Body weight continues to increase worldwide due primarily to the increase in body fat. This study analyzes the frequency of massive adiposity at hearts of patients who underwent heart transplantation (HT) determined by the ability of the heart to float in a container of 10% formaldehyde (because adipose tissue is lighter than myocardium) and compares certain characteristics of those patients with and without floating hearts. The hearts studied at HT during a 3-year period (2013 to 2015) at Baylor University Medical Center were carefully “cleaned” and weighed by the same individual and tested as to their ability to float in a container of formaldehyde, an indication of severe cardiac adiposity. Of the 220 hearts studied, 84 (38%) floated in a container of formaldehyde and 136 (62%) did not. Comparison of the 84 patients with floating hearts to the 136 with nonfloating hearts showed a significant difference in ages, but a nonsignificant difference in gender, body mass index, frequency of systemic hypertension, or diabetes mellitus. The odds of a heart being a floating one was increased in patients with a diagnosis of ischemic cardiomyopathy (unadjusted odds ratio 2.12, 95% CI 1.21 to 3.70). The frequency of massive cardiac adiposity in the native hearts of patients having HT (38%) is striking and appears to have increased in frequency in the recent decades.
Because overweightness including obesity is now a worldwide problem, it is reasonable to believe that hearts of patients who underwent heart transplantation (HT) would possess considerable quantities of adipose tissues. We studied the native hearts of 220 patients having HT at Baylor University Medical Center in a 3-year period (2013 to 2015) and compared various clinical and morphologic variables in those with massive (floating hearts) versus nonmassive quantities of cardiac adipose tissue.
Methods
All cardiovascular specimens removed at operation at the Baylor University Medical Center since April 1993 have been described by one of us (W.C.R.) and most have been photographed by one of us (J.M.K.). After removing all extraneous tissues after fixation for 2 to 4 days, the hearts were tested for floating in a container of 10% formaldehyde. If the heart floated in the container after asserting that all air had been removed from the cardiac chambers, it was considered “a floating heart,” which indicated that the heart contained a “massive” amount of adipose tissue because adipose tissue is lighter than myocardial tissue. If the heart did not float in the container, it was considered “a nonfloating heart,” which indicates that the quantity of cardiac adipose tissue is usually less than that present in the floating heart. After excising all extraneous tissues, the hearts were weighed (by W.C.R.) after opening the cardiac chambers, removing all intrachamber clot and gently drying all exposed portions of the heart with paper towels. The scales used were accurate to 0.1 g (Ohaus Scout Pro Scale) or to 1.0 g (Acculab Vicon Digital Scale).
The clinical records were then obtained on all 220 patients through the Baylor Health Care System’s electronic medical record (Allscripts Sunrise Enterprise).
Statistical analysis was done using STATA 14.0 (StataCorp. 2015. Stata Statistical Software: Release 14, College Station, TX: StataCorp LP). The baseline characteristics of patients with floating and nonfloating hearts were compared using chi-square/Fisher’s exact tests for proportions and t -test/Wilcoxon rank-sum test for continuous variables where applicable. In addition, comparisons were repeated separately for men and women. Unadjusted odds ratios with 95% CI were obtained for these variables of interest by logistic regression analysis.
The study was approved by an institutional review board.
Results
The major findings are summarized in Tables 1 and 2 . Of the 220 hearts, 84 (38%) contained such a large quantity of adipose tissue that they floated in a container of 10% formaldehyde, and 136 (62%) did not float. The proportion of the hearts that floated in the container increased from 30% in 2013 to 40% in 2014 ( Figure 1 ). The distribution of age, body mass index, and heart weight in the patients with floating and nonfloating hearts are shown in Figure 2 . Comparison of the 84 patients with floating hearts to the 136 with nonfloating hearts showed a significant difference in mean ages, but a nonsignificanct difference in gender, body mass index, frequency of systemic hypertension, and diabetes mellitus. The odds of a heart floating in formaldehyde increased with age (unadjusted odds ratio 1.04, 95% CI 1.01 to 1.07) and ischemic cardiomyopathy (unadjusted odds ratio 2.12, 95% CI 1.21 to 3.70). The median body mass index increased over the years in those with floating hearts, whereas it decreased in those patients with nonfloating hearts ( Figure 3 ). Photographs of 2 floating hearts are shown in Figures 4 and 5 .
