Tricuspid Aortic Valve with Partial Commissural Fusion: Preliminary Report of an Apparently Common Cause of Aortic Ejection Sounds with Potential for Serious Sequelae, Illustrated by Two Cases

Abstract

We report the cases of 2 patients whose tricuspid aortic valves were found to have partial commissural fusion. Both patients experienced complications that were probably related to this abnormality: bacterial endocarditis in 1 instance and a lacunar stroke in the other. In order to illustrate the similarity of physical findings, we also describe the case of a 3rd patient, who had a typical bicuspid aortic valve. Tricuspid aortic valve with partial commissural fusion has been described in autopsy series and has been predicted to cause an ejection sound, but we could find no previously published description of this lesion in living patients.

We wish to alert others to the possible presence of aortic commissural fusion, to its potential for serious and likely preventable sequelae, and to the ability of carefully performed transthoracic high-resolution digital echocardiography to demonstrate this condition when its characteristics are found on physical examination.

Bicuspid aortic valve can be either a congenital or an acquired lesion. ^1,2 Such valves are associated with bacterial endocarditis ³ and are a recognized cause of severe aortic stenosis and insufficiency. ⁴

From May 1995 to November 1999, we examined a series of 27 patients who had physical findings identical to those associated with bicuspid aortic valve. When these patients were sent for routine transthoracic echocardiography, most were reported to have “normal aortic valves and no echocardiographic abnormalities.” However, we have begun to re-examine these patients by means of high-resolution digital echocardiography (Model 1800; Hewlett Packard; Maynard, Mass) and have focused our attention on aortic valve structure. In the first 2 patients re-examined in this fashion, we found 3 normally positioned aortic cusps, and these appeared to move normally except that 2 of the cusps were partially fused and did not open completely. We report these patients' cases, along with 1 recently observed case of classic bicuspid aortic valve, which we include for comparison.

Case Reports

Patient 1

A 51-year-old woman was seen in July 1996 for a physical examination of the sort routinely given corporate executives. Seven months earlier, she had experienced sudden onset of weakness in the left arm and on the left side of the face. During the course of inpatient evaluation, computed tomographic (CT) scanning suggested the presence of a right lacunar embolus. She was started on a daily therapy of 324 mg of enteric-coated aspirin, and her arm and facial symptoms cleared almost completely. This patient reported a history of carpal tunnel syndrome and she had been mildly overweight, but she had no prior diagnosis of rheumatic fever, heart murmur, or other cardiovascular disorder. All vital signs were normal, including her pulse rate (regular, 69 beats/min) and her blood pressure (108/66 mmHg). Auscultation revealed a grade 1/6 systolic ejection murmur in the aortic area radiating to the suprasternal notch, and an aortic ejection sound in the aortic area, which also radiated to the suprasternal notch. On palpation, we detected a bifid or double rising carotid pulse. The remainder of the physical examination was normal; of particular note were the absence of cardiomegaly, cardiac hyperdynamics, and a murmur of aortic insufficiency. The patient's serum cholesterol level was 215 mg/dL (HDL = 70 mg/dL and LDL = 128 mg/dL). The rest of her routine laboratory values were normal, as was her electrocardiogram. A chest radiograph was not available. Her private physician had requested a transthoracic echocardiogram (TTE). This showed a bulge in the interatrial septum to the left, consistent with an atrial septal aneurysm. Her aortic valve was seen to have a trileaflet structure and was interpreted as normal. Pulmonary artery pressure was estimated at 25 to 30 mmHg.

Because of the apparent cerebral embolism and the atrial septal bulge, a bubble-contrast echocardiographic study was also done. This revealed a few bubbles passing into the left atrium across the septum during a Valsalva maneuver, which was consistent with a patent foramen ovale. Because right-sided pressures were estimated to be normal, the finding of the patent foramen ovale was not considered to be an adequate explanation for her cerebrovascular accident. Subsequently, during an outpatient visit, we performed high-resolution digital transthoracic echocardiography, with attention focused on the aortic valve. This revealed a trileaflet valve with partial fusion of the right and noncoronary cusps. The leaflets did not open completely. No aortic insufficiency was detected. The patient's private physician continued enteric-coated aspirin (324 mg daily) and advised prophylaxis for subacute bacterial endocarditis (SBE).

