Balloon Aortic Valvuloplasty Using a Non-Occlusive Balloon Catheter: First Animal Experience.

BACKGROUND: Transcatheter aortic valve implants (TAVI) have revolutionised the treatment of elderly patients requiring aortic valve replacement. These patients often do not tolerate balloon valvuloplasty well, and a valvuloplasty balloon that would allow a degree of continued cardiac output during expansion would be beneficial. We tested such a balloon and describe our results in the sheep model. METHODS AND RESULTS: We developed a non-occlusive balloon (NOB) catheter. An acute experiment was performed where the NOB was inflated in six sheep in the aortic valve position without any attempt to arrest cardiac output. Two inflations were performed per animal: the first for 30 s and the second for 2-3 min. Standard occlusive balloons were inflated in two animals under rapid ventricular pacing to serve as controls. Mean pressure gradient across the NOB was 9.7 ± 5 mmHg during the inflations and all animals remained hemodynamically stable during NOB inflations. CONCLUSIONS: The novel non-occlusive balloon catheter, which permitted uninterrupted cardiac output for a prolonged period without the need for pacing-induced temporary cessation of cardiac output, is both feasible and well tolerated in the acute sheep model.

Comparison of Minimally and More Invasive Methods of Determining Mixed Venous Oxygen Saturation.

OBJECTIVE: To investigate the accuracy of a minimally invasive, 2-step, lookup method for determining mixed venous oxygen saturation compared with conventional techniques. DESIGN: Single-center, prospective, nonrandomized, pilot study. SETTING: Tertiary care hospital, university setting. PARTICIPANTS: Thirteen elective cardiac and vascular surgery patients. INTERVENTIONS: All participants received intra-arterial and pulmonary artery catheters. Minimally invasive oxygen consumption and cardiac output were measured using a metabolic module and lithium-calibrated arterial waveform analysis (LiDCO; LiDCO, London), respectively. For the minimally invasive method, Step 1 involved these minimally invasive measurements, and arterial oxygen content was entered into the Fick equation to calculate mixed venous oxygen content. Step 2 used an oxyhemoglobin curve spreadsheet to look up mixed venous oxygen saturation from the calculated mixed venous oxygen content. The conventional "invasive" technique used pulmonary artery intermittent thermodilution cardiac output, direct sampling of mixed venous and arterial blood, and the "reverse-Fick" method of calculating oxygen consumption. MEASUREMENTS AND MAIN RESULTS: LiDCO overestimated thermodilution cardiac output by 26%. Pulmonary artery catheter-derived oxygen consumption underestimated metabolic module measurements by 27%. Mixed venous oxygen saturation differed between techniques; the calculated values underestimated the direct measurements by between 12% to 26.3%, this difference being statistically significant. CONCLUSION: The magnitude of the differences between the minimally invasive and invasive techniques was too great for the former to act as a surrogate of the latter and could adversely affect clinical decision making.

Recurrence of cardiotoxicity after lipid rescue from bupivacaine-induced cardiac arrest.

Accidental intravascular administration of bupivacaine during performance of a brachial block precipitated convulsions followed by asystole. The patient was rapidly resuscitated using cardiopulmonary resuscitation, supplemented by 150 mL of 20% lipid emulsion. Nonetheless, cardiac toxicity reappeared 40 min after completion of the lipid emulsion. In the absence of further lipid emulsion, amiodarone and inotropic support were used to treat cardiotoxicity. This case suggests that local anesthetic systemic toxicity may recur after initial lipid rescue. Since recurrence of toxicity may necessitate administration of additional doses of lipid emulsion, a sufficient quantity of lipid emulsion should be available when regional anesthesia is performed.