| Variable | Total (n = 220) | Transplant (n = 220) | p-Value | Unadjusted OR (95%CI) | |
|---|---|---|---|---|---|
| Float (n = 84 [38%]) | Nonfloat (n = 136 [62%]) | ||||
| Sex | |||||
| Men | 160 (73%) | 66 (41%) | 94 (59%) | ||
| Women | 60 (27%) | 18 (30%) | 42 (70%) | 0.13 | 0.61 (0.32-1.15) |
| Age (years) (Mean±SD) | 56±11 | 59±9 | 54±12 | ||
| Range [median] | 20-76 [58] | 32-76 [62] | 20-71 [57] | 0.01 | 1.03 (1.01-1.07) |
| Men | |||||
| Mean±SD | 57±11 | 59±9 | 56±12 | ||
| Range [median] | 20-76 [60] | 32-76 [62] | 20-71 [59] | 0.1 | |
| 20-40 | 14 (9%) | 3 (21%) | 11 (79%) | ||
| 41-60 | 70 (44%) | 26 (37%) | 44 (63%) | ||
| 61-80 | 76 (48%) | 37 (49%) | 39 (51%) | 0.11 | |
| Women | |||||
| Mean±SD | 53±11 | 57±10 | 51±12 | ||
| Range [median] | 26-69 [55] | 34-69 [56] | 26-69 [54] | 0.09 | |
| 20-40 | 10 (17%) | 1 (10%) | 9 (90%) | ||
| 41-60 | 31 (51%) | 9 (29%) | 22 (71%) | ||
| 61-80 | 19 (32%) | 8 (42%) | 11 (58%) | ||
| Coronary Artery Disease | 93 (42%) | 40 (43%) | 53 (57%) | 0.21 | 1.42 (0.82-2.47) |
| Healed myocardial infarct | 73 (33%) | 35 (48%) | 38 (52%) | 0.04 | 1.84 (1.04-3.27) |
| Acute myocardial infarct | 1 (0.5%) | 1 (100%) | 0 | 0.38 | NA |
| Both | 2 (1%) | 1 (50%) | 1 (50%) | ||
| Neither | 17 (8%) | 3 (18%) | 14 (82%) | ||
| Diabetes Mellitus | 82 (37%) | 32 (39%) | 50 (61%) | 0.84 | 1.05 (0.60-1.86) |
| Hypertension (by history) | 132 (60%) | 47 (36%) | 85 (64%) | 0.34 | 0.76 (0.44-1.33) |
| Body Mass Index (kg/m 2 ) (Mean±SD) | 29.1±5 | 29.6±5 | 28.9±5 | ||
| Range [median] | 17.8-42.3 [28.9] | 20.3-39.1 [29.8] | 17.8-42.3 [28.4] | 0.18 | 1.03 (0.97-1.08) |
| 16-20 | 5 (2%) | 0 | 5 (100%) | ||
| 21-25 | 48 (22%) | 15 (31%) | 33 (69%) | ||
| 26-30 | 78 (36%) | 32 (41%) | 46 (59%) | ||
| 31-35 | 60 (27%) | 27 (45%) | 33 (55%) | ||
| 36-40 | 26 (12%) | 10 (38%) | 16 (62%) | ||
| 41-45 | 3 (1%) | 0 | 3 (100%) | 0.23 | |
| Men | |||||
| Mean±SD | 29.1±5 | 29.5±4 | 28.9±5 | ||
| BMI Range [median] | 19-41.4 [28.8] | 20.7-37.8 [29.7] | 19-41.4 [28.4] | 0.25 | |
| Women | |||||
| Mean±SD | 29.2±6 | 29.9±5 | 28.9±6 | ||
| BMI Range [median] | 17.8-42.3 [29.0] | 20.3-39.1 [30.6] | 17.8-42.3 [28.5] | 0.46 | |
| Diagnosis | |||||
| Ischemic Cardiomyopathy | 88 (40%) | 43 (49%) | 45 (51%) | 0.008 | 2.12 (1.21-3.70) |
| Men | 74 (47%) | 39 (53%) | 35 (47%) | 0.006 | |
| Women | 14 (24%) | 4 (29%) | 10 (71%) | 1.00 | |
| Idiopathic Dilated Cardiomyopathy | 88 (40%) | 29 (33%) | 59 (67%) | 0.19 | 0.69 (0.39-1.21) |
| Men | 53 (33%) | 17 (32%) | 36 (68%) | 0.13 | |
| Women | 35 (58%) | 12 (34%) | 23 (66%) | 0.57 | |
| Other ∗ | 44 (20%) | 12 (27%) | 32 (73%) | 0.09 | 0.54 (0.26-1.12) |
| Men | 33 (21%) | 10 (30%) | 23 (70%) | 0.15 | |
| Women | 11 (19%) | 2 (18%) | 9 (82%) | 0.48 | |
| Heart Weight (g)(Mean±SD) † | 486±119 | 490±103 | 483±128 | ||
| Range [median] | 215-883 [480] | 285-755 [490] | 215-883 [478] | 0.47 | 1.004 (0.99-1.003) |
| Men | |||||
| Mean±SD | 509±119 | 508±94 | 509±135 | ||
| Range [median] | 215-883 [502] | 285-695 [508] | 215-883 [494] | 0.71 | |
| >400g | 130 (82%) | 53 (41%) | 77 (59%) | 0.95 | |
| Women | |||||
| Mean±SD | 423±93 | 420±107 | 425±88 | ||
| Range [median] | 235-755 [425] | 290-755 [420] | 235-599 [429] | 0.49 | |
| >350g | 46 (78%) | 12 (26%) | 34 (74%) | 0.38 | |
| Left Ventricular Assist Device | 43 (20%) | 16 (37%) | 27 (63%) | 0.88 | 0.95 (0.48-1.89) |
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