Patient 2

In October 1998, a 52-year-old man was admitted to our institution because of bacterial endocarditis for which no valve locus could be found. He reported a 3-month history of chills, fever, night sweats, fatigue, and weight loss (12 lbs). Treatment with various oral antibiotic agents led to temporary improvement, but his symptoms recurred. Two days prior to admission, blood cultures were drawn from several sites, and 2 of these grew Streptococcus viridans. The patient also had a history of malignant melanoma that had metastasized to the small bowel and the left lung 27 years earlier. At that time, he had undergone small bowel resection and left pneumonectomy, and he has since shown no evidence of recurrent malignancy. There was a family history of melanoma in a sister and a niece. He had a 13 pack-year history of cigarette smoking but had not smoked for 15 years.

All vital signs were normal, including a temperature of 37.1 °C, a regular pulse of 87 beats/minute and blood pressure of 138/86 mmHg. Auscultation revealed a grade 1/6 systolic ejection murmur in the aortic area radiating to the suprasternal notch and an aortic ejection sound in the same area, also radiating to the suprasternal notch. There was also a grade 1/6 blowing diastolic murmur of aortic insufficiency heard in the aortic area and along the left sternal border to the cardiac apex, where the ejection sound was also clearly heard. Palpation revealed a bifid or double rising carotid pulse. The left lung field was dull to percussion from apex to base, and breath sounds had a tracheal quality with some transmitted bowel sounds. The remainder of the physical examination was normal, without indications of cardiomegaly or cardiac hyperdynamics, or peripheral signs of endocarditis or septic emboli. Chest radiography confirmed the old left pneumonectomy.

The patient was treated intravenously with gentamycin and vancomycin in the hospital, and these same drugs were continued intravenously during a 4-week outpatient course. The patient's signs and symptoms resolved, and all follow-up blood cultures were negative.

Transthoracic and transesophageal echocardiography were performed during his inpatient stay. These were interpreted to be normal, including the impression of a normal trileaflet aortic valve. Subsequently, during the course of an outpatient visit, we performed high-resolution digital transthoracic echocardiography, paying special attention to the aortic valve. This revealed a trileaflet valve with partial fusion of the right and noncoronary cusps. The leaflets did not open completely. Mild aortic insufficiency was detected. The remainder of the study was entirely normal. The patient's private physicians began aspirin therapy (324 mg daily) and advised SBE prophylaxis.

Patient 3

In November 1998, a 47-year-old woman was seen for evaluation of a heart murmur that had been present since infancy. She had experienced the onset of mild rheumatoid arthritis at age 34, but had no cardiovascular history or previous symptoms suggestive of rheumatic fever. All vital signs were normal, including a regular pulse of 88 beats/minute and blood pressure of 96/60 mmHg. Physical examination revealed a grade 2/6 systolic ejection murmur in the aortic area radiating to the suprasternal notch, an aortic ejection sound in the same area also radiating to the suprasternal notch, and a bifid or double rising carotid pulse on palpation. There was a grade 2/6 blowing diastolic murmur of aortic insufficiency in the aortic area and along the left sternal border to the apex, where the ejection sound was also clearly heard. She had moderate pectus excavatum. The remainder of the physical examination was normal. She had no serious sequelae of rheumatoid arthritis, no cardiomegaly, and no cardiac hyperdynamics. She had never undergone echocardiography.

We performed a high-resolution digital transthoracic echocardiogram, paying special attention to the aortic valve. A typical bicuspid aortic valve was found. The cusps were mildly thickened, and there was mild aortic insufficiency. The remainder of the study was entirely normal. Her private physician advised SBE prophylaxis.

Discussion

Figure 1 shows in diagrammatic format the physical findings of the 3 patients described in this report. The findings in the carotid pulse were identical in all 3 patients, regardless of whether a diastolic murmur of aortic insufficiency was heard, or seen on echocardiography. Therefore, the double rising pulse may be a result of early checking of the valve in systole rather than run-off of blood into the left ventricle in diastole from valvular insufficiency, as is postulated in the reflected-tidal-wave concept of bifid or bisferiens pulse generation. ⁵ Figure 2 shows in diagrammatic format the structural appearance of both valves, as seen on echocardiography.

Fig. 1 Diagrammatic representation of the findings on physical examination of Patients 1, 2, and 3. The findings were virtually identical except that a faint blowing murmur of aortic insufficiency was not heard in Patient 1, nor was aortic insufficiency demonstrated on any of her 3 echocardiograms. In all 3 patients, the remaining physical findings were the same: brisk bifid or double rising carotid pulse; grade 1 to 2 out of 6 aortic ejection murmur in the aortic area, radiating to the neck; and an aortic ejection sound heard in the aortic area and at the apex, with good radiation to the neck.

gr 1–2 = grade 1 to 2; ej m = systolic ejection murmur; diast. blow = diastolic blowing murmur; (A) = apex auscultation area; (N) = neck auscultation area; (2) = 2nd right intercostal space; (3) = 3rd left intercostal space; es = aortic ejection sound; 1 = 1st heart sound; 2 = 2nd heart sound; EXP. = expiration; INSP. = inspiration

Fig. 2 Diagrammatic representations of the high-resolution digital transthoracic echocardiographic appearance of the aortic valves in both the open and closed state of Patients 1 and 2 (tricuspid aortic valves with partial commissural fusion) and of Patient 3 (bicuspid aortic valve) for comparison. These diagrams are composites of several individual frames in each state.

