Robert T. Palac

Outcome of mild periprosthetic regurgitation detected by intraoperative transesophageal echocardiography

OBJECTIVES The goal of this study was to determine the outcome of trivial or mild periprosthetic regurgitation (PPR) identified by intraoperative transesophageal echocardiography (TEE). BACKGROUND The clinical significance, natural history and correlates of trivial or mild PPR detected early after surgery are unknown. METHODS Between 1992 and 1997, 608 consecutive patients underwent isolated aortic valve replacement or mitral valve replacement at Dartmouth-Hitchcock Medical Center. Of these, 113 patients (18.3%) were found to have trivial or mild PPR at surgery by TEE. Follow-up transthoracic echocardiograms (early TTEs) were obtained within six weeks of surgery in 99.0% of patients and late TTEs (mean 2.1 years) in 54.3%. Clinical, intraoperative and outcome variables associated with PPR were identified using t test, chi-square and logistic regression analyses. RESULTS By univariate analysis, compared with patients without PPR, patients with PPR were older, of smaller body surface area (BSA), had degenerative valve disease more often and were more likely to receive a bioprosthetic valve. By multivariate analysis, smaller BSA and the use of a bioprosthesis were the strongest predictors of PPR (p < 0.01). At early TTE, PPR was not observed (n = 56) or remained unchanged (n = 44) in all patients. At late TTE, four patients were found to have progression of their PPR. All four patients had bioprosthetic valves. Two of these patients had endocarditis, and one had primary valvular degeneration. The fourth patient had progressive PPR. CONCLUSIONS Trivial or mild PPR is a frequent finding on intraoperative TEE. Smaller body size and the use of a bioprosthetic valve are significantly associated with PPR. The clinical significance and natural history of PPR is benign in most cases.

Myocardial hypertrophy in the absence of external stimuli is induced by angiogenesis in mice.

Although studies have suggested a role for angiogenesis in determining heart size during conditions demanding enhanced cardiac performance, the role of EC mass in determining the normal organ size is poorly understood. To explore the relationship between cardiac vasculature and normal heart size, we generated a transgenic mouse with a regulatable expression of the secreted angiogenic growth factor PR39 in cardiomyocytes. A significant change in adult mouse EC mass was apparent by 3 weeks following PR39 induction. Heart weight; cardiomyocyte size; vascular density normalization; upregulation of hypertrophy markers including atrial natriuretic factor, beta-MHC, and GATA4; and activation of the Akt and MAP kinase pathways were observed at 6 weeks post-induction. Treatment of PR39-induced mice with the eNOS inhibitor L-NAME in the last 3 weeks of a 6-week stimulation period resulted in a significant suppression of heart growth and a reduction in hypertrophic marker expression. Injection of PR39 or another angiogenic growth factor, VEGF-B, into murine hearts during myocardial infarction led to induction of myocardial hypertrophy and restoration of myocardial function. Thus stimulation of vascular growth in normal adult mouse hearts leads to an increase in cardiac mass.

Progression of native coronary artery disease at 10 years: insights from a randomized study of medical versus surgical therapy for angina.

Repeat coronary angiography was performed in 42 patients 10 years after randomization to medical (n = 21) or surgical (n = 21) therapy for chronic angina. The native coronary arteries were classified into 15 angiographic segments and 3 arterial trunks for analysis of progression of coronary artery disease. The incidence rate of disease progression in coronary segments was 24% and 28% in medically and surgically treated patients, respectively (p = NS). Grafted segments showed a 38% rate of disease progression, which was higher than the 18% rate of for nongrafted segments (p less than 0.001) and the overall rate of 24% for medically treated patients (p less than 0.01). Similarly, 29 (94%) of 31 grafted arteries exhibited disease progression compared with 19 (59%) of 32 nongrafted arteries (p less than 0.01) and 42 (67%) of 63 arteries in medically treated patients (p less than 0.01). In grafted vessels, disease progression occurred more often in arteries proximal (84%) to the anastomosis than in arteries distal (16%) to graft insertion (p less than 0.001). Progression occurred in 46% of proximal segments compared with 23% of distal segments (p less than 0.02). Progression was seen in 23 (55%) of 43 segments with an occluded graft compared with 30 (31%) of 96 segments with a patent graft (p less than 0.02). Ten years after randomization, medically and surgically treated patients showed a comparable rate of disease progression in coronary segments. However, surgical therapy appeared to significantly accelerate atherosclerotic progression in the grafted vessels, especially in the proximal portions. Occluded grafts also correlated with an adverse effect on disease progression.(ABSTRACT TRUNCATED AT 250 WORDS)

