypoxia has been shown to be poor after periods of 20 minutes. When hypothermia was utilized with arrest, resuscitation was accomplished in all cases with ease. Therefore, these biochemical studies correlated well with the observation that the heart behaves better functionally when hypothermia is used. Since the more complicated cardiac defects often necessitate cardiac arrest for prolonged periods of time, it seemed desirable to study further the protection afforded by hypothermia when used with cardiopulmonary by-pass and hypoxic arrest, and to establish the length of time over which this protective effect might be effective. Methods Mongrel dogs, weighing 12-15 kg., were placed on cardiopulmonary bypass with a Kay-Cross disc oxygenator and a DeBakey roller pump. Right thoracotomy was performed through the fourth intercostal space.