You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Abstract: Some patients converted from ventricular fibrillation to organized rhythms by defibrillation - trained ambulance technicians(EMT - Ds) will refibrillate before hospital arrival.The authors analyzed 271 cases of ventricular fibrillation managed by EMT - Ds working without paramedic back - up.Of 111 patients initially converted to organized rhythms, 19(17 % ) refibrillated, 11(58 % ) of whom were reconverted to perfusing rhythms, including nine of 11(82 % ) who had spontaneous pulses prior to refibrillation.Among patients initially converted to organized rhythms, hospital admission rates were lower for patients who refibrillated than for patients who did not(53 % versus 76 % , P = NS), although discharge rates were virtually identical(37 % and 35 % , respectively).Scene - to - hospital transport times were not predictively associated with either the frequency of refibrillation or patient outcome.Defibrillation - trained EMTs can effectively manage refibrillation with additional shocks and are not at a significant disadvantage when paramedic back - up is not available.
Solution: Ventricular Fibrillation
Why? This term is directly present in the abstract and it is one of the main topic in it. So can be chosen as the medical subject heading.

New input: Abstract: Plantaris muscle hypertrophy resulting from surgical ablation of the synergistic gastrocnemius muscle was compared between nontumor- and GH3 tumor-bearing rat groups (n = 8-10). GH3 cells (10(6)) were subcutaneously injected into 150-g female Wistar-Furth rats to initiate the tumor. After 17 days, the tumor-bearing rats gained 5.7 g body wt/day compared with 2.0 for the nontumor-bearing rats. The left gastrocnemius muscle was surgically removed from both nontumor and tumor groups. The gastrocnemius was removed from the tumor group after an increased growth rate was achieved. Seven days after surgery, the animals were killed and plantaris muscles were removed. The wet weight of the left plantaris muscle increased 45.6 and 44.0% over the unoperated contralateral control (right side) in the nontumor and tumor groups, respectively. The right control plantaris muscle in the tumor group was 63% heavier than the right control plantaris from the nontumor group; however, the proportion of body weight for plantaris was similar between the two groups. The effect of gastrocnemius ablation and tumor treatment on plantaris weight was additive, and the percent increase over the unoperated contralateral control side was similar between the two groups. These data demonstrate that skeletal muscle hypertrophy occurs in adult animals in which growth has been stimulated by a growth hormone-secreting tumor and could suggest that the muscle growth response caused by the tumor is operating by a mechanism different than work-induced hypertrophy.
Solution:
Animal