Stability of Ascending Aortic Dilatation Following Aortic Valve Replacement

Background—Replacement of the ascending aorta (Asc Ao) at the time of aortic valve replacement (AVR) is controversial because the risk of progressive dilatation following valve replacement is uncertain. Our aim was to determine the natural history of ascending aortic dilatation following AVR. Methods and Results—We studied 185 patients undergoing AVR at our institution between 1992 and 1999. Clinical and echocardiographic data were obtained by merging our institutional echocardiographic database with the DHMC component of the Northern New England Cardiovascular Disease Study Group database. Baseline Asc Ao measurements obtained from intraoperative transesophageal echocardiograms or early (<8 weeks) postoperative transthoracic echocardiograms were compared with late follow-up measurements (mean follow-up 30.0±23.4 months). During follow-up, there was no increase in the mean Asc Ao diameter (3.6±0.6 cm versus 3.6±0.6 cm, p=NS). Progressive aortic dilatation, defined as an increase in diameter >0.3 cm, occurred in 27/185 patients (15%). Baseline Asc Ao dilatation (≥3.5 cm) was present in 107/185 patients (58%). In this subset of patients, there was no increase in mean Asc Ao diameter (4.0±0.4 versus 3.9±0.6 cm, p=NS) and progressive aortic dilatation occurred in only 10 patients (9.3%). No patients with baseline aortic dilatation (range, 3.5 to 5.3 cm) dilated beyond 5.5 cm on follow-up (range, 2.4 to 5.5 cm). There were no clinical or valvular characteristics that predicted progressive Asc Ao dilatation. Conclusions—An increase in Asc Ao dilatation occurs infrequently following AVR and therefore, argues against routine Asc Ao replacement at the time of AVR.

Defining Patient-Prosthesis Mismatch and Its Effect on Survival in Patients With Impaired Ejection Fraction

BACKGROUND How best to define patient-prosthesis mismatch (PPM) continues to be debated. Over time, the indexed effective orifice area has become the most widely used method. However, the clinical relevance of PPM remains controversial. METHODS The indexed geometric orifice area and indexed effective orifice area were calculated for 143 patients having undergone aortic valve replacement with a normal left ventricular function 0.45 or less. Using the indexed geometric orifice area method, PPM was defined as nonsignificant if 1.2 cm(2)/m(2) or greater and as significant if less than 1.2 cm(2)/m(2). Using the indexed effective orifice area method, PPM was considered as nonsignificant if greater than 0.85 cm(2)/m(2), as moderate if greater than 0.65 cm(2)/m(2) and less than or equal to 0.85 cm(2)/m(2), and as severe PPM if 0.65 cm(2)/m(2) or less. RESULTS The number of patients classified as having PPM differed according to the method used to predict its presence (PPM: Effective orifice area method = 72.7%; geometric method = 19.6%). Regardless of the method used to classify PPM there was no significant effect on mortality (adjusted hazard ratio: 2.65 at 1 year, 0.99 at 5 years, 0.92 at 9 years; p = not significant). The postoperative mean transvalvular gradient (17.1 ± 6.5 mm Hg) and left ventricular function (0.50 ± 0.145) improved significantly compared with the preoperative findings. CONCLUSIONS The method used to calculate PPM resulted in significant classification discordance. However, regardless of classification, the presence of PPM did not adversely affect long-term outcome.

A Call to Action: Variability in Guidelines for Cardiac Evaluation before Renal Transplantation

BACKGROUND AND OBJECTIVES Candidates for renal transplantation are at increased risk for complications related to cardiovascular disease; however, the optimal strategy to reduce this risk is not clear. The aim of this study was to evaluate the variability among existing guidelines for preoperative cardiac evaluation of renal transplant candidates. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A consecutive series of renal transplant candidates (n=204) were identified, and four prominent preoperative cardiac evaluation guidelines, pertaining to this population, were retrospectively applied to determine the rate at which each guideline recommended cardiac stress testing. RESULTS The rate of pretransplant cardiac stress testing would have ranged from 20 to 100% depending on which guideline was applied. The American Heart Association/American College of Cardiology (ACC/AHA) guideline resulted in the lowest rate of testing (20%). In our population, 178 study subjects underwent stress testing: 17 were found to have ischemia and 10 underwent revascularization. The ACC/AHA approach would have decreased the number of noninvasive tests from 178 to 39; it would have identified only 4 of the 10 patients who underwent revascularization. The three other guidelines (renal transplant-specific guidelines) recommended widespread pretransplant cardiac testing and thus identified nearly all patients who had ischemia on stress testing. CONCLUSIONS The ACC/AHA perioperative guideline may be inadequate for identifying renal transplant candidates with coronary disease; however, renal transplant-specific guidelines may provoke significant overtesting. An intermediate approach based on risk factors specific to the ESRD population may optimize detection of coronary disease and limit testing.

