Intraaortic balloon pumping for cardiac support: trends in practice and outcome, 1968 to 1995.

OBJECTIVES: A total of 4756 cases of intraaortic balloon pump support have been recorded at the Massachusetts General Hospital since the first clinical insertion for cardiogenic shock in 1968. This report describes the patterns of intraaortic balloon use and associated outcomes over this time period. METHODS: A retrospective record review was conducted. RESULTS: Balloon use has increased to more than 300 cases a year at present. The practice of balloon placement for control of ischemia (2453 cases, 11.9% mortality) has become more frequent, whereas support for hemodynamic decompensation (congestive heart failure, hypotension, cardiogenic shock) has been relatively constant (1760 cases, 38.2% mortality). Mean patient age has increased from 54 to 66 years, and mortality has fallen from 41% to 20%. Sixty-five percent (3097/4756) of the total patient population receiving balloon support underwent cardiac surgery. Placement before the operation (2038 patients) was associated with a lower mortality (13.6%) than intraoperative (771 patients, 35.7% mortality) or postoperative use (276 patients, 35.9% mortality). Independent predictors of death with balloon pump support were insertion in the operating room or intensive care unit, transthoracic insertion, age, procedure other than angioplasty or coronary artery bypass, and insertion for cardiogenic shock. Independent predictors of death with intraoperative balloon insertion were age, mitral valve replacement, prolonged cardiopulmonary bypass, urgent or emergency operation, preoperative renal dysfunction, complex ventricular ectopy, right ventricular failure, and emergency reinstitution of cardiopulmonary bypass. CONCLUSIONS: Balloons are being used more frequently for control of ischemia in more patients who are elderly with lower mortality. An institutional bias toward preoperative use of the balloon pump appears to be associated with improved outcomes.

Warm and cold blood cardioplegia. Comparison of myocardial function and metabolism using 31p magnetic resonance spectroscopy.

BACKGROUND: Standard myocardial protection during cardiac surgery uses hypothermic arrest, but warm heart surgery, recently introduced, is now used in many centers. We hypothesized that warm continuous blood cardioplegia (WCBC) would provide better myocardial preservation than cold continuous blood cardioplegia (CCBC). METHODS AND RESULTS: In isolated cross-perfused canine hearts, left ventricular (LV) function and myocardial O2 consumption (MVO2) were measured at constant LV volume, coronary perfusion pressure, and heart rate before and after 75 minutes of arrest at 37 degrees C or 10 degrees C. Metabolism was evaluated by 31P nuclear magnetic resonance spectroscopy. LV resting tone increased transiently after arrest by CCBC but not WCBC (38 +/- 3.9 versus 2.9 +/- 0.5 mm Hg, P < .0005). Myocardial ATP changed over time differently in the groups (P < .001), declining at the outset of CCBC and returning to control levels during the recovery period after CCBC or WCBC. Intracellular pH rose from 7.17 +/- 0.03 to 7.85 +/- 0.05 during CCBC (P < .0005 versus WCBC). MVO2 declined dramatically during arrest at either temperature but to a lower value during CCBC (P < .0005). LV pressure recovered to 86.1 +/- 5.1% of its prearrest value after CCBC and to 97.2 +/- 7.8% following WCBC (P = NS). After CCBC but not WCBC, there were small but significant increases in LV end-diastolic pressure (by 1.3 mm Hg, P < .05) and in the LV relaxation constant, tau (from 37.3 +/- 1.5 to 42.3 +/- 2.4 milliseconds, P < .05). CONCLUSIONS: The increase in intracellular pH during CCBC is largely accounted for by physicochemical factors. Group differences in ATP over time may be related to rapid cooling contracture during CCBC. The data suggest that CCBC mildly impairs LV function but that WCBC preserves function and metabolism at or near prearrest levels.

Diagnosis of a left-sided superior vena cava during placement of a pulmonary artery catheter.

We report a case of a left sided superior vena cava (SVC) that was diagnosed during placement of a pulmonary artery (PA) catheter. After entering the left internal jugular, the PA catheter passed into the left side of the heart, through the aortic valve, and into the aorta. This was an unusual cause of right-to-left shunting and persistent cyanosis in a patient who had undergone two open cardiac procedures, including repair of an atrial septal defect. Cardiac catheterization and echocardiography also failed to reveal the abnormality. The embryology and physiology of a left sided SVC is reviewed, including an historical perspective. A discussion of the variants of the syndrome is included, as is a review of aberrant placement of central venous catheters.

Norepinephrine increases the economy of pressure development in isolated canine hearts.

To test for oxygen wasting by norepinephrine (NE) without relying on normalization by measures of performance such as the pressure-volume area, myocardial oxygen consumption (MVO2) was determined for isovolumic beats at five different left ventricular (LV) end-diastolic volumes (EDV) in nine isolated cross-perfused canine hearts in each of three states: a basal anesthetic state (B); after depression with halothane (H); and after adding NE to increase contractility back to the B state (H+NE). The end-diastolic and peak systolic pressure-volume lines were identical for B and H+NE. The R2 for a linear regression of MVO2 per beat for B vs. H+NE for beats originating at the same EDV and developing similar (within 10%) peak isovolumic pressures for all hearts was 0.85. The slope and intercept were 0.83 and 0.01, which are significantly less than one (P less than 0.001) and greater than zero (P less than 0.001), respectively. These data suggest that NE increases both the economy of pressure development as well as activation energy of an isovolumically contracting LV.