Hypertrophy of neurons within cardiac ganglia in human, canine, and rat heart failure: the potential role of nerve growth factor

Background

Autonomic imbalances including parasympathetic withdrawal and sympathetic overactivity are cardinal features of heart failure regardless of etiology; however, mechanisms underlying these imbalances remain unknown. Animal model studies of heart and visceral organ hypertrophy predict that nerve growth factor levels should be elevated in heart failure; whether this is so in human heart failure, though, remains unclear. We tested the hypotheses that neurons in cardiac ganglia are hypertrophied in human, canine, and rat heart failure and that nerve growth factor, which we hypothesize is elevated in the failing heart, contributes to this neuronal hypertrophy.

Methods and Results

Somal morphology of neurons from human (579.54±14.34 versus 327.45±9.17 μm²; P<0.01) and canine hearts (767.80±18.37 versus 650.23±9.84 μm²; P<0.01) failing secondary to ischemia and neurons from spontaneously hypertensive rat hearts (327.98±3.15 versus 271.29±2.79 μm²; P<0.01) failing secondary to hypertension reveal significant hypertrophy of neurons in cardiac ganglia compared with controls. Western blot analysis shows that nerve growth factor levels in the explanted, failing human heart are 250% greater than levels in healthy donor hearts. Neurons from cardiac ganglia cultured with nerve growth factor are significantly larger and have greater dendritic arborization than neurons in control cultures.

Conclusions

Hypertrophied neurons are significantly less excitable than smaller ones; thus, hypertrophy of vagal postganglionic neurons in cardiac ganglia would help to explain the parasympathetic withdrawal that accompanies heart failure. Furthermore, our observations suggest that nerve growth factor, which is elevated in the failing human heart, causes hypertrophy of neurons in cardiac ganglia.

Long-term survival using intra-aortic balloon pump and percutaneous right ventricular assist device for biventricular mechanical support of cardiogenic shock

Right ventricular (RV) involvement in acute inferior left ventricular (LV) myocardial infarction increases the risks of cardiogenic shock and in-hospital mortality. Acutely impaired RV performance results in reduced LV preload and, in combination with impaired LV contractility, causes severely reduced LV stroke volume and cardiac output. Here we report long-term patient survival after acute biventricular myocardial infarction (MI) using simultaneous RV support with a TandemHeart percutaneous ventricular assist device (Cardiac Assist Technologies, Pittsburgh, Pennsylvania) and LV support with an intra-aortic balloon pump. Further evaluation of completely percutaneous biventricular support in acute MI is warranted.

Delayed complete heart block secondary to jailed first septal perforator

Partial or total occlusion of septal perforator branches can occur during stenting of the proximal and mid portion of the left anterior descending artery, secondary to plaque snow plowing and/or stent "jailing". Flow compromise in a sizeable septal branch can result in a myocardial infarction or in atrioventricular conduction abnormalities. Complete heart block has been described at the time of the procedure, and though it is usually transient, it may require temporary pacing. We report a case of delayed, symptomatic and permanent complete atrio-ventricular block that occurred 2 days after the index procedure, requiring implantation of a permanent pacemaker.