Live 3D echo guidance of catheter-based endomyocardial injection

Local delivery of therapeutic agents into the myocardium is limited by suboptimal imaging. We evaluated the feasibility and accuracy of live 3D echo to guide left ventricular endomyocardial injection. An intramyocardial injection catheter was positioned in the left ventricle in five healthy Yorkshire pigs using fluoroscopy. All other catheter manipulations were performed with live biplane and 3D echo guidance. In each animal, a total of 12 endomyocardial injections (volume, 50–100 μl) of echo contrast mixed with blue tissue dye were performed. Four injections, 10 mm apart, were directed to three myocardial target zones: the anterior septum at the mitral valve level (zone 1); the posterolateral wall between the heads of the papillary muscles (zone 2); and the apex (zone 3). The injections were aimed to form a transverse line in zones 1 and 2 and an inverted triangular pyramid in zone 3. The animals were sacrificed, the hearts were inspected and the left ventricular endocardium was examined to create a map of injection marks. Success, defined as a visible injection of tissue dye, was 95%, and accuracy, defined as an injection into the target zone, was 83%. There was no significant difference in accuracy between the zones. Live 3D echo can successfully guide endomyocardial injections by accurately targeting specific myocardial zones, verifying catheter apposition and, when combined with echo contrast, providing real‐time visualization of injectate deposition.

Improved survival after surgical therapy for chronic angina pectoris: one hospital's experience in a randomized trial.

SUMMARY Between 1972 and 1974, 121 patients with chronic stable angina pectoris and operative coronary artery disease, excluding significant left main coronary obstruction, were randomized to either medical therapy (60 patients) or surgical therapy (61 patients) as part of a larger Veterans Administration Cooperative Study of Surgery for Coronary Arterial Occlusive Disease. At the time of randomization, medical and surgical groups were similar with regard to clinical and hemodynamic features as well as degree of left ventricular impairment and extent of coronary disease. Follow-up to June 1, 1978, reveals significantly improved survival in surgical patients from 3 through 6 years after randomization. Sixteen cross-over patients (13 medical to surgery, and 3 surgical without surgery) do not appear to influence results. Results of this randomized study from a single hospital differ from the preliminary results of the larger cooperative study, primarily because of a higher mortality in the medical group. The medical mortality in our group is in keeping with other reports of the natural history of patients with angina pectoris, and we propose that the population of patients we randomized closely simulates the usual type of patient with chronic angina being considered for surgical treatment. Our good surgical results thus contrast significantly with the survival of medically treated patients, and this separates our study from the body of the Veterans Administration Cooperative Study.

Reversible myocardial dysfunction after traumatic brain injury: mechanisms and implications for heart transplantation.

Reversible myocardial dysfunction is known to occur in patients with cerebrovascular accidents and brain death. Several mechanisms for transient myocardial dysfunction have been proposed, including increased sympathetic activity, hormone depletion, and a reduction in coronary perfusion pressure. The relative importance of each of these mechanisms remains controversial. We report the case of a 19-year-old man who suffered traumatic brain death associated with reversible myocardial dysfunction despite elevated cardiac enzymes. Myocardial recovery occurred after correcting his hemodynamic instability and hypothermia emphasizing the importance of normalization of coronary perfusion pressure and core body temperature. The mechanisms for reversible myocardial dysfunction and their implications for heart transplantation following traumatic brain death are reviewed. A diagnostic strategy is proposed that would allow early recognition of reversible myocardial dysfunction in brain-dead patients.

The echocardiographic assessment of dyssynchrony: insights from a consecutive series of general cardiology patients with normal LVEF and narrow QRS.

Background: Prior studies have described the potential benefit of using echocardiographic rather than ECG techniques to help select the subgroup of heart failure patients that are most likely to benefit from cardiac resynchronization therapy (CRT). Currently, the most commonly used echocardiographic techniques to assess dyssynchrony include discrepancies in radial motion derived from M‐mode and in longitudinal motion derived from tissue Doppler; however, there are little data available on the range of these measurements in the general cardiology population. Methods and Results: A consecutive series of patients referred for a stress echocardiogram were screened for normal LV systolic function and normal QRS width. Fifty‐one patients met inclusion criteria and underwent dyssynchrony measurements in addition to their baseline echo. Previously proposed cutoff values were applied. We observed 17% of study subjects were above the reported normal values for radial dyssynchrony and 41% were above the reported normal values for longitudinal dyssynchrony. However, when both criteria were required to be abnormal only 4% were classified as dyssynchronous. Conclusions: Echocardiographic indices in general cardiology patients appear most accurate when radial and longitudinal parameters are used in combination. While the ideal cutoff values remain to be determined, this combination may optimize patient selection for CRT response.