Effects of timing on ventriculoarterial coupling and mechanical efficiency during intraaortic balloon pumping

A randomized multicenter clinical study to evaluate the safety and efficacy of the TandemHeart percutaneous ventricular assist device versus conventional therapy with intraaortic balloon pumping for treatment of cardiogenic shock

BACKGROUND AND AIM

Despite major advances in the treatment of heart failure, cardiogenic shock (CGS) remains associated with substantial mortality. Recent data suggest that the TandemHeart percutaneous ventricular assist device (pVAD) may be useful in the management of CGS. The aim of this prospective randomized study was to test the hypothesis that the TandemHeart (pVAD) provides superior hemodynamic support compared with intraaortic balloon pumping (IABP).

METHODS

Forty-two patients from 12 centers presenting within 24 hours of developing CGS were included in the study and treated in an initial roll-in phase (n = 9) or randomized to treatment with IABP (n = 14) or TandemHeart pVAD (n = 19). Thirty patients (71%) had persistent CGS despite having an IABP in place at the time of study enrollment.

RESULTS

Cardiogenic shock was due to myocardial infarction in 70% of the patients and decompensated heart failure in most of the remaining patients. The mean duration of support was 2.5 days. Compared with IABP, the TandemHeart pVAD achieved significantly greater increases in cardiac index and mean arterial blood pressure and significantly greater decreases in pulmonary capillary wedge pressure. Overall 30-day survival and severe adverse events were not significantly different between the 2 groups.

CONCLUSION

In patients presenting within 24 hours of the development of CGS, TandemHeart significantly improves hemodynamic parameters, even in patients failing IABP. Larger-scale studies are required to assess the influence of improved hemodynamics on survival.

Skeletal muscle ventricle aortic counterpulsation: function during chronic heart failure

BACKGROUND

Skeletal muscle ventricles (SMVs) are pumping chambers formed from latissimus dorsi muscle. The SMV aortic counterpulsator model has been proven to be stable in the long term and provide effective diastolic pressure augmentation in normal dogs. This study seeks to prove that the aortic counterpulsator model can function effectively in chronic heart failure.

METHODS

In 6 dogs, pericardium-lined SMVs were created from latissimus dorsi muscle and electrically conditioned for fatigue resistance. Each SMV was attached to the descending thoracic aorta with a two-limb bifurcated graft and the aorta ligated between the limbs. The SMV was stimulated to contract during cardiac diastole at 1:2 to 1:3 ratio. Rapid ventricular pacing was initiated at 220 to 230 beats/min for 7 weeks to induce chronic heart failure.

RESULTS

SMV contraction resulted in augmentation of the diastolic pressure time-index by 12.1% (32.8+/-15.4 versus 36.1+/-14.7 mm Hg-s, p < 0.05) at baseline, then by 33.6% (12.9+/-4.4 versus 16.8+/-4.3 mm Hg-s, p < 0.05) after 7 weeks of rapid ventricular pacing. After 7 weeks of rapid ventricular pacing, SMV counterpulsation provided significant afterload reduction with increases in peak left ventricular ejection velocity and stroke volume of 22.7% (142+/-55 versus 168+/-45 mL/s, p < 0.05) and 6.2% (13.0+/-5.1 versus 13.7+/-5.2 mL, p < 0.05), respectively. Coronary blood flow was measured in 3 animals at the 7-week measurement; augmentation averaged 47.6% (0.357+/-0.29 versus 0.432+/-0.26 mL/beat, p < 0.05).

CONCLUSIONS

The SMV aortic counterpulsator provides improved cardiac assistance relative to the failing heart.

Increased coronary artery blood flow with aortomyoplasty in chronic heart failure

BACKGROUND

We hypothesized that diastolic counter-pulsation using aortomyoplasty will increase coronary blood flow.

METHODS

In dogs (n = 6, 20 to 25 kg), the left latissimus dorsi muscle was isolated, wrapped around the descending thoracic aorta, and conditioned by chronic electrical stimulation. Heart failure was induced by rapid ventricular pacing. In a terminal study, left ventricular and aortic pressures, and blood flow in the left anterior descending coronary artery and descending aorta were measured. The endocardial-viability ratio was calculated.

RESULTS

Aortomyoplasty increased mean diastolic aortic pressure (70 +/- 5 to 75 +/- 5 mm Hg, p < 0.05) and reduced peak left ventricular pressure (86 +/- 4 to 84 +/- 4 mm Hg, p < 0.05), leading to a 16% increase in endocardial-viability ratio (1.29 +/- 0.05 to 1.49 +/- 0.05, p < 0.05). Coronary blood flow was increased by 15% (8.2 +/- 1.5 to 9.4 +/- 1.6 mL/min, p < 0.05). During muscle contraction, 2.7 +/- 0.5 mL was ejected from the wrapped aortic segment.

CONCLUSIONS

These data demonstrate that aortomyoplasty provides successful diastolic counterpulsation after muscle conditioning and heart failure.