LC = left coronary cusp; NC = noncoronary cusp;

RC = right coronary cusp

In a series of 1,950 phonocardiograms performed primarily on elderly men, Nitta, Ihenacho, and Hultgren ⁶ detected distinct aortic ejection sounds in 170 patients. In a minority of these 170 patients, the usual explanations for aortic ejection sounds were found: aortic stenosis including bicuspid aortic valve on echocardiography (28%), hypertension (10%), and a history of rheumatic fever (4%). The remainder (58%) had no apparent explanation for their ejection sounds.

Subsequently, these same investigators conducted a separate series of consecutive autopsies on 120 elderly men and found a 39% incidence of trileaflet aortic valve with partial commissural fusion. ⁶ The autopsy and phonocardiography series were unconnected except insofar as the 120 autopsy examinations were undertaken in an attempt to find an explanation for the ejection sounds detected on phonocardiography.

Of the 120 autopsied patients, 9 happened to have undergone phonocardiography within 6 months of death: of these, 2 had a long fusion (extending more than 5 mm from the commissure) and an ejection sound; 2 had a short fusion (extending less than 5 mm) and no ejection sound; 1 had a congenital bicuspid aortic valve and an ejection sound; and the remaining 4 had no valvular lesion and no ejection sound. The authors implied that long fusions (18 cases or 15% of the total series) were likely to produce an ejection sound, while short fusions from the commissure (29 cases or 24% of the total series) were not likely to produce an ejection sound.

The authors concluded that this abnormality—partial aortic commissural fusion—may be congenital or acquired and that the congenital form may in fact represent a partially bicuspid aortic valve. They postulated that a moderate degree of aortic commissural fusion could account for many aortic ejection sounds in the absence of bicuspid aortic valve, aortic stenosis, hypertension, or a history of rheumatic heart disease. They did not visualize this abnormality on echocardiography nor have others reported seeing it on echocardiography, in our review of the medical literature to date. We have found a review of other pathology reports and autopsy series of partial fusion of 2 or 3 aortic cusps, which condition is postulated to progress to severe calcific or non-calcific aortic stenosis and which is thought to be congenital or to be acquired through rheumatic or other mechanisms. ⁷ We have not, however, found any published descriptions of this lesion in living patients.

Conclusions

We have visualized partial commissural fusion in a trileaflet aortic valve in 2 patients in a series of 27 patients who have findings on physical examination that suggest a bicuspid aortic valve. These 2 patients (and most of the remaining 25) had undergone standard transthoracic echocardiography, which was reported to show normal trileaflet aortic valves. Both patients had significant complications (bacterial endocarditis and cerebral embolism) that were very likely related to the valvular abnormality. We plan to complete the re-examination of the remaining 25 patients by high-resolution echocardiography and to report our findings. Two of the remaining 25 have experienced unexplained cerebrovascular accidents, and 1 has had bacterial endocarditis.

We believe that the finding of an unexplained aortic ejection sound together with an ejection aortic systolic murmur, both radiating to the neck and accompanied by a bifid or double rising aortic pulse with or without a blowing aortic insufficiency murmur, should alert the examiner to the possibility of aortic commissural fusion even in the presence of a transthoracic or transesophageal echocardiogram reported to show a “normal aortic valve.” The exam-iner should consider a very careful re-examination by high-resolution digital echocardiography, paying careful attention to the aortic valve.

In such patients, aspirin therapy and SBE prophylaxis should perhaps be entertained even in the absence of a demonstrated aortic valve abnormality on routine echocardiography, because it could eventuate that physical examination is more sensitive in the diagnosis of this condition than is the standard transthoracic echocardiogram done today.

We are writing this preliminary report to alert others to the presence of this condition, to its potential for serious and likely preventable sequelae, ^8,9 and to the possibility of demonstrating it by carefully done transthoracic high-resolution digital echocardiography, whenever its characteristic findings appear on physical examination.

Acknowledgment

The authors thank Drs. Kendall Billick and Michael Johnson for their help in preparing material on their patient, who was Patient 2.